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Bell 407 Troubleshooting Guide

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Bell 407 FADEC System Troubleshooting Guide
Page 1 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
AD12BitFlt
73-25-04-116
Hard
Parent
N/A
Fault Description
The ECU has detected a problem with an internal chip responsible for converting input sensor analog data to digital data
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Troubleshooting Prodedure
Replace ECU
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 2 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
AD8BitFlt
73-25-04-116
Hard
Parent
N/A
Fault Description
The ECU has detected a problem with an internal chip responsible for converting input voltage and current data to digital data
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Troubleshooting Prodedure
Replace ECU
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 3 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
AF28Flt
73-25-04-117
Soft
Parent
AF28Flt
Fault Description
The ECU has detected that its power input from the aircraft dc bus was not within limits for at least 30 seconds
Fault Test Conditions
Continuous
Possible Fault Causes
Low airframe battery, FADEC circuit breaker pulled
with engine running, high voltage from ground power
source
Troubleshooting Prodedure
See troubleshooting instructions for AF28RgFlt child fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 4 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
AF28RgFlt
73-25-04-117
Soft
Child
AF28Flt
Fault Description
The ECU has detected that its power input from the aircraft dc bus was not within limits for at least 30 seconds
Fault Test Conditions
Continuous
Possible Fault Causes
Low airframe battery, FADEC circuit breaker pulled
with engine running, high voltage from ground power
source
Fault Limits
Special Limit
Low
High
Open Circuit Reading
8.5 vdc
35 vdc
N/A
Troubleshooting Prodedure
Compare AF28Raw parameter against range limits at power up with both battery and ground power source. Also monitor during engine start for low voltage.
Bell 407 FADEC System Troubleshooting Guide
Page 5 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
AL28Flt
73-25-04-111
Soft
Parent
AL28Flt
Fault Description
The ECU has detected that its power input provided by the engine PMA is not with limits for at least 4 seconds or the amount of ac ripple voltage produced by the alternator is too high
Fault Test Conditions
Test enabled at N2 > 85%
Possible Fault Causes
Bad engine PMA or one phase of the alternator is open
or shorted
Fault Limits
Special Limit
Low
High
Open Circuit Reading
8.5 vdc
60 vdc
N/A
ac ripple > 3 vac
Troubleshooting Prodedure
Compare Al28Raw parameter against range limits when the engine is running at 85% Nr. Also check that the Altripraw ac ripple is less that 3 vac. If voltage is low but ripple is
normal, replace the PMA. If voltage is low but ripple is high, check for an open or short circuit between the engine PMA and ECU. Repair effected component as necessary.
Bell 407 FADEC System Troubleshooting Guide
Page 6 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
AMFlt
73-25-04-128
Manual
Parent
N/A
Fault Description
The ECU has detected a problem with either the HMU auto/manual solenoid circuitry or a problem with the FADEC auto/manual mode selection switch
Fault Test Conditions
Continuous
Possible Fault Causes
Bad FADEC auto/manual select switch or wiring to the
HMU auto/manual solenoid
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
See troubleshooting instructions for either the AMSolFlt or AMSwFlt child faults
Bell 407 FADEC System Troubleshooting Guide
Page 7 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
AMIFlt
73-25-04-103
Manual
Child
AMIFlt
Fault Description
The ECU has detected a problem with the current flow from the HMU auto/manual solenoid
Fault Test Conditions
Continuous
Possible Fault Causes
Open circuit between ECU and HMU auto/manual
solenoid
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Auto/manual solenoid current outside 0.25 amp and
1.5 amp range when valve is energized, auto/manual
solenoid current greater than 0.3 amp with manual
mode selected
Troubleshooting Prodedure
Power up aircraft with the mode select switch in manual mode. While in manual mode, AMIBitRaw should be less than 0.3 amp. Select auto mode, AMIBitRaw should be between
0.25 amp and 1.5 amp. In either case, check wiring resistance of HMU auto/manual solenoid circuit.
Bell 407 FADEC System Troubleshooting Guide
Page 8 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
AMSolFlt
73-25-04-103
Manual
Child
AMSolFlt
Fault Description
The ECU has detected a problem with either the HMU auto/manual solenoid circuitry or a problem with the FADEC auto/manual mode selection switch
Fault Test Conditions
Continuous
Possible Fault Causes
High side short to ground from the ECU to the HMU
stepper motor or auto/manual solenoid, any phase return
from the HMU stepper motor to the ECU shorted to
ground, or the HMU auto/manual solenoid return wire
from the HMU to the ECU shorted to ground
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Auto/manual solenoid current outside 0.25 amp and
1.5 amp range when valve is energized, auto/manual
solenoid current greater than 0.3 amp with manual
mode selected, ECU auto/manual solenoid driver
circuit senses that a ground exists on the solenoid
return with manual selected, ECU auto/manual
solenoid driver circuit senses that an open circuit exists
on the solenoid return with auto selected
Troubleshooting Prodedure
If this fault occurs in the presence of a AMSwFlt, troubleshoot AMSwFlt fault first. Power up aircraft with the mode select switch in manual mode. While in manual mode, the
parameters should be: ManSel = TRUE, AutoSel = FALSE, AMVbit = FALSE, AMIBit = FALSE, SWMONVbit = FALSE. If AMIbit = TRUE, Replace ECU. If AMVbit = TRUE,
check for short on auto/manual solenoid return wiring from the HMU to the ECU. If no fault is present, select auto mode. If fault occurs, check for shorted circuits between the ECU
and HMU stepper motor and auto/manual solenoid.
Bell 407 FADEC System Troubleshooting Guide
Page 9 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
AMSwFlt
73-25-04-119
Manual
Child
AMSwFlt
Fault Description
The ECU has detected a problem with the FADEC auto/manual mode selection switch
Fault Test Conditions
Continuous
Possible Fault Causes
Bad FADEC mode select switch or wiring from the
switch to the ECU
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Fault is declared if the ECU detects that neither mode
is selected or if both modes are selected simultaneously
Troubleshooting Prodedure
Power up aircraft with the mode select switch in manual mode. While in manual mode, ManSel should be TRUE and AutoSel should be FALSE. Select Auto Mode. AutoSel should
be TRUE and ManSel should be FALSE. A grounded input makes the input TRUE. An open input makes the input FALSE. The AutoSel and ManSel inputs should not both be
TRUE or FALSE simultaneously. Troubleshoot switch and wiring as applicable.
Bell 407 FADEC System Troubleshooting Guide
Page 10 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
ARINCFltAn
73-25-04-127
Soft
N/A
N/A
Fault Description
This fault code not used in this application
Fault Test Conditions
Possible Fault Causes
ECU write to EEPROM or RAM interrupted during
engine shutdown causing erroneous recording of an
unused fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
If fault is historical, clear all faults with the MT35 program. Cycle power and verify that fault is cleared.
Bell 407 FADEC System Troubleshooting Guide
Page 11 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
ARINCHWFlt
73-25-04-116
Soft
N/A
N/A
Fault Description
This fault code not used in this application
Fault Test Conditions
Possible Fault Causes
ECU write to EEPROM or RAM interrupted during
engine shutdown causing erroneous recording of an
unused fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
If fault is historical, clear all faults with the MT35 program. Cycle power and verify that fault is cleared.
Bell 407 FADEC System Troubleshooting Guide
Page 12 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
BacCompFlt
73-25-04-116
Soft
Parent
N/A
Fault Description
The ECU has detected that it has not completed its background tasks within the allotted time period
Fault Test Conditions
Power up or during background tasks
Possible Fault Causes
Internal ECU Failure. Very unlikely to occur.
Troubleshooting Prodedure
Replace ECU
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 13 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
CJCFlt
73-25-04-116
Soft
Parent
CJCFlt
Fault Description
The ECU has detected a problem with its internal cold junction used to process its MGT input signal
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure.
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
See troubleshooting instructions for either a CJCRgFlt or CJCRtFlt child fault
Bell 407 FADEC System Troubleshooting Guide
Page 14 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
CJCRgFlt
73-25-04-116
Soft
Child
CJCFlt
Fault Description
The ECU has detected a problem with its internal cold junction used to process its MGT input signal
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure.
Fault Limits
Special Limit
Low
High
Open Circuit Reading
-80°F
250°F
N/A
Troubleshooting Prodedure
Record CJCRaw signal. Replace ECU and include value of CJCRaw signal upon ECU return.
Bell 407 FADEC System Troubleshooting Guide
Page 15 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
CJCRtFlt
73-25-04-116
Soft
Child
CJCFlt
Fault Description
The ECU has detected a problem with its internal cold junction used to process its MGT input signal
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure.
Fault Limits
Special Limit
Low
High
Open Circuit Reading
-80°F
250°F
N/A
Troubleshooting Prodedure
Record CJCRaw signal. Replace ECU and include value of CJCRaw signal upon ECU return.
Bell 407 FADEC System Troubleshooting Guide
Page 16 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
CPAntFlt
73-25-04-113
Soft
Parent
CPFlt
Fault Description
The ECU has detected a problem with its collective pitch input used to maintain rotor rpm during aggressive flight maneuvers
Fault Test Conditions
Continuous
Possible Fault Causes
Airframe collective pitch potentiometer mis rigged or
failed intermittently
Troubleshooting Prodedure
See troubleshooting instructions for CPRgFlt child fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 17 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
CPDFlt
73-25-04-127
Soft
N/A
N/A
Fault Description
This fault code not used in this application
Fault Test Conditions
Possible Fault Causes
ECU write to EEPROM or RAM interrupted during
engine shutdown causing erroneous recording of an
unused fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
If fault is historical, clear all faults with the MT35 program. Cycle power and verify that fault is cleared.
Bell 407 FADEC System Troubleshooting Guide
Page 18 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
CPFlt
73-25-04-113
Soft
Parent
CPFlt
Fault Description
The ECU has detected a problem with its collective pitch input used to maintain rotor rpm during aggressive flight maneuvers
Fault Test Conditions
Continuous
Possible Fault Causes
Airframe collective pitch potentiometer mis rigged or
failed intermittently
Troubleshooting Prodedure
See troubleshooting instructions for CPRgFlt child fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 19 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
CPRgFlt
73-25-04-113
Soft
Child
CPFlt
Fault Description
The ECU has detected a problem with its collective pitch input used to maintain rotor rpm during aggressive flight maneuvers
Fault Test Conditions
Continuous
Possible Fault Causes
Airframe collective pitch potentiometer mis rigged or
failed intermittently
Fault Limits
Low
High
Open Circuit Reading
-14.3%
110%
CpRaw < -20%
Special Limit
Troubleshooting Prodedure
Monitor CPRaw with collective full down and full up. If it fails out of range, rerig or replace collective potentiometer as required. If rigging is OK, perform some aircraft collective
sweeps while on the ground at 100% Nr. Look at recorded graph of CPRaw for the signs of downward or upward spikes in the signal. If spikes are noticed, replace the collective
potentiometer.
Bell 407 FADEC System Troubleshooting Guide
Page 20 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
ECUOTFlt
73-25-04-116
Hard
Parent
ECUOTFlt
Fault Description
The ECU has detected that its internal temperature, as measured by its cold junction, is extremely high
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure.
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
230°F
N/A
Troubleshooting Prodedure
Record CJCRaw signal. Replace ECU and include value of CJCRaw signal upon ECU return.
Bell 407 FADEC System Troubleshooting Guide
Page 21 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
EECalFlt
73-25-04-116
Soft
Child
EECalFlt
Fault Description
The ECU has detected that the calibration constants used for its internal P1 pressure transducer and its Q input have changed from initial factory settings
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure.
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Record KinP1Gn, KinP1Cal, KinQGn and KinQCal values. Replace ECU and include values upon ECU return
Bell 407 FADEC System Troubleshooting Guide
Page 22 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
EEHistFlt
73-25-04-116
Soft
Child
N/A
Fault Description
The ECU has detected that the engine history data in its memory may be corrupted
Fault Test Conditions
Continuous
Possible Fault Causes
ECU write to historical EEPROM interrupted during
engine shutdown causing erroneous history data to be
written in memory
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Record engine history data on piece of paper. Clear all of the engine history. Cycle ECU power. Check for fault reoccurance. If fault is gone, edit original engine history back into
the ECU. Cycle ECU power and check for fault reoccurance. Replace ECU if fault does not clear after this procedure.
Bell 407 FADEC System Troubleshooting Guide
Page 23 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
EEPROMFlt
73-25-04-116
Soft
Parent
N/A
Fault Description
The ECU has detected a problem with internal calibration or engine historical data
Fault Test Conditions
Continuous
Possible Fault Causes
ECU write to historical EEPROM interrupted during
engine shutdown causing erroneous history data to be
written in memory
Troubleshooting Prodedure
See troubleshooting for EECalFlt or EEHistFlt as appropriate
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 24 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
ForCompFlt
73-25-04-116
Soft
Parent
N/A
Fault Description
The ECU has detected that it has not completed its forground tasks within the allotted time period
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure. Very unlikely to occur.
Troubleshooting Prodedure
Replace ECU
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 25 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
FTempFlt
73-25-04-127
Soft
N/A
N/A
Fault Description
This fault code not used in this application
Fault Test Conditions
Possible Fault Causes
ECU write to EEPROM or RAM interrupted during
engine shutdown causing erroneous recording of an
unused fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
If fault is historical, clear all faults with the MT35 program. Cycle power and verify that fault is cleared.
Bell 407 FADEC System Troubleshooting Guide
Page 26 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
GainFlt
73-25-04-116
Hard
Parent
GainFlt
Fault Description
The ECU has detected a problem with a voltage reference used to process some of its input signals
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Troubleshooting Prodedure
See troubleshooting instructions for GainRgFlt child fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 27 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
GainRgFlt
73-25-04-116
Hard
Child
GainFlt
Fault Description
The ECU has detected a problem with a voltage reference used to process some of its input signals
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
2738 cnts
3019 cnts
N/A
Troubleshooting Prodedure
Record GainVin signal. Replace ECU and include value of GainVin signal upon ECU return.
Bell 407 FADEC System Troubleshooting Guide
Page 28 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
HardFlt
73-25-04-128
Hard
Parent
N/A
Fault Description
The ECU has detected that a hard fault has occurred. This is the parent fault for all hard faults.
Fault Test Conditions
Continuous
Possible Fault Causes
Determined by any sub-tier hard fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
This fault will only appear when using the MT35 program. Troubleshoot sub-tier child hard faults to correct the problem. This fault is the parent of all hard faults.
Bell 407 FADEC System Troubleshooting Guide
Page 29 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
HLRfFlt
73-25-04-116
Hard
Parent
HLRfFlt
Fault Description
The ECU has detected a problem with a voltage reference used to process some of its input signals
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Troubleshooting Prodedure
See troubleshooting instructions for HLRfRgFlt child fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 30 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
HLRfRgFlt
73-25-04-116
Hard
Child
HLRfFlt
Fault Description
The ECU has detected a problem with a voltage reference used to process some of its input signals
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
3890 cnts
4077 cnts
N/A
Troubleshooting Prodedure
Record HLRfRaw signal. Replace ECU and include value of HLRfRaw signal upon ECU return.
Bell 407 FADEC System Troubleshooting Guide
Page 31 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
IgnFlt
73-25-04-116
Soft
Parent
IgnFlt
Fault Description
The ECU has detected a problem with its control of the airframe igniter relay during an auto mode start attempt
Fault Test Conditions
N1 between 50 and 60% during start or during auto-relight.
Possible Fault Causes
Open circuit between airframe igniter relay return and
ECU or an ECU failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
ECU detects an open circuit on the return wire from
the igniter relay
Troubleshooting Prodedure
Monitor IgnVBit after power up. Parameter should be FALSE. If TRUE, check for short on relay return wire to ECU. Perform auto mode engine start. At 50% N1, IgnVBit should
become TRUE. If still FALSE, check for short to ground on relay return wire from airframe igniter relay.
Bell 407 FADEC System Troubleshooting Guide
Page 32 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
IgnIFlt
73-25-04-120
Soft
Parent
IgnIFlt
Fault Description
The ECU has detected a problem with its control of the airframe igniter relay prior to or during an auto mode start attempt
Fault Test Conditions
N1 between 50 and 60% during start or during auto-relight.
Possible Fault Causes
Faulty 1K3 FADEC Start Relay
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Airframe igniter relay current outside 0.015 amp and
0.4 amp range when relay is energized, relay current
greater than 0.12 amp when relay should be off
Troubleshooting Prodedure
Monitor IgnIBitLag after power up. Current should be within limits when off. If not, replace ECU. If OK, select manual mode. Pull N1 indicator circuit breaker. Igniters should
fire immediately. If not, troubleshoot wiring. If OK, swap FADEC Start Relay (1K3) with light dimming relay which is the same part number as the 1K3 relay. Perform auto mode
engine start. Recheck for fault. If OK, problem is fixed. If not, depower aircraft. Remove airframe electrical connector at ECU. Select auto mode. With a jumper wire, ground Pin-7
to ECU ground strap. Apply power to aircraft. Igniters should fire immediately. If not, troubleshooting wiring as required. If OK, replace igniter relay.
Bell 407 FADEC System Troubleshooting Guide
Page 33 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
LoadSelFlt
73-25-04-127
Soft
N/A
N/A
Fault Description
This fault code not used in this application and applies only to twin engine applications
Fault Test Conditions
Possible Fault Causes
ECU write to EEPROM or RAM interrupted during
engine shutdown causing erroneous recording of an
unused fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
If fault is historical, clear all faults with the MT35 program. Cycle power and verify that fault is cleared.
Bell 407 FADEC System Troubleshooting Guide
Page 34 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
LoadSHdFlt
73-25-04-127
Soft
N/A
N/A
Fault Description
This fault code not used in this application and applies only to twin engine applications
Fault Test Conditions
Possible Fault Causes
ECU write to EEPROM or RAM interrupted during
engine shutdown causing erroneous recording of an
unused fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
If fault is historical, clear all faults with the MT35 program. Cycle power and verify that fault is cleared.
Bell 407 FADEC System Troubleshooting Guide
Page 35 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
MGTFlt
73-25-04-110
Soft
Parent
MGTFlt
Fault Description
The ECU has detected a problem with its MGT input signal
Fault Test Conditions
Continuous
Possible Fault Causes
Loose or corroded connection at the MGT thermocouple
junction on the engine
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
See troubleshooting instructions for either a MGTRgFlt or MGTRtFlt child fault
Bell 407 FADEC System Troubleshooting Guide
Page 36 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
MGTRgFlt
73-25-04-110
Soft
Child
MGTFlt
Fault Description
The ECU has detected a problem with its MGT input signal which has gone out of range
Fault Test Conditions
Continuous
Possible Fault Causes
Loose or corroded connection at the MGT thermocouple
junction on the engine
Fault Limits
Low
High
Open Circuit Reading
-77°F
2400°F
MGTRaw > 2400 °F
Troubleshooting Prodedure
Monitor MGTRaw. If out of range high or low, check for open circuit between ECU and MGT thermocouple connection.
Special Limit
Bell 407 FADEC System Troubleshooting Guide
Page 37 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
MGTRtFlt
73-25-04-110
Soft
Child
MGTFlt
Fault Description
The ECU has detected an intermittant problem with its MGT input signal
Fault Test Conditions
Continuous
Possible Fault Causes
Loose or corroded connection at the MGT thermocouple
junction on the engine
Fault Limits
Low
High
Open Circuit Reading
-77°F
2400°F
MGTRaw > 2400 °F
Troubleshooting Prodedure
Monitor MGTRaw. If out of range high or low, check for open circuit between ECU and MGT thermocouple connection.
Special Limit
Bell 407 FADEC System Troubleshooting Guide
Page 38 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Ng12Flt
73-25-04-109
Hard
Parent
NgFlts
Fault Description
The ECU has detected a problem with both the Ng1 and Ng2 speed input signals or difference exists between both Ng inputs
Fault Test Conditions
Np > 45% OR either Ng1 or Ng2 is between 10 and 130%
Possible Fault Causes
Loose or corroded connection at the N1 speed sensor on
the engine
Troubleshooting Prodedure
See troubleshooting instructions for Ng related child faults
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Ng1 and Ng2 differ by more than 5%
Bell 407 FADEC System Troubleshooting Guide
Page 39 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Ng1CyFlt
73-25-04-109
Soft
Child
NgFlts
Fault Description
The ECU has detected a continuity problem with its Ng1 speed input signal
Fault Test Conditions
Continuous
Possible Fault Causes
Loose or corroded connection at the Ng1 speed sensor or
a bad engine harness
Fault Limits
Low
High
Open Circuit Reading
8%
130%
Ng1CyBit = OPEN
Special Limit
Ng fault detection includes continuous continuity
(trickle curret) testing
Troubleshooting Prodedure
Monitor Ng1CyBit upon power up. If OPEN, check for open circuit between ECU and Ng1 output of speed sensor. If OK, flex harness connections to attempt to duplicate the
problem. Repair/replace effected component as required.
Bell 407 FADEC System Troubleshooting Guide
Page 40 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Ng1Flt
73-25-04-109
Soft
Parent
NgFlts
Fault Description
The ECU has detected a problem with its Ng1 speed input signal
Fault Test Conditions
Np > 45% OR either Ng1 or Ng2 is between 10 and 130%
Possible Fault Causes
Loose or corroded connection at the Ng1 speed sensor or
a bad engine harness
Troubleshooting Prodedure
See troubleshooting instructions for Ng1 related child faults
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 41 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Ng1RgFlt
73-25-04-109
Soft
Child
NgFlts
Fault Description
The ECU has detected an open, shorted or intermittent problem with its Ng1 speed input signal
Fault Test Conditions
Np > 45% OR either Ng1 or Ng2 is between 10 and 130%
Possible Fault Causes
Loose or corroded connection at the Ng1 speed sensor or
a bad engine harness
Fault Limits
Low
High
Open Circuit Reading
8%
130%
Ng1CyBit = OPEN
Special Limit
Ng fault detection includes continuous continuity
(trickle curret) testing
Troubleshooting Prodedure
Monitor Ng1raw with the engine operating at 100% Nr. Take a sample trend of the user defined screen and analyze traces for signs of Ng1 signal fallout under various engine
operating conditions. Replace Ng sensor, wiring, etc. if fallout is noted.
Bell 407 FADEC System Troubleshooting Guide
Page 42 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Ng1RtFlt
73-25-04-109
Soft
Child
NgFlts
Fault Description
The ECU has detected an intermittent problem with its Ng1 speed input signal
Fault Test Conditions
Np > 45% OR either Ng1 or Ng2 is between 10 and 130%
Possible Fault Causes
Loose or corroded connection at the Ng1 speed sensor or
a bad engine harness
Fault Limits
Low
High
Open Circuit Reading
8%
130%
Ng1CyBit = OPEN
Special Limit
Ng fault detection includes continuous continuity
(trickle curret) testing
Troubleshooting Prodedure
Monitor Ng1raw with the engine operating at 100% Nr. Take a sample trend of the user defined screen and analyze traces for signs of Ng1 signal fallout under various engine
operating conditions. Replace Ng sensor, wiring, etc. if fallout is noted.
Bell 407 FADEC System Troubleshooting Guide
Page 43 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Ng2CyFlt
73-25-04-109
Soft
Child
NgFlts
Fault Description
The ECU has detected a continuity problem with its Ng2 speed input signal
Fault Test Conditions
Continuous
Possible Fault Causes
Loose or corroded connection at the Ng2 speed sensor or
a bad engine harness
Fault Limits
Low
High
Open Circuit Reading
8%
130%
Ng1CyBit = OPEN
Special Limit
Ng fault detection includes continuous continuity
(trickle curret) testing
Troubleshooting Prodedure
Monitor Ng2CyBit upon power up. If OPEN, check for open circuit between ECU and Ng2 output of speed sensor. If OK, flex harness connections to attempt to duplicate the
problem. Repair/replace effected component as required.
Bell 407 FADEC System Troubleshooting Guide
Page 44 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Ng2Flt
73-25-04-109
Soft
Parent
NgFlts
Fault Description
The ECU has detected a problem with its Ng2 speed input signal
Fault Test Conditions
Np > 45% OR either Ng1 or Ng2 is between 10 and 130%
Possible Fault Causes
Loose or corroded connection at the Ng2 speed sensor or
a bad engine harness
Troubleshooting Prodedure
See troubleshooting instructions for Ng2 related child faults
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 45 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Ng2RgFlt
73-25-04-109
Soft
Child
NgFlts
Fault Description
The ECU has detected an open, shorted or intermittent problem with its Ng2 speed input signal
Fault Test Conditions
Np > 45% OR either Ng1 or Ng2 is between 10 and 130%
Possible Fault Causes
Loose or corroded connection at the Ng2 speed sensor or
a bad engine harness
Fault Limits
Low
High
Open Circuit Reading
8%
130%
Ng2CyBit = OPEN
Special Limit
Ng fault detection includes continuous continuity
(trickle curret) testing
Troubleshooting Prodedure
Monitor Ng2raw with the engine operating at 100% Nr. Take a sample trend of the user defined screen and analyze traces for signs of Ng2 signal fallout under various engine
operating conditions. Replace Ng sensor, wiring, etc. if fallout is noted.
Bell 407 FADEC System Troubleshooting Guide
Page 46 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Ng2RtFlt
73-25-04-109
Soft
Child
NgFlts
Fault Description
The ECU has detected an intermittent problem with its Ng2 speed input signal
Fault Test Conditions
Np > 45% OR either Ng1 or Ng2 is between 10 and 130%
Possible Fault Causes
Loose or corroded connection at the Ng2 speed sensor or
a bad engine harness
Fault Limits
Low
High
Open Circuit Reading
8%
130%
Ng2CyBit = OPEN
Special Limit
Ng fault detection includes continuous continuity
(trickle curret) testing
Troubleshooting Prodedure
Monitor Ng2raw with the engine operating at 100% Nr. Take a sample trend of the user defined screen and analyze traces for signs of Ng2 signal fallout under various engine
operating conditions. Replace Ng sensor, wiring, etc. if fallout is noted.
Bell 407 FADEC System Troubleshooting Guide
Page 47 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
NgDFlt
73-25-04-109
Hard
Child
NgFlts
Fault Description
The ECU has detected that its Ng1 and Ng2 inputs do not agree within 5%
Fault Test Conditions
Ng1 or Ng2 > 13%
Possible Fault Causes
Loose or corroded connection at the Ng1 or Ng2 speed
sensor output or a bad engine harness
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Ng1 and Ng2 differ by more than 5%
Troubleshooting Prodedure
Monitor Ng1Raw and Ng2raw with the engine operating at 100% Nr. Take a sample trend of the user defined screen and analyze both Ng traces for signs of signal fallout under
various engine operating conditions. Replace Ng sensor, wiring, etc. if fallout is noted.
Bell 407 FADEC System Troubleshooting Guide
Page 48 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
NgOFlt
73-25-04-127
Soft
N/A
N/A
Fault Description
This fault code not used in this application and applies only to twin engine applications
Fault Test Conditions
Possible Fault Causes
ECU write to EEPROM or RAM interrupted during
engine shutdown causing erroneous recording of an
unused fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
If fault is historical, clear all faults with the MT35 program. Cycle power and verify that fault is cleared.
Bell 407 FADEC System Troubleshooting Guide
Page 49 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
NgORgFlt
73-25-04-127
Soft
N/A
N/A
Fault Description
This fault code not used in this application and applies only to twin engine applications
Fault Test Conditions
Possible Fault Causes
ECU write to EEPROM or RAM interrupted during
engine shutdown causing erroneous recording of an
unused fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
If fault is historical, clear all faults with the MT35 program. Cycle power and verify that fault is cleared.
Bell 407 FADEC System Troubleshooting Guide
Page 50 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
NgORtFlt
73-25-04-127
Soft
N/A
N/A
Fault Description
This fault code not used in this application and applies only to twin engine applications
Fault Test Conditions
Possible Fault Causes
ECU write to EEPROM or RAM interrupted during
engine shutdown causing erroneous recording of an
unused fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
If fault is historical, clear all faults with the MT35 program. Cycle power and verify that fault is cleared.
Bell 407 FADEC System Troubleshooting Guide
Page 51 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Np12Flt
73-25-04-108
Hard
Parent
NpFlts
Fault Description
The ECU has detected a problem with both the Np1 and Np2 speed input signals
Fault Test Conditions
Ng > 71% OR either Np1 or Np2 is between 45 and 160%
Possible Fault Causes
Loose or corroded connection at the N2 speed sensor on
the engine
Troubleshooting Prodedure
See troubleshooting instructions for Np related child faults
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 52 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Np1CyFlt
73-25-04-108
Soft
Child
NpFlts
Fault Description
The ECU has detected a continuity problem with its Np1 speed input signal
Fault Test Conditions
Continuous
Possible Fault Causes
Loose or corroded connection at the Np1 speed sensor or
a bad engine harness
Fault Limits
Low
High
Open Circuit Reading
20%
160%
Np1CyBit = OPEN
Special Limit
Np fault detection includes continuous continuity
(trickle curret) testing
Troubleshooting Prodedure
Monitor Np1CyBit upon power up. If OPEN, check for open circuit between ECU and Np1 output of speed sensor. If OK, flex harness connections to attempt to duplicate the
problem. Repair/replace effected component as required.
Bell 407 FADEC System Troubleshooting Guide
Page 53 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Np1Flt
73-25-04-108
Soft
Parent
NpFlts
Fault Description
The ECU has detected a problem with its Np1 speed input signal
Fault Test Conditions
Ng > 71% OR either Np1 or Np2 is between 45 and 160%
Possible Fault Causes
Loose or corroded connection at the Np1 speed sensor or
a bad engine harness
Troubleshooting Prodedure
See troubleshooting instructions for Np1 related child faults
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 54 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Np1RgFlt
73-25-04-108
Soft
Child
NpFlts
Fault Description
The ECU has detected an open, shorted or intermittent problem with its Np1 speed input signal
Fault Test Conditions
Ng > 71% OR either Np1 or Np2 is between 45 and 160%
Possible Fault Causes
Loose or corroded connection at the Np1 speed sensor or
a bad engine harness
Fault Limits
Low
High
Open Circuit Reading
20%
160%
Np1CyBit = OPEN
Special Limit
Np fault detection includes continuous continuity
(trickle curret) testing
Troubleshooting Prodedure
Monitor Np1raw with the engine operating at 100% Nr. Take a sample trend of the user defined screen and analyze traces for signs of Np1 signal fallout under various engine
operating conditions. Replace Np sensor, wiring, etc. if fallout is noted.
Bell 407 FADEC System Troubleshooting Guide
Page 55 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Np1RtFlt
73-25-04-108
Soft
Child
NpFlts
Fault Description
The ECU has detected an intermittent problem with its Np1 speed input signal
Fault Test Conditions
Ng > 71% OR either Np1 or Np2 is between 45 and 160%
Possible Fault Causes
Loose or corroded connection at the Np1 speed sensor or
a bad engine harness
Fault Limits
Low
High
Open Circuit Reading
20%
160%
Np1CyBit = OPEN
Special Limit
Np fault detection includes continuous continuity
(trickle curret) testing
Troubleshooting Prodedure
Monitor Np1raw with the engine operating at 100% Nr. Take a sample trend of the user defined screen and analyze traces for signs of Np1 signal fallout under various engine
operating conditions. Replace Np sensor, wiring, etc. if fallout is noted.
Bell 407 FADEC System Troubleshooting Guide
Page 56 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Np2CyFlt
73-25-04-108
Soft
Child
NpFlts
Fault Description
The ECU has detected a continuity problem with its Np2 speed input signal
Fault Test Conditions
Continuous
Possible Fault Causes
Loose or corroded connection at the Np2 speed sensor or
a bad engine harness
Fault Limits
Low
High
Open Circuit Reading
20%
160%
Np1CyBit = OPEN
Special Limit
Np fault detection includes continuous continuity
(trickle curret) testing
Troubleshooting Prodedure
Monitor Np2CyBit upon power up. If OPEN, check for open circuit between ECU and Np2 output of speed sensor. If OK, flex harness connections to attempt to duplicate the
problem. Repair/replace effected component as required.
Bell 407 FADEC System Troubleshooting Guide
Page 57 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Np2Flt
73-25-04-108
Soft
Parent
NpFlts
Fault Description
The ECU has detected a problem with its Np2 speed input signal
Fault Test Conditions
Ng > 71% OR either Np1 or Np2 is between 45 and 160%
Possible Fault Causes
Loose or corroded connection at the Np2 speed sensor or
a bad engine harness
Troubleshooting Prodedure
See troubleshooting instructions for Np2 related child faults
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 58 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Np2RgFlt
73-25-04-108
Soft
Child
NpFlts
Fault Description
The ECU has detected an open, shorted or intermittent problem with its Np2 speed input signal
Fault Test Conditions
Ng > 71% OR either Np1 or Np2 is between 45 and 160%
Possible Fault Causes
Loose or corroded connection at the Np2 speed sensor or
a bad engine harness
Fault Limits
Low
High
Open Circuit Reading
20%
160%
Np2CyBit = OPEN
Special Limit
Np fault detection includes continuous continuity
(trickle curret) testing
Troubleshooting Prodedure
Monitor Np2raw with the engine operating at 100% Nr. Take a sample trend of the user defined screen and analyze traces for signs of Np2 signal fallout under various engine
operating conditions. Replace Np sensor, wiring, etc. if fallout is noted.
Bell 407 FADEC System Troubleshooting Guide
Page 59 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Np2RtFlt
73-25-04-108
Soft
Child
NpFlts
Fault Description
The ECU has detected an intermittent problem with its Np2 speed input signal
Fault Test Conditions
Ng > 71% OR either Np1 or Np2 is between 45 and 160%
Possible Fault Causes
Loose or corroded connection at the Np2 speed sensor or
a bad engine harness
Fault Limits
Low
High
Open Circuit Reading
20%
160%
Np2CyBit = OPEN
Special Limit
Np fault detection includes continuous continuity
(trickle curret) testing
Troubleshooting Prodedure
Monitor Np2raw with the engine operating at 100% Nr. Take a sample trend of the user defined screen and analyze traces for signs of Np2 signal fallout under various engine
operating conditions. Replace Np sensor, wiring, etc. if fallout is noted.
Bell 407 FADEC System Troubleshooting Guide
Page 60 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
NpDFlt
73-25-04-108
Soft
Parent
NpFlts
Fault Description
The ECU has detected that its Np1 and Np2 inputs do not agree within 5%
Fault Test Conditions
Ng > 71% OR either Np1 or Np2 is between 45 and 160%
Possible Fault Causes
Loose or corroded connection at the Np1 or Np2 speed
sensor output or a bad engine harness
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Np1 and Np2 differ by more than 5%
Troubleshooting Prodedure
Monitor Np1Raw and Np2raw with the engine operating at 100% Nr. Take a sample trend of the user defined screen and analyze both Np2 traces for signs of signal fallout under
various engine operating conditions. Replace Np sensor, wiring, etc. if fallout is noted.
Bell 407 FADEC System Troubleshooting Guide
Page 61 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
NpOSFlt
73-25-04-124
Soft
Parent
NpOSFlt
Fault Description
The ECU has detected that the Np speed frequency to voltage circuits within its overspeed circuitry are at Np levels which do not agree with actual Np speed from the speed pickups
Fault Test Conditions
Test active at Np > 55% or during overspeed system shutdown test
Possible Fault Causes
ECU internal failure. May be caused by an Np1Flt or
Np2Flt so correcting the Np faults will fix the NpOSFlt
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Np speed from frequency to voltage conversion within
ECU does not agree with actual Np within 2.5%
Troubleshooting Prodedure
If fault code is present with either an Np1Flt, Np2Flt or NpDFlt, follow troubleshooting for these faults first. If not, monitor signals with engine running at Nr = 100%. Before
replacing the ECU, take a sample data trend and return the trend data with the ECU.
Bell 407 FADEC System Troubleshooting Guide
Page 62 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
NpQExLmAdv
73-25-04-129
Soft
Parent
N/A
Fault Description
The ECU has detected an Np maximum limit exceedance > 113.3% for 1 second
Fault Test Conditions
Continuous when in run mode
Possible Fault Causes
Overspeed while controlling engine in manual mode,
selection of manual mode on the ground with throttle in
flight position
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Record NpQNppkExLm and NpQQpkExLm from ECU engine history. Perform engine maintenance as required.
Bell 407 FADEC System Troubleshooting Guide
Page 63 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
NpQRnLmAdv
73-25-04-129
Soft
Parent
N/A
Fault Description
The ECU has detected an Np maximum run limit exceedance > 102.1% for 15s
Fault Test Conditions
Continuous when in run mode
Possible Fault Causes
Overspeed while controlling engine in manual mode,
selection of manual mode on the ground with throttle in
flight position
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Record NpQNppkRnLm and NpQQpkRnLm from ECU engine history. Perform engine maintenance as required.
Bell 407 FADEC System Troubleshooting Guide
Page 64 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
NrAntDsb
73-25-04-114
Soft
N/A
N/A
Fault Description
This fault code not used in this application and applies only to twin engine applications
Fault Test Conditions
Possible Fault Causes
ECU write to EEPROM or RAM interrupted during
engine shutdown causing erroneous recording of an
unused fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
If fault is historical, clear all faults with the MT35 program. Cycle power and verify that fault is cleared.
Bell 407 FADEC System Troubleshooting Guide
Page 65 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
NrCyFlt
73-25-04-114
Soft
Child
NrFlt
Fault Description
The ECU has detected a continuity problem with its Nr speed input signal
Fault Test Conditions
Continuous
Possible Fault Causes
Loose or corroded connection at the Nr speed sensor or
a bad airframe harness
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Nr fault detection includes continuous continuity
(trickle curret) testing
Troubleshooting Prodedure
Monitor NrCyBit upon power up. If OPEN, check for open circuit between ECU and Nr output of speed sensor. If OK, flex harness connections to attempt to duplicate the problem.
Repair/replace effected component as required.
Bell 407 FADEC System Troubleshooting Guide
Page 66 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
NrDFlt
73-25-04-127
Soft
N/A
N/A
Fault Description
This fault code not used in this application and applies only to twin engine applications
Fault Test Conditions
Possible Fault Causes
ECU write to EEPROM or RAM interrupted during
engine shutdown causing erroneous recording of an
unused fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
If fault is historical, clear all faults with the MT35 program. Cycle power and verify that fault is cleared.
Bell 407 FADEC System Troubleshooting Guide
Page 67 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
NrFlt
73-25-04-114
Soft
Parent
NrFlt
Fault Description
The ECU has detected a problem with its Nr speed input signal
Fault Test Conditions
Ng > 71% OR either Np1 or Np2 is between 45 and 160% and engine
not in test cell
Possible Fault Causes
Loose or corroded connection at the Nr speed sensor or
a bad airframe harness
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
See troubleshooting instructions for NrCyFlt or NrRgFlt child faults
Bell 407 FADEC System Troubleshooting Guide
Page 68 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
NrRgFlt
73-25-04-114
Soft
Child
NrFlt
Fault Description
The ECU has detected an open, shorted or intermittent problem with its Nr speed input signal
Fault Test Conditions
Ng > 71% OR either Np1 or Np2 is between 45 and 160% and engine
not in test cell
Possible Fault Causes
Loose or corroded connection at the Nr speed sensor or
a bad airframe harness
Fault Limits
Low
High
Open Circuit Reading
40%
150%
NrCyBit = OPEN
Special Limit
Nr fault detection includes continuous continuity
(trickle curret) testing
Troubleshooting Prodedure
Monitor Nrraw with the engine operating at 100% Nr. Take a sample trend of the user defined screen and analyze traces for signs of Nr signal fallout under various engine operating
conditions. Replace Nr sensor, wiring, etc. if fallout is noted.
Bell 407 FADEC System Troubleshooting Guide
Page 69 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
NrRtFlt
73-25-04-114
Soft
Child
NrFlt
Fault Description
The ECU has detected an intermittent problem with its Nr speed input signal
Fault Test Conditions
Ng > 71% OR either Np1 or Np2 is between 45 and 160% and engine
not in test cell
Possible Fault Causes
Loose or corroded connection at the Nr speed sensor or
a bad airframe harness
Fault Limits
Low
High
Open Circuit Reading
40%
150%
NrCyBit = OPEN
Special Limit
Nr fault detection includes continuous continuity
(trickle curret) testing
Troubleshooting Prodedure
Monitor Nrraw with the engine operating at 100% Nr. Take a sample trend of the user defined screen and analyze traces for signs of Nr signal fallout under various engine operating
conditions. Replace Nr sensor, wiring, etc. if fallout is noted.
Bell 407 FADEC System Troubleshooting Guide
Page 70 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
OffsFlt
73-25-04-116
Hard
Parent
OffsFlt
Fault Description
The ECU has detected a problem with a voltage reference used to process some of its input signals
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Troubleshooting Prodedure
See troubleshooting instructions for OffsRgFlt child fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 71 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
OffsRgFlt
73-25-04-116
Hard
Child
OffsFlt
Fault Description
The ECU has detected a problem with a voltage reference used to process some of its input signals
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
169 cnts
872 cnts
N/A
Troubleshooting Prodedure
Record OffsRaw signal. Replace ECU and include value of OffsRaw signal upon ECU return.
Bell 407 FADEC System Troubleshooting Guide
Page 72 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
OpenMvFlg
73-25-04-122
Soft
Parent
N/A
Fault Description
The ECU has detected that the HMU manual mode pistons are not properly parked
Fault Test Conditions
Test conducted at Ng < 8% while in start mode or shutdown
Possible Fault Causes
Engine last shutdown while in manual mode, airframe
power turned off prematurely prior to a complete N1
coastdown
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
WfSel > 16 pph prior to start
Troubleshooting Prodedure
None required. Perform HMU piston parking procedure. Notify pilots to allow an additional 20s after VID N1 indication reaches 0% before turning off airframe power
Bell 407 FADEC System Troubleshooting Guide
Page 73 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Or28Flt
73-25-04-128
Soft
Parent
Or28Flt
Fault Description
The ECU has detected that the voltage at the output of its internal power selection diodes is out of range. The diodes select the higher voltage between the airframe bus and the PMA
power input. The winner supplies the power to the ECU.
Fault Test Conditions
Continuous
Possible Fault Causes
Low airframe battery voltage upon power up.
Troubleshooting Prodedure
See troubleshooting instructions for Or28RgFlt child fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Fault declared if voltage is out of range for at least 30
seconds
Bell 407 FADEC System Troubleshooting Guide
Page 74 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
Or28RgFlt
73-25-04-128
Soft
Child
Or28Flt
Fault Description
The ECU has detected that the voltage at the output of its internal power selection diodes is out of range. The diodes select the higher voltage between the airframe bus and the PMA
power input. The winner supplies the power to the ECU.
Fault Test Conditions
Continuous
Possible Fault Causes
Low airframe battery voltage upon power up.
Fault Limits
Special Limit
Low
High
Open Circuit Reading
7.5 vdc
60 vdc
N/A
Fault declared if voltage is out of range for at least 30
seconds
Troubleshooting Prodedure
Monitor Or28Raw and AF28Raw signals upon power up with airframe battery. If voltage is below low limit, replace/recharge battery, otherwise replace ECU with recorded value of
AF28Raw and Or28Raw
Bell 407 FADEC System Troubleshooting Guide
Page 75 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
OrDiodeFlt
73-25-04-116
Soft
Parent
OrDiodeFlt
Fault Description
The ECU has detected that the voltage drops across its internal power selection diodes is out of range. The diodes select the higher voltage between the airframe bus and the PMA
power input. The winner supplies the power to the ECU.
Fault Test Conditions
Continuous
Possible Fault Causes
High airframe voltage upon power up due to improperly
adjusted power cart, high voltage output of engine PMA
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Monitor signals after power up and check for excessively high voltage inputs. If none are noticed, run engine at 100% Nr and check for a high voltage output from the PMA on
Al28Raw. Replace PMA if required. Otherwise, if ground power cart is set correctly, replace ECU.
Bell 407 FADEC System Troubleshooting Guide
Page 76 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
OSFlag
73-25-04-129
N/A
N/A
N/A
Fault Description
The ECU has detected that an Np overspeed has occurred whereby the HMU overspeed valve was energized to limit the Np speed
Fault Test Conditions
OSFlag declared if overspeed valve is energized while Np > 106%
Possible Fault Causes
Overspeed while controlling engine in manual mode,
selection of manual mode on the ground with throttle in
flight position
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Record NpQ exceedance values and OSCtr from ECU engine history. Perform engine maintenance as required.
Bell 407 FADEC System Troubleshooting Guide
Page 77 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
OSFlt
73-25-04-128
Soft
Parent
OSFlt
Fault Description
The ECU has detected a failure in its internal overspeed protection circuitry or the overspeed shutdown test has failed or its power up test of the overspeed system has failed.
Fault Test Conditions
Fault declared due to either a NPOSFlt, failure of the overspeed
system shutdown or power up tests
Possible Fault Causes
See troubleshooting for NPOSFlt or other OS related
child faults
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
See troubleshooting for NPOSFlt or other OS related child faults
Bell 407 FADEC System Troubleshooting Guide
Page 78 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
OSI12Flt
73-25-04-104
Soft
Child
OSI12Flt
Fault Description
The ECU has detected a failure in the current flow from the HMU overspeed solenoid valve
Fault Test Conditions
Test conducted during overspeed system shutdown live test or upon
power up with throttle off
Possible Fault Causes
Open circuit between HMU overspeed valve and ECU,
or an ECU failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Fault declared if solenoid current flow > 3 amps when
HMU overspeed solenoid valve is on
Troubleshooting Prodedure
Monitor OSIBitRaw signal during overspeed shutdown test. If current is > 3 amps, check overspeed valve circuit resistance. Repair/replace wiring/HMU as required. If overspeed
test does not shut the engine down, check for open circuit between HMU overspeed solenoid and ECU.
Bell 407 FADEC System Troubleshooting Guide
Page 79 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
OSTst1Flt
73-25-04-104
Soft
Child
OSFlt
Fault Description
The ECU has detected a failure in its ability to control the HMU overspeed solenoid valve during its power up test
Fault Test Conditions
Test conducted during power up with throttle off in auto mode
Possible Fault Causes
Open/short circuit between HMU overspeed valve and
ECU, or an ECU failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Apply power to aircraft with FADEC mode switch in manual and the throttle off. Start a signal trend and select auto mode. Retain data. Check for open/short ciruit between ECU
and HMU overspeed solenoid. Repair/replace wiring as necessary.
Bell 407 FADEC System Troubleshooting Guide
Page 80 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
OSTst2Flt
73-25-04-104
Soft
Child
OSFlt
Fault Description
The ECU has detected a failure in its ability to control the HMU overspeed solenoid valve during its power up test
Fault Test Conditions
Test conducted during power up with throttle off in auto mode
Possible Fault Causes
Open/short circuit between HMU overspeed valve and
ECU, or an ECU failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Apply power to aircraft with FADEC mode switch in manual and the throttle off. Start a signal trend and select auto mode. Retain data. Check for open/short ciruit between ECU
and HMU overspeed solenoid. Repair/replace wiring as necessary.
Bell 407 FADEC System Troubleshooting Guide
Page 81 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
OSTst3Flt
73-25-04-104
Soft
Child
OSFlt
Fault Description
The ECU has detected a failure in its ability to control the HMU overspeed solenoid valve during its power up test
Fault Test Conditions
Test conducted during power up with throttle off in auto mode
Possible Fault Causes
Open/short circuit between HMU overspeed valve and
ECU, or an ECU failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Apply power to aircraft with FADEC mode switch in manual and the throttle off. Start a signal trend and select auto mode. Retain data. Check for open/short ciruit between ECU
and HMU overspeed solenoid. Repair/replace wiring as necessary.
Bell 407 FADEC System Troubleshooting Guide
Page 82 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
OSTst4Flt
73-25-04-104
Soft
Child
OSFlt
Fault Description
The ECU has detected a failure in its ability to control the HMU overspeed solenoid valve during its power up test
Fault Test Conditions
Test conducted during power up with throttle off in auto mode
Possible Fault Causes
Open/short circuit between HMU overspeed valve and
ECU, or an ECU failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Apply power to aircraft with FADEC mode switch in manual and the throttle off. Start a signal trend and select auto mode. Retain data. Check for open/short ciruit between ECU
and HMU overspeed solenoid. Repair/replace wiring as necessary.
Bell 407 FADEC System Troubleshooting Guide
Page 83 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
OSTst5Flt
73-25-04-104
Soft
Child
OSFlt
Fault Description
The ECU has detected a failure in its ability to control the HMU overspeed solenoid valve during its power up test
Fault Test Conditions
Test conducted during power up with throttle off in auto mode
Possible Fault Causes
Open/short circuit between HMU overspeed valve and
ECU, or an ECU failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Apply power to aircraft with FADEC mode switch in manual and the throttle off. Start a signal trend and select auto mode. Retain data. Check for open/short ciruit between ECU
and HMU overspeed solenoid. Repair/replace wiring as necessary.
Bell 407 FADEC System Troubleshooting Guide
Page 84 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
OSTst6Flt
73-25-04-104
Soft
Child
OSFlt
Fault Description
The ECU has detected a failure in its ability to control the HMU overspeed solenoid valve during its power up test
Fault Test Conditions
Test conducted during power up with throttle off in auto mode
Possible Fault Causes
Open/short circuit between HMU overspeed valve and
ECU, or an ECU failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Apply power to aircraft with FADEC mode switch in manual and the throttle off. Start a signal trend and select auto mode. Retain data. Check for open/short ciruit between ECU
and HMU overspeed solenoid. Repair/replace wiring as necessary.
Bell 407 FADEC System Troubleshooting Guide
Page 85 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
OSTst7Flt
73-25-04-104
Soft
Child
OSFlt
Fault Description
The ECU has detected a failure in its ability to control the HMU overspeed solenoid valve during its power up test
Fault Test Conditions
Test conducted during power up with throttle off in auto mode
Possible Fault Causes
Open/short circuit between HMU overspeed valve and
ECU, or an ECU failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Apply power to aircraft with FADEC mode switch in manual and the throttle off. Start a signal trend and select auto mode. Retain data. Check for open/short ciruit between ECU
and HMU overspeed solenoid. Repair/replace wiring as necessary.
Bell 407 FADEC System Troubleshooting Guide
Page 86 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
OSTstFlt
73-25-04-123
Soft
Child
OSFlt
Fault Description
The ECU has detected a failure of the HMU during an overspeed system shutdown test
Fault Test Conditions
Test conducted during aircraft overspeed system shutdown test
Possible Fault Causes
HMU failure or test conducted at high altitude.
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Replace HMU or repeat overspeed system shutdown test at a lower altitude.
Fault declared if N1 speed does not decrease by more
that 1% when HMU solenoid valve is energized
Bell 407 FADEC System Troubleshooting Guide
Page 87 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
OSTstSwFlt
73-25-04-118
Soft
Child
OSTstSwFlt
Fault Description
The ECU has detected a failure of the cockpit overspeed test switch
Fault Test Conditions
Continuous
Possible Fault Causes
Overspeed test switch stuck closed or held in too long
during shutdown test. Fault declared if Overspeed test
switch pressed or shorted for more than 30s.
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Fault declared if cockpit test switch closed for more
that 30 sec
Troubleshooting Prodedure
Monitor OSTestSw while pressing and releasing the test switch. When switch is pressed, OSTestSw should be TRUE. When released it should be FALSE. When pressed, a ground
should be sensed at the input. When released, the input should be open circuit. The fault will be declared if the ECU senses that the switch is held in or shorted for more than 30s.
Replace switch/repair wiring as required.
Bell 407 FADEC System Troubleshooting Guide
Page 88 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
OSVFlt
73-25-04-116
Soft
Parent
OSVFlt
Fault Description
The ECU has detected a problem with a voltage reference used within its overspeed protection circuitry
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Troubleshooting Prodedure
See troubleshooting instructions for OSVRgFlt child fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 89 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
OSVRgFlt
73-25-04-116
Soft
Child
OSVFlt
Fault Description
The ECU has detected a problem with a voltage reference used within its overspeed protection circuitry
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
4.5 vdc
6.0 vdc
N/A
Troubleshooting Prodedure
Record OSVRaw signal. Replace ECU and include value of OSVRaw signal upon ECU return.
Bell 407 FADEC System Troubleshooting Guide
Page 90 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
P1DFlt
73-25-04-127
Soft
N/A
N/A
Fault Description
This fault code not used in this application and applies only to twin engine applications
Fault Test Conditions
Possible Fault Causes
ECU write to EEPROM or RAM interrupted during
engine shutdown causing erroneous recording of an
unused fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
If fault is historical, clear all faults with the MT35 program. Cycle power and verify that fault is cleared.
Bell 407 FADEC System Troubleshooting Guide
Page 91 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
P1Flt
73-25-04-115
Soft
Parent
P1Flt
Fault Description
The ECU has detected a failure of its internal P1 ambient pressure transducer
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
See troubleshooting instructions for P1RgFlt or P1RtFlt child faults
Bell 407 FADEC System Troubleshooting Guide
Page 92 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
P1HdFlt
73-25-04-115
Hard
Parent
P1Flt
Fault Description
The ECU has detected a failure of its internal P1 ambient pressure transducer and can not calculate a syntesized P1 to accommodate the failure
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure and a Q failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Record P1Raw signal. Replace ECU and include value of P1Raw signal upon ECU return.
Bell 407 FADEC System Troubleshooting Guide
Page 93 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
P1RgFlt
73-25-04-115
Soft
Child
P1Flt
Fault Description
The ECU has detected a failure of its internal P1 ambient pressure transducer where its P1 signal was out of range
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
5 psia
16 psia
N/A
Troubleshooting Prodedure
Record P1Raw signal. Replace ECU and include value of P1Raw signal upon ECU return.
Bell 407 FADEC System Troubleshooting Guide
Page 94 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
P1RtFlt
73-25-04-115
Soft
Child
P1Flt
Fault Description
The ECU has detected a failure of its internal P1 ambient pressure transducer where its P1 signal failed at a high rate of change
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
5 psia
16 psia
N/A
Troubleshooting Prodedure
Record P1Raw signal. Replace ECU and include value of P1Raw signal upon ECU return.
Bell 407 FADEC System Troubleshooting Guide
Page 95 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
PLA12Flt
73-25-04-106
Soft
Parent
PLAFlts
Fault Description
The ECU has detected that both throttle inputs have failed or that they do not agree within 5 degrees
Fault Test Conditions
Continuous
Possible Fault Causes
HMU PLA potentiometer failure or throttle min/max
stops on HMU quadrant shifted during initial HMU
installation
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
See troubleshooting instructions for PLA1RgFlt or PLA2RgFlt child faults
Bell 407 FADEC System Troubleshooting Guide
Page 96 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
PLA1Flt
73-25-04-106
Soft
Parent
PLAFlts
Fault Description
The ECU has detected that its PLA1 input has failed
Fault Test Conditions
Continuous
Possible Fault Causes
HMU PLA potentiometer failure or throttle min/max
stops on HMU quadrant shifted during initial HMU
installation
Troubleshooting Prodedure
See troubleshooting instructions for PLA1RgFlt
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 97 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
PLA1RgFlt
73-25-04-106
Soft
Child
PLAFlts
Fault Description
The ECU has detected that its PLA1 input has failed out of range
Fault Test Conditions
Continuous
Possible Fault Causes
HMU PLA potentiometer failure or throttle min/max
stops on HMU quadrant shifted during initial HMU
installation
Fault Limits
Low
High
Open Circuit Reading
-5 deg
110 deg
PLA1Raw > 120°
Special Limit
Troubleshooting Prodedure
Monitor signals when throttle position at cutoff and fly. Check PLA1 and PLA2 values against range limits. Replace HMU if values near range limits. If PLA range is OK, trend data
while manipulating throttle between cutoff and fly back to cutoff repeatedly for 60 seconds. Analyze data traces for signs of spikes on graphs. If spikes are noticed, replace HMU.
Bell 407 FADEC System Troubleshooting Guide
Page 98 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
PLA2Flt
73-25-04-106
Soft
Parent
PLAFlts
Fault Description
The ECU has detected that its PLA2 input has failed
Fault Test Conditions
Continuous
Possible Fault Causes
HMU PLA potentiometer failure or throttle min/max
stops on HMU quadrant shifted during initial HMU
installation
Troubleshooting Prodedure
See troubleshooting instructions for PLA1RgFlt
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 99 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
PLA2RgFlt
73-25-04-106
Soft
Child
PLAFlts
Fault Description
The ECU has detected that its PLA2 input has failed out of range
Fault Test Conditions
Continuous
Possible Fault Causes
HMU PLA potentiometer failure or throttle min/max
stops on HMU quadrant shifted during initial HMU
installation
Fault Limits
Low
High
Open Circuit Reading
-5 deg
110 deg
PLA2Raw > 120°
Special Limit
Troubleshooting Prodedure
Monitor signals when throttle position at cutoff and fly. Check PLA1 and PLA2 values against range limits. Replace HMU if values near range limits. If PLA range is OK, trend data
while manipulating throttle between cutoff and fly back to cutoff repeatedly for 60 seconds. Analyze data traces for signs of spikes on graphs. If spikes are noticed, replace HMU.
Bell 407 FADEC System Troubleshooting Guide
Page 100 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
PLADFlt
73-25-04-106
Soft
Parent
PLAFlts
Fault Description
The ECU has detected that both throttle inputs do not agree within 5 degrees
Fault Test Conditions
Continuous
Possible Fault Causes
ECU failure or wiring problem between ECU and HMU
PLA potentiometer
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Fault declared if PLA1 and PLA2 are not within 5
degrees of eachother
Troubleshooting Prodedure
Monitor signals when throttle position at cutoff and fly. Compare PLA1 and PLA2 values against eachother. If they don't agree, check the wiring between the ECU and HMU PLA
pot for the signal which does not agree with the physical throttle postion. If they agree, trend data while manipulating throttle between cutoff and fly back to cutoff repeatedly for 60
seconds. Analyze data traces for signs of spikes on graphs. If spikes are noticed, replace the ECU.
Bell 407 FADEC System Troubleshooting Guide
Page 101 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
PLAHdFlt
73-25-04-106
Hard
Parent
PLAFlts
Fault Description
The ECU has detected that both throttle inputs have failed or that they do not agree within 5 degrees prior to the throttle reaching the flight position or the problem exists when the
engine is shutdown or on powerup
Fault Test Conditions
Continuous
Possible Fault Causes
HMU PLA potentiometer failure or throttle min/max
stops on HMU quadrant shifted during initial HMU
installation
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Monitor signals when throttle position at cutoff and fly. Check PLA1 and PLA2 values against range limits. Replace HMU if values near range limits. If PLA range is OK, trend data
while manipulating throttle between cutoff and fly back to cutoff repeatedly for 60 seconds. Analyze data traces for signs of spikes on graphs. If spikes are noticed, replace HMU.
Bell 407 FADEC System Troubleshooting Guide
Page 102 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
PLARfFlt
73-25-04-106
Soft
Parent
PLAFlts
Fault Description
The ECU has detected that the voltage supply reference to the HMU PLA potentiometer has failed
Fault Test Conditions
Continuous
Possible Fault Causes
ECU Failure or shorted wiring between ECU and HMU
PLA potentiometer
Troubleshooting Prodedure
See troubleshooting instructions for PLARfRgFlt child fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 103 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
PLARfRgFlt
73-25-04-106
Soft
Child
PLAFlts
Fault Description
The ECU has detected that the voltage supply reference to the HMU PLA potentiometer has failed out of range
Fault Test Conditions
Continuous
Possible Fault Causes
ECU Failure or shorted wiring between ECU and HMU
PLA potentiometer
Fault Limits
Special Limit
Low
High
Open Circuit Reading
4.95 vdc
5.05 vdc
N/A
Troubleshooting Prodedure
Monitor PLARfRaw signal with engine harness disconnected from ECU and when it is connected to the ECU. If no change in PLA reference voltage and the reference is out of limits,
replace the ECU. If in limits only when harness is disconnected, check for short circuit between ECU and HMP +5V PLA supply wiring. Replace/repair effected component as
required.
Bell 407 FADEC System Troubleshooting Guide
Page 104 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
PROMFlt
73-25-04-116
Hard
Parent
N/A
Fault Description
The ECU has detected that its program checksum does not agree with the value stored at the factory
Fault Test Conditions
Power up and background tasks
Possible Fault Causes
Internal ECU Failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Record value of ID on the MT35 program header and return ECU with ID value. The ID value should be 443F.
Bell 407 FADEC System Troubleshooting Guide
Page 105 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
PW10Flt
73-25-04-116
Hard
Parent
PW10Flts
Fault Description
The ECU has detected a failure of its internal pulse width modulated voltage used to control the +28V dc supply output to the HMU stepper motor
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Troubleshooting Prodedure
See troubleshooting instructions for PW10RgFlt child fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 106 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
PW10RgFlt
73-25-04-116
Hard
Child
PW10Flts
Fault Description
The ECU has detected a failure of its internal pulse width modulated voltage used to control the +28V dc supply output to the HMU stepper motor
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
6.5 vdc
11 vdc
N/A
Troubleshooting Prodedure
Record value of PW10Raw signal and return ECU with PW10Raw value
Bell 407 FADEC System Troubleshooting Guide
Page 107 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
QFlt
73-25-04-112
Soft
Parent
QFlt
Fault Description
The ECU has detected a problem with its torque input signal or has determined the torque input is invalid
Fault Test Conditions
Continuous
Possible Fault Causes
Loose or corroded connection at the TMOP sensor on
the engine, oil in TMOP sensor connection, bad TMOP
sensor
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
See troubleshooting instructions for either a QRgFlt or QRtFlt child fault
Bell 407 FADEC System Troubleshooting Guide
Page 108 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
QRgFlt
73-25-04-112
Soft
Child
QFlt
Fault Description
The ECU has detected a problem with its torque input signal which has gone out of range
Fault Test Conditions
Continuous
Possible Fault Causes
Loose or corroded connection at the TMOP sensor on
the engine, oil in TMOP sensor connection, bad TMOP
sensor
Fault Limits
Special Limit
Low
High
Open Circuit Reading
-10%
200%
QRaw > 200%
Low limit of 5% if N1 > 85% under steady state
conditions
Troubleshooting Prodedure
Monitor QRaw. If out of range high or low, check for open circuit between ECU and engine TMOP sensor connection. If normal, run engine at 100% Nr and compare Qraw
indication to that of the cockpit after scaling cockpit reading. If they differ substantially, replace TMOP sensor. Take a trend under these condtions and look for spikes on the Qraw
trace while flexing harnesses. Replace wiring as required.
Bell 407 FADEC System Troubleshooting Guide
Page 109 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
QRtFlt
73-25-04-112
Soft
Child
QFlt
Fault Description
The ECU has detected an intermittant problem with its torque input signal
Fault Test Conditions
Continuous
Possible Fault Causes
Loose or corroded connection at the TMOP sensor on
the engine, oil in TMOP sensor connection, bad TMOP
sensor
Fault Limits
Special Limit
Low
High
Open Circuit Reading
-10%
200%
Qraw > 200%
Low limit of 5% if N1 > 85% under steady state
conditions
Troubleshooting Prodedure
Monitor QRaw. If out of range high or low, check for open circuit between ECU and engine TMOP sensor connection. If normal, run engine at 100% Nr and compare Qraw
indication to that of the cockpit after scaling cockpit reading. If they differ substantially, replace TMOP sensor. Take a trend under these condtions and look for spikes on the Qraw
trace while flexing harnesses. Replace wiring as required.
Bell 407 FADEC System Troubleshooting Guide
Page 110 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
QSwFlt
73-25-04-156
Soft
Parent
QMSwFlt
Fault Description
The ECU has detected a problem with the FADEC Quiet Mode switch (Optional)
Fault Test Conditions
Continuous
Possible Fault Causes
Bad FADEC quiet mode select switch or wiring from the
switch to the ECU. Corrosion/moisture in airframe
harness.
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Fault is declared if the ECU detects that both quiet
mode switch inputs do not agree.
Troubleshooting Prodedure
Monitor QMSw1 and QMSw2. When not in quiet mode, both should be FALSE. Select quiet mode. Both should be TRUE. A grounded input makes the input TRUE. An open
input makes the input FALSE. Both inputs should be the same simultaneously. Troubleshoot switch and wiring as applicable.
Bell 407 FADEC System Troubleshooting Guide
Page 111 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
QVldFlt
73-25-04-112
Soft
Child
QVldFlt
Fault Description
The ECU has determined that its torque input signal is invalid when it is compared to theoretical engine shaft horsepower determined from N1 speed
Fault Test Conditions
Continuous
Possible Fault Causes
Air trapped in TMOP sensor supply tube from the
engine gearbox, bad TMOP sensor or erroneous P1 or
T1 input to the DECU
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Np times Q times 0.06 > estimated engine horsepower
as a function of N1 corrected speed
Troubleshooting Prodedure
Monitor QRaw, P1 and T1 when engine running at 100% Nr. Check if P1 and T1 are consistant with actual ambient conditions. If P1 is not reading correctly, replace the ECU. If T1
is not reading correctly, replace the engine T1 sensor. Otherwise, replace the TMOP sensor after first checking for air within the TMOP transducer supply tube from the gearbox.
Bleed any air and recheck.
Bell 407 FADEC System Troubleshooting Guide
Page 112 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
RAMFlt
73-25-04-116
Hard
Parent
N/A
Fault Description
The ECU has detected a problem with its internal Random Access Memory (RAM)
Fault Test Conditions
Power up and background tasks
Possible Fault Causes
Internal ECU Failure
Troubleshooting Prodedure
Replace ECU
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 113 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
SgFlag
See AMM
Soft
N/A
N/A
Fault Description
The ECU has detected that the engine has surged
Fault Test Conditions
Continuous when in engine run mode
Possible Fault Causes
Inefficient engine compressor or faulty bleed band
actuator
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Record the value of SgCtr in ECU engine history. Check for ECU MGT exceedances. Check engine compressor for signs of FOD damage or erosion. Check for proper closure and
operation of the engine bleed band actuator
Bell 407 FADEC System Troubleshooting Guide
Page 114 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
SMFlt
73-25-04-101
Hard
Parent
SMFlt
Fault Description
The ECU has detected a problem with its control of the HMU stepper motor
Fault Test Conditions
Power up test only with throttle off
Possible Fault Causes
Wiring problem between ECU and HMU stepper motor
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
See troubleshooting instructions for SmPhAVFlt, SmPhBVFlt, SmPhCVFlt, SmPhDVFlt or SmPhIFlt child faults
Bell 407 FADEC System Troubleshooting Guide
Page 115 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
SMPhAVFlt
73-25-04-101
Hard
Child
SMFlt
Fault Description
The ECU has detected a problem with the control of phase A of the HMU stepper motor
Fault Test Conditions
Power up test only with throttle off
Possible Fault Causes
Wiring problem between ECU and HMU stepper motor
phase A return. Internal ECU phase A driver failure.
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Apply power to aircraft with FADEC mode switch in manual. Check that all SmPh voltage bits are false. If SmPhAVbit is TRUE, check for ground in wiring from ECU to HMU
stepper motor phase A. If SmPhAVbit is FALSE, select auto mode with throttle in cutoff and take trend data. Compare the SmTstCnt value against the states of the SmPh voltage bits
as follows: SmTstCnt (1-4: All Vbits FALSE), SmTstCnt (5-8: SmPhAVbit = TRUE), SmTstCnt (9-12: SmPhBVbit = TRUE), SmTstCnt (13-16: SmPhCVbit = TRUE), SmTstCnt
(17-20: SmPhDVbit = TRUE), SmTstCnt (21: SmPhCVbit = TRUE), SmTstCnt (22: SmPhBVbit = TRUE), SmTstCnt (23: SmPhAVbit = TRUE), SmTstCnt (24: All Vbits =
FALSE). Check for open/short ciruit in wiring on effected stepper motor phase.
Bell 407 FADEC System Troubleshooting Guide
Page 116 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
SMPhBVFlt
73-25-04-101
Hard
Child
SMFlt
Fault Description
The ECU has detected a problem with the control of phase B of the HMU stepper motor
Fault Test Conditions
Power up test only with throttle off
Possible Fault Causes
Wiring problem between ECU and HMU stepper motor
phase B return. Internal ECU phase B driver failure.
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Follow troubleshooting instructions for SmPhAVFlt referencing SmPhBVbit
Bell 407 FADEC System Troubleshooting Guide
Page 117 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
SMPhCVFlt
73-25-04-101
Hard
Child
SMFlt
Fault Description
The ECU has detected a problem with the control of phase C of the HMU stepper motor
Fault Test Conditions
Power up test only with throttle off
Possible Fault Causes
Wiring problem between ECU and HMU stepper motor
phase C return. Internal ECU phase C driver failure.
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Follow troubleshooting instructions for SmPhAVFlt referencing SmPhCVbit
Bell 407 FADEC System Troubleshooting Guide
Page 118 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
SMPhDVFlt
73-25-04-101
Hard
Child
SMFlt
Fault Description
The ECU has detected a problem with the control of phase D of the HMU stepper motor
Fault Test Conditions
Power up test only with throttle off
Possible Fault Causes
Wiring problem between ECU and HMU stepper motor
phase D return. Internal ECU phase D driver failure.
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Follow troubleshooting instructions for SmPhAVFlt referencing SmPhDVbit
Bell 407 FADEC System Troubleshooting Guide
Page 119 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
SMPhIFlt
73-25-04-101
Hard
Child
SMFlt
Fault Description
The ECU has detected a problem with current flow from on of the HMU stepper motor phases
Fault Test Conditions
Power up test only with throttle off
Possible Fault Causes
Wiring problem between ECU and HMU stepper motor.
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
SmIBitRaw not between 0.1 amp and 1.5 amp when
phase turned on. SmIBitRaw > 0.2 amp when phase
supposedly off.
Troubleshooting Prodedure
Apply power to aircraft with FADEC mode switch in manual. Check that SmIBitRaw is less than 0.2 amps. If greater, check wiring from ECU to HMU stepper motor. If OK, select
auto mode with the throttle in cutoff and take trend data. Compare the SmTstCnt value against the SmIBitRaw value as follows: SmTstCnt (1-4: no current), SmTstCnt (5-8: current
from phase A), SmTstCnt (9-12: current from phase B), SmTstCnt (13-16: current from phase C), SmTstCnt (17-20: current from phase D), SmTstCnt (21:current from phase C),
SmTstCnt (22: current from phase B), SmTstCnt (23: current from phase A), SmTstCnt (24: no current). Check for open/short circuit in wiring on effected stepper motor phase.
Bell 407 FADEC System Troubleshooting Guide
Page 120 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
StepCntFlt
73-25-04-121
Hard
Parent
StepCntFlt
Fault Description
The ECU has detected that the HMU stepper is not moving when commanded to move
Fault Test Conditions
Continuous when engine is running (start or run mode) If this fault
occurs, a WFhdFlt will also be declared which is not resettable by
cycling the FADEC mode switch, only by cycling ECU power.
Possible Fault Causes
Auto start attempt after initial HMU installation on
engine with insufficient HMU fuel bleed procedure,
engine auto start attempted after engine shutdown in
manual mode without subsequent piston parking
procedure performed, wiring problem affecting HMU
Wf feedback signal, HMU stepper motor failure, HMU
Wf feedback potentiometer failure, wiring problem
between ECU and HMU stepper motor or auto/manual
solenoid
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Difference between WfmvRaw fuel flow and Wfstp
stepcount fuel flow greater than 42 PPH
Troubleshooting Prodedure
Check if the fault was possibly caused by procedural error as identified in fault probable causes. Monitor WfmvRaw parameter while flexing electrical harnesses and taking trend
data. Analyze trace for signs of Wfmvraw instability from its nominal -10 pph position at power up. If the signal changes with flexing, repair/replace wiring. Select manual mode.
Trend data while flexing harnesses. Ensure that no SM Vbits change to TRUE during the flexing. Check wiring between ECU and HMU stepper motor and auto/manual solenoid per
instructions provided for AMSolFlt and SMFlt. If faulty grounded wiring is found on any of the HMU stepper motor phase returns, the HMU may be damaged internally. If electrical
checks pass, replace HMU.
Bell 407 FADEC System Troubleshooting Guide
Page 121 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
StrFlt
73-25-04-116
Soft
Parent
StrFlt
Fault Description
The ECU has detected a problem with its control of the airframe starter relay during an auto mode start attempt
Fault Test Conditions
Start switch pressed in auto mode during start or auto-relight
Possible Fault Causes
Open circuit between airframe starter relay return and
ECU or an ECU failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
ECU detects an open circuit on the return wire from
the starter relay
Troubleshooting Prodedure
Monitor StrVBit after power up. Parameter should be FALSE. If TRUE, check for short on relay return wire to ECU. Next, motor engine to 10% N1. StrVbit should become TRUE
when start switch is pressed. If still FALSE, check for open circuit on relay return wire from airframe starter relay.
Bell 407 FADEC System Troubleshooting Guide
Page 122 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
StSFlt
73-25-04-102
Soft
Parent
StSFlt
Fault Description
The ECU has detected a problem with its control of the HMU start fuel solenoid
Fault Test Conditions
In auto mode, StSIbitRaw current > 0.08 amps when engine off or
ECU detects that the start fuel solenoid is on with the engine off or it is
not on when commanded during an auto mode start attemp at 10% N1
Possible Fault Causes
Grounded wire between ECU and return from HMU
start fuel solenoid
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
In auto mode, StSIbitRaw current > 0.08 amps when
engine off or ECU detects that the start fuel solenoid is
on with the engine off or it is not on when commanded
during an auto mode start attemp at 10% N1
Troubleshooting Prodedure
Monitor STSVBit after power up. Parameter should be FALSE. If TRUE, check for short on return wire from HMU start fuel solenoid to the ECU. STSIbitRaw should by less than
0.08 amps. If not, check wiring for cross short to ECU start fuel solenoid return. If all OK, perform auto mode start and trend data. Check that STSVbit changes to TRUE when
STSEnb changes to TRUE. If not, check for open circuit between ECU and return of HMU start fuel solenoid.
Bell 407 FADEC System Troubleshooting Guide
Page 123 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
StSIFlt
73-25-04-102
Soft
Parent
StSFlt
Fault Description
The ECU has detected a problem with the current flow from the HMU start fuel solenoid
Fault Test Conditions
In auto mode, StSIbitRaw current not between 0.05 amp and 1.0 amp
when HMU start fuel solenoid energized
Possible Fault Causes
Grounded or open wire between ECU and return from
HMU start fuel solenoid
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
In auto mode, StSIbitRaw current not between 0.05
amp and 1.0 amp when HMU start fuel solenoid
energized
Troubleshooting Prodedure
Monitor STSIBitRaw after power up. Motor the engine without ignition to 15% N1. Check that STSIBitRaw changes to within its current range at 10% N1. If not, check for open or
short circuit between ECU and return of HMU start fuel solenoid. Repair as required.
Bell 407 FADEC System Troubleshooting Guide
Page 124 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
SWIntFlt
73-25-04-116
Soft
Parent
N/A
Fault Description
The ECU has detected that abnormal software interrupts have occurred
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Troubleshooting Prodedure
Replace ECU
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 125 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
T1ABFlt
73-25-04-107
Hard
Parent
T1Flts
Fault Description
The ECU has detected that both T1 ambient temperature inputs have failed or that they do not agree within 30°F
Fault Test Conditions
Continuous
Possible Fault Causes
Engine T1 sensor connection loose or corroded, T1
sensor failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
See troubleshooting instructions for T1ARgFlt, T1ARtFlt, T1BRgFlt and T1BRtFlt child faults
Bell 407 FADEC System Troubleshooting Guide
Page 126 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
T1AFlt
73-25-04-107
Soft
Parent
T1Flts
Fault Description
The ECU has detected a failure in its T1A ambient temperature input
Fault Test Conditions
Continuous
Possible Fault Causes
Engine T1A sensor output wiring loose or corroded
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
See troubleshooting instructions for T1ARgFlt and T1ARtFlt child faults
Bell 407 FADEC System Troubleshooting Guide
Page 127 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
T1ARgFlt
73-25-04-107
Soft
Child
T1Flts
Fault Description
The ECU has detected a failure in its T1A ambient temperature input which has gone out of range
Fault Test Conditions
Continuous
Possible Fault Causes
Engine T1A sensor output wiring loose or corroded
Fault Limits
Low
High
Open Circuit Reading
-75°F
225°F
T1ARaw < -90 °F
Special Limit
Difference between T1ARaw and T1BRaw > 30°F
Troubleshooting Prodedure
Monitor T1ARaw after powerup. Open circuit indicated if T1ARaw < -90°F. Repair as required. If T1ARaw is normal after powerup, flex harness while taking trend data. Analyze
trace for signs of sensor output instability. Repair as required.
Bell 407 FADEC System Troubleshooting Guide
Page 128 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
T1ARtFlt
73-25-04-107
Soft
Child
T1Flts
Fault Description
The ECU has detected a failure in its T1A ambient temperature input which was intermittant
Fault Test Conditions
Continuous
Possible Fault Causes
Engine T1A sensor output wiring loose or corroded
Fault Limits
Low
High
Open Circuit Reading
-75°F
225°F
T1ARaw < -90 °F
Special Limit
Difference between T1ARaw and T1BRaw > 30°F
Troubleshooting Prodedure
Monitor T1ARaw after powerup. Open circuit indicated if T1ARaw < -90°F. Repair as required. If T1ARaw is normal after powerup, flex harness while taking trend data. Analyze
trace for signs of sensor output instability. Repair as required.
Bell 407 FADEC System Troubleshooting Guide
Page 129 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
T1BFlt
73-25-04-107
Soft
Parent
T1Flts
Fault Description
The ECU has detected a failure in its T1B ambient temperature input
Fault Test Conditions
Continuous
Possible Fault Causes
Engine T1B sensor output wiring loose or corroded
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
See troubleshooting instructions for T1BRgFlt and T1BRtFlt child faults
Bell 407 FADEC System Troubleshooting Guide
Page 130 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
T1BRgFlt
73-25-04-107
Soft
Child
T1Flts
Fault Description
The ECU has detected a failure in its T1B ambient temperature input which has gone out of range
Fault Test Conditions
Continuous
Possible Fault Causes
Engine T1B sensor output wiring loose or corroded
Fault Limits
Low
High
Open Circuit Reading
-75°F
225°F
T1BRaw < -90 °F
Special Limit
Difference between T1ARaw and T1BRaw > 30°F
Troubleshooting Prodedure
Monitor T1BRaw after powerup. Open circuit indicated if T1BRaw < -90°F. Repair as required. If T1BRaw is normal after powerup, flex harness while taking trend data. Analyze
trace for signs of sensor output instability. Repair as required.
Bell 407 FADEC System Troubleshooting Guide
Page 131 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
T1BRtFlt
73-25-04-107
Soft
Child
T1Flts
Fault Description
The ECU has detected a failure in its T1B ambient temperature input which was intermittant
Fault Test Conditions
Continuous
Possible Fault Causes
Engine T1B sensor output wiring loose or corroded
Fault Limits
Low
High
Open Circuit Reading
-75°F
225°F
T1BRaw < -90 °F
Special Limit
Difference between T1ARaw and T1BRaw > 30°F
Troubleshooting Prodedure
Monitor T1BRaw after powerup. Open circuit indicated if T1BRaw < -90°F. Repair as required. If T1BRaw is normal after powerup, flex harness while taking trend data. Analyze
trace for signs of sensor output instability. Repair as required.
Bell 407 FADEC System Troubleshooting Guide
Page 132 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
T1DFlt
73-25-04-107
Hard
Parent
T1Flts
Fault Description
The ECU has detected that both T1 ambient temperature inputs do not agree within 30°F
Fault Test Conditions
Continuous
Possible Fault Causes
Engine T1 sensor connection loose or corroded, T1
sensor failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
See troubleshooting instructions for T1ARgFlt, T1ARtFlt, T1BRgFlt and T1BRtFlt child faults
Difference between T1ARaw and T1BRaw > 30°F
Bell 407 FADEC System Troubleshooting Guide
Page 133 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
TempFlt
73-25-04-128
Soft
Parent
N/A
Fault Description
The ECU has detected a problem with its MGT input signal or its internal cold junction used to compensate the MGT input
Fault Test Conditions
Continuous
Possible Fault Causes
Loose or corroded connection at the MGT thermocouple
junction on the engine or internal ECU failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
See troubleshooting instructions for either a MGTFlt or CJCFlt child fault. TempFlt name only viewable with MT35 maintenance software
Bell 407 FADEC System Troubleshooting Guide
Page 134 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
TestCelFlt
73-25-04-126
Soft
Parent
TestCelFlt
Fault Description
The ECU has detected that its test cell input is grounded but it is still getting a rotor speed input
Fault Test Conditions
Test for grounded Testcell input when Nr > 50%
Possible Fault Causes
Erroneous ground on ECU TestCell Input
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
Monitor value of TestCell after powerup. Trend data while flexing harness. Analayze trend data. TestCell should always be FALSE. If TRUE, check wiring for ground in harness on
pin P2-58.
Bell 407 FADEC System Troubleshooting Guide
Page 135 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
UARTFlt
73-25-04-116
Soft
Parent
N/A
Fault Description
The ECU has detected a problem with its RS-423 interface during its power up self test and/or background tests
Fault Test Conditions
Power up or during background tasks
Possible Fault Causes
Internal ECU Failure. Very unlikely to occur.
Troubleshooting Prodedure
Replace ECU
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 136 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
UUIntFlt
73-25-04-116
Soft
Parent
N/A
Fault Description
The ECU has detected that a software interrupt occurred from one which has not been assigned by the software
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Troubleshooting Prodedure
Replace ECU
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 137 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
V15Flt
73-25-04-116
Hard
Parent
V15Flt
Fault Description
The ECU has detected a problem with an internal 15 volt dc power supply reference
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Troubleshooting Prodedure
See troubleshooting instructions for V15RgFlt child fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 138 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
V15RgFlt
73-25-04-116
Hard
Child
V15Flt
Fault Description
The ECU has detected a problem with an internal 15 volt dc power supply reference
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
2.4 vdc
3.6 vdc
N/A
Troubleshooting Prodedure
Record V15Raw signal. Nominal value is 3 vdc. Replace ECU and include value of V15Raw signal upon ECU return.
Nominal V15 voltage is 3 vdc
Bell 407 FADEC System Troubleshooting Guide
Page 139 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
V5Flt
73-25-04-116
Hard
Parent
V5Flt
Fault Description
The ECU has detected a problem with an internal 5 volt dc power supply reference
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Troubleshooting Prodedure
See troubleshooting instructions for V5RgFlt child fault
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 140 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
V5RgFlt
73-25-04-116
Hard
Child
V5Flt
Fault Description
The ECU has detected a problem with an internal 5 volt dc power supply reference
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Fault Limits
Special Limit
Low
High
Open Circuit Reading
4.5 vdc
5.5 vdc
N/A
Troubleshooting Prodedure
Record V5Raw signal. Replace ECU and include value of V5Raw signal upon ECU return.
Bell 407 FADEC System Troubleshooting Guide
Page 141 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
WDTFlt
73-25-04-116
Soft
Parent
N/A
Fault Description
The ECU has detected a problem with its watch dog timer during its self test
Fault Test Conditions
Continuous and transitions from manual into auto
Possible Fault Causes
Internal ECU Failure
Troubleshooting Prodedure
Replace ECU
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 142 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
WDTOutFlt
73-25-04-116
Soft
Parent
N/A
Fault Description
The ECU has detected that its watch dog timer has timed out once during software execution
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Troubleshooting Prodedure
Replace ECU
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 143 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
WDTTimeOut
73-25-04-125
Hard
Parent
N/A
Fault Description
The ECU has detected that its watch dog timer has failed
Fault Test Conditions
Continuous
Possible Fault Causes
Internal ECU Failure
Troubleshooting Prodedure
Replace ECU
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 144 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
WfHdFlt
73-25-04-128
Hard
Parent
N/A
Fault Description
The ECU has detected that the HMU stepper is not moving or can not initialize its step count fuel flow
Fault Test Conditions
Continuous
Possible Fault Causes
See possible fault causes for StepCntFlt and WfmvFlt
Troubleshooting Prodedure
See troubleshooting instructions for StepCntFlt and WfmvFlt
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
WfHdFlt declared if a WfmvFlt exists on power up or
during a switchover attempt from manual into
automatic
Bell 407 FADEC System Troubleshooting Guide
Page 145 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
WfLimFlag
73-25-04-130
N/A
Parent
WfLimFlag
Fault Description
The ECU has detected that its fuel flow limiter was active for at least 2 seconds
Fault Test Conditions
Continuous when engine is in run mode
Possible Fault Causes
HMU internal contamination, kinked fuel delivery
system supply lines, clogged CEFA filter, faulty in-range
Wf feedback potentiometer signal
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Engine operating on fuel flow limiter for at least 2
seconds
Troubleshooting Prodedure
Monitor WfActual with engine operating at ground idle. Fuel flow should be approximately 100 pph at S.L. If WfActual is > 140 pph, replace HMU. If indications are normal,
perform troubleshooting instructions for an WfmvFlt. Repair if required. Otherwise, after inspecting airframe fuel delivery for kinked hoses, clogged filters, etc., replace HMU. If
contamination is found within the CEFA filter, replace HMU and purge fuel system lines.
Bell 407 FADEC System Troubleshooting Guide
Page 146 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
WfmvFlt
73-25-04-105
Soft
Parent
WfmvFlt
Fault Description
The ECU has detected a problem with its fuel flow feedback input from the HMU Wf potentiometer
Fault Test Conditions
Continuous
Possible Fault Causes
HMU feedback potentiometer intermittant failure, wiring
intermittant between ECU and HMU Wf feedback
potentiometer
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Troubleshooting Prodedure
See troubleshooting instructions for either a WfmvRgFlt or WfmvRtFlt child fault
Bell 407 FADEC System Troubleshooting Guide
Page 147 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
WfmvRgFlt
73-25-04-105
Soft
Child
WfmvFlt
Fault Description
The ECU has detected a problem with its fuel flow feedback input from the HMU Wf potentiometer which has gone out of range
Fault Test Conditions
Continuous
Possible Fault Causes
HMU feedback potentiometer intermittant failure, wiring
intermittant between ECU and HMU Wf feedback
potentiometer
Fault Limits
Low
High
Open Circuit Reading
-121.7 pph
568.0 pph
WfmvRaw < -100 PPH
Special Limit
Troubleshooting Prodedure
Monitor WfmvRaw after power up. Should be approximately -10 pph. Trend data while flexing harness. Analyze WfmvRaw data for signs of signal fallout or a wandering signal.
Replace and repair wiring as required. If OK, replace HMU. Note: Never replace an ECU for this fault. Resistance checks of Wf potentiometer readings are at on fixed position
(shutoff) only. This failure is most likely caused by the internal Wf potentiometer within the HMU but wiring problems have also caused this fault.
Bell 407 FADEC System Troubleshooting Guide
Page 148 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
WfmvRtFlt
73-25-04-105
Soft
Child
WfmvFlt
Fault Description
The ECU has detected a problem with its fuel flow feedback input from the HMU Wf potentiometer which has failed intermittantly
Fault Test Conditions
Continuous
Possible Fault Causes
HMU feedback potentiometer intermittant failure, wiring
intermittant between ECU and HMU Wf feedback
potentiometer
Fault Limits
Low
High
Open Circuit Reading
-121.7 pph
568.0 pph
WfmvRaw < -100 PPH
Special Limit
Troubleshooting Prodedure
Monitor WfmvRaw after power up. Should be approximately -10 pph. Trend data while flexing harness. Analyze WfmvRaw data for signs of signal fallout or a wandering signal.
Replace and repair wiring as required. If OK, replace HMU. Note: Never replace an ECU for this fault. Resistance checks of Wf potentiometer readings are at on fixed position
(shutoff) only. This failure is most likely caused by the internal Wf potentiometer within the HMU but wiring problems have also caused this fault.
Bell 407 FADEC System Troubleshooting Guide
Page 149 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
WfStFlt
73-25-04-121
Hard
Parent
N/A
Fault Description
The ECU has detected that its step count fuel flow is not within range
Fault Test Conditions
Continuous when engine is in run mode
Possible Fault Causes
See possible fault causes for StepCntFlt and WfmvFlt
Troubleshooting Prodedure
See troubleshooting instructions for StepCntFlt and WfmvFlt
Fault Limits
Special Limit
Low
High
Open Circuit Reading
N/A
N/A
N/A
Bell 407 FADEC System Troubleshooting Guide
Page 150 of 150
Fault Name
FIM Task
Failure Type
Fault Level
Fault Test File
WfStRgFlt
73-25-04-121
Hard
Child
N/A
Fault Description
The ECU has detected that its step count fuel flow is not within range
Fault Test Conditions
Continuous when engine is in run mode
Possible Fault Causes
See possible fault causes for StepCntFlt and WfmvFlt
Troubleshooting Prodedure
See troubleshooting instructions for StepCntFlt and WfmvFlt
Fault Limits
Special Limit
Low
High
Open Circuit Reading
-121.7 pph
568.0 pph
N/A
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