Incident Diamond DA42 Twin Star F-HCTE, Wednesday 17 February 2010
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Date:Wednesday 17 February 2010
Time:
Type:Silhouette image of generic DA42 model; specific model in this crash may look slightly different    
Diamond DA42 Twin Star
Owner/operator:CNFA (SFACT)
Registration: F-HCTE
MSN: 42.360
Fatalities:Fatalities: 0 / Occupants:
Other fatalities:0
Aircraft damage: None
Category:Incident
Location:Muret-Lherm Aerodrome, Haute-Garonne 31 -   France
Phase: En route
Nature:Unknown
Departure airport:Muret-Lherm Airport (LFBR)
Destination airport:Saint-Yan-Charolais Bourgogne Sud Airport (SYT/LFLN)
Investigating agency: BEA
Confidence Rating: Information verified through data from accident investigation authorities
Narrative:
The pilot explained that during the climb to 3000 feet, the "R ECU A FAIL" and "R ECU B FAIL" alarms came on. He noticed a simultaneous slight power loss on the right engine. The pilot applied the abnormal procedure "L/R ECU A FAIL". He pressed the "ECU test" button for more than two seconds, the alarms disappeared but the power indication of the right engine did not vary. The pilot decided to divert to Carcassonne. When he arrived at his destination, shortly before the start of the IFR procedure, the "R ECU A FAIL" and "R ECU B FAIL" alarms lit up again, without any change in the right engine parameters. Pressing the "ECU test" button did not make these alarms disappear. The pilot landed without other problem.
On the ground, the piping of intake air pressure on the channel B of the FADEC was found pierced.
The visual examinations carried out on the pipe revealed two cracks, one on the inner layer, the other on the outer layer, allowing an air leak and which could explain an erroneous information of the air inlet pressure on the FADEC channel B. No pre-damage was observed in the area of the two cracks.

 The engine manufacturer explains that with the software version installed on the FADEC on the day of the incident, the logic was as follows: the two channels (A and B) of the FADEC compare their information in real time. When a discrepancy is detected, the switch to the second channel is automatic and definitive. In the F-HCTE incident, channel A was active and, after detection of the deviation, the switchover to channel B was therefore automatic. However, since the fault was located on channel B, the erroneous measurement was retained for the regulation of the right engine.
 The FADEC worked with software version 2.7. Since version 2.9, available since July 2008, this logic was modified: the identification of failures of the active channel is delayed by half a second. As a result, the inactive channel identifies failures first. This prevents the automatic switchover to the inactive channel if its health level is already degraded.

 Conclusion: The incident (decrease of the motor power) was due to :
- the failure of the intake air pressure tap pipe,
- the use of an obsolete software version of the FADEC.

Sources:

https://bea.aero/en/investigation-reports/notified-events/detail/diminution-de-la-puissance-dun-moteur-en-croisiere-deroutement/

Revision history:

Date/timeContributorUpdates
12-Oct-2022 08:38 harro Added

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