Cirrus France wrong engine repair causes SR22 crash says BEA report

[SR22lover]

N19BV SR22 2016 crash with aircraft destruction and serious injuries because of Cirrus France - Aerolithe wrong engine repair and lack of mandatory inspection says November BEA (French NTSB) official report.

[possel]

Here's the missing link, and click on "publications": https://www.bea.aero/en/investigation-reports/notified-events/detail/event/accident-to-the-cirrus-sr22-registered-n19bv-on-05162016-at-ailly-sur-somme/ (https://www.bea.aero/en/investigation-reports/notified-events/detail/event/accident-to-the-cirrus-sr22-registered-n19bv-on-05162016-at-ailly-sur-somme/)

[rnzoli]

Thanks for the link.
The pilot's decision making is also interesting.
Loss of alternator not deteced for c.a. 20 minutes.
Then pilot sees battery low alert, and consider continuing to destination.
Then pilot decides not to land on the aerodrome directly under him, but continue to another airport for the sake of convenient repair.
Then engine power is gone before reaching the diversion aerodrome, so pilot decides to make a precautionary off-aerodrome landing at a suitable spot.
Then pilot activates BRS chute at too low altitude, without remembering it.

Being caught off guard in the first place seems to be a trigger for a lot of bad choices later on. Those who have the benefit of detecting the problem earlier are better at assessing the implications and making up a better action plan, I guess.

[Grummaniser]

Can anyone with the necessary knowledge of mechanical engineering explain how the different faces of the thrust washer affect its operation. Just interested...

[Pilot DAR]

Complete guess on my part, but perhaps it was intended to read thrust bearing. Many accessories have two opposed thrust bearings, one each end of a shaft. If they are not installed so as to oppose each other, the shaft may move out of position. I've seen this mistake made on other Continental accessories, and am always careful to watch for it.

That said, I'm not sure I see how an alternator failure would cause a need for an urgent landing, or parachute deployment . The aircraft will be certified for 30 minutes flying on the battery, and thereafter the engine will still run, even with a flat battery.

[rnzoli]

That said, I'm not sure I see how an alternator failure would cause a need for an urgent landing, or parachute deployment . The aircraft will be certified for 30 minutes flying on the battery, and thereafter the engine will still run, even with a flat battery.

Here is the answer from the report "The alternator driven gear (No 4 on Figure 3), situated at the front right side of the engine was found embedded in the inner left wall of the engine housing which was pierced, also puncturing a machined oil duct in the housing (see Figure 4)."

So not only the pilot failed to recognize the lack of charging for nearly 20 minutes (out of the certified 30 minutes on battery), he also failed to recognize the escape of oil from the engine. He elected to make a precautionary landing due to reduction of engine power, which means that the engine was out of lubrication by that time. Although the report doesn't specify when the alternator-driven gear pierced the oil line, it is not so difficult to imagine that it also happened at the time of the alternator failure.

Which even more underlines that while troubleshooting one problem, we shouldn't develop a tunnel vision for many reasons. One of them is that multiple systems may be effected, more than the one we currently focus on.

[Jonzarno]

Complete guess on my part, but perhaps it was intended to read thrust bearing. Many accessories have two opposed thrust bearings, one each end of a shaft. If they are not installed so as to oppose each other, the shaft may move out of position. I've seen this mistake made on other Continental accessories, and am always careful to watch for it.

That said, I'm not sure I see how an alternator failure would cause a need for an urgent landing, or parachute deployment . The aircraft will be certified for 30 minutes flying on the battery, and thereafter the engine will still run, even with a flat battery.

And on a Cirrus you still have the equipment powered by the No 2 Alternator which powers the Essential Bus.

[Grummaniser]

Complete guess on my part, but perhaps it was intended to read thrust bearing. Many accessories have two opposed thrust bearings, one each end of a shaft. If they are not installed so as to oppose each other, the shaft may move out of position. I've seen this mistake made on other Continental accessories, and am always careful to watch for it.

Thanks. Now that I've looked more closely at the photos I can see that it's a more complex profile than just a plain washer. Apologies for the thread drift - back to the main story!

[Pilot DAR]

Apologies for the thread drift - back to the main story!

Very worthwhile thread drift discussion, and thanks to Rnzoli for the added information, that makes a lot more sense....