Das ist auch auf Beechtalk ein großes Thema. Natürlich.
Hier der Post von Matt Anker - Das war der mit der engine failure von der Mike Busch spricht. Lucky he can talk about it. Engine Failure in IMC, und es zur nächsten Piste geschafft.
Er hat jetzt sozusagen sein eigenes AD, Zitat "Good thing I have a sense of humor. Better to have your very own AD than a place in a NTSB report."
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"I received a phone call from my friendly CMI air safety investigator this afternoon regarding my engine failure back on December 26th, 2015. This was off the record, verbal stuff, to keep their legal department happy.
Reference the original thread:
https://www.beechtalk.com/forums/viewtopic.php?f=41&t=117010
The initial investigation was contained in that thread:
https://www.beechtalk.com/forums/viewtopic.php?f=41&t=117010&start=237
I didn't feel like resurrecting it in CrashTalk.
So in summary, to those late to the game, or those who haven't read Nate's e-book, I had an in flight engine failure in a 2001 CMI zero-timed IO-520-BA because the cam gear shed about 3 teeth, then promptly proceeded to machine clearance out of itself where the cam shaft stopped turning. My P/N was 655516A. You can go to the thread referenced above to see all the gory pictures.
The new revelation today was that the metallurgical analysis revealed that the gear failed "in fatigue" and that there were no metallurgical defects found.
Now here's what's going on in the background with the FAA ACO regarding the failure. . .
CMI has a new cam gear called the 656818 with a wider face that must have come out in 2009, and has zero Service Difficulty Reports (SDR) against it. The one previous to it is the 656031, which presumably came out in 2005, has 2 SDR against it for premature wear and tooth shedding. Prior to that were the 655516 and 631845 which all have failure history.
In 2005, revised in 2009, CMI issued the service bulletin SB 05-8A specifically covering these gears, and calling for them to be retired at overhaul or any time the case is split.
https://www.tcmlink.com/pdf2/SB05-8A.pdf
Depending on how many failures can be linked to these parts, and the extent of the carnage, you could see an AD on this in the future. This would target inspections on engines built during a specific data range that have not shown compliance with SB05-8A targeting specifically the cam gear or SB97-6B which specifies mandatory parts replaced at overhaul. There typically isn't any logbook data specifying which gear is installed. I suspect the suspect gears could be identified by inspection with the starter adapter removed to allow measurement.
To be very clear. . . . I'm not personally lobbying for any airworthiness directive on this matter. I'm not dead, my overhauled engine no longer has the affected part.
However, if you have an engine that may have this gear, you might think twice about stretching past TBO. The fact that fatigue cracks are occurring is a very scary design flaw, and it gives zero warning (like making metal). It's clearly known to CMI, and a matter of time before a FAA cost-benefit analysis could turn it into an AD. Make of this what you will."
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Dieser Post stammt vom Juli 2016, und Matt sieht das mögliche Eintreten einer AD ja bereits voraus. Der Rest der Gespräche sind im Wesentlichen Fragen, ob nicht TCM hier liable ist.
