Mooney crash ADS

[Marc_B]

CSB recommends: "Inspect at next 100-hour or Annual inspection (whichever is applicable based on type of operation or inspection requirements) or next maintenance event when the camshaft gear is made available (whichever comes first). Continue with recurring inspections every 100-hour/Annual inspection until superseded gears are replaced with camshaft gear, P/N 656818 no later than next overhaul."

So you inspect until you see failure?  I'd be curious to know how many cases of imminent failure or damage have been found prior to critical failure?

 

[MikeOH]

This has to be the most bizzare SB I've seen...they list specific P/Ns that are, presumably, at risk of catastrophic failure, yet allow 'inspection'???  WTH?  Just how are you suppose to inspect a hardened steel gear to determine if it's about to fail in the next 100 hours?

If I 'inspected' and found any of the suspect P/Ns that engine would NOT go back together until that gear was tossed and replaced by the new P/N.

[N201MKTurbo]

You can inspect the gear if you take a mag off.

[MikeOH]

59 minutes ago, N201MKTurbo said:

You can inspect the gear if you take a mag off.

Can you determine/see the part number?

[KSMooniac]

1 hour ago, MikeOH said:

Can you determine/see the part number?

Yes, one of the attached documents outlines the inspection, including carefully cleaning/wiping the gear to read the part number, and rotating the prop until it is visible.

I would be absolutely shocked if anyone could reliably detect any fatigue cracks in situ during such an inspection, though.  And I would suspect the time between a visible crack and failure would be absurdly short, so catching one every 100 hrs/annual inspection would require a bit of luck.

This sure seems like it should have been an AD.  The FAA has condemned many good cylinders for far less than this critical gear that was undersized.

[kortopates]

i believe you have to remove the starter adapter to read the part # on the gear- which is a bit more involved. But the engine doesn’t have to be disassembled to replace the gear.


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[1980Mooney]

19 hours ago, Aerodon said:

As far as I can see this could have been a 1600 or 1800 TBO engine with 2000 hours.

We had an O360 (TBO 2000) that was running fine at 2900 hours.  We made a decision to overhaul at 3000 hours because we did not want to put ourselves in the position of trying to answer that question.

This was not such an easy CSB to comply with and I may not have complied with it.  But this report is making me more conservative, so I think this should be one of the issues to take into account when stretching your TBO

 

21 minutes ago, KSMooniac said:

Yes, one of the attached documents outlines the inspection, including carefully cleaning/wiping the gear to read the part number, and rotating the prop until it is visible.

I would be absolutely shocked if anyone could reliably detect any fatigue cracks in situ during such an inspection, though.  And I would suspect the time between a visible crack and failure would be absurdly short, so catching one every 100 hrs/annual inspection would require a bit of luck.

 

10 minutes ago, kortopates said:

i believe you have to remove the starter adapter to read the part # on the gear- which is a bit more involved. But the engine doesn’t have to be disassembled to replace the gear.

 

3 hours ago, Marc_B said:

CSB recommends: "Inspect at next 100-hour or Annual inspection (whichever is applicable based on type of operation or inspection requirements) or next maintenance event when the camshaft gear is made available (whichever comes first). Continue with recurring inspections every 100-hour/Annual inspection until superseded gears are replaced with camshaft gear, P/N 656818 no later than next overhaul."

So you inspect until you see failure?  I'd be curious to know how many cases of imminent failure or damage have been found prior to critical failure?

This was a Rocket Engineering "Rocket 305" conversion of the M20K.  The owner's Accident Report and Engine Examination in the Docket shows:

• Continental TSIO-520-NB17 (s/n 822302-R) (Rocket always put Factory Rebuilt Cont. Engines in the Rocket 305 and Missile 300 unless the owner specified and paid extra for New)
• The owner stated he owned the plane 22 years and had flown it 2000 hours.  He also stated the engine hours were 2000, and that it had been 2000 hours since Overhaul so that means he bought the used K and had Rocket Engineering convert it in 2000.
• That means the engine had not been overhauled in 2000 hours and 22 years.
  • Continental states that for TSIO-520 below ser. no 1006000, that TBO is 1600 hours and 12 years.
  • Time Between Overhaul (TBO) Periods (captoscana.com)
  • This engine was 400 hours and 10 years over TBO.

[1980Mooney]

2 hours ago, kortopates said:

i believe you have to remove the starter adapter to read the part # on the gear- which is a bit more involved. But the engine doesn’t have to be disassembled to replace the gear.

Correct.  It comes off the back of the engine.  This video shows the gears on a 520 that has been pulled but it can be done in place.