It could have ended differently---a lot differently

[donkaye, MCFI]

27 minutes ago, LANCECASPER said:

@Amelia 2016

 

Some people have great memories.  I just reread that thread.  I even had posted in it.  This issue has been around long time.  I think it should have been an AD to get it fixed, then everyone would have known about it.  It is easy to Monday morning quarterback.  And it's often helpful.  I'm going to check it out on my airplane, but the manual was not clear to me that disabling ESP with the AP on also disables it with the AP off.   Had I tried it before, I don't think I would have turned it off, and the issue would have resolved itself with an immediate down trim.  But that would have just masked the problem.  The fact is that a servo can cause the trim jackscrew to lock up if the SB has not been implemented and that is a major issue that should be addressed before an accident happens.  Even knowing the issue was discussed 9 years ago here didn't help because I had forgotten about it.

Regarding other solutions such as bank angles;  We were configured for slow flight with gear and full flaps.  I'd be a little reluctant to go into a bank of greater than about 20° due to stall speed increase.  That being the case 20° is not going to help much because the wing isn't loaded enough.  At 45° where it would help, the plane would already have gone into a spin, having stalled earlier.

[Marc_B]

I might have missed it but what changed to have some year models have the service bulletin and others not?  What did Mooney changed in ~1990 that changed this behavior??

Was it just incorporation of a stepped stop nut around 1990?  Any pictures of original vs stepped?

[Will.iam]

Probably a shorter jack screw. Boeing fixed theirs with the same problem by using a shorter travel jackscrew as they didn’t need that much up trim. 

[PT20J]

The original service instruction, SIM20-88, was issued in 1990, so the change would have probably been incorporated in production airplanes around that time. My 1994 MSE came from the factory with the stepped nuts.

We often hear that service bulletins (mandatory or otherwise) need not be complied with for part 91 operations, and this is true. But, sometimes complying is the smart and safe thing to do. The owner/operator is primarily responsible for maintaining the aircraft in a safe and airworthy condition. It's not difficult to search Mooney's website for all the SIs and SBs that apply to your airplane and check the logbooks to see which have been complied with. 

[Slick Nick]

30 minutes ago, PT20J said:

The original service instruction, SIM20-88, was issued in 1990, so the change would have probably been incorporated in production airplanes around that time. My 1994 MSE came from the factory with the stepped nuts.

We often hear that service bulletins (mandatory or otherwise) need not be complied with for part 91 operations, and this is true. But, sometimes complying is the smart and safe thing to do. The owner/operator is primarily responsible for maintaining the aircraft in a safe and airworthy condition. It's not difficult to search Mooney's website for all the SIs and SBs that apply to your airplane and check the logbooks to see which have been complied with. 

My 1991 MSE came with the stepped nuts also. They probably implemented the fix pretty quickly on the assembly line.