Loose trim tab actuator during ferry flight

[fatsportpilot]

I bought a used Dova Skylark and it's in the process of being ferried to California. The ferry pilot felt some vibration that got worse at high speeds, and he slowed it down to 60 kts to land safely. It turns out that something holding the trim tab actuator got loose.

What could have caused this to be missed during the prebuy? Is there a specific part that is likely to break on this airplane or was this just bad luck?

I'll know more details about this later when it gets repaired but that'll take a while.

[ShawnM]

It appears that the servo trim motor has come loose from its mount. You'll have to drill out those 7 perimeter rivets on the plate that holds the trim servo. Then you can drop it out of the elevator and see what came loose. I'd suggest some nut plates instead of rivets on the reinstall so it's easier to service in the future. Looks like a simple fix though.

[JimParker256]

As for the "how could this be missed on a pre-buy?" question, that falls into the "you'll never know the true answer to that" category. The trim time could have still been absolutely fine during the pre-purchase inspection, then come loose during the ferry flight. If it was already loose, then the ferry pilot also missed it, so to me this is the most likely scenario... Stuff happens.

But if we're honest about our capabilities as human beings, it could have been ever-so-slightly loose, but went unnoticed during both inspections. We'd all like to think "I would never have missed that!" but the reality is that we can, and do, make honest mistakes all the time. Hopefully, we survive those mistakes long enough to learn from them. I'll wager that the trim tab actuator mount will receive a lot more scrutiny by your ferry pilot going forward!

I went to Utah to pick up my RANS S-6 a few years ago. It had just come out of a very thorough annual inspection conducted by a trie RANS "guru" and was in amazing condition. I conducted multiple pre-flight inspections and made several flights in it (did some transition training before flying it home). I spent extra time learning all the "systems" on the airplane, and distinctly remember going over the elevator trim mechanism with the CFI. As it turns out, two different A&P/IAs, the CFI, and myself all overlooked an ever-so-slightly loose retaining screw securing the trim cable sleeve at the elevator. It wasn't loose enough to turn by hand, but apparently just loose enough that 7 hours of air loading on that trim tab caused the sleeve to begin creeping ever-so-slowly towards the tail - effectively removing the "nose-up" trim. After a few hours of ferry flight, I noticed that I was having to apply a good bit back-pressure on the stick (even with full nose-up trim) to maintain level flight, but it came on so gradually that I though I was just getting tired. It wasn't until I got home and did a very thorough inspection of the trim system that I discovered the problem. Once the cable was returned to its proper position, and the screw tightened down (with some TorqLock applied), all was well.