If you have a stabilator, this is worth the watch.

SixPapaCharlie

SixPapaCharlie

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Even if you don't, its interesting. These two are lucky, skilled, or both.
It's long but worth watching. This whole thing seems scary AF.

 
Mostly lucky. This is ERAU 2.0 from where I sit. Garden variety [lack of]M-IF. Typical puppy mill maintained 50 year trainers never meant to be banging around this long anyways (painted over the bolt assembly, appears to be his leading theory). I don't know if he meant proverbially/conjecture, given they never found the bolt? At any rate, a frozen bolt assembly is going to score that bolt and create stress concentrators, the rest is done by fatigue (good ol delta_K, doing the devil's work of crack propagation back there). My engine thrubolt failed (I suspect, the next owner will probably find out what really happened, when they open that literal secret santa special) by fatigue, though through a different mechanism. So this sutff isn't limited to flight control surfaces.

Non-revenue Seneca owners should count themselves lucky this school doesn't cost them another AD (facbuilt FTW). Though in fairness that would be a cheap one, compared to the one I ate on the Arrow (both on implementation, and resale hit) on account of ERAU's moral hazard.

As to stabilators as some sort of widow maker because of the possibility of anti-servo failure? Meh. I no longer own one, but I have no reservations flying them. To each their own as always.


That said, Pipers are death traps, everybody knows that. I'm just grateful anybody was willing to buy me out of that coffin. /s
 
hindsight2020 said:
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That said, Pipers are death traps, everybody knows that. I'm just grateful anybody was willing to buy me out of that coffin. /s
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Is this sarcasm? Pipers are death traps more so than any other 4 place SEL aircraft? Statistics I found don't agree they are any worse, not that the statistics are great for GA in the first place...
 
hindsight2020 said:
Non-revenue Seneca owners should count themselves lucky this school doesn't cost them another AD (facbuilt FTW).
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What makes you think it won’t?

A few more and they will all get combined into one comprehensive Piper AD:

1 - Remove baggage area carpet.
2 - Replace all remaining parts.
3 - Re-install baggage area carpet.
 
Thanks for posting this BrianY. Although I know mine is fairly new as it was replaced with the trim barrel, I’m going to go recheck that bolt and all the other bolts too.

<—-deathtrap driver /s
 
Timbeck2 said:
Thanks for posting this BrianY. Although I know mine is fairly new as it was replaced with the trim barrel, I’m going to go recheck that bolt and all the other bolts too.

<—-deathtrap driver /s
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Yeah, I went and looked mine over after watching this.
It adds a few seconds to the pre flight but if I skip sumping, its a net win.
 
Interesting. The video is borderline unwatchable, but I think I got the highlights. That is a teeny-tiny little bolt. My instructor used to call it "the Jesus bolt" and told me to check it on every preflight. I do check it, but I also know it's really the trim control, and always wondered if the plane would be controllable if it came out. Did the examiner in the video mention specifically pre-flighting that bolt?

In related news, I've been chasing a vibration in my plane, and recently noticed some slop in that bolt. We measured the slop in the tab, and it was well within spec. My mechanic tightened it up anyway and most of the vibration went away. Now I'm worried about what condition the bolt is in.
 
Timbeck2 said:
Ya pull a prank on a guy and he hounds you for the rest of you life :sigh:
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I’m still waiting on an opportunity to try it on someone else. :)

I hate that I don’t go to Tucson for training anymore. Hopefully the new gig will give me the opportunity to come have a beer with the guy in the maroon golf shirt. :)
 
Jim K said:
Now I'm worried about what condition the bolt is in.
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Then replace it prophylactically, and eat the MIF opportunity cost; and present day prices/labor of course.

Don't fret (pun very much intended) about it; 'Fly to fail' is only reserved for those of us "cheapskates" who like to practice our engine-out procedures in Squid Game mode. :D

All that said, given the amount of trash flying out there, stabilator-equipped lawnmowers are not falling out of sky with statistically greater frequency than elevator/stabilizer assemblies, whether conventional or canard arranged. Occam told me: Don't fly puppy mill airplanes and you're largely out of the woods regarding this nonsense.
 
Jim K said:
In related news, I've been chasing a vibration in my plane, and recently noticed some slop in that bolt. We measured the slop in the tab, and it was well within spec. My mechanic tightened it up anyway and most of the vibration went away. Now I'm worried about what condition the bolt is in.
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You should be. Loose bolts get worn thinner on the shank, and they can fail A careful mechanic would have taken the bolt out and examined it.

Such wear is also found in other places. Clevis pins or bolts in the control system, seats and seat backs, and so on. I have found worn clevis pins in Cessna seat backs, worn to the point ready to snap and let the seat back fall back on takeoff. Guess what the pilot uses to pull himself back up? The control wheel and throttle. Crash. All because of a pin worth a lot less than a buck.
hindsight2020 said:
All that said, given the amount of trash flying out there, stabilator-equipped lawnmowers are not falling out of sky with statistically greater frequency than elevator/stabilizer assemblies, whether conventional or canard arranged.
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So far. With the old stuff wearing out and mechanics not catching it, there will be increasing numbers of accidents until the governments force huge ADs on everyone to get the stuff inspected properly. A mechanic is supposed to be suspicious of everything in that airplane, not taking anything for granted. If something is sloppy, why is it sloppy?

Before the school had its own twin, one student took her twin training at another airport, in a Grumman Cougar. She flew it in. Walking past it, the trim tab bellcrank looked suspicious. It was really, really loose. It was attached to the tab with Cherrymax rivets that had wallowed out their holes in the tab. If it fell off in flight, flutter would have torn the tail off almost instantly. Inexcusable, that.
 
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Dan Thomas said:
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With the old stuff wearing out and mechanics not catching it, there will be increasing numbers of accidents until the governments force huge ADs on everyone to get the stuff inspected properly.
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De facto service/calendar limits by insurance companies seems more likely to me, or, less likely, a "major overhaul" requirement for airframes every X decades, but I doubt that, with pilot error being the biggest slice of the accident pie.

I have learned a ton of things as an owner that I would probably not have learned as a renter or club member. There's a "the only way out is through" feeling, a disillusionment, going from unknown unknowns ("doesn't look like anything to me...") to known unknowns ("that doesn't look right...") to preventative maintenance enlightenment. I wonder if there's a better way?
 
So I took the time to watch the whole video. The Examiner mentions that they did make a point of preflighting the bolt in question. Theirs actually had a cotter pin through it in addition to a nylock so the head had to have popped off the bolt. I believe mine is only a locking nut. As I understand that assembly, there's a bronze bushing inside the eye on the rod, and then the bolt actually pinches another bronze bushing to the stamped link, and the only moving surface SHOULD be the the two bronze bushings nested inside each other. The most likely scenario I think is that the bolt got loose and was spinning in the link, and he mentioned (as I understood it, the audio was pretty poor) that they did a visual check but didn't try to turn it. Probably is worth replacing those bolts once in a while as they're both critical and relatively cheap, as well as touching/trying to twist it during preflight. Good to know about, and hopefully someone can capture a better quality version of the speech at some point.... Too bad there's no good youtubers in Texas :biggrin:. Seriously I hope @Daniel Millican would consider having him on.
 
Jim K said:
As I understand that assembly, there's a bronze bushing inside the eye on the rod, and then the bolt actually pinches another bronze bushing to the stamped link, and the only moving surface SHOULD be the the two bronze bushings nested inside each other.
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The internal one might be steel, but that bolt, as you say, is to pinch that internal bushing so that the only movement is between it and its bearing.

This is a common arrangement everywhere on light airplanes, whether the cheap elevator and rudder hinges on the smaller Cessnas or at rod ends on push-pull rods. Also found on Cessna nosegear torque links. A common (and very expensive) problem one is the stabilizer trim pivots on the Cessna 180/185/old 182s; same thing there. But too many mechanics think the bolt is the hinge, and they leave it loose, and stuff gets beat up and worn and torn and cracked.
 
How hard is it to turn those Seneca elevator trim wheels in flight?
 
Jim K said:
So I took the time to watch the whole video. The Examiner mentions that they did make a point of preflighting the bolt in question. Theirs actually had a cotter pin through it in addition to a nylock so the head had to have popped off the bolt. I believe mine is only a locking nut. As I understand that assembly, there's a bronze bushing inside the eye on the rod, and then the bolt actually pinches another bronze bushing to the stamped link, and the only moving surface SHOULD be the the two bronze bushings nested inside each other. The most likely scenario I think is that the bolt got loose and was spinning in the link, and he mentioned (as I understood it, the audio was pretty poor) that they did a visual check but didn't try to turn it. Probably is worth replacing those bolts once in a while as they're both critical and relatively cheap, as well as touching/trying to twist it during preflight. Good to know about, and hopefully someone can capture a better quality version of the speech at some point.... Too bad there's no good youtubers in Texas :biggrin:. Seriously I hope @Daniel Millican would consider having him on.
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AOPA did an Air Safety podcast. Much easier to listen to. Follow the link.
 
Mass Flyer said:

AOPA did an Air Safety podcast. Much easier to listen to. Follow the link.
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Yep, listened to that one last week. Had to be one of Mr. McSpadden's last interviews. Much easier to follow, which some good questions from Dick, as you might imagine. Well worth the listen.
 
Does anyone have a picture/parts diagram or something identifying the specific bolt we're talking about? Is it the one that goes through the jackscrew and connects the arm on the anti-servo tab?
 
If you watch this on youtube, speed the playback up to 1.25. That works really well.
 
cowman said:
Does anyone have a picture/parts diagram or something identifying the specific bolt we're talking about? Is it the one that goes through the jackscrew and connects the arm on the anti-servo tab?
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Screenshot_20240302-170458.png

 
Changed ours out on the club arrow. Now we’re just drawing straws to see who gets to test fly it.
 
cowman said:
Nice, that's what I was looking for.

My next question is should we also be looking at the other bolt(part 108) and the associated bushings? Same basic part and in the same mechanism.
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All of that stuff likely need checking. From FAR 43, Appendix D, which has the MINIMUM requirements for an annual:

1709677073153.png

ALL components and systems in the empennage (tail controls and surfaces). That means that the tail fairing must come off and a good examination of all the stuff in there. Not just a peek with a flashlight through the slot, and a squirt of LPS to sort of lubricate stuff.
 
Dan Thomas said:
All of that stuff likely need checking. From FAR 43, Appendix D, which has the MINIMUM requirements for an annual:

View attachment 126283

ALL components and systems in the empennage (tail controls and surfaces). That means that the tail fairing must come off and a good examination of all the stuff in there. Not just a peek with a flashlight through the slot, and a squirt of LPS to sort of lubricate stuff.
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I know my A&P always has that fairing off at annual but as far as I know he just looks it over and lubes everything. If I understand this issue correctly you wouldn't be able to detect a problem without removing the bolt which I don't expect most mechanics would do without a reason.
 
Question: I know some people have mentioned they've replaced the in-question stabilator bolt prophylactically.

However has anyone inspected their stabilator bolt and found it - or the cotter pin - to be actually defective in any way?
 
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