Elevators safety and trim tab function

[lucaperazzolli]

I was thinking about the safety of the elevator and trim function.

My idea : in the rare case that the nut&bolt go off from the elevator horns linkage, the airplane will have two elevators free into the wind

It's ok, the pilot will need to control the pitch with engine and trim...BUT we have the trim tab only in the left elevator

Probably it's supposed (by design) that the pilot will have less pitch control with only one elevator and the other one will stay 'neutral' with no catastrofic event ...

Maybe a simple hole/bolt/spacer/nut between the horns will solve this case.

What's your thought about ?




ps: the nut in the image is a temporary one !

[lucaperazzolli]

No curiosity or thughts about ?

[Ron B.]

You should have purchased the RV-10 as each elevator has a trim tab!!! Just joking. I don't have enough experience to have a serious opinion.

[pierre smith]

One of our airshow pilots, Sean Tucker, had the rod-end bearing housing break during a snap roll, losing elevator control a few years ago. It was a high-powered Pitts and he decided that he couldn't land it, so he went up to near 10,000' and jumped out over open land.

That airplane had elevator trim as well.

I'd just keep a close eye on all control systems at each annual/condition inspection, Luke.

Best,

[roee]

Luca,

It seems to me the best solution to protect against the scenario you describe is simply to make sure the nut can never back out inadvertently. And that's easy to do. Instead of the lock nut shown in Van's drawings, use a drilled bolt + castle nut + cotter pin. Personally, I do this on all the critical flight control linkages.

-Roee

[lucaperazzolli]

Originally Posted by pierre smith

One of our airshow pilots, Sean Tucker, had the rod-end bearing housing break during a snap roll, losing elevator control a few years ago. It was a high-powered Pitts and he decided that he couldn't land it, so he went up to near 10,000' and jumped out over open land.

That airplane had elevator trim as well.

I'd just keep a close eye on all control systems at each annual/condition inspection, Luke.

Best,

Thanks Pierre. I remember the Sean T. story and I spoke with him about in Oshkosh 2006, probably we need ten flying lives to stress our rv just an half that he does in his Pitts routine

I have a plexy window for my horns bolt so I take a look on it at every pre-flight (and a good check on annual too).

I like to have an opinion from the community because I had an extensive DAR talk yesterday helping a friend into the certification process of his F1 Rocket Evo (that has the same RV horns & trim system); he pointed his attention on this problem. I like share it with you.

[lucaperazzolli]

Originally Posted by roee

Luca,

It seems to me the best solution to protect against the scenario you describe is simply to make sure the nut can never back out inadvertently. And that's easy to do. Instead of the lock nut shown in Van's drawings, use a drilled bolt + castle nut + cotter pin. Personally, I do this on all the critical flight control linkages.

-Roee

Yes, IMHO a pal-nut is another option. So you don't have to change the design idea. Thanks !

[pierre smith]

Luke, not to be sarcastic but this fits into the category of problems to solve, that don't really exist.

Thousands of RV's are flying and only a -10 had an elevator pushrod detach...builder error.

Best,

[lucaperazzolli]

Originally Posted by pierre smith

Luke, not to be sarcastic but this fits into the category of problems to solve, that don't really exist.

Thousands of RV's are flying and only a -10 had an elevator pushrod detach...builder error.

Best,

Touch?

You are right !

[David Paule]

Use an MS17825 self-locking castelated nut with a drilled bolt and a cotter pin for additional assurance that it'll stay connected.

Dave