Tip: Elevator Trim Hinge Pin

f1rocket · #1 05-18-2005, 12:17 PM

This is an idea that many people have used in the past. Unfortunately, I found out about it after I had built my RV-6. I struggled with finding a way to secure the hinge pin on the elevator trim tab until I saw this technique used on some RVs that I looked at up at Air Venture.

As supplied in the kit, the hinge is longer than what's needed. When you trim the hinge to length, be sure to NOT cut the hinge pin. Leave it long and extending past the end of the elevator as shown above. Now bend the hinge pin so that it will lay across the web of the spar.

Take a spare piece of hinge and cut out one eye. Drill a hole in it for a #6 screw. Slip it over the hinge pin and locate the position of the screw hole in the web of the spar. Remove everything and attach a #6 nut plate behind the hole. The nut plate will fit on the forward side of the elevator trim spar web where it extends past the edge of the inside elevator rib. When you're done, you'll find that you will be able to get a long bladed screwdriver on the screw even with the trim tab mounted and in-place.

mark manda · #2 05-19-2005, 08:57 PM

Well, I got her. All I had to do was chisel out my foam job, and follow the instructions. ( those rivets on the nut plate fought me, didn't want to sit in straight.)

Had to clip a loop off, because the wire/pin wouldn't sit right, Clipped the first one, don't need it anyway; and then I'd wished I'd read line #4 and let it sink in.

I'm a loop short on length on the other end after cutting my wire...

But I got her....

http://www.pbase.com/mark2nite/image/43598455

KayS · #3 06-04-2012, 01:46 PM

thank you randy!

ppilotmike · #4 06-04-2012, 02:12 PM

I like it and have decided to use it on my RV-10 trim tabs. I have already made the bends like Vans calls for. I was waiting to buy a set of safety wire pliers before finally securing the pins. Thanks!

f1rocket · #5 06-04-2012, 04:42 PM

I can't believe I've been on this site for over seven years! BTW, you are welcome.

Buggsy2 · #6 06-04-2012, 09:33 PM

I saw this or a similar post with similar "solution" a few years ago when I too had to secure the elevator trim hinge wire. I didn't like the proposed new method and stayed with Vans' plans, as I have had for most such "improvements".

Vans method -- at least for the -9 -- is to simply safety-wire the hinge wire to the trim spar. Easy, takes a minute, and most important to me, the only failure mode is of the safety wire; unlikely from fatigue since it's quite malleable obviously. Also, easy to look at in a preflight and see if it's broken.

The proposed "improvement" is more complicated, takes considerably longer to install, and has more failure modes: the rivets, the screw, the small clamp. And the failures may not be obvious. The new method offers no improvement but several disadvantages. But it does look better...kinda more engineery.

I post this not to bash the OP but to simply put on record for any newbs out there that there is little reason to depart from Vans plans and methods. When I have done so I have come to regret it.

rockwoodrv9 · #7 06-04-2012, 09:56 PM

Quote:

Originally Posted by Buggsy2

I post this not to bash the OP but to simply put on record for any newbs out there that there is little reason to depart from Vans plans and methods. When I have done so I have come to regret it.

Buggsy2, not trying to bash your thoughts either, but how about the nose wheel? I bet there are quite a few A builders that wish they had modified the plans with the nose wheel. I wish I could plant a Warrior nose wheel on the 9a I am building.

My point is that the RV-1 is not like the RV-4, the 6 is not like the 7. Things change at times for the better. Just because it was designed by Vans, does not mean it is the best that could be done. Production costs, time, and a million other things enter into a kit. I completely agree about following the plans and it will save you time and money. It could save your life if you make a change that has not been engineered correctly. But, there are errors in my 9 plans and there are many ways posted by others that make the build easier and in many cases, better. I go back to the nose wheel. Even Vans finally made an upgrade there. In my opinion, the nose wheel is still the weakest part of the entire plane and without changing from the plans to add strength, I would not be building a Vans at all.

I was out in Sacramento a couple weeks ago near the Exec. airport off Freeport. Boy I don't miss the heat of the Sacramento Valley! I lived in Cameron Park until we moved to Colorado 5 years ago.

Bob Axsom · #8 06-04-2012, 10:24 PM

Quote:

Originally Posted by Buggsy2

I saw this or a similar post with similar "solution" a few years ago when I too had to secure the elevator trim hinge wire. I didn't like the proposed new method and stayed with Vans' plans, as I have had for most such "improvements".

Vans method -- at least for the -9 -- is to simply safety-wire the hinge wire to the trim spar. Easy, takes a minute, and most important to me, the only failure mode is of the safety wire; unlikely from fatigue since it's quite malleable obviously. Also, easy to look at in a preflight and see if it's broken.

The proposed "improvement" is more complicated, takes considerably longer to install, and has more failure modes: the rivets, the screw, the small clamp. And the failures may not be obvious. The new method offers no improvement but several disadvantages. But it does look better...kinda more engineery.

I post this not to bash the OP but to simply put on record for any newbs out there that there is little reason to depart from Vans plans and methods. When I have done so I have come to regret it.

There is a need to use judgement but a I think it is wrong to assume that every assembly method in the RV designs have been carefully studied by great engineering minds and only the best of all possible options have passed the critical design review and ended up as THE way to build the airplanes. The hinge method for mounting the rear bottom of the lower cowl, the alternate air door in the FAB that allowed parts to be sucked into the engine, the hinge pins screwed to the outside of the cowl, the FAB the hits the nose gear strut, the carb heat control connection that wears out in a few hundred hours, the FAB mount plate that was too thin and cracks after a few hundred hours, the canopy skirts that overlap the side of the fuselage, the track hole in the rear skirts that let cold air come into the cockpit on the back of the neck, the open aileron control passage that leads to frozen crotch ... and more are examples where the builder has to look at what they have and think - "there must be a better way." Maybe there is less of this in the RV-9 but I do not agree to going with "good enough" if there is a better way. My trim tab end closure and pin security are different than the one given here or the one on the drawings. They must have been in transition when our kit was produced because it had two or three control horn configurations (complete with parts) in our kit and I made my own. I don't believe it is good for a knowledgeable person to turn a blind eye to things that we know from experience could be better.

Bob Axsom