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Wobble/Play in elevator trim tab

AllThumbs

Well Known Member
I have an RV-6 (built by previous owner) with manual flaps and elevator trim. The trim shaft connection to the trim tab has a nut and cotter which seems typical but there is noticeable up/down play (1/4 inch) in the trim tab. Part of this play seems to be in the attach point to the tab and a little bit is in the solid metal shaft that connects to the cable.

So, my question is what is normal for a manual trim installation. I've been inspecting all the moving parts and rib/spar attach points very carefully after that tail crack was discovered...
 
Yes I think it is normal

When we built our RV-6A with manual trim I saw the play and called Van's. They assured me it is normal and after 1000+ flight hours over 9 years and over 50 air races at well over 200 mph I have satisfied myself that they were right. Your situation is your own unique case of course but the amount of deflection described is very similar to mine.

Bob Axsom
 
Pretty sure most of the play comes from the control knob end of the cable. Mine is pretty tight at the tab end.
 
Here's Van's answer to me on this question followed by my original question


It's actually in the cable, and there's no practical way I know to get it out. It's been there for
literally thousands of airplanes and never caused any trouble.

I tried a spring at the attach end, but it restricted the movement and prevented full travel. I
elected to fly with the play, and 1100 hours later, it still does the same thing and still hasn't
been a problem.

Forwarded by: "Support" <SUPPORT>
Forwarded to: kenS
Date forwarded: Thu, 26 Apr 2012 13:04:37 -0700
To: <[email protected]>
Subject: trim tab wiggle with manual trim
Date sent: Thu, 26 Apr 2012 12:16:48 -0700

Almost all RV's I've seen with manual trim, including Mike Seager's
RV-7, have about a 1/4" of play in the elevator trim tab. Is there
any way you know to eliminate that? I'm about ready for a DAR
inspection and want to make sure everything is as ready as can be.

Steve
91132
 
I was a bit concerned about it on the RV-6 I bought, there's a bit of flex in the cable and at the attach point just as you describe. The trim is very positive and predictable to use so I consider it normal now.
 
Thanks for the feedback

Thanks, all, for the responses. I feel better about it now.

I know it's something I've touched and wiggled hundreds of times during pre-flights but it just jumped out at me this last time when I decided to shine a flashlight into more dark corners of the airframe. I should do that more often as it gives everything a "new" look that forces me re-examine potential issues I may have grown too comfortable with.

My initial concern was for flutter as seen on the Reno P-51s. I don't go quite as fast, of course. :)

Thanks
 
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