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RV-9 Manual Trim Tab Slop?

N941WR

N941WR

Legacy Member
Today I had my final EAA tech inspection (The FAA comes on Wednesday) and we found the trim tab can move up and down a bit over a 1/4".

The Tech inspector's 6A w/ electric trim has no slop and my neighbor's -7A w/ manual trim has some slop.

What is "normal" for a -9 w/ manual trim?

Thanks for the help!
 
Zero on the -7A

Bill, I don't know that the system is any different on the -7's but mine has zero play and one of the reasons I like it over electric is the way I can make micro adjustments by feel, in flight.
 
hevansrv7a said:
Bill, I don't know that the system is any different on the -7's but mine has zero play and one of the reasons I like it over electric is the way I can make micro adjustments by feel, in flight.
Click to expand...
Thanks for the info but the -7 & -9's are just different enough here that this doesn't really help much.

I didn't deviate from the plans at all and yet I have all this slop and we are trying to figure out if this is unique to the -9 or not.
 
Trim Tab SLop

Bill,

I assume that you mean if you grab the trim tab, you can move it up/down a bit? My 9A has that. The pin that holds the cable to the trim tab isn't quite as big as the hole itself. You could probably eliminate it with a bushing of some sort. Does he see that as a problem?
 
N941WR said:
Today I had my final EAA tech inspection (The FAA comes on Wednesday) and we found the trim tab can move up and down a bit over a 1/4".
Click to expand...
Bill-
Have you isolated the source of the slop? Is it coming just from the clevis connection? 1/4" just from the clevis pin not being as big as the hole in the trim tab horn seems like a lot. Maybe not though, since we're talking about the tab itself being 4" or so deep. I'm going manual too, so I'd like to know if I should do something different when I get to the installation.
 
N523RV said:
Bill,

I assume that you mean if you grab the trim tab, you can move it up/down a bit? My 9A has that.
Click to expand...
Yes, that is what I'm talking about and it is good to hear I'm not alone.

N523RV said:
The pin that holds the cable to the trim tab isn't quite as big as the hole itself. You could probably eliminate it with a bushing of some sort. Does he see that as a problem?
Click to expand...
alpinelakespilot2000 said:
Bill-
Have you isolated the source of the slop? Is it coming just from the clevis connection? 1/4" just from the clevis pin not being as big as the hole in the trim tab horn seems like a lot. Maybe not though, since we're talking about the tab itself being 4" or so deep. I'm going manual too, so I'd like to know if I should do something different when I get to the installation.
Click to expand...
No, this is not the source. My pin is tight enough I have to really push it to get it in. The slop seems to be coming from the cable itself.
 
Guess I'll go wiggle mine again during preflight tomorrow and see where the wiggle is at on mine. My preflight always includes checking the connection. :)
 
Have you attached the cable with a few clamps at various points along it's run, especially anyplace where there is a bend in the line? If there is a lot of slack in the cable maybe that is causing the problem????? Good luck though. Let us know what you find.
 
Bill,
Some slop is normal with these cables, some more than others. What I did on my -6 is to add a small spring to pre-load the tab one way or the other. This will hold the tab steady.
The cable I bought for my bi-plane has so much slop that I'm considering not using it. I may have to redesign the trim system on it. But then it won't be the first mod on it.
 
I think it is normal

When I built my RV-6A I was concerned about the free movement of the manual trim tab as a possible source of flutter. I called Van's and I was told that the free movement of the trim tab is normal and you will detect no ill effect in flight. So I proceeded and that is exactly what I found to be the case. The function is like dialing a micrometer in flight with little or no dead band and I have flown at red line with no tendency to flutter. My experience only - yours may be different.

Bob Axsom
 
Bob Axsom said:
When I built my RV-6A I was concerned about the free movement of the manual trim tab as a possible source of flutter. I called Van's and I was told that the free movement of the trim tab is normal and you will detect no ill effect in flight. So I proceeded and that is exactly what I found to be the case. The function is like dialing a micrometer in flight with little or no dead band and I have flown at red line with no tendency to flutter. My experience only - yours may be different.

Bob Axsom
Click to expand...
On the way home from work I called Van's and was told the same thing as Bob. So fly on I will.

Thanks everyone for the input!
 
Follow up

With 12 hours now on the airplane, I have had no problems with the trim tab.

(posted just in case someone searched for this issue in the future.)
 
N941WR said:
With 12 hours now on the airplane, I have had no problems with the trim tab.

(posted just in case someone searched for this issue in the future.)
Click to expand...
Just to throw my $.02 in...I have logged over 150 hours in my 9A, and I have the same play in the trim tab. One thing that I notice is the if I encounter a gust in flight, or make an abrupt elevator control input, the trim tab will shift from low to high (or vice versa), and I will no longer be trimmed for level flight.
I think that the addition of a spring would eliminate this minor inconvenience, and I'm going to look into it when I get out to the hangar this weekend.

Ron
N379RV
 
Ron,

I now have 40.6 hours on my -9 and it hasn't been an issue but please let us know how the spring works out.
 
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