[N40ES]

RV10, I didn't build it but I have been owning, maintaining and flying it for over 7 years. Recently during pre-flight inspection my daughter noticed the elevator trim tabs are in different positions as relative to the elevator. So we tested by running them up & down and when the right tab is full up the left tab stays in neutral position, but when both tabs are put in a neutral and/or full down position they are equal. It seems as if while the tabs are moving up together the left side stops at neutral or slightly above neutral and the right side keeps on moving up to the max up position. Is this normal or is there a setting (other than the cable ends) that can be adjusted by the recently installed Garmin G3X?

 

[Jesse23]

The asymmetrical position is by design. If it’s tracking as it should either hand flying or with AP, you should be fine.

 

[Bill.Peyton]

You need to purchase the builders manual. It sounds like you trim is operating as it should

 

[rocketman1988]

It’s normal operation.

Probably more complicated than it needs to be but normal for the -10.

 

[BobTurner]

If rigged correctly both tabs should be about the same in cruise - minimal torque on the elevators.

 

[Carl Froehlich]

It’s normal operation.

Probably more complicated than it needs to be but normal for the -10.

Yep - and one has to wonder why Van’s did this Rube Goldberg design. The story I got was the original plan was for a standard trim motor mounted in one elevator connected to the one trim tab as done for the other RVs. The other trim tab linked to the flaps to put out a fixed amount as the flaps go out.

But only a story…
Carl

 

[BobTurner]

Yep - and one has to wonder why Van’s did this Rube Goldberg design. The story I got was the original plan was for a standard trim motor mounted in one elevator connected to the one trim tab as done for the other RVs. The other trim tab linked to the flaps to put out a fixed amount as the flaps go out.

But only a story…
Carl

I’ve heard the same story. So it must be true. -

 

[rocketman1988]

Using a bell crank with differential travel would seem to accomplish the same result while being far simpler to execute.

 

[Richard Connell]

If rigged correctly both tabs should be about the same in cruise - minimal torque on the elevators.

At light weight fwd CG or at gross and aft CG?
What I don’t like about this setup is the obvious complexity plus the fact that the single tab up, twisting action is inevitable at some load configuration at cruise speed. (To be fair all the other RVs are like that too)

Could be related to the early tailcone bulkhead crack SB.

I know someone who many years ago proposed a different mechanism that moved both tabs symmetrically in both directions. Even machined up some fittings to make it all work.
Seemed a reasonable idea to me. He got a talking to from vans.

There’ll be lots of discussion here to search.

Bottom line, definitely read the manual. It takes some fiddling to get it spot on. You don’t want to see one tab up and one down close to neutral.

 

[Mike S]

I’ve heard the same story. So it must be true. -

Ditto.

 

[kiwipete]

Tim has an excellent explanation and write up on his website.

Re-Rigging the Trim Tabs - PLUS - Completing Van's Service Bulletin SB-8-6-1

regards Peter