The International Cessna^® 170 Association

The very first day I saw my airplane-to-be, I noticed a fixed trim tab on the left aileron, which struck me as unusual, since Cessnas have adjustable wing incidence thru eccentric bolts. My airplane flies dead ahead, and has always made book cruise speeds, which in a low-powered airplane like the 170 indicates proper rigging.

I'm curious about this. Everything seems to line up at the fuselage-wing fillet and the flap/aileron intersection. I haven't checked the actual postion of the eccentrics, and I'm not about to change anything, since it flies so well. The tab is bent up about 7-8 degrees. Does anyone else have a fixed trim tab on their 170s aileron?

Russ Farris P.S. I'm reasonably sure it isn't legal, since the original design didn't have one and no logbook entry mentions it, let alone a 337.

Russ,

I looked at a '52 that was for sale that had the same thing. The
makeshift aileron trim tab was actually protruding *way* up into the
slip stream. To his credit, the owner was honest and said he didn't get enough washout in the wing during the rebuild (the a/c was damaged during a groundloop and subsequently rebuilt). I don't know how
you'd do it, but perhaps try to get your a/c on a level piece of
concrete, level it as best you can and verify the washout in each
wing is as it should be. Any other ideas folks?

Bela P. Havasreti
'54 C-170B N170BP

Bela,I think I know which 52 you looked at,as I recall the conscientious (spelling?) seller rebuilt the wing AGAIN to get it right. Don't know if the need for the trim tab went away or not. Can the gentleman in question enlighten us?

Eric

I have a Aerotrim electric trim tab on my left aileron which was there when I bought it. I was very excited about this but found out that it made very little difference full up or full down to the trim of the plane. You may find out the same thing if you remove your tab. Of course this makes no sense but thats the way it is for my plane.

russfarris wrote:The very first day I saw my airplane-to-be, I noticed a fixed trim tab on the left aileron, which struck me as unusual, since Cessnas have adjustable wing incidence thru eccentric bolts. My airplane flies dead ahead, and has always made book cruise speeds, which in a low-powered airplane like the 170 indicates proper rigging.

I'm curious about this. Everything seems to line up at the fuselage-wing fillet and the flap/aileron intersection. I haven't checked the actual postion of the eccentrics, and I'm not about to change anything, since it flies so well. The tab is bent up about 7-8 degrees. Does anyone else have a fixed trim tab on their 170s aileron?

Russ Farris P.S. I'm reasonably sure it isn't legal, since the original design didn't have one and no logbook entry mentions it, let alone a 337.

Yep. It's illegal.

Lets say that you discover some mod that was done to your plane that is not legal, such as the addition of the trim tab to the aileron. What do you do to correct it. In other words, now that you know it's not legal do you have an A&P remove it? Try to get it field approved? Never mention it again and hope you're never caught?

Dave

Dave, I'd recommend playing the dumb route. Stay quite and enjoy the mod if you like it. You might think that trying to correct and/or generate the paperwork to make it legal is the right thing to do...and I suppose it is, but I think once you start down this road with the FAA you'll wish you had your fingernails pulled out one by one instead. You have heard the old saying that it is far better to just do something and ask forgiveness later vs. ask permission which probably would not be granted? I think this works for airplanes as well.

Luckily I am not in this position. I don't think playing the dumb route will work. If I go and fly my plane around with uncomplied AD's and the FAA finds out they will not be happy. Does not matter if I am an A&P or not, as the owner/operator I am required to ensure my plane is in airworthy condition and all maintenance has been done.

dkalwishky wrote:Luckily I am not in this position. I don't think playing the dumb route will work. If I go and fly my plane around with uncomplied AD's and the FAA finds out they will not be happy. Does not matter if I am an A&P or not, as the owner/operator I am required to ensure my plane is in airworthy condition and all maintenance has been done.

In that case you need to either have it removed, or get the field approval. Unless you think it is a real useful item, it would be much simpler to have it removed as it is getting very difficult to get field approvals.

If you plan on removing the aileron trim tab,you need to correct the problem that prompted it's installation in the first place. I would tweak the tab to a faired (neutral) position,and see how she flies. Check the rear spar eccentrics (both sides),are they adjusted up or down as much as possible to correct the out-of-trim condition? You can also adjust the flap-up position (both sides) to correct an out-of-trim condition,if the eccentrics don't give you enough.
Is there a 337 or logbook entry indicating a major wing repair? Or anything else apparent which would cause an extremely out-of-trim condition which could not be corrected by normal means?

Eric

I was about to write a post when I saw Eric's response. DITTO!! Move the trim tab to faired, then fix the problem. Then remove the tab forever. Rig all flight controls to factory call out, then adjust excentrics as needed, then drop a flap a little if needed. Most of the time its not needed. A lot of people put on a tab because its easy not because its needed.

Kelly

I bent the aileron tab back to neutral, then flew the airplane. It wanted to roll to the right a little in cruise, so I then bent the rudder tab to correct. Perfect! It flies dead ahead, with the ailerons neutral and the ball centered, hands-off. Makes me wonder why the stupid aileron tab was installed in the first place. I'll remove it after Sun-N-Fun. Russ Farris