wing low

How to keep the Cessna 170 flying and airworthy.

Moderators: GAHorn, Karl Towle, Bruce Fenstermacher

Post Reply
Buckeyejim
Posts: 44
Joined: Sun Mar 11, 2018 9:41 pm

wing low

Post by Buckeyejim »

Even with no damage history, the left wingtip of my 170 is about 4" lower than the right wingtip. So I guess I need to add
washers under the left gear leg at the attach bolt. Any suggestions on how thick they should be?
User avatar
GAHorn
Posts: 20967
Joined: Fri Apr 12, 2002 8:45 pm

Re: wing low

Post by GAHorn »

According to a hand-written note (author unk.) in the docs I rec'd from my predecessor Tom Hall, AN960 washers will each contribute approx. 1" in wingtip height. (Guessing that a "thin" AN960L washer will affect it 1/2".) First check the opposite side to make certain no one as any installed over there which should be removed. Also, confirm that your tires are evenly worn (new?) and evenly inflated. The wingtips should be within 3" of each other at gross wt. evenly distributed.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
Buckeyejim
Posts: 44
Joined: Sun Mar 11, 2018 9:41 pm

Re: wing low

Post by Buckeyejim »

So if I install 2 washers under the left axle that should raise the left wingtip about 2", right? Will the
right wingtip drop by 2", making things more or less even?
User avatar
GAHorn
Posts: 20967
Joined: Fri Apr 12, 2002 8:45 pm

Re: wing low

Post by GAHorn »

I've already told you more than I know about it. :lol:

I've not actually performed this work, ...but thinking about it.... No... it would not likely lower the opposite side the same amount because you won't be rotating the aircraft about it's center axis. The opposite wingtip should drop somewhat, however. In fact, it's not clear that the note actually meant to raise the wingtip a full inch.... it might be implying that one washer will affect a 1-inch correction over-all. Quote: "Each washer will change the wingtip levelling one-inch."

If I knew that Tom Hall personally made that notation I'd feel a lot better about it, but he was only passing along to me what he'd received by His-predecessor. This notation may be only as reliable as those often found in the now out-of-print SRAM, which was full of anecdotal and incorrect advice.

It's important you have the aircraft weight equally distributed, of course.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
User avatar
ghostflyer
Posts: 1390
Joined: Mon Apr 21, 2008 3:06 am

Re: wing low

Post by ghostflyer »

This is a issue that a lot of people beat themselves over , and there is a procedure that you carry out first or you will get incorrect result on if your wings are not level
1. Even ground .
2. Equal fuel in all tanks
3. Loaded evenly inside the aircraft
4. Plum bob and string from a datum point under the fuselage which is fixed point as close as you can where the undercarriage spring enters the fuselage.then measure this distance to the ground and measure then the distance to a point where the axle is bolts to the undercarriage. You are measuring the 2 sides of a triangle. This will tell you that if you could have a bent undercarriage spring.plus then check for washers and correct attachment of undercarriage spring to fuselage. My aircraft has had its shim pak incorrectly fitted .its back to front ,been done long before I took ownership. Aircraft tracks great along the ground . I am leaving there .
5. Check you have the right struts on both wings . [found a 170a in Canada that had been flying for years with wrong struts and both previous owners didn’t know. It flew ok.
6. Check the wing tips are evenerly fitted .
7. Then measure from a position inline with the main spar from the wing tip to the ground .
User avatar
ghostflyer
Posts: 1390
Joined: Mon Apr 21, 2008 3:06 am

Re: wing low

Post by ghostflyer »

To a follow on from my last post and not wishing to scare you but check the main spars on both wings . Are they “straight “. We had a case here in Australia where a new owner when after landing noticed when he was walking away from his his aircraft the right wing was slightly up . The spar had corroded outboard of the strut attach point and had started to break. [this was sold as a 170b but it wasn’t but a 172a modified to look like a 170b. ,with no paper work and the rear of a fuse large of a 170b grafted on a fuselage of a 172a. ][again ,I was not involved in any way with this aircraft modification]. The joke around here as it was know as the 170 1/2 or 171.
User avatar
cessna170bdriver
Posts: 4059
Joined: Mon Apr 22, 2002 5:13 pm

Re: wing low

Post by cessna170bdriver »

Call Del Lehmann at Mountain Airframe in Mena Arkansas (search here forums or google). He performed this procedure on my B-model.
Miles

“I envy no man that knows more than myself, but pity them that know less.”
— Thomas Browne
Buckeyejim
Posts: 44
Joined: Sun Mar 11, 2018 9:41 pm

Re: wing low

Post by Buckeyejim »

I called Mr. Lehmann and he confirmed that in his experience one 960 washer shim will raise the wingtip about 1".
Limit is 3 washers. So we'll give it a go!
Buckeyejim
Posts: 44
Joined: Sun Mar 11, 2018 9:41 pm

Re: wing low

Post by Buckeyejim »

We inserted 3 AN 960 washers under the left gear leg at its attachment point. As before, I used a water level to compare the wing tip
heights. Of course I made sure the wheels were on a level floor, with axle heights off the floor identical. Now the left wingtip is 3/4"
higher than the right, compared to 4 5/8" lower before shimming.

So 3 washers changed things by a total of 5 3/8". So each washer is good for a bit over 1 3/4" total change in wing tip heights.
Your results may vary!
Post Reply