170A Flap Spring Issues

How to keep the Cessna 170 flying and airworthy.

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170A Flap Spring Issues

Postby kidalways » Wed Oct 12, 2011 1:57 pm

To all,
I am a brand new owner of a 1950 170A - I have had the plane for about two months now and have had a good opportunity to list all my likes and dislikes with the aircraft. Love the plane - love it's capabilities. Not so crazy about the flap setup. I noticed this problem on the pre - buy and knew that I could correct it given the chance. The flap retraction springs were digging a groove into the rear spar of the wing - this occurs in two instances - one - with flaps fully up or two - with flaps fully down. The spring position can be altered by the way the hook portion faces when installed - however it does not seem cure the issue it justs moves the problem to the other side of the opening. I have fabricated new brackets for the flap and carefully filed out the damage to the spar - it is all back together and I have installed anti-chaffing strips in the openings. I am still not real happy with the clearance - but I am sure I have mitigated any future damage. Any thoughts on this?
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Re: 170A Flap Spring Issues

Postby Bruce Fenstermacher » Wed Oct 12, 2011 2:37 pm

My thought is I think I have to look closer at my springs and make sure there not doing what yours have. Then maybe I'll have another thought about it.
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Re: 170A Flap Spring Issues

Postby JimNelson » Mon Jul 13, 2020 8:15 pm

Resurrecting a very old post... I've been looking closely at my new (to me) 170A trying to learn as much as I can. I noticed this problem as well. The left and right flap springs are digging grooves at the top and the bottom of the exit hole in the rear spar. About 1/4 inch long. The springs are in good shape, but this groove is a little worrying. Is this something that needs to be addressed somehow, or since it's been that way for 70 years just let it go?
1950 170A
N9955A s/n 19315
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Re: 170A Flap Spring Issues

Postby Bruce Fenstermacher » Mon Jul 13, 2020 9:53 pm

Jim hard to say, let it go but there is some relief to think it took 70 years to get where it is. If we had a picture we'd have a better idea what if anything you could do.
CAUTION - My forum posts may be worth what you paid for them!

Bruce Fenstermacher, Past President, TIC170A
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N7A '49 170A -More original than most making folks GREEN with envy
N42532 '45 J-3 Clipped Wing Cub
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Re: 170A Flap Spring Issues

Postby JimNelson » Tue Jul 14, 2020 3:47 pm

I'll get some pictures next time I'm at the hangar. I think that it's not an ongoing problem since there's no aluminum dust around the grooves. My guess is that at some time during its long history someone parked it outside in the wind with the flaps down. The wind pushed the flap further down and stretched the spring wire back and forth through the hole sawing the groove. I'm not sure what caused the groove at the top of the hole but could be the same thing with the flap up. It's most pronounced on the right flap so that could be a prevailing wind thing.
1950 170A
N9955A s/n 19315
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Re: 170A Flap Spring Issues

Postby JimNelson » Fri Jul 17, 2020 4:07 pm

Here's a picture of the hole in the rear spar that the flap spring comes through. The grooves the spring wore are at the top and the bottom of the hole. The spring rests at the bottom of the hole when the flap is all the way down, but descends into the groove when pushing the flap down a little more. (Quick fix: don't do that!) Looks like it's been that way a long time and not getting any worse. No cracks indicating added stress, so I'm not going to worry about it. Looks odd but seems to work OK. From the scratched paint it looks like someone did something there but who knows?
img_0508.jpg
1950 170A
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Re: 170A Flap Spring Issues

Postby GAHorn » Fri Jul 17, 2020 4:54 pm

If the wear becomes worrisome the structural repairs section of the Service Manual describes repairs which can be made to the web-area of wing spars. A doubler is perhaps one possibility.
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Re: 170A Flap Spring Issues

Postby ghostflyer » Sat Jul 18, 2020 12:02 am

This is a issue with a number of 170A, model. I had the same issue ,plus my springs were a little rusty [corroded] . I know I had the correct springs originally as they came out of sealed bags with all the right numbers on them . But they sawed through the rear spar. The marked area was blended out and Aero Home Depot Supplied a smaller diameter springs for a total of about $1.40. The tension is a little more but works perfectly and have been there for nearly 4 years .
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