Wing Twist, Polishing Aluminum and the Disease

Metal Master · Post by **Metal Master** » Wed Dec 15, 2004 5:07 pm

I have purchased the 1953 to 1962 maintenance manual series from McCurtain and the entire100 series. It covers 120 to 195 series airplanes up to the late 1970s some time. I purchased it because I perform maintenance on many of these airplanes. They do not have a manual that covers the 170 other than the parts catalog at all. The manual that Univair and Aircraft Spruce sell is the same manual as near as I can tell (100 series 1953 to 1962) this manual has no specific information of the 170 or 170A. I presume you guys already know this. I only state it here because I do not want to cover old ground.
I built a 100 series wing jig years ago from plans I purchased out of Trade-A-Plane. The first set of 172 wings we built flew straight and level no wings heavy and no roll tendencies with the eccentrics set at neutral. (I think we were just Lucky). Repairing one wing only for a given airplane has not had this sort of success. But I digress.

My question is this. I need the wing twist or Wash out information for the 170A wing. Does anyone have this information?

Although I am likely to just measure the right wing and make the left wing the same if all else fails. It may be the best way to go. I think Cessna may have published this information as service information for and or with wing jigs they may have sold years ago.

I have just finished compounding the 170A fuselage bottom with Nuvite F7. The fuselage is upside down in the shop waiting for the gear legs to come back from being magna-fluxed. I figured this is a good time to do the bottom of the fuselage before turning it over after the gearbox repair. I was not originally planning to polish the aircraft but I reasoned the as it is already stripped to bare metal now would be the time. My aviation fellows are sure I have lost it (mentally) I am sure I have lost it otherwise. But then they have not been in the shop since I finished with the F7. The shop glows with the gleam.

I cannot imagine what it will look like after polishing with the S, which for some reason did not get shipped with my order from perfect polish.
The hard work on the gearbox and belly skin repairs are done and soon I will move on to the left wing, which I expect to be an easier project. The sheet metal work not the polishing
I caught this disease from this web sight. I blame you guys and your pictures. I wonâ€™t tell Phyllis where I got it.

Post by **GAHorn** » Thu Dec 16, 2004 3:48 am

According to WD Thompson, in his book "Cessna, Wings for the World", the 170A had 1-degree of washout which began outboard of the strut.

spiro · Post by **spiro** » Sat Dec 25, 2004 12:09 pm

Geo keeps quoting Thompson's book on wing twist. I've got real Cessna data on this but it took me awhile to locate it in my filing system <g>. Pertinent extract follows:

********************************
SERVICE INFORMATION SUMMARY
DATE: 7-24-54
SUBJECT: Wing and Stabilizer Rigging Information

170A
Angle of incidence root +1.5Âº
Angle of incidence tip 0.5Âº
Twist 1Âº

170B
Angle of incidence root +1.5Âº
Angle of incidence tip -1.5Âº
Twist 3Âº

NOTE: Fabric wings have no built-in twist.
********************************
the copy I have of this document is pretty poor - I got it several years ago off a microfische. If anybody can find a legible version of it on a CD or TCMLink I'd sure appreciate a copy / file.

paul

Post by **Bruce Fenstermacher** » Sat Dec 25, 2004 1:34 pm

Paul I'm just curious if your document lists the information for the B wing as also for the L19/305 wing which is supposed to be the same.

I have L-19 wings on my "A model" and believe at least one of the wings was repaired at one time with a twist that is on the outer edge of the tolerance

One of these days I'll get around to checking it.

Metal Master · Post by **Metal Master** » Sat Dec 25, 2004 4:03 pm

********************************
the copy I have of this document is pretty poor - I got it several years ago off a microfische. If anybody can find a legible version of it on a CD or TCMLink I'd sure appreciate a copy / file.

paul[/quote]

Thanks this is what I needed. I just received 3 copies of the 170 book from the association and just ran across this same information in it along with some other info on where the measurements are taken which is similar to latter Cessna wings on where the measurements are taken.
I was just fitting my pilotâ€™s door last night after having completed the structural repairs to the gearbox and tail and was working on the door latch. The springs are original & broken. Someone had installed a bogus non-working additional spring also rusted beyond all recognition. I was thumbing through the 170 book and ran across an article on the very same subject written by member #00678 that gave a part number for a new spring kit SK172-16B, I did a parts search on cessnaparts.com and it came up that no part existed. Then I entered a search for just SK172-16. It came up with an available part SK172-16C @ my cost of $31. There was an additional note about a STC kit available to change the latch over to the later rotary style latches from TIC170A Co founder John Benham. Is this kit still available? I know of a couple of people that would be interested in it. They are tired of there doors popping open in flight.

N2865C · Post by **N2865C** » Sat Dec 25, 2004 6:07 pm

There is a guy on the 120 site that makes up door springs. The springs are the same on a 170.
http://www.cessna120-140.org/Classified/springs.htm

jc

zero.one.victor · Post by **zero.one.victor** » Sat Dec 25, 2004 7:16 pm

From the "hangar sale" section of the 12/02 Flypaper:
"........extended exhaust pipes complete kit STC, $425. Rotary door latch kit, $400. All items plus shipping. John D Benham 830-535-4884"
My two cents: the only trouble I've had with my original latches is the spring breaking. Check out the International Cessna 120/140 Assn website, they have instructions on making a jig to fabricate your own spring from music wire, available at your local hardware store. Go to http://www.cessna120-140.org , under "library" click on diagrams, then click on door latch spring. They recommend .040 or .050" wire, I found this stuff hard to form so I use .032". Seems to work OK. Make several springs cuz I don't think the home-made ones will hold up for another 50 years. Reassemble the door using screws instead of rivets, if it hasn't already been done.
Lots cheaper than a $400 rotary latch kit. And no paperwork required.

Eric

zero.one.victor · Post by **zero.one.victor** » Sat Dec 25, 2004 7:43 pm

More on the 120-140 Assn website-- they have forums like us, but just two, Pilot Lounge & Technical Support. Very interesting & informative to read thru the posts. After all, the 170 started out in 1948 as just an overgrown 140. Lots of common parts dificulties & similar discussions about keeping them flying.

Eric

doug8082a · Post by **doug8082a** » Sun Dec 26, 2004 1:59 pm

When it comes to door latch springs, make sure you know the part number and/or configuration of the spring before making your own. The info on the 120-140 site re: maiking springs is good, but it doesn't work on the "B"s as I recently discovered. The "B" spring is p/n 0511119 and the "U" shaped section is bent 90 deg from the rest of the assembly. The spring on the 120/140 (and presumably the 170/170A) does not have the 90 deg bend.

Metal Master · Post by **Metal Master** » Sun Dec 26, 2004 3:01 pm

Thanks for all of the information. And Merry Christmas and a Happy New year to all. My partner in the 170A has a 140A. I talked to him yesterday he said that one of his 140 buddies had given him several new homemade springs. That he had them somewhere and as suggested here he thought they are similar to the broken springs on the 170A. If he can only remember where he put them. In any case I will make springs unless he comes up with them before I get them made.

Jim

spiro · Post by **spiro** » Mon Dec 27, 2004 11:22 pm

Bruce, this document doesn't mention the L-19. But since the 170B and 180 wings have the same 3Âº of twist, I'd think the BirdDog's would too. You've probably got the earlier 305A wings (most production) which should be real similar to a 170B.

paul

blueldr · Post by **blueldr** » Tue Dec 28, 2004 4:37 am

I wouldn't be surprised if the basic L-19 wing and aileron were the same as the C-170 and the C-180, but the flap system was totally different being a hinged flap, rather than a tracked semi Fowler type, that had a maximum down position that was considerably greater than that on a C-170B.

zero.one.victor · Post by **zero.one.victor** » Tue Dec 28, 2004 7:01 am

I like Bird Dogs a lot, and have drooled over them at fly-ins, but apparently I never looked very close at the wings-- I always assumed they had tracked flaps like a B model 170. Well, I just looked at some magazine pics of an L19 & damned if BL's not right! The flaps are hinged with a sort of detached hinge, sorta like a Husky. The detached-type hinges result in the flaps being separated ( for lack of a better word) from the wing when deployed, as opposed to the simple hinged flaps on a ragwing or A model. Sorta like a B but not quite, they don't go back as far on an L19. Thanks for pointing that out, BL.

Eric

spiro · Post by **spiro** » Tue Dec 28, 2004 12:50 pm

60Âº, and electric!

Post by **Bruce Fenstermacher** » Tue Dec 28, 2004 1:36 pm

Dimensionally the airfoil and wing area of the L-19 and the B model wings are the same. I just don't know about the twist.

From my research the flap mechanisim of the L-19 or the B model can be installed in either wing as the B model flaps are installed in mine.

I believe the early L-19s had manual flaps and later L-19s had a heavier wing structure but I may not be remembering this right. L-19 flaps are a different style flap and do go to 60 degrees.

Now if only those rockets and pods weren't so expensive I'd love to hang a pair from the hard points.

The International Cessna^® 170 Association

Wing Twist, Polishing Aluminum and the Disease

Wing Twist, Polishing Aluminum and the Disease

Door springs