wheel fairing installation

jetguy · Post by **jetguy** » Thu Mar 09, 2006 12:24 am

I haven't disassembled anything yet so this question may be premature, but here goes. Using the stock backing plates (new from Cessna...thanks again for the heads-up, Doug), which I'm now in the process of relieving slightly so the Clevelands will clear, what is the correct installation sequence for all the components, starting from the gear leg and going outboard? Specifically, are the axle and shims (assembled as a unit) located together OUTBOARD of the backing plate or does the axle 'sandwich' the backing plate between itself and the shims? In other words, does the backing plate bolt directly against the gear leg or do the shims go on first? Same question (sorta) for the mud scrapers...is the tang of the scraper sandwiched between the fairing and the backing plate or is the backing plate itself sandwiched between the fairing and the scraper tang? Whew! I hope the installation turns out easier than the question.

Post by **GAHorn** » Thu Mar 09, 2006 6:35 am

The sequence is: landing gear leg, shims, backing plate, axle. (The fairing must be in alignment with the tire...not the landing gear leg.)
The scraper fits entirely within the wheel fairing.

jetguy · Post by **jetguy** » Thu Mar 09, 2006 7:51 am

Thanks, George...any suggestions on where I might find the Tinnerman clips (NAS395-28, Tinnerman A9031-10Z-3) specified? I've so far been unsuccessful locating any at the usual sources (Tinnerman/Palnut claims the part has been superceded by a non-aircraft quality[?], same configuration item, part number D9031-10). The commercial suppliers I've tried for the 'civilian' version either don't stock them or they won't sell less than 500...

Post by **GAHorn** » Thu Mar 09, 2006 4:58 pm

These are simply NAS 395 "U" clipnuts, and are carried by Spruce, but the part numbers have changed. See their catalog pg. 88. (Even Cessna has a superceded part no. S3228)

Have you looked at the Aircraft Spruce catalog, items LHA 4792-1032 and also the Monadnock clip nuts, Spruce PN 04-00153? (same page as above) They are an even sturdier clipnut, with threaded inserts, and would likely work out even better.

(Note: All the "dash numbrs" etc. of the Tinnerman designations refer to finish (cad plated, phosphor, or plain) etc. Don't let that confuse. The first 5 digits are the "family" of the fastener, and sometimes it's helpful to drop all alpha-characters when you perform searches. FYI)

jetguy · Post by **jetguy** » Thu Mar 09, 2006 6:14 pm

Actually, I've never noticed the others before but I think you're right, they would definately seem to be the way to go. Thanks again.

Post by **GAHorn** » Thu Mar 09, 2006 6:31 pm

While this may seem "obvious"...I'd hate it if I later found out I should have said something ... (sorta like the time Jamie backed the car out of the breezeway before dawn, and I avoided reminding her ...yet again!... about the house-guest's car parked out front... ask Ol' Gar/Flyguy about it.)

(That sweet girl is the only person in the world who can back into someone....and tear up the front of her car and the rear of the person she's backed into. No kidding. Ask me about it at Kelowna.)

She's got a new rear bumper-sticker. It says, "If you can read this....You're parked in the wrong place!

Anyway.... make certain you mark and KEEP ORIENTED any alignment shims you remove so you can get them reinstalled exactly as they were before. Sounds simple, heh? Well,...wait 'til you have them off, and then lay them down on the workbench, and turn around three times, and drink a beer... They look the same upside-down and inside-out and right-side-left and front-side-aft.

jetguy · Post by **jetguy** » Thu Mar 09, 2006 8:53 pm

Well, I can't top that but my ex wife did somehow manage to plow the 4WD into the side of my airport car one afternoon whilst backing up and...guess who's fault it was?

But I've seen other cautions about mixing up those shims so I've made myself a promise to mark 'em clearly and not let 'em out of my sight.

thanks

russfarris · Post by **russfarris** » Sun Mar 19, 2006 2:58 am

Greg, one thing to keep in mind is gear alignment. Don't assume that putting the shims back on the way they came off is correct.

Is your airplane hard to handle? How's the tire wear? Excessive wear on the outside of the tire is too much toe-in, wear on the inside is too much toe-out. As long as you are taking things apart, please take to time to check the gear alignment. Do a search on this site and you'll find the procedures needed to check it. Russ Farris

jetguy · Post by **jetguy** » Sun Mar 19, 2006 3:59 pm

Russ, good point and thanks for the heads-up. I've only got a limited number of hours in it but it's always seemed to handle very nicely.

I can attest to just how critical gear allignment really is, having owned a Ryan PT-22 which I bought (unbeknownst to me) with MAJOR landing gear/wing misalignment issues. Once the problem was corrected, however, it went from 'Mr. Toads Wild Ride' to an absolute pussycat.

Question: how much edge wear can be attributed to toe vs. camber? that is, don't all Cessnas exhibit outboard tire wear simply because of the gear 'drooping' while airborne? Or are there additional wear patterns which might indicate a combo of toe/camber corrections that may be required?

thanks.

Post by **GAHorn** » Sun Mar 19, 2006 6:00 pm

My own airplane handles very nicely (a subjective thing of course) and it is aligned according to the specs. In 600 hours and an equal number of landings (almost half on grass, but some very long taxies on concrete) the first set of tires showed outer wear at the 300 hour mark. I reversed them on the respective wheel to even out the wear.
At about 350 hours I fell for the classic diamond-treads and installed them. The original tires (Aero Trainers) were given to a friend who thought they'd be useful on one of his three planes. (He has a 150, 170, and a 175.) They were certainly not worn out yet, but were about 6 years old.
The point being that the outer half of the tread does indeed exhibit a certain increased amount of wear than the inside, but that if properly aligned, even cheap tires will last a fair amount of time.

russfarris · Post by **russfarris** » Mon Mar 20, 2006 10:02 pm

According to Cessna SB SLN-56 circa 1948, excessive tire wear is due to improper toe-in/out. Do a Google search on Cessna gear alignment 140 170 to read all of it (it's on the 140 clubs web site) Russ Farris