Landing Gear Axles

[Steve Pierce]

I have repaired a lot of landing gear lately and have come across a few modifications that some might not be aware of and might find interesting. This first picture is of a standard PA16 1 1/4" axle which to the best of my knowledge is about the same as a stock PA20.[attachment=3:3j15vars]100_2132 (Medium).jpg[/attachment:3j15vars] The next picture is of a PA16 axle that has been modified via an STC from Stoddard's to install a 1 1/2" axle over the standard 1 1/4" and rosette welded to allow the Colt disc brakes to be installed.[attachment=2:3j15vars]100_2127 (Medium).jpg[/attachment:3j15vars] The next picture is of a PA16 axle that was modified with an inner sleeve and pinned with a roll pin. I repaired the gear but have no logs or documents on the modification. I assume it is to strengthen the axle. According to the Clipper landing gear drawing, the axle is 1 1/4" OD x .125" thick 4130 tubing. [attachment=1:3j15vars]100_2128 (Medium).jpg[/attachment:3j15vars] The Pacer and Tri-Pacer axles I have seen are the same except the Univair Pacer gear and all of the Tri-Pacer gear I have seen were 1 1/2" OD axles. Out of all of the landing gear I have repaired, I have never seen a damaged axle. I have seen bent, broken, cracked and swelled tubes but no damaged axles. I don't have much dealings with ski flying living in Texas and I know skies tend to put a side load on the gear. From what I have seen the side loads are what causes the majority of the failures when the streamline tubing fails in compression and takes the other tubes with it. The Clipper is also prone to collapse the carry-through tube that the gear rests against when the bungees are tight. [attachment=0:3j15vars]100_2134 (Medium).jpg[/attachment:3j15vars] I have had to repair this area on several Clippers including one my Dad and I had done a thorough pre-purchase on for myself. :oops: It is not hard to repair using the inner sleeve method. I haven't seen any damaged Pacer or Tri-Pacer fuselages in the hydrasorb area except where it was so bad that it took out the whole carry-through structure. Has anyone had any experience with these type of failures?

[Airwrench]

Steve,
In days gone by the 1 1/4" axles would bend or break, typically in the area under the bearing stop if the axles weren't reinforced. It didn't matter if they were off of a Pacer, Clipper or Cub. Remember that you have a 4' +/- lever hanging from that axle when you are on skis. Regretfully most of the gear were damaged by an overzealous pilot grabbing the tail to turn the airplane with one of the skis frozen down. We used to anything from 3/4" water pipe to 1 1/8" .125 4130 driven into the cluster inboard of the brake attach. There are factory rosettes at the bearing stop and you had to file or grind out the inside of the rossete before driving the reinforcements in. (Boy, was I releived when I found out that I wasn't the round bastard that Dad mentioned, when he would send me out to work on a gear)

This is also a good place to post a reminder to make sure that the Univair wide gear service bulletin has been done, on all of our gear. I am still running into a set every year or so that has not been complied with. -SB

[andya]

regards the Univair SB on the gear, are they still providing the parts free?? :?:

[Steve Pierce]

I am not sure. I have a Pacer project here that needed the SB complied with and we just cut the gussets out of scrap. I'll ask next time I talk to them.

[Homer Landreth]

Hi Steve; Your picture above brings back a problem I had many moons ago with an A/I doing my annual. To facilitate wheel pants, I moved the brake calipers to the 5 O'Clock position such as you have shown above. Tha A/I made me change it and move them to the position which was slightly above the 3 O'Clock position. He stated that that was the only authorized position. Since I was wanting my plane and he was holding up the signature, I was hostage to his belief. Subsequently, I have Never found anything to support his contention on this position. Do you have anything that directs the positioning of the brakes on a Cleveland wheel? Thanks

[Steve Pierce]

I have the Cleveland drawing for the double puck brakes and the Stoddard's STC for the single puck Colt brakes. I will look and see what they show. I have seen them configured all sorts of ways. Some are fit in a way to install wheel pants that won't allow the brakes to be bled because the brake line and bleeder fitting are horizontal instead of verticle. I will look at the STC and drawing and post some pictures.

[andya]

steve
I would be interested in the answer to Homer's question because a friend of mine with a 22/20 had the same comment / problem with an IA doing the annual , ie brake calipers not mounted where he thought they should be....

[Steve Pierce]

Here is the Cleveland installation drawing for the 150 hp Super Cub which I have used for field approvals on other aircraft. I will have to look at my Pacer paperwork and see what is included there and also in the Stoddard's STC.[attachment=0:r0mrtteu]Cleveland drawing.pdf[/attachment:r0mrtteu]

[smcnutt]

regards the Univair SB on the gear, are they still providing the parts free?? :?:

Got mine from them late last year so I would assume they are still available. It was only a small triangle of metal about a inch or so on the sides.