Tension Springs vs. Compression Springs

[Kelley]

Gentlemen and Ladies:
I ordered the tension springs kit from Spruce PN# 06-00008, asked my mechanic to install and he flatly said "no way". When asked why, he responded that his dad had tension springs on his "taildragger" and one fell off and he nearly crashed the bird. Have anyone of you heard of this happening to other a/c? I know the reason to install the tension springs versus the compression springs, the pulling of the internal structual whence the compression spring has hit it's limit! Yes, I know that I can go to another mechanic, but I would like to present valid ideas and thoughts to this mechanic contrary to his insistance. One failure out of how many, proper installation, new modifications, etc. Any and all thoughts, constructive would be appreciated. Thanks, Kelley

[GAHorn]

Ask your mechanic to demonstrate to you where he finds that Cessna authorized compression springs on your Cessna. Then tell him you want it returned to it's factory original installation and that if he has forgotten who the customer is then you'll find someone who hasn't.

[N2255D]

Yes I have seen this happen one time on a C140 sometime in the mid 80's. We were doing a formation take off and he was lead. As the lead aircraft turned onto the runway one spring came loose. We could not find anything wrong but from then till now there is a safety wire across the open end of the spring. Never seen or heard of it again until now.

[Bruce Fenstermacher]

Pretty much what George said. I've seen chain and connecting links break but never a spring. Never heard of them coming unhooked.

Tell him you'd like to hot rod our engine with a slick racing cam and such. When he says you can't do that without approval tell him you though it was open season on unapproved mods since he insists you use unapproved springs.

[GAHorn]

Yes I have seen this happen one time on a C140 sometime in the mid 80's. We were doing a formation take off and he was lead. As the lead aircraft turned onto the runway one spring came loose. We could not find anything wrong but from then till now there is a safety wire across the open end of the spring. Never seen or heard of it again until now.

Here's what may happen: A tailwheel steering chain becomes "hooked" beneath the spring-shacle (PN 0542108, Item 15, Fig. 29 in the B-model IPC) which holds the spring-stack and interferes with tailwheel steering. It can cause a severe/tight turning moment. It can also cause the spring to become unhooked. This is usually due to the guard (PN0442125, Item 16, Fig 29) missing from the assembly, because someone didn't think it was important.

(A temporary fix can be made from a short piece of rubber tubing thru which the bolt (PN AN4-21A, item 17) passes.)

If it is a broken tailwheel steering spring, the tailwheel casters and the airplane should be controllable with brakes. But with a spring that is still connected... or with a compression spring... until that tailwheel casters the airplane will perform a slow (hopefully) ground-loop.

[N2255D]

Yes I have seen this happen one time on a C140 sometime in the mid 80's. We were doing a formation take off and he was lead. As the lead aircraft turned onto the runway one spring came loose. We could not find anything wrong but from then till now there is a safety wire across the open end of the spring. Never seen or heard of it again until now.

Here's what may happen: A tailwheel steering chain becomes "hooked" beneath the spring-shacle (PN 0542108, Item 15, Fig. 29 in the B-model IPC) which holds the spring-stack and interferes with tailwheel steering. It can cause a severe/tight turning moment. It can also cause the spring to become unhooked. This is usually due to the guard (PN0442125, Item 16, Fig 29) missing from the assembly, because someone didn't think it was important.

It was a 1946 140 with a Scott 2000 instead of a 170 but similar design. All parts were in place IAW the C140 parts manual.