The International Cessna^® 170 Association

Well Tiz the Season (Again) to get the "Ol Bird out for some fly'in". And again it's time to give it a good go'in over to ensure it's up to the task of uneventful flight.

Of late I've noticed some landing gear and tailwheel issues in the forums that caused me to think about the overall condition of these 50+ year old birds.

I did a search of the forums for any past postings that could be good for a review before going over (inspecting) the plane and found many.

I just learned that you should never use chemical paint stripper on landing gear legs. According to the FAA, that makes them permanently unairworthy.
-Scott

Very true! I think George has commented on that.

Inspection and recertification is a real grey area. I haven't seen much "Official Data" on the subject but a guy in Washington State perorts to have a certified inspection process in place that gets you a yellow tagged product. (So I've heard)

It would be nice to have such data available to the club.

North Sound Aviation
Jim Hayton
360-661-3302

If the FAA means "paint remover" when they refer to "chemical paint strippers" as condemming landing gear legs to permanent unairworthyness, I'd risk a guess that there are a hell of a lot of unairworthy Cessna landing gear legs out there. What do the paint shops do on a total repaint? I don't ever remember seeing any of them masking off the gear legs during stripping.

Could it be un-approved chemical strippers as some strippers can affect the chemical makeup of the metal.

I guess you could media blast the parts to remove the paint.

It depends on which stripper is used...and the subsequent treatment. The concern is hydrogen embrittlement.

Complete removal, bead blasting, and NDT, inspection is preferable.

I'm hearing some great points/questions to address but where is the data that addresses our questions? Any ideas??

There is the chemical stripper issue, what strippers are a NO, NO? The inspection process leading to a yellow tagged gear leg, and when is re shot peening requirered/commended and probably more.

I hope someone has this material available to the forum.

I've been using Napier SV-35/PMA (Aviation Grade) stripper. On the label it says, "SV-35/PMA is NOT Hydrogen Embrittling ASTM F 519-93". It's "non-hazardous", "non-toxic", and "biodegradable".

It is now sold under the RemovAll Brand. It's a little cheaper here.

Any one know if you can take the paint off gear legs with a wire brush on a hand grinder. Actually I am sure you could but would that damage the shot penning? Bill K

Wire brushing is BAD for almost anything on an airplane.

OBTW: Most aircraft related maintenance manuals and other reference materials (43.13) recommend against the use of wire brushes as George said. This can drive any corrosion or other contaminants into any craters or pores. Also using other than stainless steel brushes on any metals will usually set up conditions for dissimilar corrosion to begin. There is also the heat that could be generated becoming an issue.

These gear legs are from the mid to late 40s and up. I wonder how many times they were stripped back in the 50s before hydrogen embrittlement was well known, Just a thought.

mike roe wrote:These gear legs are from the mid to late 40s and up. I wonder how many times they were stripped back in the 50s before hydrogen embrittlement was well known, Just a thought.

We are all in that boat with no real replacement options or way of testing for such. UNLESS someone knows of a testing process

So when was the most recent spring gear failure? Is this a real issue?

There was one last year

http://www.cessna170.org/forums/viewtop ... ail#p66567