The International Cessna 170 Association

Earlier I've been told there isn't a known failure with these struts. I am restoring my 48 and don't know how to assure myself of adequate inspection. I am open to suggestions as I've been told to just fully expose the inside to an adequate linseed oil rinse.

Cubs have mandatory inspections of some wing struts. Check with your IA or SuperCub.org, they may have a list of approved NDT inspectors. The most preferred inspection is X-ray. It’s also a good idea to replace the clevis and attach hardware with new.

After they pass inspection, most folks slosh the internals of non-sealed struts with Paralketone or the less effective linseed oil.

Unsealed struts can also be powder-coated at approved repair stations that do powder-coating. Powder-coat after they pass inspection and before internal treatment.

Thanks so much.

Cubs and SuperCups have a completely different strut and an exhaustive AD. The strut AD has been complied with for ever by most by replacing them with new sealed struts illuminating the AD. For those who have not replaced the only approved procedure (without getting your inspection idea approved) is to use a Maule fabric tester to punch to 85lb, the bottom foot of each strut every 1/4". If there are no dents, the strut must be good. There are no publically approved NDT procedures for these struts.

The Cub procedure would not apply to a Cessna strut. No one has done any testing to determine if the procedure would prove anything. Fact is, there is no approved procedure for inspection of our Cessna struts other than common sense and perhaps anything written in Cessna's SID program.

Thank you, also. So very helpful.

Michael, Sounds like you're doing a meticulous restoration. I'd love to check it out on a Indy layover sometime.

Bruce Fenstermacher wrote:... Fact is, there is no approved procedure for inspection of our Cessna struts other than common sense and perhaps anything written in Cessna's SID program.

Bruce posted Cessna's SID document here. In Section 5-14-28, Supplemental Inspection 57-40-01 calls for a visual inspection of the strut and strut attach ends, Only if cracks or corrosion is found does it call for further magnetic particle inspection. Are the struts sealed? Following weld repairs to the engine mount Cessna says in Section 5-14-36, "After welding, while the welded area is still hot, introduce 3 cc's of unboiled Linseed oil, or 6 cc's of corrosion preventative compound conforming to MIL-PRF-81309, through the hole and reseal it using the same method as was used in the original fabrication."

I would have thought they would give similar advice for the struts but apparently not.

To add to what Gary mentioned, in the case of Cub struts, which where sealed at the bottom but not the top, they are protected by sloshing with boiled linseed oil.

or Polyfiber Tubeseal.

Gentlemen, thanks to all. Gary, the door is always open. The renovation is extensive. I am sure I have drilled over a thousand rivets. I may be reached at 317-408-9092. Please leave a vm as I only answer known numbers. Best to all who have been so constructive. Mike

melcessna wrote:... The renovation is extensive. I am sure I have drilled over a thousand rivets. ...

That's something-- especially considering you've got fabric wings! Thanks for the open door. Let me know if I need to bring some bucking bars!

Approved procedure or not, X-ray inspection of the struts would not hurt anything but would definitely show any internal corrosion if any is present.