Light Aircraft Association

I would like to use SS AN bolts in place of CAD plated bolts for all fitting attachment on a Pietenpol Air Camper. Is there any problem? If so what would be the issue?
Mark Bowler

Stainless bolts are more prone to galvanic corrosion in contact with aluminium than Cadmium plated ones.
The bolts won't corrode but the adjoining metalwork is at risk unless a suitable galvanic barrier is used.

Hello Mark - I'm making my fittings of titanium (don't ask) so no issue with aluminium. I want to know how the SS AN bolts compare strength wise to the CAD plated bolts. According to the LAS (ACS) site hardware listing, both meet the minimum tensile limit of 125ksi. Yes SS is not as strong, but both meet the minimum spec.

Stainless steel is subject to stress corrosion cracking. Stress arising in its duty and in the manufacturing process.

With Titanium/stainless the stainless will become the galvanic anode and subject to corrosion, the Titanium will be the cathode and not at risk, so you would still need a galvanic barrier.
I believe that they both meet the strength requirement of AN bolts, so that should not be an issue.

Thanks Mark - everyone seems to think SS is like jello - no strength at all.
I understand about the galvanic issue - would you think CAD plated AN hardware would be better than SS? There are issues with cadmium/titanium as well. I thought the SS hardware would be less of an issue.

Mark

Mark,

I think this is a question you should be asking LAA Engineering about.
They will be able to advise if use of SS bolts in your particular application is acceptable.

Tony

Hi Guys

There are many grades of stainless steel, with differing strengths, machining characteristics, welding characteristics and corrosion resistance. Some are magnetic, some are not. Here is a link to one source of information, and there are many others on the internet

https://continentalsteel.com/stainless-steel/grades/

The two common grades are A2 (304) and A4 (316) and they are VERY different to work with.

I hope this helps

Terry Slater
039398

High-tensile bolts are made from high-grade alloy steel, which has been quenched and tempered. They have higher hardness than standard grade 8 bolts, making them ideal for heavy-duty applications such as bridges, construction, mining equipment, and more. They are also resistant to corrosion and rust.

Stainless steel bolts, on the other hand, are made from a combination of chromium and nickel with added molybdenum or titanium for extra strength. While they are not as strong as high-tensile bolts, they are highly resistant to corrosion due to their chromium content.

A4-80 bolts are only approximately as strong as commercial 8.8 grade. AN bolts will obviously be stronger.
For any application that requires better than commercial grade 8.8, s/s will NOT do.
Anything less than A4-80 would only be any good fro non-structural applications.