An O-Ring is not just an O-ring, or is it?

An O-Ring is not just an O-Ring.

I invested days tracking down an O-Ring for an oil check valve. On the surface, it looks like any standard O-Ring but this one is special. Once upon a time, we had thousands of replacement O-Rings. Our customers that had used this quick drain could simply replace the O-Ring if they began to drip.

I can’t purchase them from the manufacturer. The part number is very specific and is a MIL-R-6855 Class 1 GR60 in a dash 109. I called all over, searched the internet and I couldn’t find anyone that will provide that O-ring in that mil-spec formulation. There were some Chinese companies that said that they could provide them, but I have trust issues about anything provided by the Chinese.

I reached out to the Valve Company Engineering department, inquiring if another O-Ring material was acceptable. I wanted to see if Viton or Silicon seals were an acceptable replacement, but I did not receive a reply, even after multiple emails and leaving voice mail.  

I think that the manufacturer of the valve wants you to buy a new valve for a couple of hundred bucks instead of a $2 O-ring. I think it’s wasteful and unnecessary. If it were me and my airplane, I would use an O-ring that is very similar, available and cheap, but I can’t sell it. God help me if something went wrong.