Tempest Fine Wire Plug Defect Failure

[dwurfel]

I was performing an Oil change and rotate fine wire plugs yesterday when much to my surprise the electrode tip separated was missing from one of the plugs.
Just flew it yesterday with no problems so not sure when it separated. The plug is a Tempest UREM35S.

Called Tempest and talked to Vince Bechtel who was very helpful. He said it had happened a limited number of times and if the laser weld was not perfect it could separate. I am sending the plug back to Tempest and they are replacing it. It had about 250 hours on it.

Tried to post a picture but for some reason it is not working.

Question to the owner group. Has this happened to anyone else. My fear is that the electrode tip may have damaged the cylinder. There are good chances it was blown out of the exhaust valve. I am going to borescope the cylinder this weekend and open up the oil filter from the change. Any other advice would be appreciated. Dave

[Rich]

The only obstacle I've run into uploading pictures is when the size of the file is too large. It has to be 1MB or less. A picture taken with a phone will usually be several MB. I alsways have to do a "file>save as" operation to reduce the resolution/size so I can upload.

I haven't had this happen. I assume you're talking about the center electrode, though the reference to a weld makes me question this. You definitely want to borescope. You're probably right about it spewing out past the exhaust valve, but carefully check with the borescope that the piece isn't still lurking in the combustion chamber. If the piece is small enough and it was a bottom plug I could even see it dropping in the space between the center ceramic cone of the plug and the body of the plug. Then when the plug is removed it drops out on the hangar floor.