EGT Probes

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   I recently had a failure of the #4 EGT probe and had a mechanic replace it. After about 30 hours of flying, the same probe failed again. After again replacing it, I had a third failure after about three hours of flying. Finally, a few minutes later, the entire EGT display on the MFD stopped working.
A little online research showed part of the problem. I found Piper "Service Spares Letter 428A" where new EGT thermocouplers were made available for my Piper 6X. My mechanic had no idea these were not generic  "Type K" probes. While we need to now replace the #4 probe with the correct Piper part, I am curious what would cause the complete failure of all EGT readouts. Would this have been caused by using the wrong EGT probe on #4 or is this an unrelated wiring or MFD issue? And should this be handled by an avionics shop or mechanic?

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jsamford Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 30 Jan 2013 Location: Savannah, GA Status: Offline Points: 11	Post Options Post Reply Quote jsamford Report Post Thanks(0) Quote Reply Topic: EGT Probes Posted: 30 Apr 2013 at 8:49am
	I recently had a failure of the #4 EGT probe and had a mechanic replace it. After about 30 hours of flying, the same probe failed again. After again replacing it, I had a third failure after about three hours of flying. Finally, a few minutes later, the entire EGT display on the MFD stopped working. A little online research showed part of the problem. I found Piper "Service Spares Letter 428A" where new EGT thermocouplers were made available for my Piper 6X. My mechanic had no idea these were not generic "Type K" probes. While we need to now replace the #4 probe with the correct Piper part, I am curious what would cause the complete failure of all EGT readouts. Would this have been caused by using the wrong EGT probe on #4 or is this an unrelated wiring or MFD issue? And should this be handled by an avionics shop or mechanic?