Stratus ES Transponder Mode C Issue

[srp_4737]

Hello all! New to the forum. Had a quick question to see if anyone has experienced something similar. I fly a Piper Cherokee 180 that has a stratus ES transponder with ADSB-out and in capability. It also has a non-WAAS Garmin 430 installed.

Anyway, almost like clockwork after about 30 minutes of operation I will get an error message on the screen that says something like "pressure altitude input failure" and then center will call me to tell me he lost my mode C. After that the mode C capability is gone even if I turn it off and turn it back on. It happens every time I fly it and sucks because I file IFR pretty regularly. Based on the error message it seems like there is some issue with the altitude encoder ("input failure")? But I don't understand why it works for a half hour then suddenly quits.

Let me know if you have any ideas.

 

[Ryan Klems]

Might just be how long it has to run for some part to heat up enough to stop working. What are you using for an encoder?

Also is your transponder an ESG, or what is your WAAS source?

 

[somorris]

My suggestion is to have an avionics shop check out the encoder for you. I think when they are going bad, the can do pretty weird things, from showing no altitude to showing the altitude way off.

 

[Jesse Saint]

It’s pretty simple and cheap to pop in a new encoder.

 

[Velocity173]

My Stratus ESG started failing above 6,700 ft PA. Replaced the encoder and works fine now.

 

[srp_4737]

The problem is still occurring but I was able to get some pictures of the failure in action. You guys still thinking encoder? An avionics shop has looked at it but can't really do much because it will wont fail when they test it. I've sent these images to the manufacturer and avionics technicians and am waiting on a response. Again, it is an ES model with a non-WAAS 430.

 

[Ryan Klems]

Definitely appears to be an issue with the encoder. Also, Is the non-WAAS 430 providing position source to the ES? If so that’s a no-no, that’s not an approved position source.

 

[MBDiagMan]

My Stratus ESG started failing above 6,700 ft PA. Replaced the encoder and works fine now.

So then, the transponder did not fail. The blind encoder did.

 

[Velocity173]

So then, the transponder did not fail. The blind encoder did.

At the time all I knew was the transponder only sent out PA up to 6,700. The transponder was also displaying a failure code that was an over temp. Thru process of elimination we went with a new encoder but same model. Works fine now.

 

[srp_4737]

Definitely appears to be an issue with the encoder. Also, Is the non-WAAS 430 providing position source to the ES? If so that’s a no-no, that’s not an approved position source.

Honestly not sure on that. I can ask some fellow club members to see.