Smoke in Cockpit.. looking for source

[jwoodlee99]

1980 Piper Saratoga T - newer avionic 2-G5 , GTN750, GTN650 , STEC 55x

Had an incident a 20hrs back where avionics autopilot spontaneously rebooted. So quick the G5s didn't go to batter mode but clearly the auto pilot/ avionic rebooted.
Last flight had turned on smoke, minutes later noticed flickering audio panel , then saw /smelt light smoke from copilot foot well. Turned of heat landed promptly.
Didnt see noticeable damage , flew for an hour / ran up.. 2 sets of mechanics looked it over and said "fly it more".

What other component would you recommending looking / testing. One suggestion Im going to track down is rheostat for panel/nav lights. What should the resistance read on this? Anything else you can recommend.

 

[jwoodlee99]

This plane has a JPI installed. How flat should we expect the voltage and amps to be. What swings are too much? I see it being very erratic.

 

[TCABM]

When I had my electrical fire, the thick wire from the main buss was slightly loose and intermittently grounding against something under the panel. The insulation around that wire was brown from the burning.

Very similar symptoms as yours.

 

[Let'sgoflying!]

That creeps the hell outta me.
If you are going to fly it, (not sure that's a great idea) be ready to snap that master off right away and have a good fire extinguisher aboard.
How does the gear extend, is it electric?

 

[Racerx]

What did the smoke smell like? Melted wires have a distinct smell

 

[Jim_R]

I had an issue after a new avionics install where the Piper instrument lighting dimmer circuit was not compatible with the avionics dimmer function. Problem only occurred at night when the instrument panel lights were turned on. Ended up burning up three avionics boxes before we figured out what was going on. (Avionics install manual now has words of caution about this!)

Think about whether there was anything unique about the configuration you were in when the smoke event occurred.

 

[jwoodlee99]

That creeps the hell outta me.
If you are going to fly it, (not sure that's a great idea) be ready to snap that master off right away and have a good fire extinguisher aboard.
How does the gear extend, is it electric?

Fixed gear model Creeps me out as well and having 4 mechanics say "keep flying" has me pretending to be sherlock holmes.

 

[jwoodlee99]

What did the smoke smell like? Melted wires have a distinct smell

Smelt electric - very limited smoke .. maybe like a resistor , not a capacitor and not a pcb.

 

[Ed Haywood]

Volts should be steady. Ammeter should be steady after initial recharge. Dunno about load meter.

 

[jwoodlee99]

Volts should be steady. Ammeter should be steady after initial recharge. Dunno about load meter.

This is the behavior im seeing from the Jpi , exported and uploaded to Savvys. V 14-14.3, A 13-30

 

[MajorTurbulence]

I had smoke and electrical smell in my 1980 Archer2 about 5 years after new. The smell came from a KX170B. It was easily and inexpensively repaired back in 1985.

In your case, you did say the audio panel flickered. I would look there if no other electrical devices or lighting was noted to be affected on that flight.
If you take the audio panel out and smell it, that might give you the “smoking gun.”

 

[Ed Haywood]

Every pilot should review their circuit diagram. It can be a big help when troubleshooting electrical issues in flight.

 

[NavAir]

I had smoke in the cockpit once - at night. Luckily, the source identified itself immediately - one of the radios, a KX155A. The display was out. Pulled the breaker and the smoke stopped.

Turned out to be a burned capacitor. Shortly after, a SB came out to replace them in the KX155A and KX165A models.

Definitely scared the you-know-what out of me.

 

[kmacht]

What kind of incompetent lazy ass mechanic tells a pilot to go fly some more after they report a flickering panel and smoke in the cockpit. What was your plan if that smoke got worse and didn't stop by shutting the breaker off on that next flight. Time to go find a new mechanic.

 

[Pinecone]

no, time to invite him along for a long, night, overwater XC.