1982 M20K Radio Fan Circuit Breaker tripped

[Van Thornock]

1982 M20K Radio Fan circuit breaker tripped. Has not happened before. It was a hot day. I am asking for recommendations and procedures on what to do to fix the problem.  Where can I purchase a new breaker?

[xavierde]

47 minutes ago, Van Thornock said:

1982 M20K Radio Fan circuit breaker tripped. Has not happened before. It was a hot day. I am asking for recommendations and procedures on what to do to fix the problem.  Where can I purchase a new breaker?

Have you checked nothing is preventing the fan to spin which in turn could make the breaker trip? I've had small debris getting inside the fan and affecting it.

[carusoam]

Welcome back, Van!

Its been a while...
 

A simple three part problem...

It is a mechanic fixes it kind of problem...

Most parts for this are available from aircraft spruce... the exact parts are available through your MSC...

If you don’t have an MSC... one can be assigned to you... Lasar is a really good resource for this...
 

1) Old worn CBs are temperature sensitive... the more Electrons flowing through them, the hotter they get... when they are worn, they trip more easily than rated... if the CB has lost its clickiness it is showing signs of wear...

If it has been terribly hot (Inside cabin temp) when the CB trips... it is showing signs of wear...

2) Anything interfering with the fan motor turning can increase the electrons flowing....

3) Any time insulation is rubbed off a wire... Electrons jump to ground... Tripping the CB as designed...

May help to have an amp meter for problem solving...

Inspecting the wires can be helpful...
 

Swaptronics may be the cheap way out... (not usually recommended... for expensive parts)
 

PP thoughts only, not a mechanic...

Best regards,

-a-

[Heidiho]

Hi Van, I couldn’t help but respond to your blog because our 231 is the same year as yours.  Several years ago we were flying over Nashville Tennessee in IMC at ten thousand feet.  We initially smelled burning wires and looked at each other asking,  “do you smell something burning?  Then  the smoke began to fill the cockpit coming between the radio and the auto pilot.  My hiusband initially thought something was happening to the auto pilot and reached to pull its fuse.  We were reaching for the fire extinguisher and preparing to declare an emergency when the smoke began to lessen and then stopped.   As soon as we got into VMC we landed and called our mechanic and checked things out under the panel.    We discovered the radio fan motor had disintegrated—but the fuse never broke—so be glad yours did.  That smoke thing was a bit unnerving...Our breaker amperage was correct—-our mechanic said sometimes the “whys” I.e. (it didn’t break) can’t be explained.   We were glad it wasn’t our auto pilot, for obvious reasons....that’s flying, though, there are bound to be some exciting moments in the sky.  I hope you will find the cause of your problem, which I am sure you will, especially if you follow the advice given by Carusoam.  He seems to be on track with the information he shares with everyone.

[Van Thornock]

Thank you Heidiho, I am glad you were able to resolve your problem without it being worse. Your experience and suggestions are very appreciated. 
Van

[Van Thornock]

Thank you carusoam for your insight. 
I appreciate your help. 
Van