Bad master battery breaker

[Scrapman1959]

Has anyone had problems with the battery master circuit breaker? Sometimes I pop both master breakers in and the avionics fan is running slowly like a low battery, and when u hit the key to spin the engine, everything goes dark. Pop the masters out and back in, and everything fires up normal. I think it has to be a bad battery master. Thoughts anyone?

[Roger Lee]

You may be right. I would check the wires on the back of the breaker. These breakers do have a service life.

[Runtoeat]

I've found a intermittent breaker for the position lights.  I squirted some Radio Shack contact cleaner / lubricant into all of the holes I could find and cycled the breaker a number of times to work this into the contacts inside.  Haven't had the problem since.  I now "excersize" all of my breakers every once in a while to work the contacts inside of them.  As for you main breaker, this gets a constant cycling and might not just have oxidized or dirty contacts. You could try the cleaner / lubricant but might be best to go with Roger's thought that these have a life cycle and it might be time to replace it?

[Rich]

Scrapman,

 

I'm not familiar with the CT main breakers or their current draw, but am with breakers in general.

Do you shut down the mains before or after all loads are shed?

If before, over time the contacts will pit and carbon will form which would cause the problem you describe.

 

A set of contacts have high points which allow for a wiping action to take place when they are cycled. Once the high points are gone your left with flat surfaced contacts which will now start to pit and carbon over.

 

It just depends on the load when turned off or the number of cycles over time. It's always better to shed the load first.

I'd rater turn off individual loads first and help save the main breaker than worry about wear on the individual switches.

 

Loosing the main in flight has the much higher risk than an individual failure.

[Scrapman1959]

I always shut all avionics and switches down before I kill the engine. Then last thing I do is pop both masters. I always thought this was the proper way of shutting down the AC. The AC is a 2011 CTLS and gets flown 2 or 3 times a week and is showing 875 hours now. I'm ordering a new fuel injected LS now. This one has sky view with a Garmin 430 WAAS for the com. It couples to the tru trac and flies perfect approaches with vertical guidance. The new one will have the 750 Garmin. It's a $19K option, ouch! I guess I should probably just replace that breaker if there are no loose wires on the connectors. Anybody looking for a great flight school plane, N469K with the 430W would be perfect. Thanks for the help guys.