Gear Popping Circuit Breakers

[donkaye]

Over the past year (or two) at various times I've had the gear warning and stall warning circuit breakers pop--together.  It started getting worse this year, so I decided it was time to solve the problem.  I realized that it didn't happen in the wintertime; only the summertime.  This year it was happening every time I flew when it was reasonably hot.  I took it in to an Avionics shop hoping it wouldn't take them too long to diagnose the issue.  They spent a lot of time trying to track down the problem and finally decided to just change out the circuit breakers.  The first flight after the new breakers were installed both breakers popped again.   That money was down the drain.  Nobody understood why both breakers popped at the same time.

Time to call Top Gun.  It turns out that the only place where the two circuits meet is the Tone Generator box located by the left rudder pedal.  Mooney still sells them--$2,000+. That's a lot of money to spend on a guess.  Turns out the product is made for Mooney by International Avionics Incorporated in Addison, Texas.  They do repairs and quoted about $650 to look at it.  I had Top Gun send it out to them.  A week later I called them to see if the problem was diagnosed.  Ken, their tech who has worked there for 30 years, said he was going to work on it the next day, but in the past they had had a number of them returned for the same issue, and as such they redesigned the power supply.  I gave them the go ahead to replace the card if necessary.  They replicated my problem, so the card was replaced.

Today, Mark installed the unit in about 15 minutes.  We tested it on the ground and with the new design the circuit breakers are independent of each other.  (In the past if you wanted to disable the stall warning you had to pull the gear warning breaker as well).  I feel comfortable that the problem is solved.

I'm posting this to save anyone else the expense of troubleshooting this issue should  they have it.  Just send in the Tone Generator for repair and your problem will be easily resolved.

PS Just got the Bill.  Less than new, but $$.

[larryb]

Thanks Don. When did the CB’s blow, master on or when one of the warnings activated? I never understood why they had to replace a nice cheap sonalert with an expensive oscillator.

[Bravoman]

If I recall correctly international Avionics is where we sent my annunciator panel when it needed to be overhauled a couple years back. They are the OEM. 

[donkaye]

15 minutes ago, larryb said:

Thanks Don. When did the CB’s blow, master on or when one of the warnings activated? I never understood why they had to replace a nice cheap sonalert with an expensive oscillator.

Every time in flight.  In the beginning I only noticed them when I put the gear down and the light didn't come on.  After a few missed heart beats, I looked down at the floor indicator and it showed the gear was down.  Then I looked at the circuit breakers and they were popped.

[donkaye]

7 minutes ago, Bravoman said:

If I recall correctly international Avionics is where we sent my annunciator panel when it needed to be overhauled a couple years back. They are the OEM. 

They had to repair my annunciator a few years ago, too.  The low/high alt lights wouldn't go out.  That was costly, too, as I had to verify the alternators were good.

[affricate]

On 8/3/2020 at 9:16 PM, donkaye said:

Every time in flight.  In the beginning I only noticed them when I put the gear down and the light didn't come on.  After a few missed heart beats, I looked down at the floor indicator and it showed the gear was down.  Then I looked at the circuit breakers and they were popped.

Happened to me coming into Tucson,