Circuit Breakers

The following information is derived from the FAAs Service Difficulty Reports and Aviation Maintenance Alerts.

Beechcraft Model F33A Bonanza

Unspecified Failure

Pitot heat switch would not stay in the on position. On troubleshooting, the technician found circuit breaker/switch (p/n 35-38013263) to be at fault. AD 2008-13-17 had been completed 2427 flight hours prior. Recommend breaker manufacturer develop a more durable product or aircraft maker look for a different source for its circuit breakers.

Part total time: 2427.0 hours

airplane circuit breaker

Beechcraft Model Super 200 King Air

Low Load

With all deice and anti-ice equipment energized, the right number 1 dual-fed bus circuit breaker (p/n 70-000150) tripped with no loss of equipment system. While reviewing the AFM, the corresponding left breaker tripped and power to all circuits on number 1 fed buss was lost. An emergency was declared and the aircraft landed incident. Troubleshooting revealed the right breaker was tripping prior to its rated load and overloading the left one, causing it to trip, open, resulting in complete power loss on the bus.

Part total time: 2592.0 hours

Cessna Model 172N Skyhawk

Internal Failure

Pilot noted a clicking noise accompanied by ammeter indicating a heavy discharge. Problem isolated to a circuit breaker that wasn’t tripping the indicator button and was working as an auto-reset breaker. A short was located within the already placarded “inop” ADF. The owner commented he thought the issue was normal operation for the pulselight system.

Part total time: 1609.0 hours

Cessna Model 208B Grand Caravan


Propeller heat reported inoperative in flight. Voltage found to be zero at all three boots. Removing the circuit breaker panel revealed a cricket had shorted the circuit across the anti-ice breaker. The adjacent circuit breaker exhibited heat damage. Installed two new circuit breakers, repaired burned wiring and tested system. Operations check was good. Found many more crickets in aircraft and cockpit area.

Cricket total time: Unknown

Diamond DA20-C1

Broken Housing

Found alternator power wire loose at 50 amp circuit breaker (p/n W23-X1A1G-50), causing signs of arcing. Breaker housing was found cracked close to connection. It was also noted that the wire insulator of the charging wire running from the alternator to the circuit breaker (p/n 24315A8) was broken at the firewall grommet, exposing the wire, although not shorting out with anything. Parts were replaced as required.

Part total time: Unknown


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