Electrical Relays

The following information is derived from maintenance facility submissions to the FAA's Service Difficulty Reports database.


Beech 95-B55 Baron

Failed Dynamic Relay

With the landing gear switch in the up position, the gear lowered via the motor on its own. Troubleshooting revealed the dynamic relay was powering the main landing gear motor for retraction or extension at the same time regardless whether the gear switch was selected up or down. There was power out from the terminal output from the dynamic relay to both up and down at the same time. The switch was confirmed normal. The malfunction was confined to the dynamic relay, which was replaced.

Part total time: Unknown

Beech C90A King Air

Stuck Avionics Relay

While en route, autopilot disconnected itself and an inoperative inverter was noticed. Selected #2 inverter, which did not work. Landed without further problems. Maintenance discovered poor connection and stuck relay K006 and K007 in nose avionics bay in junction box 01. Cleaned relay connections and cycled relays. Functional check satisfactory.

Part total time: 12,070.0 hours

Beech B300 King Air

Inoperative Wing Flaps

On approach, flaps stuck in approach setting and would not go into full-flap position. Missed approach; an uneventful no-flap landing was performed. Technicians replaced the flap control relay K105 and the aircraft was returned to service.

Part total time: 2056.0 hours

Cessna 310

Shorted Starter Relay

Aircraft lost all avionics power while in level flight; pilot landed without incident. Maintenance determined the starter relay shorted internally, which took out the avionics bus. Relay was replaced and the aircraft returned to airworthy condition.

Part total time: Unknown

Cessna 402C Businessliner

Failed Starter Relay

The pilot reported, “Right starter stays engaged.” Maintenance found right starter relay failed. Removed and replaced the relay.

Part total time: Unknown

Pilatus PC-12/47

Burning Odor In Cabin

A burning odor was noticed coming from the air conditioning system vents. System components were inspected with no defects found. The fault logs were downloaded to show fault code 21313A07CPA, low cabin inflow. The under-floor heating fan was found to run continuously due to sticking relay K162A2 (p/n 974.20.01.214).

Part total time: Unknown Θ


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