Wired

During a routine inspection, the technician noted the strobe lights would remain on after the switch was selected off. Troubleshooting revealed the switch to be defective. Removing and disassembling the switch revealed the solder joint holding the braided wire had broken and welded itself to the line post. Switch was replaced IAW AD 2008-13-17 in May 2009.

Editorial Staff

Monday, November 21, 2016 at 12:00 AM ET

Verified

Key Takeaways:

Many reported aviation incidents stem from electrical wiring issues, including chafing, shorting, and broken connections.
These wiring faults affect a wide range of aircraft systems, from strobe lights and alternators to critical avionics, engine controls, and landing gear.
Common causes include wear and tear on insulation, manufacturing defects (e.g., improper crimping), and inadequate securing or routing of wiring.
Such electrical problems can lead to diverse operational failures, often requiring detailed inspection to locate the obscured or subtle fault.

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Beechcraft Model A36 Bonanza

Strobe Light Switch

Part total time: 516.0 hours

Beechcraft Model 58 Bonanza

Intermittent Alternator

Pilot reported left alternator intermittent. Maintenance found the B+ power wire chafed at the engine intake manifold, approximately six inches below the alternator. A small hole had arced through the intake manifold. Wiring was not secured properly in this area.

Part total time: 6459.0 hours

Cessna Model 208B Grand Caravan/G1000

Avionics Failure

Prior to takeoff, a GMU-700 fail warning came up on CAS messaging system. Investigation determined the power wire to the GMU-700 unit, flight director, yaw damper and autopilot head had chafed through and was shorting out to the top of the avionics rack behind the MFD screen. No circuit breakers popped.

Part total time: 2224.0 hours

Cirrus SR20

Magneto Failure

After landing, engine was vibrating and misfiring at or below 1000 rpm. Problem was duplicated with magneto switch on right mag only. Inspection revealed coil primary lead to points had broken off. The coil lead wire had not been crimped properly. Wire had broken off its terminal end connector, causing loss of coil power to primary contact points of magneto.

Part total time: 521.0 hours

Diamond DA42 TwinStar

Engine Control Unit Failure

During cruise, experienced multiple ECU failures on right engine, power loss and rough-running condition. Engine was visually inspected and maintenance data downloaded and sent to tech support for analysis. Evaluation found oil pressure sensor wire insulation chafed and grounding out. Wire was insulated, rerouted and secured.

Part total time: 229.0 hours

Pilatus PC12-45

Unsafe Gear Indication

While on short final, left main gear indication flickered from green to red and then remained red. Aborted approach to discuss with maintenance by radio. Maintenance advised that once gear is down and locked, it will remain so even if an indicator light changes to red. Subsequent landing was uneventful. Inspection revealed a broken wire at the left downlock switch. The broken wire was obscured by the protective heatshrink.

Part total time: 17,672.0 hours