Bellanca 7ECA Shorting Ammeter Wire “While in flight,” states a technician, “the pilot reported he could smell something burning-he landed as soon as was practical. Investigation revealed the wire from the alternator to the ammeter (p/n 112) had shorted against the firewall….” “Wires 112, 114, the master relay, starter relay, voltage regulator and alternator were all replaced.” 288
Leaks and Shorts
After sitting idle on a ramp for at least 10 months, the airplane underwent maintenance. A strong fuel odor was observed in the cabin; an exterior inspection failed to detect anomalies. The odor subsided. Once the engines were started and the fuel selector placed in crossfeed, the odor returned. After removing the floorboards, a heater duct running perpendicular to the crossfeed lines was observed to be in contact, causing corrosion. Pinhole leaks had developed in both lines, p/n 5300108-53 and -54.
Key Takeaways:
- An ammeter wire in a Bellanca 7ECA shorted against the firewall, causing a burning smell in flight and requiring replacement of multiple electrical components.
- Pinhole leaks developed in the crossfeed fuel lines of a Cessna 340A due to corrosion from contact with a heater duct, causing a strong fuel odor.
- Multiple reports detailed carburetor float failures (e.g., hollow plastic or polymer floats) taking on fuel and losing buoyancy, leading to erratic engine performance and calls for recalls or design improvements due to reduced wear life.
- A Lamar starter motor experienced a commutator separation, which led to the destruction of its internal brushes.
Key takeaways sponsored by Aviator Pro | Start Your Training ->
See a mistake? Contact us.
