Loose Connection Leads To Crash

[Neal]

A reminder, especially on new aircraft. Retorquing, inspecting connections, etc. should be carefully checked at least at each annual/condition inspection. Thorough inspections are key to accident prevention. Take your time and inspect thoroughly. Put a screwdriver on screws, test other connections.

Loose Connection Leads To Crash — General Aviation News

Probable Cause: A total loss of engine power due to the loss of power to the electronic fuel injection and ignition system, which was the result of a loose connection between a common ground feed-through stud and the ground bus.

generalaviationnews.com

 

[Cactus Charlie]

According to the report the accident was caused by non-redundant system design and incorrect assembly, not by failure to inspect.

The time to catch this problem was long before the aircraft first flew.

 

[Neal]

Post-accident examination of the wreckage revealed that the ground feed-through stud that connected the battery ground terminals to the ground bus was loosely connected on the nose cone bulkhead. The feed-through nut was 3.5 turns loose, which corresponded to approximately 3.5 threads of the feed-through stud.

Additionally, neither a spring lock washer nor a secondary locking nut were present on the feed-through stud assembly, as was found on all other primary electrical connections throughout the airplane.

Probable Cause: A total loss of engine power due to the loss of power to the electronic fuel injection and ignition system, which was the result of a loose connection between a common ground feed-through stud and the ground bus.

 

[Cactus Charlie]

"Electrical system redundancy was accomplished by use of a main and auxiliary system, with two independent batteries and an alternator. The system shared a common ground line that connected the negative terminals for both batteries and was routed through a ground bus located behind the nose cone bulkhead to the engine compartment and engine case."

No redundancy. Designed-in single point failure!