Causal Factors for General Aviation Accidents/Incidents
I just ran across this FAA publication investigating accidents due to mechanical issues from 1984 to 2004.
16,213 accidents/incidents (26%) are classified with an ATA code as the causal factor. An ATA code indicates a mechanical malfunction of the aircraft’s systems. The remaining accidents/incidents were attributable to non-mechanical factors, including pilot error, human factor related problems, and improper procedures.
Just the list of definitions is informative.
Improper Operation of Brake/Flight Control on Ground:
Loss of directional ground control due to improper operation of brake or flight controls. Typical examples are: losing directional control during landing, improper use of brake system, and losing directional control during take-off.
Selected Unsuitable Terrain: Landing on unimproved areas, landing on unknown terrain condition, and veering off runway onto unimproved areas.
Unsafe Acts by Third Party:
Unauthorized ground vehicles colliding with aircraft, aircraft to aircraft collision during ground operation, maintenance induced problems, and unauthorized personnel present during ground operations.
Inadequate Preflight Inspection of Aircraft:
Failure to remove aircraft tie downs, door not latched on take-off, improper setting of seat stops prior to take-off, fuel cap not properly installed, failure to remove control locks prior to take-off, and improper setting of control trim prior to take-off.
Failure to Avoid Objects or Obstructions:
During ground or air operations such as striking towers, other aircraft on ground, power lines, ground support equipment, trees, and wild life, such as deer, on the ground.
Poor Preflight Plan/Aircraft Performance:
Exceeded ability of aircraft to climb during towing flight, operation in excessive wind or gust components, operation off of improper runway surface for aircraft type, and exceeded density altitude limit of aircraft type.
Inadvertently Retracting Landing Gear:
Pilot accidentally retracted gear, selected gear up instead of flaps up.
Landing Gear Actuator:
Failure of the landing gear actuator system including failure of down lock system, and failure of actuator motor/transmission.
Landing Gear Strut/Axle/Truck:
Failure of the strut assembly, trunnion area including bearings, torque link system, and landing gear attachment brackets/hardware.
Exceed Load Design:
Loss of aircraft integrity caused by exceeding design loads due to over speed, over weight, acrobatic flight in non-rated aircraft, and down/up drafts.
Miscellaneous Pilot Unsafe Acts: Pilot distraction induced accident/incident such landing on wrong runway or taxiway, take off without Air Traffic Control (ATC) clearance, flying too low and striking trees, other aircraft, etc., and not securing gas or oil caps resulting in loss of fuel/oil.
Observations
Landing gear issues were a primary cause for accidents of both part 91 single and multiple engine accidents. Failure of the retraction/extension system along with failure to extend the gear accounted for 12% of all part 91 accidents.
Improper operation of brakes/flight control on ground also was a leading causal factor of part 91 accidents. 6,108 events (11%) of part 91 accidents were due to improper operation of brake/flight control during ground operations.
The leading causal factor for both Cessna and Piper aircraft was improper operation of brake/flight control during ground operations. The leading causal factor for Beechcraft was failure to extend the landing gear.