Mechanical & Engine Failure · NTSB WPR09LA202

ALEXANDER THOMAS P SPORTSMAN GS-2 — El Dorado HIlls, CA

1 fatal High-time pilot
DateApril 18, 2009
LocationEl Dorado HIlls, CA
AircraftALEXANDER THOMAS P SPORTSMAN GS-2 (amateur-built)
Purpose of flightPersonal
ConditionsDay · Visual Meteorological Cond
Phase / occurrenceEmergency descent Collision with terr/obj (non-CFIT)
Pilot age60
Pilot total time1,626 hrs · Experienced
Time in type36 hrs
Fatalities1

Probable cause

The in-flight separation of the elevator control torque tube rod end bearing from the elevator torque tube as a result of incorrectly tightened rod end bearing lock nuts.

NTSB findings

  • Aircraft-Aircraft systems-Flight control system-Elevator control system-Failure - C
  • Aircraft-Aircraft systems-Flight control system-Elevator control system-Incorrect service/maintenance - C
  • Environmental issues-Physical environment-Object/animal/substance-Tree(s)-Contributed to outcome
  • Personnel issues-Task performance-Maintenance-(general)-Not specified - C

What happened

Witnesses monitoring the accident flight's departure airport common traffic advisory frequency reported that they heard a mayday radio transmission stating that "I've lost elevator control" and "I'm going down in some trees." Witnesses adjacent to the accident site reported hearing a loud whining noise followed by the sound of something impacting trees. One witness stated that the airplane was at a low altitude in an upright attitude when it struck trees. The airplane subsequently impacted terrain and came to rest near a residential structure where a post-crash fire consumed most of the fuselage. Post-accident examination of the wreckage revealed that the elevator torque tube was disconnected from the forward rod end bearing. The forward rod end bearing remained attached to the elevator bell crank assembly. No damage was observed on the forward torque tube rod end threads or forward rod end bearing threads. The forward torque tube rod end jam nut was observed threaded about one-half inch from the threaded rod end. The aft torque tube jam nut and torque tube rod end was observed against the aft rod end bearing. The aft torque tube rod end was slightly bent and did not allow movement. No evidence of "torque seal" was observed on the forward or aft jam nuts, rod end bearings, or torque tube assembly. No additional mechanical anomalies were noted with the recovered airframe.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.

View the official NTSB docket →