Accident Summary
The helicopter was on approach to an airport when witnesses observed it pitch up and yaw uncontrollably. The rotor system slowed as the aircraft descended, ultimately impacting on a city golf course.
Investigation Findings
Examination determined that the main rotor swashplate bearing had failed as a result of inadequate lubrication. The stationary swashplate venting hole had not been blocked off in accordance with Aerospatiale Service Bulletin #62.02, which was issued to prevent lubricant leakage. At the time of the accident, the swashplate bearing had been lubricated 249 hours prior.
Additionally, the fuel flow control lever and fuel shut-off control were found in the closed position, consistent with the pilot having shut down the engines before impact.
Maintenance and Airworthiness Directives
Priority Airworthiness Directive 89-21-01 had been issued to address the lubrication issue by reducing the lubrication interval from 400 to 100 hours and requiring that the vent hole in the stationary swashplate be blocked.