What happened
As the helicopter approached the airport, the aircraft was observed to pitch up and yaw uncontrollably. Witnesses reported that the rotor system slowed as the helicopter descended, eventually impacting a city golf course.
The investigation
An investigation determined that the main rotor swashplate bearing failed due to inadequate lubrication. It was discovered that the venting hole in the stationary swashplate had not been blocked off as required by Aerospatiale Service Bulletin #62.02, a measure intended to prevent lubricant leakage.
Records showed the swashplate bearing had been lubricated 249 hours prior to the accident. While Priority AD 89-21-01 had been issued to reduce the lubrication interval from 400 to 100 hours and to block the vent hole, these requirements were not met. Additionally, investigators found the fuel flow control lever and the fuel shut-off control in the closed position, suggesting the pilot may have shut down the engine before the impact.