On August 22, 1982, a Bell 47G-2A (registration N73205) operated by Washington Flying Service was involved in an aviation accident near Washington, IA. Investigators recorded the probable cause as: The nut securing the bolt for the lateral servo was not properly secured after maintenance on the lateral cyclic control, resulting in the bolt not being in place. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter crashed while being air taxied to refuel after the pilot felt a snap and lost cyclic control. Investigation found a missing bolt securing the lateral servo.
Incident
A helicopter crashed while being air taxied to the refueling location. The pilot reported that after lifting off and reaching approximately 6 feet AGL with about 20 knots forward speed, he suddenly felt a snap and the cyclic control moved fully to the left. The helicopter became uncontrollable and flew into the ground.
Investigation Findings
An investigation revealed that a bolt, part number 20-057-4-16D, which is used to secure the lateral servo to the airframe, was not in place. According to the pilot, the nut for this bolt was not properly secured after maintenance was performed on the lateral cyclic control.
Probable cause
The nut securing the bolt for the lateral servo was not properly secured after maintenance on the lateral cyclic control, resulting in the bolt not being in place.