On October 7, 1990, an Enstrom F28-C (registration N88RA) operated by Dr. Donald Gillum was involved in an aviation accident near Mesquite, TX. Investigators recorded the probable cause as: INSTALLATION ERROR OF COMPANY MAINTENANCE PERSONNEL. FACTORS WERE THE UNSUITABLE TERRAIN, THE TAILWIND, THE INABILITY OF THE PILOT TO MAINTAIN MAIN ROTOR RPM, AND THE INADEQUATE ANNUAL INSPECTION BY COMPANY MAINTENANCE PERSONNEL. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter experienced a loss of power at 300 feet AGL, leading to a vertical descent and impact. Post-accident examination revealed a chafed and arcing P-lead wire and loose magneto caps.
Accident Description
The helicopter departed from a ranch for a local area pleasure flight. At approximately 300 feet above ground level (AGL), a loss of power occurred while the helicopter was over a heavily wooded area. The pilot attempted to extend the glide by applying collective pitch and executing a right turn (quartering tailwind) toward the only available clear area. However, main rotor RPM continued to decay, and the helicopter descended vertically out of control, impacting onto an open field. The skids collapsed upon impact, and the helicopter rolled to the right.
Post-Accident Examination
Examination of the wreckage revealed that a misaligned P-lead wire in the magneto had chafed and arced. Additionally, both P-lead caps were found loose. The engine was subsequently test run, but the power loss could not be duplicated.
Maintenance Findings
The Director of Maintenance for the operator stated that he and his mechanic did not adjust the magneto timing because it was too difficult to reach on the helicopter.