On May 13, 1997, a Schweizer 269C (registration N107SM) was involved in an aviation accident near Laredo, TX. Investigators recorded the probable cause as: loss of engine power due to fuel contamination, and the pilot's failure to properly check the fuel system for evidence of water during the preflight inspection. A factor was the lack of suitable terrain for the forced landing. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During a low-altitude seismic survey flight, a helicopter's engine lost power. The pilot attempted an autorotation but experienced rotor RPM decay, resulting in a hard landing. Subsequent investigation revealed water contamination in the fuel system.
Accident Overview
The pilot reported that while conducting an airborne seismic survey at approximately 150 feet AGL, the engine lost power without warning. The pilot lowered the collective and turned the helicopter into the 10-knot prevailing wind. During the flare for an autorotation landing, the rotor RPM decreased and the helicopter touched down hard.
Fuel Contamination Investigation
A fuel sample was taken from the fuel filter sump, located between the fuel tank and the throttle body of the fuel-injected engine. Analysis of the sample revealed a substantial amount of water. FAA inspectors, accompanied by the operator, inspected the fuel storage tank used for refueling. Examination of the fuel filter in the trailer-mounted tank showed the presence of water and rust.
Aircraft Information
The helicopter was a 1995 model that had accumulated 713 flight hours at the time of the incident.