On April 7, 1999, an Enstrom F-28C (registration N51770) was involved in an aviation accident near Pendleton, OR. Investigators recorded the probable cause as: Water contamination accidentally transferred from a portable refueling barrel to the aircraft's fuel system during hot refueling. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During takeoff, a helicopter lost engine power. The pilot attempted autorotation but lacked sufficient altitude and airspeed, leading to a hard landing and rotor blade impact with the tail boom. Investigation revealed water contamination in the fuel system from a portable refueling barrel.
Incident
During a takeoff from a refueling pad, the helicopter's engine lost power. The pilot initiated an autorotation. However, because the aircraft did not yet have sufficient airspeed or altitude to complete a successful autorotation, it landed hard. The main rotor blades flexed downward and impacted the tail boom.
Investigation
It was later determined that water contamination had accidentally been transferred from a portable refueling barrel to the aircraft's fuel system during hot refueling, which was performed with the engine still running. Investigators could not determine how water was introduced into the portable refueling barrel.
Cause
The investigation established that water contamination, introduced from the portable refueling barrel into the helicopter's fuel system during hot refueling, led to the engine power loss.
Probable cause
Water contamination accidentally transferred from a portable refueling barrel to the aircraft's fuel system during hot refueling.