Accident Details
On September 5, 2009, at approximately 1530 central daylight time, a Schweizer 269C helicopter, registration N626LH, sustained substantial damage following a loss of engine power and subsequent forced landing into Lake Texoma near Preston, Texas. The helicopter was operated by Longhorn Helicopters Inc., of Denton, Texas, under 14 Code of Federal Regulations Part 91 for a local flight. Visual meteorological conditions prevailed, and a company flight plan was filed. The flight had departed from Cedar Mills Airport (3T0), Gordonville, Texas, at 1300.
Pilot Account
According to the pilot, while conducting an aerial survey at an altitude of approximately 350-450 feet above the water, the engine experienced a loss of power. Due to crowded beach conditions, the pilot elected to perform the forced landing off shore. Both the pilot and the single occupant were able to exit the helicopter unassisted and were subsequently picked up by a personal watercraft. Neither occupant was injured.
Examination and Findings
The helicopter was recovered from the lake and examined by investigators. The engine oil drain plug was removed, and water and oil were drained from the engine crankcase. The engine's lower spark plugs and valve covers were removed. The engine was manually rotated via the main drive pulley, and valve train continuity was established to each cylinder and to the accessory gears. Thumb compression was developed in each cylinder. The magnetos were dried out and produced spark to all posts when tested on a magneto test bench.
The fuel servo and injector nozzles were removed, flow checked, and disassembled for inspection, with no preexisting anomalies found. Both fuel tanks contained a quantity of a blue liquid consistent with 100 low lead aviation fuel. The electric standby fuel pump switch was found in the ON position. The pilot reported that, per company policy, the standby pump was activated at all times when flying at low altitude and that it was on for the entire accident flight.
Determination
The reason for the reported loss of engine power could not be determined.