Casualties unknown

1997-01-12: Enstrom F28A (N9087) — Saipan Island, CQ

Saipan Island, CQ

On January 12, 1997, an Enstrom F28A (registration N9087) was involved in an aviation accident near Saipan Island, CQ. Investigators recorded the probable cause as: loss of engine power due to fuel exhaustion, resulting from improper planning/decision; and the pilot's abrupt handling of the flight controls, while maneuvering to avoid swimmers, which resulted in main rotor blade contact with the tail boom. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data APIEditorial standards

An Enstrom helicopter on a sightseeing tour with two passengers experienced engine sounds of sputtering and a loud bang before impacting in shallow ocean water. Examination found main rotor blade severed tail rotor drive shaft; fuel exhaustion calculations indicated possible exhaustion within 0.1 hour of flight duration.

Incident

Shortly before 1510, the pilot started the helicopter's engine and departed on a sightseeing tour around the island with two fare-paying passengers. The operator anticipated the flight would last between 0.5 and 0.7 hours. To manage weight, the fuel load had been reduced before takeoff by an estimated 10 gallons, bringing the usable quantity to between 16 and 19 gallons, as estimated using a dipstick.

About 1558, while cruising offshore and nearly parallel to the shoreline, witnesses observed the helicopter fly past while making sounds like its engine was sputtering, stalling, or cutting in and out. The helicopter's course remained unchanged, and seconds later, other witnesses heard a loud bang sound. The helicopter then entered a rapid descent and impacted in approximately 2.5-foot-deep ocean water in front of a hotel where people were swimming.

Wreckage Examination

An examination of the wreckage revealed that a main rotor blade had impacted and severed the tail rotor drive shaft. No evidence was found indicating that the pilot had practiced autorotations in the Enstrom helicopter during the 4.5 months since becoming rotorcraft rated. During structural airframe and engine examinations, no evidence was found of precipitating mechanical malfunctions.

Fuel Calculations

Calculations based on maximum anticipated fuel consumption rates and approximations for the quantity of fuel on board revealed that fuel exhaustion could occur within 0.1 hour of the flight's duration.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001208X07309. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.