Casualties unknown

Helicopter Collides with Boat House Roof After Engine Power Loss from Clogged Fuel Injection Ports (N20SP)

Cambridge, MA, US

On February 22, 1995, an Eurocopter AS-350-B (registration N20SP) was involved in an aviation accident near Cambridge, MA. Investigators recorded the probable cause as: Clogged fuel injection ports due to contaminated fuel (iron oxide and water) from an unmaintained in-ground storage tank, combined with a lack of oversight and training in the MSP air operations. 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 2026-06-10Data APIEditorial standards

A Massachusetts State Police helicopter with four occupants experienced engine power loss after a puff of smoke from the exhaust, descended steeply, and collided with a boat house roof. Investigation found clogged fuel injection ports from contaminated fuel in an unmaintained storage tank, and a lack of oversight and training.

Incident Description

A Massachusetts State Police (MSP) helicopter departed a heliport with two crewmembers and two passengers. It climbed to approximately 600 feet above a river when witnesses observed a puff of "smoke" or vapor emanating from the engine exhaust. The helicopter then turned toward the river bank and descended at an angle between 45 and 70 degrees. Witnesses reported that the main rotor blades were either turning slowly or had stopped before the helicopter collided with a boat house roof.

Investigation Findings

Examination of the helicopter revealed no preimpact failure of the main rotor or transmission. However, inspection of the engine found that five of the six fuel injection ports were clogged. Samples from the helicopter's fuel system contained iron oxide and water.

The MSP operated a 6,000 gallon in-ground fuel storage tank that had not been maintained or secured in 14 years, aside from a filter change between 1984 and 1986. Fuel samples from this storage tank contained high levels of rust and water, as well as degraded thermal properties.

Further investigation identified a lack of oversight in the MSP air operations. Records showed no training, safety, or fuel management program. In the past five years, the pilot involved received only one training session, consisting of a two-day ground school and one formal training flight.

Probable cause

Clogged fuel injection ports due to contaminated fuel (iron oxide and water) from an unmaintained in-ground storage tank, combined with a lack of oversight and training in the MSP air operations.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001207X03023. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.