The state police helicopter which crashed into the Harvard Yacht Club in February, killing four on board, had contaminants in its fuel system that may have caused the motor to fail, a federal official told reporters at a press conference yesterday.

Dennis L. Jones, director of the Northeast Regional Office of the National Transportation Safety Board (NTSB), said federal investigators had found impurities, which they have yet to identify, in the wreckage of the helicopter's engine but are still uncertain about the cause of the crash.

"We have found some evidence of fuel contamination," Jones said. "We are nowhere close to a probable cause," he added later.

Jones said that the amount of contaminant was "relatively small" but significant enough that it would have affected fuel flow, possibly leading to a malfunction. Although investigators have yet to determine the substance's exact chemical composition, Jones described it as a "hard material, quite visible" to the naked eye.

In an article in Thursday's Boston Herald, anonymous sources said they were certain that someone had introduced the substance, which was described as a liquid, resin-based adhesive, into the helicopter's fuel tank.

"Whether it was accidental, I highly doubt it," one source told The Herald.

But Jones denied that there was any reason to believe, at least at this stage, that the helicopter's fuel tank had been sabotaged.

"We don't have any evidence whatsoever that foul play is involved," Jones said.

The police helicopter, a Eurocopter AS-350B, plunged from the sky and tore through the roof of the HarvardYacht Club on February 22. The passengers, twostate police pilots and two American Telephone andTelegraph (AT&T) technicians, died in the impact.The AT&T employees were being taken from Boston toNorfolk airport in order to do work for a statecontract.

The crash severely damaged the floatingbuilding, which houses boats for Harvard men's andwomen's sailing teams. Since then, the teams havesailed out of the boathouse of the MassachusettsInstitute of Technology sailing teams.

The Investigation

Initially, authorities expected theinvestigation to take six months, Jones said. Hesaid it is unclear when conclusive findings aboutthe cause of the crash will finally be available.

But Jones said that investigators are "close"to determining the exact chemical composition ofthe impurities. The next step is ascertaining thesource of the contaminant, he said.

Authorities are currently examining the fuel'squality, the sites where the fuel was stored andthe possibility of by-products resulting fromchemical processes in the engine, Jones said.

Maintenance problems may possibly have led tothe build-up of contaminants in the fuel system,Jones said.

In spite of the discovery of contaminants,Jones said investigators have in no way ruled outother possible causes for the crash, includingpilot error, mechanical failure and weather.