An unexplained baggage-compartment fire is a leading suspect in the crash last Friday of one of the helicopters detailed to carry Jordan's King Hussein and members of his party to Sikorsky Aircraft in Stratford, Conn., federal officials said yesterday.

Hussein and his party decided to travel by automobile from Bedford, Mass., to Stratford because of foul weather. The four people aboard the Sikorsky S76B helicopter, all Sikorsky employes, were killed during the crash into a wooded area near Sutton, Mass.

The National Transportation Safety Board "has not ruled out" the possibility that a bomb or incendiary device was placed on the aircraft, spokesman Michael Benson said yesterday. "Our people are two or three days away from deciding whether we will ask for additional help" in the investigation, he said.

Board officials said the FBI has agreed to help if its incendiary-device specialists are needed, although the FBI is not participating in the investigation.

The Secret Service, responsible for protecting visiting heads of state, is "monitoring the investigation and will be interested in the outcome," spokesman Jack Taylor said.

The helicopter's wreckage is being taken to a Sikorsky hangar in Stratford for further examination by NTSB specialists. Representatives of Sikorsky and Pratt & Whitney, the engine manufacturer, are participating in the investigation. Both companies are subsidiaries of United Technologies Corp.

"I honestly doubt very much there was any kind of sabotage," a Jordanian Embassy spokesman here said. He attributed the accident to bad weather and said the decision to drive instead of fly had been made the previous night.

A source close to the NTSB investigation said early indications point to "an in-flight fire" in the aft baggage compartment.

Benson said it has not been determined if the fire came before or after the crash. A charred bag containing an electric wire was recovered from the wreckage, Benson said, but the wire "could have been from a hair dryer," he said.

The wreckage was confined to a relatively small area, and investigators said they believe that the helicopter was essentially intact until it struck the ground.

The helicopter was flying in low-visibility weather at 6,000 feet when it disappeared from radar at the Boston Air Route Traffic Control Center. Although no discernible distress signal was received from the helicopter, a source said there was "a muffled sound just after the last" radio contact between air-traffic control and the helicopter.

"It might have been a panic call, but we may never find out," a source said. Electronic enhancement of air-traffic control recordings is a standard investigative technique.