Workers labored throughout the day to retrieve bodies of American paratroops from the rolling, snow-dusted forest near the airport runway here, as investigators disclosed that they had encountered a major obstacle in trying to determine the cause of the sudden crash here yesterday morning.

The two black box flight recorders were so badly damaged when the Arrow Air DC8 carrying 101st Airborne Division troops home from Cairo exploded into thousands of pieces after takeoff that it is unlikely that they will provide any useful information, according to the chief Canadian investigator, Peter Boag.

He also confirmed that the pilot of the Miami-based chartered airline had failed to have the aircraft de-iced before he took off in a light, grainy snow.

The operations, maintenance and personnel records of the charter company were to be examined carefully, Boag said.

By nightfall, fewer than two dozen of the bodies of the 248 soldiers and eight-member crew remained on the three-quarter-mile-long trail of wreckage strewn along a rolling hill south of the runway. But U.S. military officers said they were unable to say precisely when autopsies by Canadian pathologists here would be completed and the remains could be flown home.

Maj. Gen. John S. Crosby, deputy chief of staff for planning at the Pentagon, who is here to supervise the return of the bodies, said that an accurate manifest obtained today indicated that there were 248 soldiers aboard the plane, not 250 as initially reported. He said three women were among the 101st Airborne troops.

At the duty-free shop in the airport, salesclerks sadly recalled how happy and excited the soldiers were when they came into the lounge during the refueling stopover, the last leg of their journey home for Christmas after six months of peace-keeping duty in the Sinai Peninsula.

Some sang Christmas carols along with the airport Muzak. A few bought T-shirts that said, "I Survived Gander, Newfoundland."

"They were jolly. They were happy that they only had four hours left to go," Rose Powell, one of the clerks, said.

Early this morning, two military transport planes brought in Army morticians, pathologists and 224 metal coffins. The charred corpses were taken to a hangar, laid on tarpaulin in neat rows and covered with white sheets.

Military officials said that most of the bodies were easily identifiable by their metal military tags but that the recovery process was slowed because investigators had to chart precisely the location of bodies, shards of aircraft and equipment.

Boag said the tail section of the aircraft hit the ground first when the plane, veering slightly to the right of the flight path, crashed and exploded about half a mile below the runway.

The tops of the firs and spruce trees near the crash site were sheared off by the plane as it descended, and patches of the woods burned as the plane broke up into small, flaming pieces. The largest section of the aircraft that remained was a 20-foot shard of twisted wing, engine and fuselage.

A sharp, acrid stench still lingered over the crash site this afternoon. Although investigators had worried about forecasts of snow and rain, which would hamper the probe, the skies were sunny and clear for most of the day.

Using surveyors' instruments, Royal Canadian Mounted Police and Army soldiers worked with investigators painstakingly to mark off in quadrants of rope and narrow, yellow ribbon the locations where bodies and the bits and pieces of the airplane were found.

At Gander Lake on the edge of the rolling crash site, Newfoundland officials had erected a boom so that oil from the wreckage would not get into the lake and contaminate this town's supply of drinking water.

Jeans, fatigues, a duffel bag and weapons were strewn across the site. Boag said they had not found any evidence indicating that a piece of the plane had dropped off before the crash, but his investigators were still combing the forest to be certain.

Because the flight recorders were yielding few clues, Boag said, it was difficult at this stage to determine whether any of the operations systems of the plane had malfunctioned. He said that the pilot signaled no distress to the aircraft tower and that air traffic controllers noticed nothing unusual about the takeoff until they saw the huge fireball light up the dark, early morning sky.

"The job of examining the wreckage will be a slow process," Boag said.

"At this time, it remains to be seen if any useful information is to be retrieved" from the black boxes, he said. Boag described the flight recorders as outmoded.

Although officials here and in Washington have tended to discount theories that the crash may have been caused by a bomb or some other form of sabotage, Boag said investigators had no working theory about what had happened.

Although soldiers carried weapons with them, Boag said the investigation indicated that they had no ammunition aboard.

Shortly after the plane landed here in the predawn hours yesterday for about an hour of refueling and loading of meals, Boag said, a light, freezing rain fell. It stopped just before the charter took off.

Pilots of some of the other planes departing during that period had their aircraft sprayed with de-icing solution, but the Arrow pilot chose not to do so before taking off shortly after 7 a.m.

Ice has been the cause of other crashes.

Boag said the Arrow pilot had visibility of 12 miles at the time of takeoff and broken cloud cover of about 700 feet overhead.

The Arrow charter had left Cairo and stopped for refueling in Cologne, West Germany, before the stopover here at Gander, a plain, friendly town of about 12,000 on the northern tip of the Canadian island of Newfoundland.

Located on the "great circle route," the shortest distance between Europe and North America, Gander was founded in the mid-1930s as a jumping-off point for flying boats and other experimental aircraft.

During World War II, its importance was heightened as it became a major refueling and servicing point for planes manufactured in the United States that were being sent to Allied forces in Europe.