The aged Arrow Air DC8 that crashed Dec. 12 at Gander, Newfoundland, killing all 256 American soldiers and crew aboard, had been plagued by numerous problems in the days before the disaster, according to the results of an official Canadian investigation.

Crew members who flew on the 25-year-old aircraft the day before the crash told investigators that a couple of warning lights on the plane came on at times and that one of the engines was running about 100 degrees hotter than the others, requiring adjustments at takeoff. The crew on the plane reported that it was also burning more fuel than normal.

This information was passed on to repair technicians at Cologne, West Germany, the last stop before the plane flew to Newfoundland for refueling, investigators reported, but no attempt was made to determine the cause of the defects nor were entries made in the aircraft maintenance log.

In addition, passengers traveling on the plane the day before the crash said there were these other problems, according to investigators:

*Although some windows and paneled areas were taped with duct tape, air leaked into the cabin near the front passenger door.

*There was an occasional burst of flame from one of the engines on the left side of the plane. One passenger told investigators he had seen fluid dripping from the top of the wing near that engine.

*When the plane landed in Cairo on Dec. 11, the crew had tremendous difficulty opening the forward cargo door. They had to use a fire-ax and a pocketknife to pry it loose.

*Potable water and coffee were not available because of faulty aircraft water systems. Leaks were observed on the exterior of the aircraft. Inside, the floor around the toilets was unusually squishy.

While citing these troubles, investigators nevertheless told an official inquiry that began here yesterday that they still have not been able to determine the exact reasons for the crash of the jet, which was bringing 248 U.S. 101st Airborne Division soldiers home from peace-keeping duties in the Middle East.

Peter Boag, chief investigator of the crash for the Canadian Aviation Safety Board, told the hearing that his team had been unable to find any evidence of failure in the engines or in the structure of the plane, which broke up into thousands of pieces when it slammed into a wooded area just across from the runway at Gander.

He said a number of factors may have combined to cause the crash.

Contributing factors could include ice on the wings accumulated during the landing at Gander or while the plane spent an hour on the ground being refueled and underestimation of the weight of passengers and baggage.

Paul Garrett, a refueling worker at Gander International Airport, testified that he saw frost on the underside of the plane's wing. It "formed a 20- to 25-square-foot circle under the wing between the two engines," he said.

A weather forecaster testified that a freezing drizzle ended a half hour before the crash.

The investigation has turned up no evidence that the crash was caused by an explosion, Boag said.

The plane had reached normal speed, "but at or shortly after takeoff the aircraft's performance deviated from the norm," Boag said.

"The airspeed increased only marginally after takeoff and there had to be either a significant increase in drag or decrease in engine thrust," he said.

In testimony today, Rudy Kiffor, training director for Arrow Air, acknowledged that unclear instructions had been given its crews on how they should go about calculating the weight of planes carrying military troops and their gear.

Kiffor also acknowledged having received complaints from Arrow Air pilots who were scheduled to be on duty for 18 to 20 hours.