FORT CAMPBELL, Ky. (AP) _ Army crews Wednesday retrieved the last eight bodies of 17 soldiers killed when two helicopters on a night training mission collided, then plunged 250 feet to the ground and caught fire.

The UH-60 Blackhawk helicopters from Fort Campbell spewed wreckage for hundreds of yards and charred the partially wooded, gently rolling site six miles from the choppers' air field Tuesday night.

''One aircraft is located in the trees. One aircraft is right on the edge of a clearing,'' said Maj. Randy Schoel, Fort Campbell spokesman.

It was the worst Army aviation disaster since 248 soldiers based at Fort Campbell were killed in 1985 in the crash of a chartered plane in Gander, Newfoundland, Schoel said.

The Blackhawk, one of the newer helicopters used by the Army, Air Force and Marine Corps, has been grounded four times in three years. Last summer officials said about 40 people had been killed in crashes of the helicopter since 1978.

''I would say now there is no indication of any mechanical factor'' in the crash, said Chief Warrant Officer Joe Adams of the investigation team from the Army Safety Center at Fort Rucker, Ala. ''We are looking at human and environmental factors. The human factors might include some restriction of vision.''

Four bodies were taken from the wreckage of each helicopter Wednesday, Schoel said.

Schoel said the crash occurred on the western Kentucky-Tennessee border during a ''routine night mission,'' and left no survivors.

''Obviously, there's an element of risk in everything we do. We train up to a standard that reduces that risk to an absolute minimum,'' Schoel said. ''Yes it can be, but it's not necessarily, more dangerous to fly at night.''

The helicopters were flying at 92 mph air speed and about 250 feet from the ground when they collided, Schoel said. One of three helicopters flying in formation was hit by a fourth, said William Harralson, deputy public affairs officer at the fort.

''There were three aircraft in formation, if you want to say ducks in a row, headed east, and another who was flying solo, hit one of those,'' said Harralson. ''There can be 10 or 12 battalion-sized groups working at Fort Campbell at one time.''

''We have been told by the tower that the weather was good,'' he said.

The solo helicopter carried four servicemen; the 13 others were in the other aircraft.

Adams said the weather was good, which in military terms means visibility of better than a mile and a cloud ceiling of at least 500 feet.

One helicopter crashed on the Tennessee side of the border, the other in Kentucky. Although the soldiers were carrying personal weapons, such as M-16 rifles, the helicopters were not armed, Schoel said.

One of the other Blackhawk helicopters returned to the air field; the other landed at the crash site.

''They witnessed the accident. They were providing statements to the investigators, and the decision was made not to make them fly it back,'' Schoel said.

A team from the Army Safety Center at Fort Rucker, Ala., was called to investigate. A safety expert from Sikorsky Aircraft in Stratford, Conn., the helicopter's manufacturer, also sent a safety expert.

The Army identified three of the dead as Staff Sgt. Charles L. Shirley, 21, of Arkansas; Sgt. Dennis Sabot, 28, of Iowa; and Spec. 4 Samuel A. Hintz, 23, of Ohio, all from the 2nd Battalion, 502nd Infantry. Home towns were not provided. Names of the other victims were withheld pending notification of relatives.

The Army's fleet of 820 UH-60s was grounded twice in May 1987, once for inspection and once because of a design flaw. The entire fleet also was grounded in April 1985 and March 1986 after fatal crashes. In 1985, the Army identified a defect in the main rotor assembly and ordered it corrected.

Army Undersecretary James R. Ambrose said in November he had confidence in the Blackhawk. Noting news reports that radio and microwave towers on the ground can interfere with the aircraft's electronic control systems, he said no safety hazard had been found.

''The Blackhawk has a safety record at least four times better than the aircraft it replaced,'' said Bob Stangarone, a spokesman for Sikorsky, a division of United Technologies.

Stangarone noted the Army has shown its confidence in the Blackhawk by awarding Sikorsky multiyear contracts for the helicopter.

The Blackhawk is designed primarily as a utility and assault aircraft and is used in air assault, air cavalry and medical evacuation, said Maj. Phil Soucy, a spokesman for the Army in Washington.

Soucy said there had been no move by safety investigators to ground the Blackhawk fleet as a result of the accident.

The helicopter normally is operated with a crew of three and can carry 11 combat-equipped soldiers.

Fort Campbell was the home base of 248 soldiers killed Dec. 12, 1985, when a chartered jet bringing them home for Christmas from peacekeeping duties in the Sinai Peninsula crashed in Gander, Newfoundland.