WASHINGTON -- An Air Force pilot who investigated the deaths of two friends in a UH-1N helicopter crash a year ago and helped uncover a mysterious mechanical problem was himself killed in an October crash involving the same kind of aircraft.
The death of Capt. Jay D. Burdett and two other men near Edwards Air Force Base, Calif., on Oct. 10 came nine months after the first accident and a week after the Air Force issued a warning to all military services about the UH-1N's "high accident potential," based partly on his findings.
The Sun recently disclosed that these two Air Force accidents and two Marine Corps UH-1N crashes have killed 11 servicemen in the past 18 months. The Air Force also had two close calls during flights in Oregon and Florida last spring and summer, both of which ended safely.
By many accounts, the transmission and drive shaft of Captain Burdett's aircraft failed, and the main rotor tore off the mast, slicing through a cargo door and severing a crewman's arm. The helicopter fell 8,000 feet to the ground, with pieces scattering and bursting into flames.
As a member of an Air Force mishap board looking into a UH-1N accident that killed his friends on Jan. 14, 1991, Captain Burdett had discovered problems with the chopper's main drive shaft and the grease used to lubricate it, according to friends, relatives and Air Force personnel.
The cause of these problems has not been determined, senior Air Force officials conceded this week.
The tragedy of Captain Burdett and his friends -- all members of the same Air Force test squadron at Edwards -- is only one of the real reasons why questions persist in the military about the safety of the twin-engine UH-1N Huey, a variant of the Army's single-engine transport helicopter made by Bell Helicopter Textron Inc. of Fort Worth, Texas.
Recent Marine inspections have revealed at least six UH-1Ns with drive shaft-related problems, said knowledgeable Marine officials, who insisted on anonymity. Similar problems were found last year during helicopter inspections at Vandenberg Air Force Base, according to civilians with access to Air Force reports.
But military investigators say they have been unable to pinpoint the mechanical problem causing UH-1N drive shafts to fail, even as the Air Force and Marines have allowed their helicopters to fly under vastly different policies, according to interviews and documents obtained by The Sun.
While the Air Force has declared that its Hueys may fly without restrictions, the Marines may fly theirs for no more than three hours at a time and must follow rigorous 25-hour maintenance requirements. A Marine spokeswoman said these precautions and "the considerable attention focused on this system" should allow potential problems to be identified and corrected "before becoming hazards to flight."
As a matter of Air Force policy, "you can't stop everything if you don't know what caused the accidents," said Capt. Betsy Freeman, an Air Force spokeswoman at the Pentagon. "Until the accident investigations are over, we have no reason to change anything we're doing."
Air Force officials are now reporting, however, that the maintenance interval for UH-1N drive shaft couplings has been reduced to 100 hours from the customary 600-hour period between overhauls. After a Huey made an emergency landing at Eglin Air Force Base, Fla., on June 27, the interval dropped to every 20 hours, but officials eased that requirement to 100 hours in August, claiming that the problems were under control.
Then came Captain Burdett's accident in October.
The Air Force grounded only four UH-1Ns belonging to the Air Force Systems Command, allowing as many as 70 helicopters deployed to tactical and airlift commands to fly without restrictions, officials said. On Dec. 10, the Air Force rescinded the action after determining that "we didn't have a problem that was life-threatening," said Lt. Col. John Kirkwood, spokesman for the Systems Command.
A spokesman at Edwards Air Force Base said that the two remaining UH-1Ns there will not return to the skies until crews are "requalified" to fly them. In the meantime, Bell Helicopter technicians are expected to take apart and rebuild the aircraft,a task that some officials said was intended mainly to bolster pilot confidence in the safety of the aircraft.
Captain Burdett's investigation of the January 1991 crash has not been closed, although a confidential Air Force document obtained by The Sun shows that the mishap board "concluded the main drive shaft front coupling failed" because of problems linked to Syn-Tech grease, a synthetic lubricant supplied by a Bell Helicopter subcontractor and used for years by the military.
The board found that the crash "most likely" involved the same 1987 batch of substandard grease used in a Marine Corps UH-1N that crashed and killed two men near Yuma, Ariz., on July 27, 1990.
That document, warning of a "high accident potential" for UH-1Ns, was sent to all military services last Oct. 3, a week before Captain Burdett's accident. A second Marine UH-1N developed a drive shaft problem and crashed Oct. 16, killing four Marines from Camp Pendleton, Calif.
"Jay was not afraid to fly, but he told friends about the grease," recalled Susan Preston, Captain Burdett's sister. "I would ask him about it, and he would hem and haw. He didn't want to worry me."
Both Air Force and Marine officials now suspect a variety of possible problems behind the drive shaft failures, claiming that there is less and less convincing evidence showing that Syn-Tech grease is the culprit. While Marine investigators said they cannot rule out the grease as a cause, Air Force officials said this week that they are virtually certain the blame lies elsewhere, possibly in the drive shaft alignment, a locked transmission clutch, flight control tubes or defective parts.
"It is mechanical . . . but it's not the grease. That's what I think," Col. Tom Reiter, manager of the Air Force's rotary wing program office in Georgia, said last week. "It's a very emotional issue, and there's no absolute conclusive evidence."
Mrs. Preston and the relatives of other Air Force crash victims said in interviews that they were distressed at official Air Force declarations that the helicopters are safe to fly. Many of them are worried that officials confronted with a baffling series of accidents may find it expedient to blame the accidents on pilot error or declare that a cause will be impossible to find.
"I'm real nervous that other people will be killed," Mrs. Preston said.