2 Say Cave-In Caused Fatal Titan Rocket Accident : Investigations: Officials refuse to comment until the inquiry at Edwards Air Force Base is completed.

The fatal Titan rocket accident at Edwards Air Force Base last week occurred because ground gave way beneath a huge crane that was transporting the rocket motor, a union official and an executive with the company that owns the crane said Tuesday.

Air Force and Cal/OSHA investigators refused to comment on possible causes of the accident, which killed one man Friday morning and injured nine others at the base’s Astronautics Laboratory.

But George Morse, marketing director of Neil F. Lampson Inc., manufacturer and operator of the crane, said the crane was not at fault.

“I have reason to believe the ground yielded” beneath the crane, Morse said in a telephone interview from the company’s headquarters in Kennewick, Wash. Morse said the crane had received its state-mandated safety checks and did not malfunction.

Alan M. Quimby, a civilian worker, was killed by falling counterweights used to anchor the 400-foot crane when the boom of the crane dropped and the Titan 4 rocket motor segment skidded down a hillside, erupting in a spectacular fire. The crane was transferring the 30-foot motor segment of the Titan 4 Advanced Solid Rocket from a test stand to a nearby storage stand.

A union official, who asked not to be identified, said Tuesday that one of four men operating the crane at the time of the accident told him that the motor fell when an underground tunnel connecting utility cables to the outdoor rocket testing stand collapsed. He said the ground gave way beneath one of the moving tank-like treads of the crane, causing the boom and the motor segment filled with 255,000 pounds of solid fuel to drop suddenly.

Another worker at the lab, who was near the accident scene and spoke on condition of anonymity, said, “One of the tunnels collapsed, that’s what started it.”

Morse said he had heard reports that the cause of the ground failure was a collapsed utility tunnel but was not prepared to pinpoint that as the cause.

Astronautics Lab spokesman Ranney Adams had no comment pending the results of the investigation.

Cal/OSHA spokesman Rick Rice also refused to confirm or deny the reports, saying, “That’s the type of thing it takes time and engineers to figure out.”

Morse said the crane, a Lampson Transi-Lift 900 with a 900-ton capacity, had no defects and had received its required annual safety certification from a state-designated inspector in February. Lampson operated the crane for the Hercules Corp., an Air Force subcontractor that built the Titan motor, Morse said.

Rice said he could not comment on the crane’s safety certification because of the investigation. State officials had said Monday that they had asked the Lampson company to provide proof of the safety certification and had not yet received it.

The Air Force investigation is being headed by Brig. Gen. Ralph Tourino, who arrived Tuesday at Edwards, Adams said. In addition to representatives of Lampson and Hercules, the investigation team includes officials from Wyle Laboratories, a subcontractor that operates the test stand, and Martin Marietta Corp., the contractor for the Titan 4 rocket program.

There also will be a probe by the International Union of Operating Engineers, which represents the crane operators, said Business Manager Bill Wagner of Local 12.