Nimitz Conducting Full Safety Investigation Navy Unsure If Death Caused By Human Error, Equipment Failure

Military investigators Saturday were trying to determine whether a fatal accident aboard the aircraft carrier USS Nimitz was caused by equipment failure or human error.

Three sailors were doing maintenance Friday night on the carrier’s aircraft “arresting gear,” or landing system, when a 100-pound cylinder end cap on a hydraulic-powered engine part blew off. One sailor was killed and the other two were injured.

“As the system was being worked on, a cap was being removed. That cap should not have had air pressure on the other side of it. Apparently, there was some air pressure behind it because as it was being removed, the cap blew off,” said Nimitz spokesman Lt. Robert Durand.

Killed was Petty Officer 2nd Class Daniel J. Avilla, 28, of Bremerton.

Petty Officer 3rd Class Ronald Dortch, 21, of Jefferson, Ala., was treated at Navy Hospital Bremerton for two broken ribs. He was to be released today. Petty Officer 3rd Class Patrick Gray, 22, of Greenville, Miss., was treated on board the Nimitz for minor injuries.

“We’ll be doing a full safety investigation to figure out exactly what happened,” Durand said. “Our immediate operational concern is to find out if we have an equipment problem or procedural problem or if there’s something we’re doing wrong systemically that could hurt someone again.”

The Nimitz, based in Bremerton, is in the final stages of an overhaul at the Puget Sound Naval Shipyard in Bremerton.

Crew members will be interviewed and the machinery will be inspected as part of the probe, Durand said.

The three sailors were in a machinery compartment below the flight deck doing work on one of four large hydraulic systems that maintain tension on cables stretched across the flight deck of the nuclear-powered aircraft carrier.

Jet warplanes snag the cables with hooks beneath their tails upon landing. The cables stop the planes on the deck.

Within the hydraulic system is a cylinder and piston with compressed air on one side and hydraulic fluid on the other. The sailors were apparently trying to unscrew the 100-pound, 20-inch-in-diameter cylinder end cap when a sudden release of air pressure caused it to shoot out with tremendous force.

“Procedurally, just like any pressurized system, you would depressurize before you work on it. That’s what investigators will be looking at, to see if those procedures were followed or if perhaps they had erroneous readings or what not,” Durand said.

There was no explosion or fire and the accident did not involve the ship’s nuclear reactor.

Durand said all the landing-gear hydraulic systems on the Nimitz will be shut down and inspected until investigators find out what happened.

The overhaul of the Nimitz is expected to be finished by the end of the month. The carrier is slated for sea trials in February off San Diego before re-entering deployment in November, most likely in the Persian Gulf and Indian Ocean.

Durand said the accident shouldn’t affect that timetable.

The 1,040-foot vessel, which went into service in 1975, carries a crew of 5,680 and can hold 85 planes.