Arcing wires on Sea Dragon again cause concern

By Mike Hixenbaugh
The Virginian-Pilot

Two weeks ago over the Arabian Gulf, a Navy helicopter crew saw an electrical arc burst from a bundle of wires inside the darkened cabin of their MH-53E Sea Dragon, and for a moment must have feared the worst.

Only a few days earlier, the Navy marked the one-year anniversary of a Sea Dragon crash that killed three sailors – a crash caused by an electrical arc that connected with a stream of jet fuel and burst into flames.

The scare on Jan. 15 was very different – some naval aviators might argue it was a relatively minor malfunction – but it still raised alarm among the sailors who fly and maintain the Navy’s aging fleet of Sea Dragons, given the helicopter’s history of wiring problems.Several sources from within the Norfolk-based command described the incident to The Virginian-Pilot on the condition of anonymity, and the Navy later confirmed the broad details of their accounts.

Two sets of wires had been silently rubbing together during a routine training flight, wearing down their protective coatings and causing the electrical arc, which shorted out an onboard generator.

Because it was nighttime, the three crew members in the cabin spotted the burst of electricity and rushed to prevent fire from catching and spreading, according to sources. One sailor wrapped the damaged wires with electrical tape as the pilots diverted to an airfield in Kuwait.

The helicopter was repaired the next day and flown back to its home base in Bahrain, said Cmdr. Mike Kafka, a spokesman for Naval Air Force Atlantic.

Maintenance workers at the two Norfolk-based Sea Dragon squadrons were briefed on the incident and instructed to inspect cabin wiring on all other aircraft, Kafka said.

Aircraft malfunctions that result in no casualties and only minor damage don’t usually make headlines, even in a military town. But after last year’s deadly crash off the coast of Virginia Beach – which revealed systemic problems with the way the Navy had inspected and cared for wiring inside its oldest helicopters – some Sea Dragon crew members are wary of even minor incidents.

“This one was just a close call. What if next time it’s more serious?” said a sailor when asked to describe the general reaction at his command.

One of the policy changes made last year to help alleviate the concerns: From now on, every Sea Dragon must be thoroughly inspected every 400 flight hours to ensure no wires or fuel lines are chafing or damaged.

Although some of the helicopters are outfitted with wiring from the 1980s – now brittle and prone to sparking fires – nobody had been required to regularly inspect Sea Dragon wires for signs of damage over the helicopter’s three decades in service.

The latest incident didn’t involve the old wiring, known as Kapton, and the helicopter had recently gone through the newly mandated inspection, officials said.

Yet, according to the Navy’s account, “a wire bundle from the supervisory panel chaffed against the wiring harness for the tow boom, causing arcing.”

A sailor familiar with the aircraft explained the difficulty. Because the massive helicopters bend and twist under the stress of flying, he said, an inspection in the hangar doesn’t guarantee wires won’t rub against other components once in the air.

“A fuel line can be two inches from rubbing anything, and once off the ground that same line could be hard-pressed against other things,” the sailor said, on the condition of anonymity. “You can’t apply preventative maintenance to something that was poorly designed.”

For that reason, and due to the helicopters’ advanced age, a safety investigation conducted after last year’s crash recommended the Navy go beyond inspections: “Physically isolating aircraft wiring from all critical aircraft components is necessary to prevent catastrophic chafing between maintenance intervals,” the report said.

In August, Naval Air Systems Command – the three-star command responsible for overseeing maintenance of Navy and Marine Corps aircraft – issued guidance requiring that wires near fuel lines inside Sea Dragons must be clamped off to ensure at least a half-inch of clearance during flight.

The Maryland-based command isn’t done studying the issue.

Next month, it plans to begin a full wiring assessment of Sea Dragons to determine whether further inspections, repairs or engineering changes are needed.

The Navy plans to keep the helicopters flying for another decade.