Inquiry: Frayed wire led to fatal Navy helicopter crash

By Mike Hixenbaugh
The Virginian-Pilot

A Navy helicopter was dragging a mine-sweeping device through the Atlantic Ocean seven months ago when, inside the cabin, an electrical arc shot from a wiring bundle and connected with a worn fuel line, igniting an explosive fire.

Within seconds, the MH-53E Sea Dragon crashed into frigid water off the coast of Virginia Beach on Jan. 8, killing three of the five sailors aboard – including both pilots – and badly injuring the two others.

The Navy uncovered those details after inspecting the wreckage and interviewing survivors in the weeks that followed. Investigators completed their work earlier this summer, though the Navy has not yet released the findings.

The basic narrative of the crash, however, is widely known among the community of sailors who work at two Sea Dragon squadrons based at Norfolk Naval Station. The Virginian-Pilot reviewed a copy of the investigation and interviewed sources from within the command who spoke on condition of anonymity.

The helicopter that crashed, known by call sign Vulcan 543, had spent the night before its final flight thawing inside a hangar at Helicopter Mine Countermeasures Squadron 14. Several of its components had frozen a day earlier when it was left out on the flight line on one of the coldest days of the year.

While doing their preflight checks on the morning of the crash, crew members noticed that the overhead heater in the helicopter’s cabin was flaming out and puffing smoke. The problem wasn’t new; pilots familiar with the issue had devised a way to manipulate the heater to keep it going.

Working around mechanical problems is part of the culture at the squadrons responsible for flying the Navy’s oldest and most maintenance-intensive helicopter. The glitchy heater was later ruled out as a factor in the crash.

Vulcan 543 lifted off around 8 that morning for its training mission off the coast of Virginia. During the flight, a fire warning light flickered in the cockpit. The crew members inspected the engine compartments and the heater, which continued flaming out during the flight, and soon concluded that the warning flicker was triggered by the early morning sunlight from the horizon, another common glitch.

About 2-1/2 hours after takeoff, one of the pilots tried to send out a distress signal. A massive fireball had shot through the cabin and into the cockpit, filling the helicopter with black smoke and flames.

Crew members in the back reached for a fire extinguisher and dropped to the floor; One of them called for the pilots to cut off the heater, mistakenly thinking that it was the source of the fire. About 20 seconds later, the Sea Dragon hit the 40-degree water.

Four of the occupants managed to escape the sinking wreckage, while one of the pilots was trapped in the cockpit. Another Sea Dragon flying nearby issued a distress call after crew members noticed the wreckage. Within minutes, Navy rescue helicopters hoisted the four sailors from the water and took them to a hospital in Norfolk, where two of them died. The trapped pilot’s remains were recovered days later.

Using forensic clues, crash investigators traced the cause of the fire back to a wiring bundle that had been chafing against an aluminum fuel line in the Sea Dragon’s cabin.

A plastic zip tie holding the wires in place likely wore a hole in the fuel transfer line over time. The wires released an electrical arc, a sustained charge that connected with the degraded fuel line, sparking an uncontrollable fire.

In-flight fires have been a recurring problem in Sea Dragons, which have crashed at a rate three times higher than other Navy helicopters over the past 30 years.

Many of the previous fires were related to an airflow problem in the helicopter’s No. 2 engine compartment. Overheating of the No. 2 engine, however, does not appear to have been a factor in this crash.

Faulty wiring has also been scrutinized over the years.

In a report to Congress in 2012, the Navy listed old electrical wires – known commonly as Kapton wiring – as “the highest ranked safety risk” to the remaining fleet of 28 Sea Dragons and the Marine Corps counterpart, the CH-53E Super Stallion.

Since 2004, the Navy has spent $37 million replacing the most dangerous Kapton wiring in Sea Dragons and Super Stallions, but a majority of the helicopters still have at least some of the old wires, according to information provided by Naval Air Systems Command. Two Sea Dragons are still totally outfitted with Kapton wiring.

The biggest threat from Kapton wiring: The risk of fire resulting from electrical arcing. That’s according to the Navy, which first identified the problem back in 1987 while many of the Sea Dragons were still being built.

Vulcan 543 had undergone the first phase of repairs to remove the most critical Kapton wiring, but it was still partially outfitted with the obsolete wires, according to the Navy. The Navy never recovered the wiring bundle implicated in the crash, and the investigative report does not address whether Kapton wiring was a contributing factor.

The report says the helicopter had been maintained properly prior to the crash and does not blame any individual for the accident.

The Navy won’t comment on the findings until the investigation is made public. That is expected to happen in the coming days, said Cmdr. Mike Kafka, a spokesman for Naval Air Force Atlantic.

“The Navy will release the redacted findings of the investigation to the media only after the families have received copies and we have answered any questions they might have,” Kafka said in an email.

Most of the Sea Dragon fleet didn’t fly in the weeks after the crash. During that time, aircraft maintainers inspected all fuel lines running within 12 inches of wiring bundles.

The result, according to sources within the command: Inspectors discovered evidence of fuel lines chafing against electrical wires in several other Sea Dragons.

In at least half of the helicopters, degraded fuel lines needed to be replaced.

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