Crewmembers aboard the USS Gunston Hall direct an MH-53E Sea Dragon helicopter during landing somewhere in the Atlantic Ocean, Dec. 7, 2013

NORFOLK, Va. — The Navy has asked Sikorsky Aircraft Corp. to study ways to reduce the risk of engine fires in its MH-53E Sea Dragon helicopters.

The Navy says the study is part of an ongoing effort to correct a known defect in the helicopter’s No. 2 engine and was not prompted by the crash of a Sea Dragon off the coast of Virginia two months ago. Three sailors were killed and two others were injured in the Jan. 8 accident, which remains under investigation.

The Navy’s plan to study the engine issue was posted Tuesday on a government website that tracks federal contracts. Specifically, the Navy plans to negotiate a sole-source contract with Sikorsky to study ways to “reduce or eliminate the risk of inflight fires and heat damage in the No. 2 engine compartment as a result of engine exhaust backflow ingestion,” according to the document.

The Connecticut-based company will study the same problem in the Marine Corps version of the helicopter, the CH-53E Super Stallion.

This isn’t the first time the Navy has asked the Sea Dragon’s manufacturer to examine airflow and overheating problems.

The “No. 2 engine exhaust backflow hazard” was identified in 1991, Kelly Burdick, a spokeswoman for Naval Air Systems Command, told a Virginian-Pilot reporter last month. Sikorsky was paid to study the problem, and steps were taken over the next several years to mitigate the hazard, including the installation of an engine heat warning system and fire-resistant fuel lines.

When the engine exceeds a certain temperature, pilots are instructed to shut it down and land as soon as possible, according to the Sea Dragon flight manual.

The helicopter has three engines; it needs only two to fly.

In 2005, families of sailors killed in a Sea Dragon crash in southern Italy sued Sikorsky, alleging that the company failed to correct the problems that led to overheating and fires in the No. 2 engine. Sikorsky denied the allegation and settled the case out of court for an undisclosed amount of money.

The Navy has continued to work with Sikorsky to mitigate the risk of fire and improve efficiency, Lt. Robert Myers, a Navy spokesman, said Thursday. The company was last tapped to study the issue in 2011.

“The No. 2 engine backflow contract builds upon continuing discussions between the Navy and industry to improve the airflow efficiency through the engine compartment of the MH-53E helicopter,” Myers said.

The Sea Dragon was introduced to the fleet in the mid-1980s as part of the Navy’s effort to more effectively detect and destroy sea mines. Since then, no Navy helicopter has crashed at a higher rate.

After a spate of mishaps in 2012, including a fatal crash in Oman that claimed the lives of two Norfolk sailors, the Navy uncovered systemic problems in its aging Sea Dragon fleet.

The service has since pumped millions of dollars into the program to improve maintenance, command leadership and training.

The Navy has not said what factors might have led to the accident two months ago, and the service has not commented on the ongoing investigation, which is expected to last several months. Multiple sources within the Sea Dragon community say survivors of the crash reported fire in the cabin before the helicopter splashed down in the frigid Atlantic Ocean, but the Navy has not confirmed that.

Many of the Navy’s remaining 28 Sea Dragons – most of them based at Norfolk Naval Station – did not fly for much of the past two months to allow for safety inspections and repairs.

Some of the helicopters of Helicopter Mine Countermeasures squadrons 14 and 15 returned to the skies over Hampton Roads this week.

mike.hixenbaugh@pilotonline.com

