The U.S. Naval Air Systems Command (Navair) issued new inspection guidance for Sikorsky CH/MH-53E helicopters on February 9, further responding to the crash of an MH-53E in January 2014 that claimed the lives of three sailors. The directive contains instructions for inspecting for chafing damage involving cabin fuel and hydraulic tubes and any hoses and electrical wiring within 18 inches of those components.

Navair released the AFB-346 corrective action directive after a Navy and Marine Corps review board met on February 6 and decided that maintainers require more explicit instructions, as well as photographs, to perform inspections. “After an initial assessment by Navair’s Heavy Lift Helicopters Program, the in-service support team indicated that additional measures were needed to ensure causal factors from the January 2014 mishap would be fully mitigated,” the command said in a release.

On Jan. 8, 2014, an MH-53E Sea Dragon assigned to Helicopter Mine Countermeasures Squadron 14 at Naval Station Norfolk, Va., crashed in the ocean while conducting a routine training exercise. A Judge Advocate General Manual investigation determined that a fire broke out in the wall of the cabin, filling the cabin and cockpit with smoke and disorienting the crew. Chafing between insulation covering electrical wires and the surface of an aluminum fuel transfer tube had likely enabled an electrical arc from a wire to breach the transfer tube and ignite the fuel inside, the Navy accident investigation found.

Following the crash, the Navy ordered a one-time inspection of all CH/MH-53 cabin fuel tubes and electrical wiring within 12 inches of each other for signs of chafing. After the recent assessment by the heavy-lift helicopters program office, Vice Adm. David Dunaway, Navair’s commander, issued temporary flight restrictions that prohibit fuel cross-transferring in flight, aerial refueling, and refueling the Exelis MK-105 Airborne Mine Countermeasures magnetic minesweeping system used on the MH-53E. The MK-105 is a remotely controlled platform the helicopter tows; it is designed to safely detonate mines.

The Navy dispatched wiring and fuel-line experts to train maintainers in Pohang, Korea; Manama, Bahrain; Futenma, Japan; Norfolk, Va.; Miramar and San Diego, Calif.; Cherry Point and New River, N.C.; and Joint Base McGuire-Dix-Lakehurst in New Jersey, Navair said.

CH/MH-53 E-models entered service in the 1980s. Navair lists a fleet of 28 Navy MH-53Es the Navy uses for airborne mine countermeasures and vertical onboard delivery to ships; and 152 CH-53E Super Stallions, which the Navy and Marines use for heavy lift and amphibious assault missions. The Navy envisions using the MH-53E until around 2025; the requirement for the CH-53E extends through 2027.