Engine shutdown caused fatal Army helicopter crash in Feb.: military
Summary
An Army investigation found that a sudden engine failure caused the February crash of an AH-1S Cobra helicopter in Gapyeong County that killed two warrant officers. Officials said a misaligned internal cylinder led to shaft whirling, extreme heat, and an engine flameout during a training landing. The Army said it will discuss speeding up the helicopter’s retirement and will adjust replacement plans for the LAH-1 Miron. It also plans to shift aviation safety management functions to the Army Headquarters Combat Readiness and Safety Group by April next year.
Key Facts
- The helicopter crashed during emergency landing familiarization training in Gapyeong County, about 55 kilometers northeast of Seoul, on Feb. 9.
- The crash killed two warrant officers on board, and no civilian damage was reported.
- The Army said the AH-1S was first introduced in 1988 and deployed in 1991, with retirement originally planned to begin in 2028.
- The Army said it will consult with the Joint Chiefs of Staff on accelerating the helicopter’s retirement and will work with the Defense Acquisition Program Administration on the LAH-1 Miron replacement plan.
- Aviation safety management functions and personnel will be moved from the Army Aviation Command to the Army Headquarters Combat Readiness and Safety Group by April next year.
Military authorities cordon off the scene where an Army Cobra attack helicopter crashed in Gapyeong, Gyeonggi Province, Feb. 9. Yonhap
A sudden engine failure has been identified as the main cause behind the deadly crash of a military helicopter in February that killed two soldiers, Army officials said Thursday.
The AH-1S Cobra helicopter of an Army aviation unit crashed during an emergency landing familiarization training in Gapyeong County, about 55 kilometers northeast of Seoul, on Feb. 9, killing the two warrant officers on board. No civilian damage was reported.
The military had since been investigating to determine the exact cause of the crash.
According to official findings, an internal cylinder in the helicopter engine was slightly misaligned, causing the engine's central drive shaft to wobble as it turned.
The wobble caused violent vibrations, and the spinning shaft began whipping around widely like a jumping rope, known as "shaft whirling," the Army said.
When the pilot pushed the throttle back up to climb, the spinning power shaft slammed into a second spinning shaft, instantly generating extreme heat that melted the components, ultimately shutting down the engine.
"We have concluded that the cause of the accident was a physical factor — an engine flameout resulting from a fault in the internal cylinder in the aircraft engine's exhaust diffuser, rather than environmental or human errors," an Army official said in a press briefing.
The Army said it plans to consult with the Joint Chiefs of Staff to consider accelerating the helicopter's retirement. Retirement for the crashed AH-1S, first introduced in 1988 and deployed in 1991, was planned to begin in 2028.
"We will also work closely with the Defense Acquisition Program Administration to adjust the operational deployment plan for its replacement, the LAH-1 Miron, to ensure its stable fielding," it said.
To strengthen oversight, the Army said it will transfer aviation safety management functions and personnel from the Army Aviation Command to the Army Headquarters Combat Readiness and Safety Group by April next year.
"For airfields operating both helicopters and drones, we will improve the safety management system by transitioning from individual checks to an integrated inspection for manned and unmanned platforms," the Army said.
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