Ground Self-Defense Force helicopter accident investigation report details revealed Is “rollback” the cause?

The contents of the investigation report into last year's accident in which a Ground Self-Defense Force helicopter crashed off the coast of Miyakojima in Okinawa Prefecture, killing 10 people, have been revealed.

The cause is said to be a phenomenon called ``rollback,'' in which the engine's output gradually decreases, and the details are expected to be announced soon.

Last April, a Ground Self-Defense Force UH60 helicopter crashed off the coast of Miyakojima, Okinawa Prefecture, killing all 10 people on board, including the then 8th Division commander.

As a result of this accident, the contents of the report compiled by the Japan Ground Self-Defense Force's investigation committee became clear.

According to the report, while the helicopter was flying at an altitude of approximately 300 meters, a phenomenon called ``rollback'' occurred in which the power of the right engine gradually decreased, causing a loss of power, followed by a loss of power from the left engine. The engine also lost power and crashed.

The time it took to crash was approximately 90 seconds after the power of the right engine began to decrease, and approximately 40 seconds after the power of the left engine began to decrease, making it extremely difficult to perform emergency maneuvers to reduce the impact of landing on water. I think it was difficult.

"Rollback", in which the engine's output gradually decreases, can occur when the supplied fuel is insufficient, and there is an abnormality such as a leak or blockage in the piping that supplies air to the device that controls the engine. It is assumed that these factors are the cause.

This is the first time that "rollback" has been confirmed on a Self-Defense Force aircraft, and it is an extremely rare phenomenon that was not even mentioned in the aircraft's instruction manual.

On the other hand, regarding the left engine, it is said that the cause may have been an abnormality in a part that affects control or output, or the operation of a lever that adjusts output by the crew, but there is no data to support either of these. It was concluded that the cause could not be identified.

Measures to prevent recurrence include conducting detailed inspections of engine-related parts, establishing emergency operating procedures in the event of a rollback, and ensuring that everyone is thoroughly informed.

The contents of the report are expected to be published soon.