Uncontained engine failure leads to forced landing

No fatalities • Scottsdale, United States of America • Takeoff (climb)

An aircraft experienced an uncontained engine failure during its initial climb, resulting in a forced landing and subsequent post-impact fire.

What happened

During the initial climb phase following takeoff, the aircraft experienced an uncontained failure of the right engine, which led to a loss of power. Due to the loss of performance, the aircraft was unable to maintain its climb, necessitating an emergency descent. To avoid obstacles including automobiles and street light poles, the pilot executed a forced landing on a street.

Upon touchdown, the aircraft performed a gear-up landing. During the landing sequence, the plane slid into a block wall. A fire broke out following the impact, triggered by a fuel leak originating from the left wing. There were 0 fatalities and 0 injuries reported in the immediate aftermath of the crash.

Findings

Investigations into the engines conducted at the manufacturer's facilities identified the source of the failure. The right engine showed evidence of an uncontained separation of the second stage turbine rotor disk. Analysis of the fragments from the disk indicated that the failure occurred via a low cycle fatigue fracture mode.

This fatigue process began at several points located at and near the inside diameter bore surface on the aft side of the disk. The engine manufacturer determined that these multiple initiation points were linked to porosity and primary carbides within the cast material that were too small to be detected during standard inspections. No other material or casting defects were found in the fractures throughout the wheel.

Probable cause

The engine failure was caused by a low cycle fatigue fracture of the second stage turbine rotor disk originating from uninspectable porosity and carbides in the cast material.

Frequently asked questions

What happened in the 1996-07-20 Mitsubishi MU-2 Marquise accident near Scottsdale, United States of America?

An aircraft experienced an uncontained engine failure during its initial climb, resulting in a forced landing and subsequent post-impact fire.

Were there any fatalities in the 1996-07-20 Mitsubishi MU-2 Marquise accident?

No fatalities were recorded in this accident.

What aircraft was involved and where did it happen?

The accident on 1996-07-20 involved a Mitsubishi MU-2 Marquise, registration N999FA, operated by Med Arizona, at Scottsdale, United States of America.

What was the probable cause of the accident?

The engine failure was caused by a low cycle fatigue fracture of the second stage turbine rotor disk originating from uninspectable porosity and carbides in the cast material.

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