NTSB Identification: CHI05LA045.
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Accident occurred Tuesday, December 14, 2004 in South Bend, IN
Probable Cause Approval Date: 01/31/2007
Aircraft: Pilatus PC-12/45, registration: N922RG
Injuries: 5 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The airplane was substantially damaged during a forced landing following a loss of engine power. The pilot stated that shortly after takeoff, the engine "abruptly and smoothly rolled back." Movement of the power control lever had no effect. He stated that use of the manual override (MOR) system did not restore engine power. He secured the engine and executed a forced landing on a roadway. The airplane's wing struck two utility poles during rollout. Data downloaded from the accident aircraft indicated that the recorded engine interstage turbine temperature (ITT) exceeded published limits during the event. The post accident engine inspection revealed turbine damage consistent with an over-temperature event. The inspection also revealed a leak in the compressor discharge pressure (CDP) sensor bellows within the fuel control unit (FCU). The leak prevented the bellows assembly from responding to throttle inputs and resulted in the FCU providing minimum fuel flow to the engine regardless of the throttle setting. Following this accident an improved FCU design which incorporated a more robust bellows design was released and retrofited into the entire in-service and production fleet. The airframe manufacturer issued a revision to the pilot's operating handbook to provide an improved procedure for use in the event of an in-flight engine power loss. It also updated information regarding the Manual Override (MOR) system.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

Failure of the fuel control unit (FCU) bellows which resulted in a significant loss of engine power and the pilot's encounter with unsuitable terrain during the subsequent forced landing. A contributing factor was the pilot's inadvertent exceedence of the engine temperature limitations during use of the manual override (MOR) system. Additional factors were the roadway and the utility poles struck during the forced landing.

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