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Aviation Accident

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NTSB Identification: WPR16FA102
14 CFR Part 91: General Aviation
Accident occurred Saturday, May 07, 2016 in Surprise, AZ
Probable Cause Approval Date: 09/04/2018
Aircraft: BEECH G35, registration: N4401D
Injuries: 1 Fatal, 1 Serious.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

The flight instructor was asked to complete a maintenance test flight of the airplane following the installation of a repaired carburetor. He elected to use the flight to provide instruction to the private pilot who had requested a checkout in the airplane. The private pilot reported that the flight was initially normal, but then the engine stopped responding to throttle control. According to the private pilot, the engine remained at idle power as the airplane descended and impacted trees in a residential area.

Examination of the wreckage revealed that the carburetor throttle cable was detached from the throttle body linkage. The bolt and castellated nut used to secure the throttle cable to the linkage were found lying separately in the engine cowling; there was no evidence that a cotter pin had been used to secure the nut on the bolt, as required.

It is likely that the loss of engine power resulted from the failure of the mechanic who installed the carburetor to install the cotter pin when he attached the throttle cable to the carburetor. During the maintenance test flight, the castellated nut backed off of the bolt, which resulted in a loss of throttle control.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
  • The mechanic's failure to properly secure the bolt connecting the throttle cable to the carburetor during the installation of the carburetor, which resulted in a loss of engine power.