Pilot Debrief

Cessna 172 near Melba, ID — 2019-03-01

Final reportWPR19LA092
Sign in to save
Date
2019-03-01
Location
Melba, ID, USA
Airport
MAN
Aircraft
Cessna 172
Registration
N6486J
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Maneuvering

Probable cause

The total loss of engine power due to a separated carburetor idle mixture adjustment screw and spring assembly for reasons that could not be determined.

NTSB narrative

The flight instructor and student pilot were performing maneuvers when the engine lost total power. The instructor pitched the nose of the airplane down and asked the student pilot to restart the engine. The student pilot was unable to rotate the engine using the starter, and the flight instructor verified that the master switch was in the “ON” position. The instructor tried to start the engine himself and was unsuccessful. The flight instructor performed a forced landing in a field. Examination revealed that the idle mixture adjustment screw and spring assembly had separated from the carburetor and were found in the lower cowling area. After the airplane was relocated to a nearby road the engine rotated via the starter. Examination of the idle mixture adjustment screw and spring assembly revealed no anomalies. The reason that the screw backed out of the carburetor could not be determined. The starter solenoid was removed and disassembled. The starter solenoid was examined and revealed a frayed and separated wire from the coil to a terminal end. The reasons for this fraying and separation could not be determined. Although the starter solenoid was faulty, it is unlikely that the engine would have restarted due to the separated idle mixture screw and spring assembly.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Instructor could have checked carburetor settings before last stall maneuver.

NTSB coding

Evidence available

  • Photos
  • 10 docket documents
View NTSB final reportView NTSB docket

Docket documents10

Related mishaps