Pilot Debrief

CESSNA 172P near Nutwood, IL — 2015-09-16

Final reportCEN15LA414
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Date
2015-09-16
Location
Nutwood, IL, USA
Aircraft
CESSNA 172P
Registration
N65191
Category
Airplane
Highest injury
Minor
Fatalities
0
Phase of flight
Maneuvering

Probable cause

A partial loss of engine power due to the undetected loosening of the four carburetor bolts that connect the throttle body to the bowl assembly.

NTSB narrative

The pilot reported that, while maneuvering the airplane at 3,000 ft mean sea level, the engine lost partial power and began running roughly. After unsuccessfully attempting to regain normal engine power, the pilot executed a forced landing into a field, during which the airplane nosed over. Postaccident examination of the carburetor revealed a gap between the throttle body and bowl assembly, and all four bolts connecting the throttle body to the bowl assembly were found loose. Both the engine and carburetor manufacturers had previously issued service bulletins (SB) regarding possible leakage between the bowl assembly and throttle body, likely due to loose bowl to throttle body screws. The SBs recommended inspecting the carburetor screws every 100 hours of engine operation. The last 100-hour inspection of the engine occurred 89 hours before the accident.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Inspection of carburetor screws not documented, leading to loose connections.

NTSB coding

Evidence available

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

Docket documents4

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