Pilot Debrief

CESSNA 172S near Wellston, OH — 2017-08-09

Final reportCEN17LA311
Sign in to save
Date
2017-08-09
Location
Wellston, OH, USA
Aircraft
CESSNA 172S
Registration
N5274Q
Category
Airplane
Highest injury
Minor
Fatalities
0
Phase of flight
Maneuvering

Probable cause

The failure of a connecting rod small end bushing, which resulted in a loss of engine power.

NTSB narrative

The commercial pilot and observer were conducting an aerial observation flight of a pipeline. The pilot reported that, while maneuvering at a low altitude toward an airport to refuel, he heard a "significant boom" and noticed a reduction in engine rpm. The pilot unsuccessfully attempted to regain engine power and then initiated a forced landing to a space between trees. During the forced landing, the airplane impacted rolling, uneven grass terrain and a barbed wire fence. Examination and disassembly of the engine revealed a large hole on the top of the engine crankcase inboard of the No. 4 cylinder. The examination revealed that the No. 4 connecting rod had failed due to the installation of a nonconforming small end connecting rod bushing. Five days before the accident, the engine manufacturer had issued a mandatory service bulletin indicating that the accident connecting rod bushing may not have met engine specifications and may require followup action. Six days after the accident, the Federal Aviation Administration issued an airworthiness directive that required inspecting the connecting rods, replacing affected connecting rod small end bushings, and accomplishing the instructions in the engine manufacturer's mandatory service bulletin.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Failure to inspect connecting rod bushings as per mandatory service bulletin.

NTSB coding

Evidence available

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

Docket documents12

Related mishaps