Pilot Debrief

CESSNA 152 near Moore, SC — 2010-03-24

Final reportERA10LA187
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Date
2010-03-24
Location
Moore, SC, USA
Aircraft
CESSNA 152
Registration
N93441
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Maneuvering

Probable cause

The certificated mechanic's improper installation of a helicoil, which resulted in the separation of a sparkplug and the helicoil and led to a partial loss of engine power.

NTSB narrative

The local instructional flight had departed from the airport about 30 minutes prior to the accident. After completing several aerial maneuvers, including slow flight and power-off stalls, the student pilot had begun a recovery from another power-off stall. When he applied throttle, the engine immediately began to run rough. The certificated flight instructor decided to perform a forced landing in a farm field. During the landing roll, the nosewheel came in contact with the soft soil and the airplane nosed over. A postaccident examination of the engine by a Federal Aviation Administration inspector revealed that the bottom sparkplug and associated helicoil on the No. 4 cylinder had separated from the cylinder. After new sparkplug and helicoil was installed in the engine, it ran normally. The airplane's engine maintenance logbook showed that four days prior to the accident, the bottom sparkplug and helicoil had been replaced on the No. 4 cylinder due to a bad helicoil. The mechanic had installed a standard helicoil contrary to the engine manufacturer's recommendation to install oversize helicoil spark plug inserts.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
CFI could have prevented student from jamming throttle during maneuvers.

NTSB coding

Evidence available

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

Docket documents9

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