Pilot Debrief

CESSNA 150 near Fayetteville, WV — 2010-09-10

Final reportERA10LA475
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Date
2010-09-10
Location
Fayetteville, WV, USA
Aircraft
CESSNA 150
Registration
N7922E
Category
Airplane
Highest injury
Serious
Fatalities
0
Phase of flight
Initial climb

Probable cause

A loss of engine power due to the failure of the left magneto system’s distributor gear as a result of the improper maintenance of the magnetos by maintenance personnel.

NTSB narrative

The pilot stated that during the initial climb the airplane engine's rpm gauge indicated 1900 and the airplane would not gain altitude which resulted in a forced landing. Postaccident examination of the airplane revealed fuel in the fuel tanks and carburetor system. All cylinders had compression when checked. The right magneto developed sparks to all corresponding plugs. The left magneto produced spark to one plug only. A teardown examination of the left magneto revealed the distributor gear had 12 gear teeth sheared from the disk. Review of the engine's maintenance records showed that the ignition system had several inspections as required by airworthiness directives and service bulletins (SB) throughout its time in service. The distributor gear was required to be replaced with a redesigned gear as outlined in SB658; however, both magnetos had the old-style distributor gear, dating to before 1978. Additionally, the gear tooth separation was noted starting and ending at the magneto timing block location marker. The manufacturer of the magneto warned not to use a gear holding tool during installation, which may cause hidden damage to the distributor gear and subsequent engine failure.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have aborted takeoff upon initial signs of engine power loss.

NTSB coding

Evidence available

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

Docket documents13

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