Pilot Debrief

Cessna 172 near Fresno, CA — 2020-05-02

Final reportWPR20LA136
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Date
2020-05-02
Location
Fresno, CA, USA
Airport
E79
Aircraft
Cessna 172
Registration
N734NW
Category
Airplane
Highest injury
Minor
Fatalities
0
Phase of flight
Initial climb

Probable cause

The partial loss of engine power for reasons that could not be determined based on available evidence.

NTSB narrative

Shortly after takeoff on runway 30, as the airplane reached about 300 to 400 ft above ground level, the engine lost partial power. The pilot prepared for a downwind landing to runway 12 and when he realized the airplane had excess energy, he deployed the flaps and performed a forward slip maneuver. The airplane touched down about halfway down the runway and continued off the end and through a fence. The airplane then passed over the two westbound lanes of a road and nosed over in the median. Examination of the engine revealed low compression on two of the six cylinders (around 25 to 75 percent compression loss on cylinder numbers 3 and 5). The valve rocker arms were tapped with a rubber mallet and compression recovered to approximately 25 percent loss in the number 3 cylinder and 15 percent loss in the number 5 cylinder. An internal borescope examination of the engine cylinders revealed the piston tops and cylinder sidewalls appeared normal and no evidence of foreign object ingestion was observed. No other pre-impact mechanical anomalies were identified during the examination. Although the reason for the low compression could not be determined, it was noted that the engine was disassembled 1.9 hours before the accident flight.

Analysis

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

NTSB coding

Evidence available

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

Docket documents5

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