Pilot Debrief

MORRISON MARVIN E JR RV 6A near Petaluma, CA — 2018-05-27

Final reportWPR18FA150
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Date
2018-05-27
Location
Petaluma, CA, USA
Airport
O69
Aircraft
MORRISON MARVIN E JR RV 6A
Registration
N4269Y
Category
Airplane
Highest injury
Fatal
Fatalities
2
Phase of flight
Takeoff roll

Probable cause

A partial loss of engine power during initial climb after takeoff due to a loose left magneto, and the pilot's decision to turn back to the airport and his exceedance of the airplane's critical angle of attack, which resulted in an aerodynamic stall/spin and impact with terrain.

NTSB narrative

The commercial pilot was departing in his experimental, amateur-built airplane. During the initial climb, when the airplane was between 500 to 800 ft above ground level, the engine backfired several times before losing power. The airplane entered a 180° turn back toward the airport; however, during the second half of the turn, the bank angle increased, and the airspeed slowed. The airplane entered an aerodynamic stall and spin and subsequently impacted terrain. Postaccident examination of the engine revealed that the left magneto was loose on its mounting pad and free to rotate by hand. This would have resulted in erratic engine-to-magneto timing for that magneto and would likely account for the engine backfiring and the partial loss of engine power. There were no additional mechanical anomalies that would have precluded normal operation. No maintenance records were recovered, and whether any magneto-related maintenance was performed before the accident could not be determined. The area beyond the departure end of the runway comprised a golf course and open fields that would have been favorable for a straight-ahead, forced landing. The pilot's decision to turn back toward the runway at low altitude and his subsequent exceedance of the airplane's critical angle of attack during the turn resulted in an aerodynamic stall/spin and a loss of control.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have aborted takeoff after hearing engine backfire.

NTSB coding

Evidence available

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

Docket documents7

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