Pilot Debrief

CASSUTT IIIM near Rosamond, CA — 2018-07-14

Final reportWPR18LA196
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Date
2018-07-14
Location
Rosamond, CA, USA
Airport
L00
Aircraft
CASSUTT IIIM
Registration
N43SJ
Category
Airplane
Highest injury
Minor
Fatalities
0
Phase of flight
Takeoff roll

Probable cause

The pilot's failure to maintain adequate airspeed during a low-altitude maneuver after a partial loss of engine power, which resulted in exceedance of the airplane’s critical angle of attack and a subsequent accelerated stall. Contributing to the accident was a loose primary venturi in the carburetor due to improper maintenance, which resulted in a disruption in fuel flow and the subsequent partial loss of engine power.

NTSB narrative

The pilot was departing in his experimental, amateur-built airplane configured for aerial racing. He reported that when the airplane entered its initial climb and was about 50 ft above ground level, the engine performance reduced by about 300 rpm. The pilot attempted to continue the takeoff to complete a circuit in the airport traffic pattern. A witness saw the airplane turn left, and the nose immediately dropped and impacted the ground, followed by the right side of the airplane. The airplane sustained substantial damage to the forward fuselage and right wing. It is likely that, while the pilot was maneuvering at low altitude after the partial loss of engine power, he failed to maintain adequate airspeed, which resulted in the airplane exceeding its critical angle of attack and a subsequent accelerated stall. Postaccident examination of the engine and most of the accessories did not reveal any preimpact mechanical anomalies. However, a teardown of the carburetor showed multiple discrepancies, the most notable of which was a loose primary venturi. This condition is likely to have caused the partial loss of engine power during takeoff due to the delivery of inconsistent vacuum pressure and a disruption in fuel flow. An airworthiness directive (AD) issued 20 years before the accident required that the venturi be inspected at each annual, 100-hour, or conditional inspection. It is unknown if this AD was complied with, as the pilot/owner did not possess any records that showed the carburetor's maintenance history.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Inspect carburetor for loose primary venturi before flight.

NTSB coding

Evidence available

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

Docket documents10

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