Accident Details
During a local test flight, the pilot of a twin-engine conversion of a Grumman G-164B aircraft encountered a partial power loss on the number two engine shortly after lift-off. The pilot executed a left turn and began dumping the load, at which time the number one engine also experienced power loss. The aircraft stalled, but the pilot was able to regain a level attitude before impact.
Aircraft and Flight
The aircraft was a twin-engine conversion of the Grumman G-164B. For the test flight, the hopper was filled with water to simulate flight conditions near the operating gross weight. The flight was intended to evaluate performance under those conditions.
Engine Power Loss
After lift-off, the pilot noted a partial power loss on the number two engine. While turning left and dumping the load, the number one engine also lost power. The aircraft subsequently stalled, but the pilot recovered to a level attitude prior to impact.
Fuel System Examination
The aircraft incorporated a common fuel and fuel vent system for both engines. Each engine had its own fuel shutoff valve, fuel filter, and fuel pump. Examination of the fuel system revealed a partial restriction in the fuel vent system when the vent line was disconnected. However, due to impact damage to the fuel vent system, the precise nature of the restriction could not be determined.
Pilot Recommendation
Following the incident, the pilot recommended the installation of an air pressure operated vane on the fuel vent openings.