What happened
The pilot arrived at Logan Airport at 1830. At that time, the temperature was 90 degrees Fahrenheit, resulting in a calculated density altitude of approximately 7,000 feet. While there was initially no wind reported, an airport employee suggested using runway 35. After some difficulty starting the engine, the pilot completed all pre-takeoff checks and proceeded to taxi. During the taxi, the pilot observed a wind from 050 degrees at 15 knots and elected to use runway 17 instead.
The pilot leaned the mixture to 2,200 rpm, accelerated to 80 knots, and rotated. Following rotation, the aircraft continued to accelerate but would only climb approximately 20 to 25 feet above the runway. The pilot attempted to adjust the mixture and add more power, but the engine failed to respond. With no remaining runway, the pilot continued on the departure heading and performed a forced landing in a field just past the end of the runway. There were no injuries reported.
The investigation
An examination of the aircraft systems showed that the airplane was full of fuel, the throttle was at idle, the mixture was lean, the propeller was at high rpm, and the flaps were retracted. Although the landing gear selector lever was in the "up" position, ground scars at the initial impact point and damage to the landing gear were consistent with the gear being in the extended position.
An examination of the engine revealed that all spark plugs were worn in a "football" shape. Additionally, shielding was exposed on the number 5 cylinder's bottom spark plug wire, and a small hole, approximately the size of a pencil tip, was found on the manifold pressure tube for the number 5 cylinder. The propeller pitch control was found full forward and in contact with the pedestal stop prior to the governor stop, which restricted its travel to full rpm by 1/8 inch. In this condition, it would not have been possible for the engine to reach the required takeoff rpm of 2,700.