Amateur-built Vans RV9-A N159AS accident near Princeton, New Jersey

Probable cause

A loss of engine power due to the pilot/owner's improper installation of a new ignition/fuel control system for the engine. Contributing was the unsuitable terrain for a forced landing.

NTSB analysis

Prior to the accident flight, the airplane had accumulated about 1 flight hour since the pilot completed the installation of a new aftermarket fuel injection and ignition system. Shortly after takeoff on the accident flight, as the pilot turned onto the crosswind leg of the traffic pattern, the engine lost power, and the propeller "stopped." The pilot added that he believed the electrical system was functioning at the time because the electronic flight instrument system and the communication radio continued to function. The pilot subsequently performed a forced landing into the dense forest below. Although the wreckage was fire-damaged during the recovery process, examination of the engine revealed that while the pilot had installed a new after market fuel injection/ignition system , an original-equipment diode bridge remained in place. The diode bridge provided dual electrical paths to the engine control unit, thereby providing electrical power to the ignition system. The original ignition system, for which the diode bridge was designed, drew between 4 and 6 amperes for operation, while the aftermarket system drew between 8 and 12 amperes. The only manifestation of a failure of the diode bridge would be on engine operation; the remainder of the electrical system would continue to function normally.

Text from the NTSB. Open the NTSB docket for NYC08LA107 for the full record.