Amateur-built Sonerai-II N28MD accident near Leonardtown, Maryland

Probable cause

The pilot's continued operation of the airplane with a known mechanical deficiency. Contributing to the accident was the improper installation of the electronic ignition system.

NTSB analysis

According to the pilot/owner of the amateur-built airplane, after performing an engine check, he noticed the sole engine-driven magneto was not operating normally. However, since he had an electronic ignition system, he felt it would be acceptable to remain in the traffic pattern at the airport. While climbing through approximately 400 feet on his sixth takeoff, the engine started to lose power. The pilot/owner manipulated the throttle; however, the engine failed to respond. During the off-airport forced landing, the airplane impacted a tree with the outboard portion of the right wing. Following the recovery of the wreckage, the No. 2 cylinder exhaust pipe was observed detached and the exhaust outlet was in close proximity to the electronic ignition and coil that provided power to the cylinders. Additionally, the fuse to the ignition system was also found blown. After replacing the fuse, the engine operated normally utilizing the electronic ignition system. Manufacturer guidance indicates that the installation of the electronic ignition system should be on the accessory gear box next to the engine driven magneto, in order to prevent excessive temperatures to the coils. In the accident airplane, the electronic ignition system was mounted on the firewall, near the No. 2 exhaust.

Text from the NTSB. Open the NTSB docket for ERA09LA187 for the full record.