What happened
On July 25, 2015, a Sanford Zenith CH 601XL experimental amateur-built airplane, N9601, crashed near Binzel Airport (WI95) in Bristol, Wisconsin. The flight originated from Porter County Regional Airport (VPZ) in Indiana, with the intended destination being Oshkosh, Wisconsin.
At approximately 11:15 a.m., radar and GPS data indicated the aircraft performed a left turn followed by a right turn. Shortly after, the aircraft's groundspeed decreased significantly, dropping to 45 knots or slower. During this period, the aircraft descended from 1,722 feet MSL to 1,152 feet MSL. Witnesses on the ground reported seeing the airplane perform several "corkscrew-type twirls" before the nose dropped behind the tree line. One witness noted that the propeller appeared to be stationary during the descent.
The aircraft impacted the terrain, resulting in 2 fatal injuries. The wreckage was located the following day in an open field.
The investigation
Engine examination conducted by a representative of Jabiru USA revealed that the engine was missing its exhaust and the carburetor heat shield was damaged. Investigators found that the ignition coils installed in the engine were not genuine Jabiru replacement parts. During post-accident testing, the left ignition coil failed to produce sparks, while the right coil was functional only after being connected to a different distributor cap.
Detailed analysis of the right distributor cap showed that the center coil socket tower had separated due to an overstress fracture caused by bending forces.
Data from the aircraft's Dynon FlightDEK-D180 and Garmin GPSMAP 396 units confirmed the flight path and recorded the final moments of the flight. The Dynon data showed that in the final seconds, the aircraft experienced decreasing oil pressure, decreasing RPM, and decreasing indicated airspeed, alongside an increase in pitch attitude.
Findings
- The pilot failed to maintain adequate airspeed and airplane control following a loss of engine power.
- The engine lost power due to the installation of non-manufacturer-approved ignition coils.
- The left ignition coil was inoperative, and the right distributor cap failed due to mechanical overstress.