N736MM

On June 22, 2018, about 1830 central daylight time, an amateur-built experimental Zenith Aircraft Company STOL CH-701 airplane, N736MM, sustained substantial damage during a forced landing after a loss of engine power in the traffic pattern at Maple Lake Municipal Airport (MGG), Maple Lake, Minnesota. The left seat private pilot and the right seat certificated flight instructor (CFI) sustained no injury. The airplane was registered to a private individual and was operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91 as a visual flight rules personal flight. Day visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed. The flight originated from MGG about 1820.

In a conversation with the National Transportation Safety Board investigator-in-charge on June 26, the pilot reported that the purpose of the local area flight was to fly with his friend, who was a CFI, to help increase his dual pilot flight instruction time. The pilot reported that, upon taking off, he smelled a "burnt electrical" smell in the cockpit. The pilot and the CFI decided to remain in the traffic pattern due to the smell. On the second traffic pattern circuit, while on the downwind leg for runway 10, the smell dissipated, and the engine began to backfire. The backfiring sequence occurred about 10 minutes into the flight. During the backfiring sequence, the pilot observed the engine tachometer "jumping all over the gauge" from zero to a maximum indication. About 10 seconds after the backfiring began, the engine experienced a total loss of power while about 700 ft above ground level and at an airspeed of about 50 miles per hour.

The pilot attempted to troubleshoot the engine failure by switching fuel tanks, turning the fuel boost pump on, and attempting a restart of the engine with no success. The pilot reported he decided to attempt a forced landing to runway 10. However, due to the presence of power lines that he would be unable to maintain clearance over, the pilot attempted a forced landing onto a road. The airplane landed about 20 ft short of the road and impacted a ditch. The airplane came to rest in a grass-covered field about 400 ft to the northwest of the runway threshold for runway 10, as shown below in figure 1. During the forced landing, the nosewheel collapsed resulting in substantial damage to the fuselage and the engine mount. The right wing sustained substantial damage from impacting a street sign.

Figure 1 – View of the front of the airplane (courtesy of the Wright County Sheriff's Office).

The pilot reported that the airplane had an adequate amount of fuel for the flight and there were no known previous issues with the airframe or engine that would have precluded normal operation. The owner of the airplane reported the airplane departed with over ten gallons of fuel onboard.

On June 26, 2018, a Federal Aviation Administration (FAA) aviation safety inspector (ASI) from the FAA Minneapolis Flight Standards District Office traveled to MGG to examine the airframe and engine. Adequate fuel was found onboard the airplane. Flight control continuity was established for the airframe. The airplane's engine originated from a Suzuki Geo Metro subcompact automobile. All components of the engine were present and intact. All engine lines, wires, and hoses appeared to be connected. The engine would not start after multiple attempts. The FAA ASI attempted to use a vehicle code reader; however, no data was gathered because the reader required the vehicle identification number from the Suzuki Geo Metro that the engine originated from. No evidence or a pre or postimpact fire were noted with the airframe and engine. During the examination, no preimpact mechanical malfunctions or failures were found with the airframe and engine.