Loehle Acft CORP 5151 Mustang accident near Hector, Minnesota, May 11, 2023

The NTSB's narrative final · quoted from the NTSB record

The pilot of the experimental, amateur-built airplane overhauled the engine carburetor and modified the airplane’s fuel system with an additional fuel tank after removing the airframe ballistic parachute system. The pilot also adjusted the ground-adjustable propeller to attain an engine rpm of 6,200. The pilot then performed a static ground run of the airplane for about 28 minutes before attempting a test flight. During takeoff, with the newly installed fuel tank selected, the engine only attained 6,100 rpm and the pilot suspected that something was wrong. There was another aircraft close to the airport and the accident pilot radioed the other aircraft and notified the pilot of engine issues and asked for its position from the airport. The pilot of the other aircraft responded that they were about 3 miles from the airport. The accident pilot told the other aircraft to go ahead and land and that he would land behind him. As the accident pilot turned the airplane toward the runway, the engine lost total power and the airplane landed in a soft field about 250 ft short of the runway, resulting in substantial damage. The pilot stated that he thought the loss of engine power was the result of fuel starvation and that there may have been a problem with the vent of the newly installed fuel tank. Postaccident examination of the engine revealed that the front carburetor was not intact within its flange. The carburetor separation was likely due to impact forces during the accident that also damaged the engine cowl around the carburetor. There were no other mechanical anomalies noted during the examination. Though the pilot performed an extended engine runup before flight, the runup did not account for dynamic effects from aircraft velocity that may have been simulated by performing a high-speed taxi test to determine if the anticipated propeller speed could be attained. Also, the pilot attempted a test flight to encompass multiple system modifications and maintenance, contrary to proper flight testing by using a build-up and risk mitigating approach. Additionally, even though the pilot observed a propeller rpm that was lower than anticipated, he chose to continue the takeoff and delay the precautionary landing to allow for another airplane to land. It is possible that the pilot may have been able to land on the runway had he not chose to delay his landing.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.