CEN24FA167 · Vertical Aviation Technologies Hummingbird 260L

The pilot departed in the experimental helicopter with a pilot-rated passenger to perform a golf ball drop for a charity event. Flight track data showed that the beginning of the flight was not captured, as the first data point indicated the helicopter was in flight and was approximately 4.3 miles to the northeast of the departure airport and about 1.8 miles to the northwest of the planned golf ball drop location. The data showed the helicopter flying to the southwest of the first data point. The helicopter continued to travel to the southwest, and it then turned to the southeast where the data terminated shortly thereafter at the accident site, which was located about 1.4 miles to the northwest of the departure airport. Multiple witnesses near the accident site heard the engine produce sputtering and coughing noises just prior to impact. Security camera footage showed the helicopter impact a grass field in a residential area, in front of a house. A postimpact explosion and fire occurred, which consumed the wreckage. While no mechanical anomalies were found during the airframe and the engine examination, the examination was limited due to the extensive fire damage present. Multiple golf balls were found in the wreckage, which is indicative that the golf ball drop was not completed. The recovered flight track data showed that the helicopter was possibly flying back to the departure airport; however, the intended flight path was not established. The pilot had previously contacted the helicopter kit manufacturer about ethanol in fuel “eating up” the fuel bladder in the helicopter and causing the fuel lines to “clog.” The kit manufacturer offered to sell the pilot a new fuel bladder to install in the helicopter, but they never heard back from the pilot. According to the FAA, ethanol in automobile fuel is not compatible with the rubber seals and other materials used in aircraft, which could cause fuel system deterioration and malfunction. The current helicopter maintenance records were not available for review, and the investigation was unable to determine what maintenance had been performed on the airframe and the engine in the several years prior to the accident. Based upon the statements of multiple witnesses, the engine likely sustained a total loss of engine power, which resulted in a forced landing and a subsequent impact with terrain. While it is possible that the cause of the loss of the engine power may have been due to the deterioration of the fuel system from the presence of ethanol in fuel, the extensive fire damage precluded examination. Due to heart disease, the pilot was at increased risk of a sudden impairing or incapacitating cardiac event, including angina, arrhythmia, or heart attack. There is no autopsy evidence that such an event occurred. However, such an event does not leave reliable autopsy evidence if it occurs immediately before death. The pilot’s toxicological results indicated use of gabapentin, which the FAA considers a “do not fly” medication. Based on the gabapentin levels measured in the pilot’s heart blood, he was possibly experiencing some effects from his use of the gabapentin; however, specific effects are uncertain and whether he may have been impaired could not be determined based on the level detected alone.

Verbatim NTSB analysis and probable cause from the NTSB dataset