CEN24FA167

A total loss of engine power for undetermined reasons, which resulted in a forced landing and a subsequent impact with terrain.

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.

According to the pilot’s family, he was a retired building inspector. Prior to that, he had retired from the U.S. Air Force, where he served as a pilot operating the Sikorsky MH-53 series helicopters. He had accumulated over 5,000 flight hours during his career in the U.S. Air Force, where he also served in training roles. The pilot held a type rating for the Bell 212 series helicopters. The pilot’s logbook was not available for review. The pilot also held a repairman experimental aircraft builder certificate for the helicopter. The pilot built the experimental helicopter from a kit in 2012. Per the kit manufacturer, the helicopter is based on the Sikorsky S-52 series helicopter design. According to the pilot’s family, the pilot would perform maintenance work on the helicopter, and he did not mention any mechanical concerns before the accident flight. The current airframe and engine maintenance records were not available for review. The airframe total time and the time since the last maintenance work was performed could not be determined, nor was a current helicopter weight and balance sheet available for review. A review of historical engine maintenance records showed that the fuel-injected automobile engine (V8, 7.0 liter) had originated from a Chevrolet Corvette sports car. The pilot additionally installed a nitrous oxide system onboard the helicopter to use with the engine. According to a tenant at 1T7, the pilot had non-ethanol 91 octane fuel (obtained the fuel from a local automobile fuel station) in a container in his hangar that he used in the helicopter. A fuel sample from the container was free of debris and tested negative for water presence. According to a representative of the kit manufacturer, who had known the pilot for multiple years, the pilot previously contacted him 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. The flight manual for the helicopter discussed fuel and stated in part: The engine is serviced with minimum 91 octane automobile fuel or 100 low lead aviation fuel. One fuel tank having a capacity of 57 gallons with expansion space for one gallon, is located below the rear portion of the cabin. The helicopter was not equipped with a crash resistant fuel system, nor was it required to be. Photographs of the helicopter taken right before departure from 1T7 showed the rear left door was removed to facilitate the air drop operations. According to the flight manual for the helicopter, doors-off operations are allowed. Pilot The Travis County Medical Examiner’s Office performed the pilot’s autopsy. According to the pilot’s autopsy report, his cause of death was blunt trauma, and the manner of death was accident. A review of the pilot’s personal medical records for the three years prior to the accident identified that the pilot was being treated for several chronic conditions, including obesity, high blood pressure, high cholesterol, peripheral neuropathy of the hands and feet without motor deficits, and a bicep tendon injury. The pilot’s last primary care medical examination prior to the accident was on April 15, 2024. No new conditions or medication changes were noted during that examination. The pilot’s autopsy identified 60% focal narrowing of the left main coronary artery and 50% focal narrowing of the left anterior descending coronary artery. Postmortem toxicological testing by the FAA Forensic Science Laboratory detected gabapentin in heart blood at 3,209 ng/mL and in urine at 383,858 ng/mL. Gabapentin is a prescription medication that is commonly used to treat nerve-related pain. It may also be used to treat seizures and other conditions. It typically carries a warning that use may cause drowsiness, dizziness, and sedation. Precautions are advised for driving a vehicle or operating heavy machinery until the user can assess the impact of dosing on alertness and motor activities. The FAA considers gabapentin to be a “do not fly” medication. Pilot-Rated Passenger The Travis County Medical Examiner’ Office performed the pilot-rated passenger’s autopsy. According to the pilot-rated passenger’s autopsy report, his cause of death was blunt trauma, and his manner of death was accident. Postmortem toxicological testing by the FAA Forensic Science Laboratory did not detect drugs. On April 29, 2024, about 1512 central daylight time, a Vertical Aviation Technologies Hummingbird 260L helicopter, N829SH, was destroyed when it was involved in an accident near Spring Branch, Texas. The airline transport pilot and the pilot-rated passenger sustained fatal injuries. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 air drop flight. The purpose of the flight was to perform a charity golf ball drop at the River Crossing Club (a private golf club), in Spring Branch, Texas. The planned time for the golf ball drop was 1530, and the planned location was on the driving range. According to the pilot’s family, the golf ball drop was originally supposed to occur sometime during the morning; however, it was pushed back to later in the day due to the presence of fog in the area. The helicopter departed from the Kestrel Airpark (1T7), Spring Branch, Texas, for the local area flight. 1T7 is where the pilot based the helicopter. Preaccident photos of the helicopter taken right before departure from 1T7 showed the pilot stationed in the front right seat (which is required per the helicopter flight manual) and the pilot-rated passenger stationed in the rear left seat. A postaccident search did not reveal any ADS-B or radar data for the accident flight. A fire-damaged Appareo Straus 3 device was recovered from the wreckage and the data was downloaded. No data was recorded for the beginning of the flight, as the first data point indicated the helicopter was in flight and was approximately 4.3 miles to the northeast of 1T7 and about 1.8 miles to the northwest of the River Crossing Club. 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 shortly terminated thereafter at the accident site, which was located about 1.4 miles to the northwest of runway 12 at 17T. 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. All the major structural components were located at the accident site, and the wreckage was examined at the accident site. Due to the fire damage, only partial flight control continuity was established; airframe-to-engine control continuity could not be established. The airframe fuel system was destroyed by fire. Multiple golf balls were located throughout the wreckage. The engine was separated from the airframe. The engine case was intact; however, the oil sump had a hole present from fire damage. The various engine accessories all had extensive fire damage. The engine fuel system, engine oil system, engine cooling system, engine air induction system, engine ignition system, and the engine exhaust were all destroyed by fire. The limited examination of the engine revealed no mechanical anomalies. The engine computer was destroyed by the fire and data could not be recovered. Due to the fire damage, fuel samples were not available from the airframe or the engine. Postaccident examination of the main driveshaft universal joint assembly revealed an overall fracture pattern consistent with ductile overstress fracture. The pilot-rated passenger’s Garmin D2 Smartwatch, which sustained fire