WPR24FA123

The pilot’s failure to adequately monitor his fuel supply, resulting in fuel exhaustion, a total loss of engine power, and the airplane’s impact with terrain.

On the morning of the accident, the pilot departed from the operator’s base and flew the airplane about 174 miles northeast, to an airstrip near a rice farm. About 1230, after performing multiple flights to drop wild rice in the paddies near the airstrip, the pilot asked the fuel truck operators to fuel the airplane until the tanks were 3/4 full and subsequently departed the airstrip to continue spreading rice. When the pilot returned to the airstrip about 1400, he said he was not feeling well and was going to apply one last load of rice before leaving work. The pilot declined to have more fuel added to the fuel tanks. The pilot was seen with his safety harnesses fastened when he last departed. About 1444, witnesses near the rice farm heard the airplane crash and saw it inverted and partially submerged in the rice paddy. When they opened the airplane’s canopy, they found the pilot unbuckled from the safety harness, unresponsive. Examination of the airplane revealed an unusable amount of fuel (less than 2 gallons) in the fuel system, and no fuel sheen was observed in the water. No preaccident mechanical failures or malfunctions that would have precluded normal operation were found. The propeller blade damage signatures at the accident site were consistent with low rotational energy at impact. The airplane’s fuel system was intact, and there was no evidence of fuel leakage. After the pilot departed the operator’s facility, he had texted the mechanic stating the airplane’s fuel gauge was inoperative and that the airplane’s fuel gauge was slower to respond to fuel quantity changes than other airplanes. The mechanic explained that the gauge did not read fuel quantities greater than 82 gallons per tank; additionally, the cockpit fuel gauge noted that fuel quantities above 82 gallons were “ungageable.” Postaccident testing of the airplane’s fuel gauge and level senders indicated that they were operating to the manufacturer’s specifications. Fuel consumption calculations indicate that, with the reported fuel load, the airplane would have had an endurance of 2.1 to 2.9 hours. Although the airplane sustained substantial damage, the accident appeared to be survivable. The pilot’s autopsy identified no obvious fatal traumatic injuries, and the cause of death was determined to be hypertensive and atherosclerotic cardiovascular disease. However, the accident circumstances provide no clear evidence of in-flight pilot incapacitation, and it is unlikely that the pilot’s cardiovascular disease contributed to the accident. Additionally, severe acute mental or physical stress may be a trigger for cardiac events in individuals with underlying heart disease. It is possible that the airplane’s impact with the water of the rice paddy, followed by it becoming partially submerged and inverted, could have resulted in such a cardiac event in the setting of the pilot’s preexisting heart disease. The lack of fuel at the accident site and onboard the airplane during postaccident examination is consistent with fuel exhaustion, which resulted in the airplane’s impact with terrain. Though the pilot reported he was feeling unwell in the hours before the accident, available evidence is insufficient to determine what specific symptoms he was experiencing, or whether his symptoms contributed to the accident.

According to a mechanic who worked for the operator, the airplane had been purchased recently, and the pilot had not flown it before the day of the accident. The accident airplane, which was equipped with an AlliedSignal TPE-331-10 engine, differed from other aircraft in the fleet, which were equipped with different engines. The mechanic stated the airplane burned about 80 gallons per hour during takeoff, and about 60 to 65 gallons of fuel per hour during other phases of flight. The airplane’s Type Certificate Data Sheet indicated that the airplane had a usable fuel quantity of 228 gallons, stored in two wing tanks, each with a capacity of 115 gallons. The airplane’s fuel gauge in the cockpit was labeled, “USEABLE FUEL 114 U.S. GAL. FUEL ABOVE 82 GAL IS UNGAGEABLE.” The pilot’s autopsy identified hypertensive and atherosclerotic cardiovascular disease as the cause of death, and his manner of death was natural. Morbid obesity and pulmonary emphysema were listed as significant conditions contributing to death. The pilot’s heart was described as enlarged and had a thickened left ventricle. Slight coronary artery disease was present in multiple coronary arteries, with maximum narrowing of 40%. No recent coronary artery clot was identified, and no old heart muscle scarring was visible. The only traumatic injuries identified during autopsy were three rib fractures. Review of the pilot’s medical records revealed a medical history that included obesity, high blood pressure, high cholesterol, as well as chronic obstructive pulmonary disease (COPD) with components of both bronchitis and emphysema. During visits to his primary care provider in October and December 2023, the pilot reported increasing shortness of breath over the previous year. Four days before the accident, the pilot underwent a cardiac stress test. The pilot did not report chest pain during this examination. The interpreting cardiologist noted below-average functional capacity, with an exaggerated blood pressure response, frequent premature atrial and ventricular contractions. Postmortem toxicological testing detected acetaminophen and salicylic acid in peripheral blood and urine. Desmethylsildenafil, albuterol, and lisinopril were detected in urine and were not detected in peripheral blood. Desmethylsildenafil is a metabolite of sildenafil. Sildenafil (which was not detected in this case) is a prescription medication commonly used to treat erectile dysfunction, as a sexual enhancement aid, or in the treatment of certain other conditions, including pulmonary hypertension. Sildenafil is not typically impairing, although the FAA states that pilots should wait 8 hours after using it before flying, to monitor for side effects. Albuterol is a prescription medication commonly used as needed to relax tight lungs and improve wheezing and cough in conditions such as asthma and COPD. The pilot’s documented home medication levalbuterol is a form of albuterol. Albuterol is not typically impairing. According to the FAA medical case review for this accident, pilot use of albuterol as needed up to twice weekly is acceptable, but pilot medical certification on albuterol depends on the underlying condition. Lisinopril is a prescription medication commonly used to treat high blood pressure, and was documented as one of the pilot’s home medications in reviewed personal medical records. Acetaminophen is a pain- and fever-reducing medication widely available over the counter, including cold and flu products. Salicylic acid is the primary active metabolite of aspirin, a widely available over-the-counter medication that can be used to control pain and fever and to reduce cardiovascular risk. Salicylic acid also is a metabolite of some other drugs and is used as a topical skin exfoliant in a variety of retail products. Lisinopril, acetaminophen, and salicylic acid/aspirin, are not generally considered impairing. On April 9, 2024, at 1444 Pacific daylight time, an Ayres Corporation S2R-G10 airplane, N40261, was substantially damaged when it was involved in an accident near Derner, California. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 137 aerial application flight. According to the pilot’s co-workers, about 0830 on the day of the accident, the pilot flew the airplane from the operator’s facility in Williams, California, to an airstrip near a rice farm about 174 miles northeast. The airplane departed with full fuel tanks, and the co-workers stated the flight normally takes about 70 to 90 minutes. After the pilot departed the operator’s facility, he texted the mechanic, stating the airplane’s fuel gauge was inoperative. The mechanic explained that the gauge did not read fuel quantities greater than 82 gallons per tank. The pilot also told the mechanic that the airplane’s fuel gauge was slower to respond to fuel quantity changes than other airplanes. About 0930, the pilot landed at the airstrip where workers loaded the airplane’s hopper with wild rice, and the pilot subsequently seeded eight hopper loads of rice on the paddies. About 1230, the pilot returned to the airstrip, requested another load of rice, and asked the fuel truck operators to fuel the airplane to 3/4 of its capacity. The pilot then applied another seven or eight loads of rice to the fields. About 1400, the pilot returned to the airstrip and informed his co-workers that he was feeling unwell and was going to conclude the workday early after applying one more load of rice to the field. The pilot was asked if more fuel was needed for the airplane, but the pilot declined to refuel and returned to the aircraft. A witness saw the pilot don his helmet and safety harness before departing. A witness who was in a building about 2.5 miles from the airstrip stated he heard a crash and looked out the building’s door to see the airplane inverted in the rice paddy. The witness reached the accident site and attempted to open the airplane’s cabin door without success. A shovel was then used to pry the door open. The witness stated that the pilot was unresponsive and that the pilot’s safety harness was unbuckled. The airplane came to rest inverted on the western edge of a rice paddy about 2.3 miles southwest of the departure airstrip. The rice paddy was filled with about 2 ft of standing water, and the upper portion of the airframe was submerged. The outboard right wing, vertical stabilizer, and rudder were crushed and deformed. All flight control surfaces remained attached, and flight control continuity was confirmed between the cabin controls and control surfaces. The flaps were partially extended. The cabin was generally intact. The windscreens were shattered, with portions missing from the frames. The instrument panel was intact. The engine power lever was in the mid-travel position, and the engine speed lever was near the fully forward position. The fuel selector valve was On. The emergency fuel cutoff lever was Off (open). No obvious fuel sheen was observed on the surface of the water, and both wing tanks were empty. The header tank, which had a capacity of 5 gallons, contained about 1 gallon of fuel. The fuel shutoff valve and emergency shutoff valve cabin controls were in the open position, and their corresponding valves were in the open positions. All fuel lines from the fuel controller to the auxiliary fuel pump and header tank were clear of obstruction and contained no fuel. All fuel line fittings and hoses were tight throughout the entire system, and all fuel vent lines were clear. There was no evidence of fuel leak at any fitting, nor were any fuel streaks observed on any airframe skin. The fuel senders remained attached at their respective fittings on the inboard side of each tank. Both senders could be moved freely by hand and did not appear to be hung up on any part of the tank structure. The electrical resistance for both senders vari