ERA20LA197 · Schweizer 269C-1

The pilot, who held a pilot certificate with ratings for airplanes, was training for a helicopter rating through the flight school. After conducting a dual instructional flight with his instructor, the pilot serviced the helicopter with fuel and departed on a solo flight, during which he planned to perform several takeoffs and landings at a nearby airport. Security cameras at the nearby airport captured the helicopter performing takeoffs and landings on the runway. A witness next saw the helicopter over a tree line about 1 mile from the runway. The witness described that the helicopter was "sputtering” and that it turned back in the direction it had come from. The engine sounds then ceased, and the helicopter dove and impacted the ground.

Postaccident examinations of the accident site, helicopter, and engine did not reveal evidence of any preimpact mechanical failure or malfunction of the structure, engine, drivetrain, or flight controls that would have precluded normal operation. There also was no evidence of any fire or explosion. Although no anomalies were found with the engine or drivetrain, no power signatures were present on the drivetrain or leading edges of the rotor blades, suggesting that the engine may not have been operating at the time of impact. The fuel tank and carburetor were impact damaged and displayed no evidence of residual fuel. There was no odor of fuel, and no observed fuel blight (browning of vegetation) in the vicinity of the wreckage.

Further examination of the wreckage showed corrosion on the fuel quantity sensor fasteners, and on the adjustment screws used to calibrate the unit. The aluminum probe shaft, which should have been in the fuel tank, was missing, along with the side wires. The ends of the side wires, which were broken and corroded where they came out of the assembly, indicated that the probe and side wires may not have been present before the accident. The fuel tank filler cap was found hanging by its chain. It would attach to the fuel tank but was heavily rusted and there was little or no positive friction to ensure that the cap would remain in place.

During a postaccident interview, the pilot’s instructor stated that he checked the helicopter’s fuel level when he performed a preflight inspection before the 1.4 hour-long lesson that preceded the pilot’s solo flight. The instructor noted that there appeared to be about 20 gallons of fuel in the 33-gallon fuel tank when he checked it. After the dual flight lesson, when the pilot refueled the helicopter, the instructor observed the pilot place the nozzle in the fuel tank filler of the helicopter fuel tank and was carrying on a conversation with the student from the driver’s seat of the fuel truck. The student pilot then told the instructor; “Good to go” and gave a “thumbs up.” The instructor did not see the student pilot secure the fuel tank filler cap on the fuel tank filler. It is possible that the conversation between the student and the flight instructor may have distracted the student during the fueling procedure.

The amount of fuel onboard the helicopter when the pilot departed on the accident flight could not be determined based on available evidence, nor could it be determined if the pilot failed to properly secure the fuel tank cap or if it opened inflight due to its condition; however, given the lack of fuel at the accident site, no evidence of fuel spillage, and the absence of mechanical anomalies, the circumstances of the accident are consistent with a total loss of engine power due to fuel exhaustion.

The flight instructor stated that the accident helicopter’s fuel gauge worked, but it was not 100% accurate and that the low fuel caution lights did not work on the accident helicopter or on the flight school’s other operable helicopter. He stated that a few months before the accident, the flight school placarded the low fuel lights on both helicopters they operated as inoperative. Additionally, the flight school’s fuel truck was not equipped with a meter to record the quantity of fuel dispensed. Instead, users would estimate the amount of fuel that was in the helicopters by using the fuel gauges and checking the tank visually.

According to the helicopter’s Rotorcraft Flight Manual, if the amber FUEL LOW caution light came on in flight, about 1 gallon of usable fuel remained in the fuel tank. The manual instructed that, “If fuel low caution light comes on during flight, land immediately.” Although the fuel low caution system was found placarded as inoperative, review of the helicopter’s maintenance log revealed no entries documenting the malfunction and deferral. The Federal Aviation Administration (FAA) Master Minimum Equipment List (MMEL) for the helicopter indicated that the fuel low caution light system should have been repaired within 10 days after the malfunction was recorded in the aircraft maintenance logs. Further review of the MMEL also indicated that the low fuel caution light, “May be inoperative provided procedures for monitoring fuel quantity are established and used.”

During an interview with an FAA inspector, the owner of the flight school initially stated that several weeks before the accident, during an inspection of the helicopter, the fuel low caution system was found to be inoperative. The mechanic then placarded the helicopter. The owner also explained that “everyone” knew the system was inoperative and as a policy, the helicopters were always rented with a full tank of fuel. In a subsequent letter to the FAA, the owner of the flight school advised that only one of the flight school’s helicopters had an inoperative low fuel caution system. He further advised that the placard that was placed on the accident helicopter was placed there by mistake, and that it was supposed to be placed only on the other helicopter. He stated that, at the time of the accident, the low fuel caution system in the accident helicopter was functioning properly, as was the fuel quantity indicating system, and that the fuel quantity gauge in the helicopters were very accurate and reliable.

The owner of the flight school also stated that the MMEL allowed for having a fuel low caution system inoperative if there was a procedure for monitoring fuel quantity. The procedure they employed in the event that the low fuel caution system was not working was to always fully refuel the helicopters between flights and limit flights to a length of 1.5 hours. He also advised that the flight school used the fuel quantity gauge in the helicopter, in addition to the refuel policy and the flight length limit, to do this. Review of the written operational documents provided by the operator showed that none of these policies were documented.

Given the conflicting statements provided by the flight school owner and the flight instructor regarding the operational status of the fuel quantity indicating system, it was unclear whether the fuel low caution system was operable at the time of the accident. Given the condition of the fuel quantity indicating system components documented during the postaccident examination of the wreckage, and the statement by the flight instructor that the fuel quantity indicating system was not “100% accurate,” it was unlikely that the system was able to provide the pilot with an accurate accounting of the helicopter’s fuel state. The condition of the fuel quantity indicating system, the fuel tank cap, and the uncertainty surrounding the documentation of the operational state of the low fuel caution system suggested that the operator lacked an adequate system to ensure the airworthiness of the helicopters that it was providing to its customers. Had these systems been fully operational at the time of the accident, it is possible that the student pilot might have recognized and/or avoided the helicopter’s critical fuel state before the fuel was completely exhausted and the engine lost total power.

Verbatim NTSB analysis and probable cause from the NTSB dataset