Aviation Accident Summaries

Aviation Accident Summary DEN02LA046

Moab, UT, USA

Aircraft #1

N191RH

Bell 206B-III

Analysis

According to the pilot, he started the day with approximately 50 gallons of fuel on board. He departed from his home base, for a 10 minute flight to pick up several passengers, taking groups of them on 5 to 10 minute photo flights, for a total mission duration of approximately 80 to 90 minutes. After dropping off the last group, he returned to his home base. According to the fuel gauge, there was approximately 12 to 13 gallons of fuel remaining when he departed for the 10 minute repositioning flight back to his home base. Based on a fuel burn rate of approximately 25 gallons per hour, he calculated that he had 30 minutes of fuel remaining. He also stated that, due to noise abatement, he always approached his helipad at a "high airspeed and with a fast rate of descent and then about 100 feet, power up to make a high power, steep landing." Being "low on fuel," he did the same thing on this approach, starting his descent at approximately 80 to 100 knots. At 50 to 75 feet above ground level (agl), he initiated a 10 to 20 degree flare and began the descent to land. The fuel boost pump light illuminated, the "auto-relight" light came on, and the "engine out" light illuminated. His first thought was that he "ran the aircraft out of fuel." He realized that he was going too fast to land at his helipad. He adjusted his approach, and attempted to land in a parking lot just beyond his pad. He applied forward cyclic control, to level out the helicopter, hoping the boost pump light would go out and that the "auto relight" would reignite the fuel if it started pumping. The helicopter struck the ground hard with its right landing gear skid, bounced, slid forward approximately 15 feet, turned to its left approximately 90 degrees and slowly rolled over on its right side. The aircraft continued to turn to the left another 90 degrees and came to rest on its right side, facing 180 degrees from the direction of the approach. During the hard landing, the main rotor blades struck the tail boom, separating the vertical stabilizer, tail rotor and tail rotor gearbox. The main rotor hub and blade assembly was intact and remained attached to the main rotor mast.

Factual Information

On May 23, 2002, at approximately 1925 mountain daylight time, a Bell 206B-III helicopter, N191RH, operated by Shier Aviation Corp., was substantially damaged during a hard landing near Moab, Utah. The airline transport pilot, the sole occupant on board, was not injured. Visual meteorological conditions prevailed. No flight plan was filed for this positioning flight being conducted under Title 14 CFR Part 91. The flight originated at Harley Bates Ranch, Moab, Utah, at approximately 1915. According to the pilot, he started the day with approximately 50 gallons of fuel on board. He departed from his home base, helipad #1991, on South Highway 191, Moab, Utah, for a 10 minute flight to Harley Bates Ranch. He picked up several passengers, taking groups of them on 5 to 10 minute photo flights, for a total mission duration of approximately 80 to 90 minutes. After dropping off the last group, he returned to his home base. On the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2), the pilot stated that, according to the fuel gauge, there was approximately 12 to 13 gallons of fuel remaining when he departed Harley Bates Ranch for the 10 minute repositioning flight back to his home base. Based on a fuel burn rate of approximately 25 gallons per hour, he calculated that he had 30 minutes of fuel remaining. He also stated that, due to noise abatement, he always approaches his helipad at a "high airspeed and with a fast rate of descent and then about 100 feet, power up to make a high power, steep landing." Being "low on fuel," he did the same thing on this approach, but was a little fast and started his descent at a lower altitude, approximately 75 feet. On this approach, he was approximately 80 to 100 knots, and at 50 to 75 feet above ground level (agl) he initiated a 10 to 20 degree flare and began the descent to land. The fuel boost pump light illuminated, the "auto-relight" light came on, and then the "engine out" light illuminated. His first thought was that he "ran the aircraft out of fuel." During the approach, the pilot realized that he was going too fast to land at his helipad. He adjusted his approach, and attempted to land in a parking lot just beyond his pad. The parking lot was approximately 20 to 25 feet higher then his pad and 100 feet further away. He applied forward cyclic control, to level out the aircraft, hoping the boost pump light would go out and that the "auto relight" would reignite the fuel if it started pumping. At "15 to 20 feet from touchdown, I was still too fast both forward and downward. I did a slight flare, rotor rpm must have been to low because it didn't help much." The helicopter struck the ground hard with its right landing gear skid, bounced, slid forward approximately 15 feet, turned to its left approximately 90 degrees and slowly rolled over on its right side. The aircraft continued to turn to the left another 90 degrees and came to rest on its right side, facing 180 degrees from the direction of the approach. During the hard landing, the main rotor blades struck the tail boom, separating the vertical stabilizer, tail rotor and tail rotor gearbox. The main rotor hub and blade assembly was intact and remained attached to the main rotor mast. In a statement to the Grand County Sheriff's Department, the pilot said that he "felt the engine flamed out due to low fuel." Further examination of the aircraft revealed that both fuel boost pumps were operational, neither the forward or aft fuel boost pump lights illuminated, and the fuel gauge indicated 6 to 7 gallons of fuel. The fuel tank was drained and 7 and one half gallons of fuel was recovered. According to the manufacturer, the pilot operating handbook (POH) for the Bell 206B-III, the unusable fuel is 1 and one half gallons. In the system malfunction section, there is this warning: "Operation with both fuel boost bumps inoperative is not authorized. Due to possible fuel sloshing in unusual attitudes or out of trim conditions and one or both fuel boost pumps inoperative, the unusable fuel is 10 gallons," and "One or both fuel boost pumps inoperative, descend to 6000 feet pressure altitude if flight permits. Land as soon as practical." The section also includes a note that states, "The engine will operate without boost pump pressure under 6000 feet pressure altitude and one boost pump will supply sufficient fuel for normal engine operations under all conditions of power and altitude. Both fuel boost pumps shall be ON for all normal operations." This aircraft, serial number 3177, did not come equipped with a low fuel warning light. Weather conditions at the time of the accident were; wind, 300 degrees at 11 knots; temperature, 17 degrees C; altimeter setting, 29.91. The elevation at the accident site was 5,000 feet msl. The calculated density and pressure altitudes were, 6,422 feet msl and 5,010 feet msl respectively.

Probable Cause and Findings

The pilot's failure to maintain rotor rpm during a forced landing. A contributing factor was fuel starvation.

 

Source: NTSB Aviation Accident Database

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