IMPERIAL, CA, USA
N61865
HUGHES OH-6A
The pilot reported that he was airborne for 5.5 hours on an observation mission. He was returning to the airport and was about 3 miles from landing, when the engine flamed out. The pilot initiated an autorotation and landed hard, severing the tail boom. A post-accident examination of the helicopter revealed that the fuel tank was empty. The fuel system was pressurized and found to be intact. The remaining fuel was drained and found to be 1.5 pints total in quantity. No contaminates were found in the drained fuel, the fuel lines, or filter. No other malfunctions or anomolies were found in the fuel system, including the low fuel level panel warning light. The performance charts showed the helicopter had a maximum endurance of 4.25 hours. The low fuel warning light was designed to illuminate when there was about 70 pounds of fuel remaining.
On October 20, 1995, at 1230 hours Pacific daylight time, a Hughes OH-6A helicopter, N61865, sustained substantial damage during a hard landing from an autorotation near Imperial, California. The autorotation was precipitated by a loss of power as the aircraft was returning from an observation mission. The aircraft was owned and operated by the U.S. Border Patrol as a public-use aircraft. Visual meteorological conditions prevailed at the time and an internal agency flight plan was filed. The commercial pilot, the sole occupant, was not injured. The flight originated from Imperial County Airport at 0700 on the day of the accident. The pilot reported in verbal and written statements that he was airborne continuously from departure on an observation mission. He was returning to the airport and was about 3 miles from landing when the engine flamed out. The pilot initiated an autorotation and landed hard, severing the tail boom. A U.S. Border Patrol officer who examined the helicopter reported that the fuel tank was empty. The aircraft operator conducted a post-accident examination of the aircraft. The fuel system was pressurized and found to be intact. The remaining fuel was drained and found to be about 1 1/2 pints in quantity. No contaminates were found in the drained fuel, the fuel lines, or filter. No other malfunctions or anomalies were reported with the fuel indicating systems, including the low fuel warning panel light. The accident aircraft was equipped with an Allison 250-C20B turboshaft engine. The pilot operating manual states that the fuel burn at sea level and 90 knots is about 175 pounds per hour; the burn rate at 60 knots at sea level is about 160 pounds per hour. The pilot stated that he departed on the accident flight with about 104 U.S. gallons (676 pounds) onboard. The pilot operators manual also states that "fuel low" warning light will illuminate with about 70 pounds of fuel remaining. Using the above data, the low fuel warning light would have illuminated about 24 minutes before the accident.
The pilot's improper planning/decision and failure to ensure there was an adequate supply of fuel, which led to fuel exhaustion and a forced (autorotative) landing.
Source: NTSB Aviation Accident Database
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