Aviation Accident Summaries

Aviation Accident Summary ANC08LA085

McCarthy, AK, USA

Aircraft #1

N80596

CESSNA 185

Analysis

The solo commercial pilot was on a flight in conjunction with a lodge operation under 14 Code of Federal Regulations Part 91. The pilot said that he ran one main fuel tank dry 10 minutes into the flight and that, after switching fuel tanks, he turned on the auxiliary fuel pump but was unable to restart the engine. During a forced landing on a sandbar, the airplane stalled about 10 feet in the air, landed hard, and nosed over, damaging the wings and fuselage. The pilot said that he had learned the procedure of running a fuel tank dry in-flight from a more experienced pilot and that it was a fairly common operating procedure. He reported that there were no known mechanical problems with the airplane prior to the accident. He wrote that he thought fatigue and unfamiliarity with the airplane may have contributed to the accident. The airplane's Pilot Operating Handbook (POH) states that takeoff and landing should be made with the fuel tank selector valve in the "BOTH" position to prevent inadvertent operation on an empty tank. The POH further describes the procedure if the pilot "desires to completely exhaust a fuel tank quantity in flight." The restart procedure after the engine has quit due to fuel starvation is "immediately switch to a tank containing fuel at the first indication of fuel pressure fluctuation and/or power loss. Then place the right half of the auxiliary fuel pump switch in the "ON" position momentarily (3 to 5 seconds) with the throttle at least 1/2 open. Excessive use of the auxiliary fuel pump and full rich mixture can cause flooding of the engine."

Factual Information

On July 3, 2008, about 1730 Alaska daylight time, a Cessna 185 airplane, N80596, sustained substantial damage during an emergency, off-airport landing, about 22 miles southeast of McCarthy, Alaska. The airplane was being operated by Ultima Thule Outfitters, Chitina, Alaska, as a visual flight rules (VFR) local other work use flight under Title 14, CFR Part 91, when the accident occurred. The solo commercial pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed. The flight departed a remote lodge airstrip about 1720. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on July 4, the pilot said he ran one main fuel tank dry 10 minutes into the flight. He said he turned on the auxiliary fuel pump, switched the fuel tank selector to the full tank, and advanced the throttle full forward, but the engine did not restart. After several failed attempts to restart the engine, he concentrated on landing the airplane on a sandbar. He said the airplane stalled about 10 feet in the air, landed hard, bounced, and nosed over. The wings and fuselage received substantial damage during the accident. During a telephone conversation with the IIC, the pilot said there were no known mechanical problems with the airplane prior to the accident. He further stated that he had learned the procedure of running a fuel tank dry in-flight from a more experienced pilot, and that it was a fairly common operating procedure. The Cessna 185F Pilot Operating Handbook (POH), Airplane & Systems Descriptions section, Fuel System, states that takeoff and landing should be performed with the fuel tank selector valve in the "BOTH" position to prevent inadvertent operation on an empty tank. The POH describes the procedure to exhaust a tank, if the pilot "desires to completely exhaust a fuel tank quantity in flight." According to the POH, the procedure for restarting the engine after the engine has quit due to fuel starvation is, "immediately switch to a tank containing fuel at the first indication of fuel pressure fluctuation and/or power loss. Then place the right half of the auxiliary fuel pump switch in the ON position momentarily (3 to 5 seconds) with the throttle at least 1/2 open. Excessive use of the auxiliary fuel pump and full rich mixture can cause flooding of the engine." In a written statement dated July 10, the pilot wrote that he did not know if the auxiliary fuel pump was working, and that fatigue, and unfamiliarity with the airplane played a part in the accident. As a result of the accident, the IIC surveyed 89 fuel related accidents involving Cessna, single-engine airplanes. The survey showed that 11 accidents were associated with intentionally running a fuel tank dry in-flight, and 41 accidents were associated with unintentionally running a fuel tank dry in-flight. These accidents accounted for 56% of the accidents surveyed, and all 89 of the accidents resulted from the pilot's inability to restart the engine after starving it of fuel in-flight. The same procedure was found in all of Cessna's single-engine, fuel-injected, airplane pilot operating handbooks. A survey of Piper and Beechcraft handbooks showed that these two manufacturers treat running a fuel tank dry in-flight as an emergency procedure, and do not advocate exhausting fuel from a tank in-flight as a normal procedure. The FAR/AIM, and two basic flight instruction manuals surveyed, direct pilots to follow the manufacturer's fuel management procedures.

Probable Cause and Findings

The pilot's improper fuel management which resulted in fuel starvation and a loss of engine power during cruise flight. Contributing to the accident was an aerodynamic stall during the emergency landing, the pilot's fatigue, and his unfamiliarity with the airplane.

 

Source: NTSB Aviation Accident Database

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