SCOTTSDALE, AZ, USA
N27181
Piper PA-31-350
The airplane collided with a berm in a construction area after making an emergency landing. Following a flight of about 1.5 hours and after starting a descent, the pilot felt the left engine surge, and saw the left boost pump warning light flashing. The left engine continued to surge and the boost pump light remained fully illuminated. He chose not to feather the left propeller. He engaged both emergency fuel boost pumps and advanced the throttles and propellers for both engines. In this configuration the engines did not produce enough power to sustain flight. ATC identified two nearby airports for the pilot; one airport was 6 miles away and the other was 2 miles away. At 4,000 feet agl, the pilot felt he would not make either airport. According to the manufacturer's published emergency procedures, once an inoperative engine has been identified and an unsuccessful engine restart attempt is made, the pilot should feather the propeller. During the recovery, personnel noted that the inboard fuel tanks were full of fuel. Both outboard tanks were empty; however, fuel was found on the ground by one of the outboard fuel tanks. According to the operator, once a month the pilot's are encouraged to burn out the fuel in the outboard fuel tanks in VFR conditions. Following the accident, a functional check was conducted of the continuous duty fuel boost pumps and emergency fuel boost pumps. No discrepancies were noted. According to the pilot's operating handbook (POH), the continuous duty fuel boost pump warning lights will illuminate when pressure to the system drops below 3 PSI or the boost pumps have failed. Engagement of the emergency fuel boost pumps provides steady fuel pressure. The POH further reports that the fuel system has right and left fuel warning lights. The fuel flow warning lights illuminate to warn the pilot of an impending fuel flow interruption. These lights are located underneath the fuel boost pump warning lights. If the fuel level near the tank outlet drops to a point where a fuel flow interruption and power loss could occur, a sensing probe will illuminate its corresponding warning light. An inspection of the fuel system revealed that the system was intact and operated normally. The cross feed valves were operated and fuel was observed to flow to each engine from the opposite side wing fuel tank. No mechanical anomalies were noted.
HISTORY OF FLIGHT On December 10, 1999, at 1800 hours mountain standard time, Union Flights 45, a Piper PA-31-350, N27181, experienced a loss of left engine power and struck a berm during the ensuing emergency landing in a construction area 4 miles southwest of the Scottsdale Airport, Scottsdale, Arizona. Aero Leasing, d.b.a. Union Flights, operated the airplane under the provisions of 14 CFR Part 135 as a nonscheduled domestic cargo flight. The aircraft sustained substantial damage, and the commercial pilot was not injured. Visual meteorological conditions prevailed and a visual flight rules (VFR) flight plan had been filed. The flight departed from the Flagstaff Pulliam Airport, Flagstaff, Arizona, at 1720. The flight was scheduled to terminate at Phoenix Sky Harbor International Airport, Phoenix, Arizona. The pilot's written statement noted no discrepancies were discovered during the preflight inspection. During the takeoff climb he noted the oil temperature gage on the right engine was at redline. He opened the right cowl flap and richened the mixture. About 15 minutes into the flight, the pilot experienced what he thought was turbulence and felt the left engine surge. He did a cursory check of the left engine instruments, with no anomalies noted. In addition, the pilot reported that the fuel selectors were positioned to the inboard main fuel tanks. There were no further discrepancies noted during the remainder of the 40-minute flight. After his entry into the Phoenix Class B airspace, the pilot was cleared to descend from 5,500 feet mean sea level (msl) down to 4,000 feet msl. He stated that the descent power settings were 21 inches of manifold pressure, 2,400 rpm, and 155 knots. Prior to leveling off at 4,000 feet, the airplane experienced a sudden surge of power in the left engine. The pilot simultaneously saw the flashing illumination of the left fuel boost pump warning light. He stated that "immediately thereafter the surging continued nonstop" and the left fuel boost pump light fully illuminated. The pilot decided not to feather the left propeller. He engaged both fuel boost pumps. He completed a GUMPS check that included advancing the throttles, mixtures, and propellers for both engines to the full forward position. He detected no change and reported that collectively both engines were not producing enough power for sustained flight. He contacted Phoenix Approach and declared an emergency. Phoenix Approach suggested two airports that were near his current position: Deer Valley, 6 miles to his southwest; and Scottsdale, 2 miles to his southeast. He informed them that he would be unable to make either airport. During the ensuing forced landing the airplane struck a berm. When the airplane was recovered from the accident site, recovery personnel from Air Transport of Phoenix, Arizona, noted that the inboard main fuel tanks were "full." There was no fuel found in the outboard tanks; however, there was fuel on the ground. Recovery personnel further indicated that the fuel selectors were found selected to the "MAIN" tanks. PERSONNEL INFORMATION According to the pilot's written statement, he had a total flight time of 4,000 hours; 1,600 hours in multiengine airplanes, and 26 hours in make and model. He also reported that he had 26 hours in the last 30 days. Review of Federal Aviation Administration (FAA) Medical Certification records revealed that the pilot held a first-class medical certificate issued on August 24, 1999, with limitations for near vision. AIRCRAFT INFORMATION Review of the airplane and engine logbooks disclosed that the operator conducted inspections based on an FAA approved Aircraft Inspection Program. The last "A" check was conducted on September 23, 1999. The last "B" check was conducted on November 18, 1999. Mattituck Airbase, Inc., an FAA certified repair station, overhauled both engines. The left engine was reinstalled on June 15, 1998, and had accrued 814.8 hours since overhaul. The right engine was reinstalled on June 30, 1998, and had accrued 835.9 hours since overhaul. According to fuel receipts, the airplane was refueled on December 10, 1999, with 32.4 gallons of 100LL aviation fuel. Company policy concerning fueling procedures required that a minimum of 1-hour fuel reserve for both Instrument Flight Rules (IFR) flights and VFR flights be maintained. The Director of Operations stated that pilot's are encouraged "to accomplish this . . . by maintaining half tanks, 20 gallons, in each of the outboard auxiliary tanks . . . ." Pilots are encouraged to burn the auxiliary tanks down once a month in VFR conditions and refuel with "fresh fuel." He further indicated that the Phoenix to Flagstaff route is heavily traveled in the morning and traffic in the evening between Flagstaff and Phoenix is lighter. The pilots are encouraged to refuel in Flagstaff by topping off the inboard mains, thereby making a refueling purchase in Phoenix unnecessary. The airplane manufacturer's emergency procedures section of the PA-31-350 pilot's operating manual for engine failures that occur during flight above 76 KIAS explains the proper procedure to identify an inoperative engine. It also states that the operative engine has to be readjusted to attain and maintain a required airspeed of 106 KIAS. An engine restart may be attempted if there is sufficient altitude once the inoperative engine has been identified and the operative engine adjusted to maintain the 106 KIAS. The emergency procedures section further indicates that if the restart was unsuccessful the pilot should secure the engine using the "Engine Securing Procedure (Feathering Procedure)." Prior to securing (feathering) the inoperative engine the pilot should check to make sure there is a sufficient fuel flow to the engine. If fuel flow is deficient the emergency fuel pumps should be placed in the ON position. If an unsuccessful engine restart occurs, the engine should be secured using the "Engine Securing Procedure (Feathering Procedure)." A landing at the nearest suitable airport as soon as practical is encouraged. TESTS AND RESEARCH The airframe and power plant examinations were conducted at Air Transport in Phoenix on January 5, 2000, under the supervision of a Safety Board investigator. Representatives from New Piper Aircraft, Inc., and Textron Lycoming were parties to the investigation. A functional check of the electrical system of the airplane was conducted. When the electrical system was engaged the continuous duty fuel boost pumps operated with no discrepancies. Neither of the annunciator lights illuminated for the continuous duty boost pumps. The annunciator light test buttons were activated and functioned properly. The boost pump circuit breakers were pulled to disable the boost pumps. The annunciator warning lights illuminated and remained on until the circuit breakers were reset. According to the aircraft manufacturer's pilot's operating handbook (POH), the continuous duty fuel boost pumps are operated continuously and are provided to maintain fuel under pressure to the other fuel pumps. There are no control switches or pressure gages provided for the continuous duty boost pumps. The continuous duty fuel boost pump warning lights illuminate when the fuel boost pump pressure is less than 3 PSI. This informs the pilot that there was a boost pump failure or the pressure had dropped below 3 PSI. According to the POH, the emergency fuel boost pumps should be activated to provide steady fuel pressure. Once the fuel pressure remains steady and above 34 PSI, the emergency fuel boost pumps can be switched to the OFF position. The POH further indicates that the right and left fuel flow warning lights illuminate to warn the pilot of an impending fuel flow interruption. The fuel flow warning lights are located underneath the fuel boost pump warning lights. A sensing probe mounted near each inboard fuel tank outlet activates the fuel flow warning lights. If the fuel level near the tank outlet drops to a point where a fuel flow interruption and power loss could occur, the sensing probe will illuminate its corresponding warning light. A switch located on the overhead panel for the emergency fuel pumps was activated and found to function properly. The fuel systems' cross feed valves were operated. Fuel flowed through the fuel injector nozzles of both engines from the opposite wing fuel tank. The left and right gascolator and fuel injector inlet screens were examined visually. They were clean and free of contaminates. A visual inspection of both engines was conducted with no discrepancies noted. A compression check of the engines was conducted via manual rotation of the respective engine's propellers. Compression was obtained in each cylinder in firing order. No further anomalies were noted. The fuel injector servo's, fuel nozzles, and engine driven fuel pumps were bench tested at Airmotive Carburetor in Burbank, California, on September 25, 2000. There were no discrepancies noted with any of the functional checks. ADDITIONAL INFORMATION The airplane was released to the owner's representative on January 20, 2000. The fuel system and airplane records were returned to the owner on October 30, 2000.
The pilot's failure to follow the manufacturer's published emergency procedures for engine loss of power resulting in a forced landing in an open construction area where the airplane collided with a berm. A related factor was the loss of engine power in the left engine due to fuel starvation.
Source: NTSB Aviation Accident Database
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