Aviation Accident Summaries

Aviation Accident Summary DFW06LA010

Round Rock, TX, USA

Aircraft #1

N978FE

Cessna 208

Analysis

The airplane was fueled with 65-gallons of jet-A in preparation for the evening's flight. The 6,600-hour pilot stated that no abnormalities were noted during the engine start, and takeoff. However; shortly after departure, and after the pilot had leveled off at 7,000-feet, he reported to air traffic control that he had an engine failure and a total power loss. During the descent, the pilot attempted both an air and battery engine restart, but was not successful. The inspection on the engine was conducted on November 30, 2005. The accessory gearbox had a reddish-brown stain visible beneath the fuel pump/fuel control unit. The accessory gearbox was turned; rotation of the drive splines in the fuel pump (splines for the fuel control unit) was not observed. The fuel pump unit was then removed, the area between the fuel pump and accessory gearbox was stained with a reddish brown color. The fuel pump drive splines were worn. Additionally, the internal splines on the fuel pump drive coupling were worn. The wear on the spline drive and coupling prevented full engagement of the spline drives. Both pieces had evidence of fretting, with a reddish brown material present. The airplane had approximately 130 hours since a maintenance inspection (which included inspection of the fuel pump). The engine had accumulated approximately a total time of 9,852 hours, with 5,574 hours since overhaul.

Factual Information

On October 18, 2005, approximately 2315 central daylight time, a single-engine Cessna 208 turbo-prop airplane, N978FE, was substantially damaged during a forced landing after a reported loss of engine power near Round Rock, Texas. The airline transport pilot, sole occupant of the airplane, sustained minor injures. The airplane was registered to Federal Express Corporation, of Memphis, Tennessee, and was being operated by Baron Aviation Services, of Vichy, Missouri. Night visual meteorological conditions prevailed and an instrument flight rules flight plan was filed for the 14 Code of Federal Regulations Part 135 air cargo flight. The cross-country flight originated from the Austin-Bergstrom International Airport (AUS), near Austin, Texas, at 2251, and was destined for the Fort Worth Alliance Airport (AFW), near Fort Worth, Texas. The night cargo flight was a regularly scheduled run between AUS and AFW. Earlier in the day, the airplane was fueled with 65-gallons of Jet-A fuel in preparation of the evening's flight. According to the 6,600-hour airline transport pilot, he preformed a normal pre-flight inspection prior to departure and no abnormalities were noted during the engine start and take-off. However, shortly after departure and after the pilot had leveled-off at 7,000-feet, he reported to air traffic control that he "had an engine failure and a total power loss." During the descent, the pilot attempted both an air and battery engine start; the attempts to restart the engine were not successful. The pilot elected to perform a night forced landing on a road; however, the right wing collided with a utility pole, turning the airplane, which then impacted the ground. The airplane came to rest on its nose, with the top of the airplane leaning against a residential home. There were no reported injuries to anyone in the building. A Federal Aviation Administration (FAA) inspector responded to the accident site and reported the aircraft sustained structural damage to the wings and fuselage. He reported that there was no post-crash fire, and that fuel was found in the left and right wing tanks. The wreckage was recovered from the site and secured at a near-by fixed based operator (FBO) for further investigation. The PT6A-114A engine was removed and shipped to the engine manufacturer's service center in Addison, Texas, for a detailed examination. The inspection on the engine was conducted on November 30, 2005, under the supervision of the NTSB investigator in charge (IIC). On this engine design, the engine fuel pump is bolted to and driven from the accessory gearbox by a spline/spline coupling. The fuel control unit is attached to the fuel pump and driven by a spline arrangement from the fuel pump. Pratt & Whitney's maintenance manual calls for a "in-situ" inspection of this pump every 600 hours by looking for a reddish brown (iron oxide) stain inside the fuel pump drain port. A review of the engine's eminence logs revealed this inspection was completed approximately 130 hours prior to the accident. The engine had accumulated approximately a total time of 9,852 hours, with 5,574 hours since overhaul. The engine had evidence of light external impact damage, the compressor, and power turbine sections were turned by hand; continuity was established through the accessory gearbox. The fuel control unit was removed; the drive spline coupling was intact and the fuel control unit spun freely. With the powerplant removed from the airframe for the inspection and the fuel control unit removed, a reddish-brown stain was visible on the accessory gearbox, originating from the attachment point for the fuel pump/fuel control unit. The accessory gearbox was turned; rotation of the drive splines in the fuel pump (splines for the fuel control unit) was not observed. The fuel pump unit was then removed, the area between the fuel pump and accessory gearbox was stained a reddish brown color. The fuel pump drive splines were found to be worn. Additionally, the internal splines on the fuel pump drive coupling were also worn. The wear on the spline drive and coupling prevented full engagement of the spline drives. Both pieces had evidence of fretting, with a reddish brown material present. At 2253, the automated weather observing system at AUS, reported wind from 190 degrees at 5 knots, 10 statute miles visibility, a clear sky, temperature 68 degrees Fahrenheit, dew point 61 degrees Fahrenheit, and an altimeter setting of 29.98 inches of Mercury.

Probable Cause and Findings

The loss of engine power due to the failure of the engine-driven fuel pump. A contributing factor was the inadequate inspection of the engine driven fuel pump.

 

Source: NTSB Aviation Accident Database

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