CEN12FA164

The loss of flight instrumentation due to a failed vacuum pump while flying a night without a discernable horizon, which resulted in the pilot's spatial disorientation and an in-flight loss of control and impact with terrain. Contributing was the continued operation of the airplane with a recalled and unsafe vacuum pump.

After leveling at a cruise altitude of 9,500 feet mean sea level the pilot reported that he had lost instrument suction and his attitude indicator. Radar data showed that the airplane made a climbing right turn and then descended rapidly. Radar and radio contact were lost and the wreckage was found the next morning. Ground and airplane impact signatures showed evidence of a nearly vertical nose down collision with terrain. Other pilots in the area reported a reduction in visibility with blowing dust, which severely restricted visibility and resulted in the loss of a visible horizon. The manufacturer of the vacuum pump had issued a service letter 4 years earlier that indicated that the pump was beyond its mandatory replacement time and must be removed from service. A postaccident examination revealed that the vacuum pump had a preimpact failure that resulted in the loss of all vacuum driven flight instruments. It is likely that the pilot inadvertently encountered instrument meteorological conditions (IMC) with reduced visibility and the lack of a visible horizon. The airplane's subsequent turning ground track and rapid, near-vertical descent are consistent with the pilot's loss of control of the airplane because of spatial disorientation following the loss of flight instrumentation while flying at night without a discernable horizon. According to FAA Advisory Circular 60-4A "Pilot's Spatial Disorientation," "Surface references and the natural horizon may at times become obscured, although visibility may be above visual flight rule minimums. Lack of natural horizon or surface reference is common on over-water flights, at night, and especially at night in extremely sparsely populated areas or in low visibility conditions. A sloping cloud formation, an obscured horizon, a dark scene spread with ground lights and stars, and certain geometric patterns of ground lights can provide inaccurate visual information for aligning the aircraft correctly with the actual horizon. The disoriented pilot may place the aircraft in a dangerous attitude."

HISTORY OF FLIGHT On February 20, 2012, about 1936 central standard time, a Piper PA-24-250 single-engine airplane, N7147P, impacted terrain near Albany, Texas. The private pilot and passenger were fatally injured. The airplane was substantially damaged. The airplane was registered to Baga Air, Inc., and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Dark night visual meteorological conditions prevailed and no flight plan was filed. The flight departed Abilene Regional Airport (ABI), Abilene, Texas, at 1920, and was destined for the University of Oklahoma Westheimer Airport (OUN), Norman, Oklahoma. The airplane had climbed to cruise altitude and was level at 9,500 feet mean sea level (msl). About three minutes later the pilot made a radio call that he needed to return to ABI because he had lost suction and his attitude indicator. The controller cleared the airplane to return to ABI. Radar data showed the airplane made a climbing turn to the right and the airplane then descended rapidly. Radar and radio contact was lost about 1936. The wreckage was found the next morning. Ground and airplane impact signatures showed evidence of a nearly vertical nose down collision with terrain. The outboard section of the right wing and the right aileron were found about one mile southeast from the main wreckage. PERSONNEL INFORMATION The pilot, age 48, held a private pilot certificate with a rating for airplane single land which was initially issued on April 10, 2007. He was most recently issued a third class airman medical certificate, with limitations, on May 10, 2010. The pilot's logbook showed entries beginning on June 7, 1994, with the last entry on February 1, 2012. An endorsement showed a flight review was completed on July 25, 2011, and a high-performance endorsement was entered on December 4, 2008. A review of the logbook showed that that pilot had logged 502.0 hours of total flight experience in single engine airplanes, with about 186 hours of flight experience in Piper PA-24 airplanes. The pilot had logged 68.0 hours of night flight experience. During the previous 15 flights logged between ABI and OUN, 12 of the flights were logged as night flights. The pilot had logged a total 3.6 hours of flight instruction in simulated instrument conditions. The logbook did not contain a listing of any instrument flights more recently than December 31, 2006. AIRCRAFT INFORMATION The four-seat, low-wing, retractable landing gear, single engine airplane, serial number (s/n) 24-2312, was manufactured in 1960. It was equipped with a 250-horsepower Lycoming model O-540-E4B5 engine, s/n L-20394-40A, which drove a Hartzell, model HC-C3YR-1RF, 3-blade metal alloy propeller, s/n DY-4365-A. A review of the airframe logbooks and engine logbooks showed an entry dated July 4, 2011, which certified that an annual inspection had been completed at 4,800.1 total aircraft hours. The most recent airframe logbook entry was made on December 15, 2011, at an aircraft total time of 4854.4 hours, when engine, s/n L-20394-40A, was installed on the accident airplane. At that time, the engine had accumulated 2794.8 hours, with 636.8 hours since its most recent overhaul. Engine logbook entries showed that engine, s/n L-20394-40A had previously been installed on N33033, a Piper PA-32-260 airplane, until N33033 was damaged by a hurricane about October 19, 2005. The damaged airplane was later sold as scrap. Maintenance records for N33033 showed that an overhauled vacuum pump, Airborne part number 211CC, s/n 1706, which was overhauled on December 16, 1999, was installed on engine serial number L-20394-40A on January 21, 2000. There were no other airframe logbook entries or engine logbook entries for N33033 which mentioned a vacuum pump. Based on a review of the maintenance records for N33033 and the engine logbook entries, the total hours of operation of vacuum pump, s/n 1706, were estimated as about 636 hours, for the period from January 21, 2000 until October 19, 2005 At the time of the accident N7147P had been operated an additional 3.2 hours following the engine installation on December 15, 2011. This estimate was based on a review of the pilot's logbook which showed a flight of 1.4 hours on January 29, 2012, a flight of 1.5 hours on February 1, 2012, and an estimated 0.3 hours of operation during the accident flight on February 20, 2014. At the time of the accident the airplane had an estimated aircraft total time of 4857.6 hours, and vacuum pump, s/n 1706, had been operated for more than 12 calendar years and an estimated total of about 639 hours since overhaul. The accident airplane was also equipped with an S-TEC System 60 two axis autopilot with an optional electric pitch trim actuator, and a vacuum driven attitude gyro and vacuum driven directional gyro. METEOROLOGICAL INFORMATION At 1852, the automated weather observation station at ABI reported wind from 300 degrees at 12 knots, visibility 3 miles in haze and blowing dust, skies clear below 12,000 feet, temperature 14 degrees Celsius (C), dew point temperature -11 degrees C, altimeter 30.03 inches of Mercury. Data from the United States Naval Observatory indicated that Sunset occurred at 1827, and Moonset occurred at 1734. At the time of the accident both the Sun and the Moon were more than 14 degrees below the horizon and provided no illumination. A pilot report in the general area showed the reported cloud tops were as high as 12,000 feet msl with the dust tops to 12,000 feet msl. A pilot operating his aircraft in the vicinity indicated that flight visibility was marginal at best, and indicated that the area was impacted with blowing dust with an estimated in-flight visibility of 1 to 3 miles. The pilot indicated that he could only faintly see ground lights, but at times could not distinguish between ground and sky. A medical helicopter pilot operating in the area at the time of the accident reported that he was operating with his night vision goggles due to the dark nighttime conditions, and that even with the night vision goggles the dust and lack of surface lights restricted his view of any sense of horizon and made flying under visual meteorological conditions very difficult. COMMUNICATIONS AND RADAR Following is a timeline of selected communications between the pilot of N7147P and Federal Aviation Administration (FAA) Air Traffic Control (ATC). A summary of the FAA ATC radar contacts is included. 1920: the controller cleared N7147P cleared for takeoff from runway 35L at ABI 1921:31: N7147P reported he was at 2,600 feet and was climbing to 9,500 feet 1931:38: radar showed N7147P was at a transponder reported altitude of 9,500 feet 1933:49: radar showed N7147P was at a transponder reported altitude of 9,700 feet and began a slight change in flight track to the right. 1933:55: N7147P requested to return to Abilene 1934:04: N7149P reported "we've lost our suction and our attitude indicator" 1934:20: the controller responded and gave clearance to return to Abilene 1934:52: radar showed that N7147P's rate of right turn increased. 1935:10: radar showed that N7147P was at 9,300 feet and the remainder of the radar returns showed an erratic flight path 1935:30: radar showed N7147P was at a transponder reported altitude of 10,300 feet, and it then began descending 1935:38: the controller asked N7149P to verify that he was "VFR" 1935:43: N7147P reported "affirmative we are v f r but we are having trouble four seven …" (there was a change in the sense of urgency noted in the voice of the pilot and the end of the transmission was cut off) 1935:46: the controller responded giving the location of the nearest airport, however there were no further communications received from N7147P 1936:14: radar showed N7147P was at a transponder reported altitude