RADIUM SPRINGS, NM, USA
N47402
PIPER PA-28R-201T
AT 10,000 FT, THE PILOT REPORTED THAT SHE WAS IN LIGHT SNOW. SUBSEQUENTLY, SHE REPORTED THAT SHE HAD LOST THE ATTITUDE INDICATOR, WAS IN IMC, AND '...WE'RE IN TROUBLE.' NO FURTHER TRANSMISSIONS WERE RECEIVED. THE AIRPLANE SUBSEQUENTLY BROKE UP IN FLIGHT. MICROSCOPIC EXAMINATION OF THE WARNING LIGHT BULB FOR THE VACUUM SYSTEM REVEALED A STRETCHED FILAMENT. PITTING AND SCORING WAS NOTED IN THE BASE OF THE VACUUM PUMP CASE. ENERGY DISPERSIVE X-RAY SPECTROSCOPY PRODUCED SPECTRA OF PARTICLES FOUND IN THE VACUUM PUMP REGULATOR VALVE SIMILAR TO THAT OF THE VACUUM PUMP ROTOR AND VANE FRAGMENTS. WITH 2.2 INCHES OF MERCURY DIFFERENTIAL AIR PRESSURE, THE NORMAL TEST PRESSURE, THE ROTOR OF THE ATTITUDE GYRO ASSEMBLY STARTED, BUT THE ROTOR BEARINGS WERE VERY ROUGH. THIS WAS THE PILOT'S FIRST KNOWN FLIGHT IN ACTUAL INSTRUMENT METEOROLOGICAL CONDITIONS.
HISTORY OF FLIGHT: On March 14, 1993, at approximately 1942 mountain standard time, during cruise flight to Las Cruces, New Mexico, a Piper PA 28R 201T, N47402, was destroyed during an inflight breakup. The instrument rated commercial pilot and the one passenger sustained fatal injuries. Instrument meteorological conditions prevailed at the flight altitude for the personal cross country flight. PERSONNEL INFORMATION: A review of pilot records and portions of the logbook by the investigator in charge revealed a total of 105.9 hours of simulated instrument flight as of March 9, 1993. The flight on March 14, 1993, was the first known flight in actual instrument meteorological conditions. AIRCRAFT INFORMATION: The airplane was issued an original airworthiness certificate on September 7, 1977. A review of the Federal Aviation Administration records by the investigator in charge indicated the airplane had been listed as destroyed on September 2, 1983. The airplane was rebuilt and returned to service on November 7, 1987. Aircraft logbooks prior to that date were not available and the installation dates of the vacuum system components could not be determined. Aircraft logbooks reviewed by the investigator in charge revealed that the vacuum suction had been set to 5 inches of mercury at 2,000 revolutions per minute in July, 1992, following installation of a rebuilt directional gyro. Logbook entries indicated that the system was flight checked prior to return to service. On September 11, 1992, logbook entries indicated installation of the Laminar Flow Systems speed enhancement kit contouring the forward sections of the wings with filler material. An engine overhaul was completed on February 17, 1993, and the engine was reinstalled on the airframe on March 8, 1993. The airplane had flown approximately 2.5 hours since the overhaul. METEOROLOGICAL INFORMATION: A review of flight service station data (included as part of this report) by the investigator in charge produced the following information concerning the proposed flight. Albuquerque Flight Service Station provided a standard weather briefing and accepted a flight plan from the pilot of N47402 via telephone at 1725. The proposed flight plan was from Albuquerque, New Mexico to Las Cruces, New Mexico. A review of the air traffic control data (included as part of this report) by the investigator in charge revealed the following information concerning the departure flight. Albuquerque Tower issued the pilot of N47402 the instrument flight clearance at 1823. Following the departure from Albuquerque, New Mexico, the pilot was instructed to maintain 10,000 feet and to contact Albuquerque Center. At 1842, the pilot contacted Albuquerque Center. During the cruise phase of flight the altitude varied from 9,500 feet to 10,400 feet. Beginning at approximately 1935, the controller observed several heading changes made by the airplane. The controller subsequently suggested to the pilot a heading of one four zero degrees for Las Cruces, New Mexico. At approximately 1940, the pilot reported that she had lost the attitude indicator, was in instrument meteorological conditions, and in trouble. Controller contact was lost thirteen miles north of Las Cruces, New Mexico, at 1941:43. Albuquerque Center, Albuquerque Flight Service Station, and New Mexico State Search and Rescue initiated the search for the airplane. A dark night, overcast sky, storms, and rugged terrain hampered the search. On March 15, 1993, at approximately 0615, search teams located the airplane approximately eight miles northwest of Radium Springs, New Mexico. National Weather Service had issued Airmet Zulu for moderate to isolated severe rime icing in clouds from 10,000 to 20,000 feet throughout portions of New Mexico. They had also issued Airmet Tango for moderate to isolated severe turbulence below 15,000 feet in portions of New Mexico. At approximately 1907 the pilot had reported to the controller that the airplane was picking up a little light snow. The pilot of an aircraft in the flight area at 11,000 feet was vectored by air traffic control to the last radar position of N47402 and monitored 121.5. That pilot reported flying below an overcast and encountering a cloud and some light rain with an outside air temperature of eight degrees Centigrade. COMMUNICATIONS: A review of the air traffic data by the investigator in charge revealed the following summary of transmissions between the controller and the pilot. All times have been converted to mountain standard time. 1933:00 Pilot was given the El Paso altimeter setting two niner niner three and requested to report Las Cruces in sight for a visual. 1935:14 Pilot reported to the controller that she had a visual and would descend. 1935:18 The pilot was asked by the controller if she was cancelling IFR and the pilot responded negative. She further stated that she had some lights at Las Cruces and was going to descend to 8,500 feet. 1935:27 The controller advised the pilot to maintain 10,000 feet and that he showed the aircraft heading of about 265 toward Hatch, New Mexico. He further told the pilot that Las Cruces was a bearing of about 148. 1935:47 The pilot advised that she would remain at 10,000 feet. 1937:56 The controller suggested a heading of 140 for Las Cruces. 1940:17 The pilot reported receiving the Las Cruces NDB and was cleared direct to the beacon. 1940:22 The pilot reported that she had lost the attitude indicator. 1940:33 The pilot reported being in instrument meteorological conditions. 1940:58 The pilot reported that she was in trouble. 1941:43 Radar contact was lost on the Las Cruces 325 bearing at 16 miles. WRECKAGE AND IMPACT INFORMATION: The airplane fuselage, engine, and propeller assembly came to rest on a measure heading of 340 degrees approximately 100 feet below the top of the Northern slope of a canyon at an estimated elevation of 4,800 feet. The canyon was approximately 1/2 mile wide and each side of the canyon sloped approximately 12 degrees. Crush lines along the propeller hub and lower fuselage skin measured approximately 10 degrees. Airplane wings came to rest approximately 300 feet below the top of the Southern slope of the canyon. The right wing rested on the leading edge of the wing with the main gear extending to the ground. The top surface of the right wing from the spar area to the leading edge was covered with filler. The left wing came to rest on the upper surface with the main gear in the wheel well. Leading edge crushing and buckling was observed on the left wing. Numerous pieces of paint and wing filler were observed along a ground scar approximately the length of the leading edge of the left wing. A red left wing navigation lens was crushed on a rock at the end of the ground scar. Wing spars exhibited positive overloads with torsional twisting. Upper surfaces of both wings showed compression, tension, and buckling. Left wing fuel tank integrity was compromised. There was physical evidence of fuel in the area. Fuel remaining in the right wing was estimated as ten gallons. The right wing fuel tank had been compromised near the aft edge of the tank. Empennage components came to rest on the top of the Southern slope of the canyon. The vertical stabilizer exhibited positive overloads and bending to the left. The right and left portions of the horizontal stabilizer spar showed positive and negative overloads. The engine was intact with impact damage to the right side. Cylinder heads one, three, and five had impact damage. The crankshaft had separated aft of the propeller attachment flange and the oil sump was crushed. Both magnetos were separated from the engine. The diaphragm of the fuel manifold was intact, the fuel screen was clean, and fuel was found in the interior. The vacuum pump remained attached to the engine and all vacuum pump connections and hoses were attached. Scoring was noted on both sides of the propeller blades. Both propeller blades were bent. MEDICAL AND PATHOLOGICAL INFORMATION: An autopsy on the pilot was performed by The University of New Mexico, located in Albuquerque, New mexico. TEST AND RESEARCH: The vacuum system components were examined; the vacuum pump drive shaft was intact, three of the vanes were separated into several pieces, pitting and scoring was noted along the edges of the vanes, scoring was observed in the base of the vane case, and black particles were found in the vacuum regulator valve. The annunciator vacuum warning light bulb filament was observed stretched when examined utilizing 30X magnification. Filters for the vacuum lines and the regulator valve did not show any debris that would have affected the system operation. The vacuum pump, regulator valve, warning light bulb, and the attitude indicator were sent to the NTSB metallurgical lab for further examination. The metallurgical laboratory report revealed the information in this paragraph and that report is included. Binocular examination of the vacuum system light bulb revealed the filament was stretched. Energy dispersive x ray spectroscopy of the vacuum pump rotor, vane fragments, and numerous particles located within the vacuum pump regulator produced spectra containing high peaks of carbon. The attitude gyroscope assembly was pressurized causing the internal components to rotate. The attitude qyroscope was forwarded to Sigma Tek, Inc. for operating specifications evaluation. Prior to disassembly, the gyro rotor was started. With 2.2 inches of mercury differential air pressure, the normal test pressure, the rotor started but the rotor bearings were rough. During disassembly there were no scrape marks found on the rotor assembly nor the rotor housing. ADDITIONAL DATA: The airplane was released to the owner's representative following the investigation.
A TOTAL FAILURE OF THE AIRPLANE'S VACUUM SYSTEM. FACTORS WHICH CONTRIBUTED TO THE ACCIDENT WERE: THE DARK NIGHT, SNOW, THE PILOT'S LOSS OF AIRCRAFT CONTROL, AND THE PILOT'S LACK OF EXPERIENCE IN FLYING IN ACTUAL INTRUMENT METEOROLOGICAL CONDITIONS.
Source: NTSB Aviation Accident Database
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