MONUMENT VALLEY, UT, USA
N73780
Cessna T207A
The takeoff for the sightseeing flight seemed normal until approximately 500 feet agl. The pilot observed the airspeed decreasing and the manifold pressure drop from 36.5 inches to 23 inches. He turned the auxiliary fuel pump on and was unable to restart the engine. He performed a forced landing in rough, sandy terrain. Postcrash examination of the airplane revealed that the upper induction tube, which conducted compressed turbocharger intake air to the throttle body, was found separated at a rubber connecting sleeve approximately 10 inches prior to the throttle body. Scenic Airlines maintenance personnel had installed a remanufactured zero time engine on July 30, 1996. The T207A Information Manual did not provide abnormal operating procedures for continued engine operation following turbocharger failure. There is no current FAA requirement to include information regarding the proper operation of an airplane by the aircraft manufacturer in the event of a loss of compressed induction air while flying a turbocharged airplane.
HISTORY OF FLIGHT On March 24, 1998, approximately 1500 mountain standard time, a Cessna T207A, N73780, was substantially damaged during a forced landing following a loss of engine power shortly after takeoff from Monument Valley Airport Monument, Utah. The commercial pilot and two passengers received minor injuries; however, three passengers received serious injuries. The airplane was being operated by Scenic Airlines, Inc., of Page, Arizona, under Title 14 CFR Part 135. Visual meteorological conditions prevailed for the cross-country sightseeing flight which originated approximately 5 minutes before the accident. A company VFR flight plan had been filed with a destination of Page, Arizona. According to the pilot, after departing runway 34, "everything seemed normal until approximately 500 feet [agl]." He observed the airspeed decreasing; he pitched the nose down to gain airspeed; he did not hear or feel anything unusual. Simultaneously, he noticed the manifold pressure had dropped from 36.5 inches to 23 inches. He applied full throttle and turned the auxiliary fuel pump on. He switched the fuel selector to the left tank, and applied full fuel mixture. Unable to restart the engine, he notified his passengers to prepare for an emergency, and he performed a forced landing to soft, sandy terrain. The airplane landed on its three fixed landing gear, nosed over, and became airborne again. The airplane tumbled inverted while in the air and came to rest inverted tail forward. PERSONNEL INFORMATION The pilot was hired by Scenic Airlines, Inc. on March 11, 1998. On the same day he, successfully passed his FAA check ride for his multi-engine airplane rating (which was a prerequisite for employment). During the month of February, the pilot had received 45 hours of ground training from Scenic Airlines using an FAA approved FAR Part 135 company ground training program (see attached company training documentation form). Company documents indicate that on March 11, 1998 the pilot was given FAR Part 135 check rides in the Cessna 210 and the Cessna T207A. On the morning of the accident, the pilot took two additional FAR Part 135 check rides in the Cessna 182 and the Cessna 172. At the time of the accident, the pilot had accumulated a total of 1,342 flight hours. He reported to the Investigator-In-Charge (IIC) that approximately 27 hours of this flight experience was in turbocharged airplanes, 13 hours in Cessna T207s, and 15 hours in Cessna T210s. AIRCRAFT INFORMATION The accident airplane was manufactured by the Cessna Aircraft Company in 1980 and had accumulated 10,511 hours of flight time. The airplane's remanufactured Teledyne Continental TSIO-520-M engine was installed by Scenic Airlines maintenance personnel on July 30, 1996. According to company maintenance records, the airplane received its last 100-hour inspection on March 16, 1998. METEOROLOGICAL INFORMATION Blanding, Utah (51 nm northeast of Monument Valley), reported weather at 1357: wind 180 degrees at 10 knots; scattered clouds at 8,000 and 14,000 feet; temperature 21 degrees C. (70 degrees F.); dew point -2 degrees C. (28 degrees F.); and remarks, sea level pressure 1008.8 millibars of mercury. Another Scenic Airlines pilot who witnessed the accident reported that "runway 34 departure wind was a left quartering tailwind, 5 to 10 knots." The density altitude at the time of the accident was computed to be 7,101 feet. AERODROME INFORMATION Monument Valley Airport (71V) elevation 5,192 feet msl is a private uncontrolled airstrip which has an elevation of 5,192 feet and is located in Monument Valley, Utah. The airplane departed runway 34 (4,000 feet x 75 feet), which was half asphalt and half dirt. WRECKAGE AND IMPACT INFORMATION The airplane came to rest inverted 324 degrees for 1.32 nm from the departure end of runway 34 (37 degrees 08.248 minutes north latitude, 110 degrees 12.696 minutes west longitude). The topography was flat, 70 percent covered with bushes, and sandy, with surrounding mountainous terrain. The longitudinal axis of the airplane was oriented 158 degrees. All major airplane components were located either on the airplane or at the initial touchdown point, and all control cables to the engine and the flight control surfaces demonstrated continuity. Three ground scars were observed beginning 161 feet prior to the aircraft's final resting point (see attached wreckage diagram.) The "chin" of the airplane was crushed aft on a 45 degree angle, the engine was displaced aft into the firewall, and the propeller spinner was found nearly undamaged (see attached photographs). The nose landing gear separated from the airplane and was found at the northwest end of the center ground scar. Oil streaks were noted on the bottom of the airplane fuselage (see attached operator's maintenance letter.) The turbocharger oil supply line was found separated approximately 1 inch above the inlet fitting on the main bearing of the turbocharger. No splattered oil was identified in the area surrounding the supply line separation. The upper induction tube, which carries compressed turbocharger intake air to the throttle body, was found separated at a rubber connecting sleeve approximately 10 inches prior to the throttle body. The airplane's flaps were retracted. TESTS AND RESEARCH The turbocharger was examined at the facilities of Air Transport in Phoenix, Arizona, on April 7, 1998, and again at AlliedSignal Automotive in Torrance, California, on May 5, 1998. No structural or functional discrepancies were noted. The engine was removed from the airplane, boxed, and shipped to Teledyne Continental Motors in Mobile, Alabama. On July 24, 1998, the engine was test run. No structural or functional discrepancies were noted. According to the engine manufacturer's representative, in the event of cessation of turbocharged compressed air, the engine will continue to operate with reduced performance characteristics comparable to that of a normally aspirated engine. Its power output is dependent on the density altitude and leaning procedures used by the pilot. According to an FAA inspector, who experienced compressed induction air failure on three separate occasions in the turbocharged Cessna T207s (with similar density altitudes and weight characteristics as the accident airplane), his aviation experience taught him to lean the mixture out and "carefully fly the airplane." He further stated that he had never seen anything in writing in airplane information manuals or other literature which would give a pilot guidance on how to operate a turbocharged engine if compressed induction air was compromised. A review of several airplane information manuals from different makes and models of turbocharged airplanes (including the C-T207), as well as other available literature from manufacturers and the FAA, indicated a lack of guidance to pilots regarding the continued operation of turbocharged engines when compressed induction air was either reduced or non existent due to a malfunction or failure of the turbocharging system. Although the aircraft manufacturer produces the airplane Information Manual (or Operating Handbook), which includes the emergency procedures and abnormal operating procedures, the FAA must approve these manuals for the aircraft to be airworthy. Based on information from the aircraft and engine manufacturers, there is no current FAA requirement to include information regarding the proper operation of an airplane in the event of a loss of compressed induction air while flying a turbocharged airplane. ADDITIONAL DATA In addition to the Federal Aviation Administration, parties to the investigation included Cessna Aircraft Corporation, Teledyne Continental Motors, AlliedSignal Aerospace, and Scenic Airlines, Inc. The airplane was released to the owner, Scenic Airlines, Inc., on July 14, 1998. No parts were retained.
The engine's total power loss due to the induction air ducting separating because of inadequate maintenance by company personnel. Factors were the failure of the manufacturer to provide non-standard operating procedures in their airplane's information manual, and the failure of the FAA to require non-standard operating procedures in the manufacturer's airplane information manual; and the soft, sandy, unsuitable terrain on which to perform a forced landing.
Source: NTSB Aviation Accident Database
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