History of Flight
On April 16, 2011, about 0900 mountain standard time, a Cessna 172S, registration N1835U, was substantially damaged when it impacted terrain following a touch-and-go landing at Payson Airport (PAN), Payson, Arizona. The certificated private pilot and his passenger were not injured. The instructional flight was operated under 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan had been filed.
The pilot, enrolled in an ab-initio flight training program at Deer Valley Airport (DVT), Phoenix, Arizona, had obtained his private pilot certificate in March 2011 and accumulated about 110 hours of total flight experience. He planned the 50-mile flight from DVT to PAN to build time toward his instrument rating. Before departure, the airplane was topped off with fuel. During descent for landing at PAN, the pilot enriched the mixture from its cruise setting and entered the traffic pattern for a touch-and-go on runway 24, using 30 degrees of flaps. After touchdown, he retracted flaps to 0 degrees, added power, and lifted off.
The pilot stated the airplane underperformed on climbout, so he enriched the mixture. That did not rectify the problem, and he heard the engine make "popping" sounds. Despite full throttle, airspeed was lower than normal, and the tachometer indicated about 1,800 rpm instead of the target 2,300 rpm. The pilot began a right turn back toward the airport and lowered the nose to increase airspeed, but the airplane did not seem to accelerate. He heard the stall warning horn during the attempted turn. The airplane impacted terrain about 3,500 feet from the runway.
Aircraft and Pilot Information
The pilot held a private pilot certificate with approximately 109 total hours, all in the accident airplane make and model. He was enrolled at Westwind School of Aeronautics, a Part 141 flight training organization at DVT. His most recent flight review and first-class FAA medical certificate were completed in March 2011 and December 2010, respectively.
The airplane, manufactured in 1995, was equipped with a Lycoming IO-360 series piston engine, registered to a corporation, and operated and maintained by Westwind School of Aeronautics. Maintenance records showed the most recent annual inspection on February 11, 2011 (tachometer 2,721.5 hours) and the most recent 100-hour inspection on March 30, 2011 (tachometer 2,819.0 hours). Discrepancies in recorded times between the school and maintenance records could not be explained, but examination revealed no items warranting further investigation.
Meteorological and Airport Information
The PAN 0855 automated weather observation reported calm wind, visibility 10 miles, clear skies, temperature 18°C, dew point 16°C, and altimeter setting 30.08 inches of mercury. The pilot received a weather briefing from Lockheed Martin Flight Service for the flight from DVT to PAN.
Deer Valley Airport (DVT), the departure airport, has an elevation of 1,478 feet above mean sea level (msl). Payson Airport (PAN), the destination, has an elevation of 5,157 feet msl. PAN is a non-towered airport with runway 24 dimensions of 5,500 by 75 feet and a traffic pattern altitude of 6,200 feet msl. Based on reported conditions, the density altitude at PAN was calculated to be approximately 6,200 feet.
Wreckage and Examination
First responders and an FAA inspector reported that the airplane impacted trees and terrain about 3,500 feet northwest of the departure end of runway 24, coming to rest upright. There was no debris or ground-scar path, and nearly all surrounding vegetation was undisturbed. The right wing was rotated about 90 degrees tip-forward, and the left wing was bent tip-down about 15 degrees. The fuselage, engine cowling, and both wings were deformed by crush damage. The spinner was crushed, and the two-blade metal propeller exhibited tip curling with chordwise gouges and scoring. The cockpit hour meter registered 3,477.1 hours after the accident. First responders reported the right fuel tank appeared nearly empty with a breached fuel line, and the left tank was about half full. There was no post-accident fire.
A joint NTSB and FAA examination at Air Transport, Phoenix, Arizona, on January 4, 2012, found all observed damage consistent with the airplane impacting the ground in a left spin, with the engine operating at a low power setting. Detailed examination of the engine and components revealed no evidence of preimpact mechanical malfunction that would have precluded normal operation and continued flight.
Organizational Information
The flight school's ab-initio training consisted of private, instrument, and commercial segments. Students cycled through in groups. After the accident, the school implemented a 1-week stand-down for all flying for the accident pilot's class. The school had standard operating procedures in electronic format but not in a single document. The dispatch department handled airplane scheduling and release but did not share in flight preparation or decisions. High density altitude operations were covered in classroom segments, but the school had no specific requirements for actual practice at high density altitude airports. The pilot was not required to obtain approval to fly to a high density altitude airport or to conduct touch-and-go operations there. After the accident, the school prohibited solo operations at high density altitude airports for the accident pilot's class until each received actual training with an instructor, and revised training requirements to ensure future students receive such training.
Additional Information
The Pilot's Operating Handbook (POH) Section 4 (Normal Procedures) included checklist and amplified procedures. The "DESCENT" checklist stated: "Mixture – ADJUST if necessary to make the engine run smoothly." The "BEFORE LANDING" checklist stated: "Mixture Control – RICH." The "BALKED LANDING" checklist contained no mixture reference, but the amplified procedures stated: "Above 3000 feet pressure altitude, lean the mixture to obtain maximum RPM." The "NORMAL TAKEOFF" checklist stated: "Mixture Control – RICH (Above 3000 feet pressure altitude, lean for maximum RPM)."
Several months after the accident, a former flight instructor alleged that other Westwind School of Aeronautics airplanes experienced similar partial-power events. The instructor cited two events during stall demonstrations but did not specify altitudes. The maintenance technician reported that some airplanes were referred for maintenance but no systemic issues were found and problems could not be duplicated; all were test-flown before return to service. The chief pilot stated the cited airplane was examined and no relevant abnormalities were detected, and no systemic issues were noted. The FAA principal maintenance inspector had not heard of these events prior to the allegations.