20121106024669A

On November 6, 2012 at approximately 1842 UTC, N21391, a Cessna 172, depart the modesto city airport (kmod) with two people on board. The aircraft was piloted by a private pilot with 520 hours or flight experience. Another person occupied the right seat of the aircraft and was on board to take pictures for his photography business. The passenger has a commercial pilot certificate but has not flown using his certificate for some time because of medical eligibility issues. The aircraft departed with full fuel and no reported discrepencies on board. This was the first flight after the aircraft had been returned to service following its 100 hour maintenance inspection. The pilot operated the aircraft at 1200' for the entire flight. While the aircraft was orbiting the orchard for photography work, the pilot had the airplane at 1700RPM with the carburator heat on and was flying at approximately 80 knots. The photographer asked for a higher altitude to take one more photo. The pilot pitched the airplane for a climb and added throttle. The pilot says she got no power from the throttle change and witnessed the RPM drop. She tried various power settings confirmed the mixture was rich, and tried the carburator heat off and on. She visually checked the magnetos, and engine gauges but observed no other abnormal indications. With the engine producing no power the pilot began emergency landing procedures and selected the alfalfa field. During the descent the pilot says she used 10% of flaps and the photographer observed full flaps. While at the scene I didn't see an indication that flaps were used, but the lever may have moved during the landing causing flap retraction. During descent the photographer says the propeller was still turning. The pilot does not recall if the propeller was turning during the descent. Propeller damage suggests the propeller was not producing power but may have been windmilling. The pilot says that on the descent she had the elevator all the way back and needed the photographers help to pull the elevator full aft. The photographer says he did not assist with the elevator input. Both occupants agree that somewhere between 8 and 15 feet the airplanes nose dropped and struck the ground . The full aft controls and nose dropping near the ground indicate a full stall before touchdown. Approximately 40 gallons of fuel were drained from the wing tanks during post crash inspection and recovery. We disconnected the throttle cable and pumped fuel from the carburator bowl using the accelerater pump. Inspection of the throttle cable revealed a frayed throttle cable outer housing/casing. Rapid movement of the throttle cable made it curl rather than push the throttle lever on the carburator. We also noticed the starter was engaged and had not disengaged from the flywheel. This may have been associated with the ground impact. The pilot says she did not touch the key, she only visually verified it was on both. The aircraft was moved to modesto aviation's hanger located on the modest airport. Further engine inspection done on 11/07/2012 by airworthiness inspector ghs revealed no damage to the carburator. The bowl, float, filter and butterly were clean and operational. The spark plugs had oil residue on them from the engine being inverted, but they appeared to be clean and were operating correctly.