Accident Overview
On August 31, 2012, about 1145 eastern daylight time, a Cessna 172M, registration N391R, landed short of the intended runway during a precautionary landing at Flying Dollar Airport in Canadensis, Pennsylvania. The airplane, registered to and operated by a private individual, was on a personal flight from Princeton Airport (39N) in Princeton/Rocky Hill, New Jersey, to Cherry Ridge Airport (N30) in Honesdale, Pennsylvania. Visual meteorological conditions prevailed, and VFR flight following was being provided. The flight originated from 39N about 1110. The airplane sustained substantial damage; the private pilot, one passenger, and a dog were not injured.
Pilot Actions
The pilot reported that the purpose of the flight was pleasure, with an estimated flight time of 52 minutes. He performed a preflight inspection using a checklist, including fuel quantity checks with a dipstick and checking for contaminants. The left tank contained about 10 gallons of 100LL fuel, the right tank about 12 gallons. Engine oil was checked at 6.1 quarts, and 1.0 quart was added. An engine run-up including magneto checks showed each magneto drop about 50 rpm.
The flight departed with the fuel selector on both, climbed to 4,500 feet, and proceeded north. After about 5 to 10 minutes, the pilot reduced throttle and leaned the fuel mixture until rough, then enriched it. Later, the engine sound changed, described as a cylinder not firing, with significant vibration. He performed emergency procedures: verified primer in and locked, fuel selector on both, mixture full rich, checked magnetos (engine ran on left, right, and both), and added carburetor heat, but no correction occurred.
Declaring PAN PAN PAN, the controller vectored the flight to 8N4. The flight was about 6.5 miles east and 3,000 feet above field elevation. With partial power, the controller advised runway 02/20 orientation. Wind favored runway 20, so he continued, minimizing altitude loss. Vibration increased with decreased rpm, so he set power midrange. He flew left base to final for runway 20 (2,405-foot grass strip), performed an aggressive forward slip with no flaps due to being high. The airplane touched down fast, bounced, and he added power to correct. Near the runway end and a terrain drop, he executed a go-around. He made a 180-degree turn to land on runway 02. On final approach, the plane was 10 to 15 feet below runway altitude. He pulled back on the yoke, and while flying at 40 mph, impacted 45-degree upsloping terrain. The airplane nosed over; all occupants exited. The pilot noted the engine never quit nor the propeller stop.
Postaccident, the pilot re-examined the airport and noted runway 20 is downsloping. The airport owner indicated landings are usually on runway 02 due to the downslope.
Postaccident Examination
An FAA airworthiness inspector examined the airplane and engine after recovery. Adequate fuel remained with no contamination; the fuel strainer contained fuel. Engine inspection showed crankshaft, camshaft, and valve train continuity; no stuck valves. Hand rotation revealed no detectable compression at No. 4 cylinder (leakage past exhaust valve). Magnetos were tightly installed and properly timed; however, one magneto “had very little spark” during hand rotation. Bottom spark plugs were oil-soaked. Fuel and air induction systems were satisfactory. The pilot reported having to lean the fuel/air ratio to burn off carbon from the spark plugs.