Accident
On January 5, 2008, at 1545 eastern standard time, a Cessna R172K, registration N758FQ, operated by a private pilot, collided with a fence and trees during a forced landing near Spotsylvania, Virginia. The personal flight was conducted under Title 14 Code of Federal Regulations Part 91 on an instrument flight rules flight plan. Visual meteorological conditions prevailed. The pilot reported minor injuries, and the airplane sustained substantial damage.
The flight departed from Manassas Regional/Harry P. Davis Field, Manassas, Virginia, at 1520 and was en route to Newport News/Williamsburg International Airport, Newport News, Virginia.
Pilot Actions and Forced Landing
The pilot stated that after approximately 30 minutes of cruise flight at 5,000 feet, the engine began to run roughly. Shortly thereafter, he detected fuel fumes and informed Potomac Approach Control that he needed to land. The controller advised that the nearest airport was 12 miles on a heading of 280 degrees. The pilot observed an open field and initiated a forced landing. The engine stopped less than a minute after his transmission. The pilot did not attempt to restart the engine, citing sufficient fuel and a strong fuel odor in the cabin. He landed long, about halfway down the field at approximately 90 knots, rolled through a fence, and into trees.
Investigation Findings
Examination of the forced landing area by the Federal Aviation Administration and parties to the investigation revealed an open field oriented east-west, 1,050 feet long with a down slope. The airplane struck a low barbed wire fence post 3 to 4 feet tall, 900 feet from the approach end. Three landing gear imprints were found 70 feet beyond the post. The aircraft continued 80 feet forward, struck trees, and came to rest 50 feet beyond the far end. The total distance from the start of the forced landing area to the resting point was 1,100 feet.
The Cessna R172K Information Manual, Figure 5-10, indicates a landing roll distance of 610 feet at a gross weight of 2,650 pounds at 63 knots with a temperature of 10 degrees Celsius. Section 3 emergency procedures for an engine-out landing recommend an airspeed of 70 KIAS (flaps up) or 65 KIAS (flaps down), full flaps, touchdown slightly tail low, and heavy braking.
Aircraft and Engine Examination
The wreckage was recovered to a facility in Fredericksburg, Virginia. Examination of the airframe and flight controls found no pre-crash mechanical failure. The fuselage was compromised aft of the baggage compartment; the left wing was displaced forward, and the left flap was buckled, blocking the left cabin door. The fuel selector valve was in the "both" position. The left main fuel tank was intact with fuel present; the right wing separated from the airframe, and the right main fuel tank was ruptured. The flaps were extended 10 degrees.
Upper spark plugs exhibited sooty dark deposits. The oil cap and dipstick were intact, indicating about 1/8 inch of oil. Cylinder borescope inspection showed light gray deposits. The No. 2 piston was near the top of the barrel and would not move during crankshaft rotation. The engine was disassembled at Teledyne Continental Motors, revealing the No. 2 connecting rod cap separated from the rod and metallic particles in the oil sump. The No. 4 top spark plug insulator was cracked, and the No. 4 piston showed burn-through erosion consistent with a pre-ignition/detonation event that allowed excessive crankcase pressure, evacuating oil through the breather and leading to failure of the No. 2 connecting rod cap and loss of engine power. The piston skirt, rings, pin, and plug exhibited scoring, thermal damage, or mechanical damage.
Maintenance History
According to logbooks, the most recent annual inspection was completed on March 29, 2007, at which time the engine had accumulated 1,538.5 hours since overhaul. The pilot reported an additional 54.4 hours of operation since that inspection.