Introduction
On September 28, 2012, about 1715 Pacific daylight time, a Cessna 152, registration N95840, was substantially damaged during a forced off-airport landing near Eugene, Oregon, following a complete loss of engine power during cruise flight. Both the certificated flight instructor and the student pilot sustained minor injuries. The instructional flight was conducted under 14 CFR Part 91 in visual meteorological conditions. No flight plan was filed with the FAA.
Flight History
The airplane was based at Mahlon Sweet Field Airport (EUG) and operated by Lane Community College. The CFI was providing primary instruction to a student with about 2 hours of total flight experience. After departing EUG, the flight conducted basic airwork several miles south of the airport. About 0.6 to 0.7 hours into the flight, while returning to EUG and approximately 10 miles south of the airport, the engine sputtered and rpm dropped to about 1,900. The CFI took control, verified fuel selector and throttle positions, and applied carburetor heat. The rpm continued to decrease, and after 2 to 3 minutes, the engine lost all power. The CFI declared an emergency and selected a field for landing. While approaching the field, the CFI turned right to avoid powerlines, the airplane partially stalled, landed hard, bounced, touched down again, and struck a ditch, coming to rest about 100 feet beyond. Both occupants exited unassisted.
Aircraft Information
The 1985 Cessna 152 was powered by a Lycoming O-235 series engine. Total airframe time was 10,098 hours; engine time since overhaul was 1,025 hours. The airplane had dual wing fuel tanks with a total usable capacity of 24.5 gallons. The fuel selector had ON and OFF positions, and electric fuel quantity gauges were installed. The airplane was maintained under a progressive inspection program; the most recent inspection was completed on July 18, 2012. Approximately 6 weeks prior, a new exhaust riser and overhauled carburetor were installed.
Wreckage and Impact
The airplane came to rest upright in a grassy field about 8 miles southwest of EUG. The right main landing gear separated, the nose gear collapsed, and the engine cowling and mount were damaged. Propeller damage was consistent with the engine not developing power at impact. The right wing was partially separated at the root, but neither wing tank was breached. No fuel lines were disrupted. The aft fuselage sustained significant fracture and buckling damage. No fire occurred. An individual who falsely identified as a mechanic accessed the aircraft multiple times despite instructions from law enforcement; the investigation could not determine what changes, if any, were made.
Fuel and Maintenance Findings
Post-impact examinations revealed very little fuel. Recovery personnel found the left tank empty and collected about 1.5 gallons from the right tank and fuel lines. The fuel line between the gascolator and carburetor was undisturbed and contained no fuel; the gascolator bowl was empty and uncontaminated. The wing flaps were found retracted, but the cockpit handle was near the full-down position; impact damage disrupted the indicator mechanism. The investigation could not determine when the master electrical switch was turned off.
Evidence suggested substandard maintenance. The FAA inspector noted debris and corrosion inside the airplane, putty protruding from the gascolator fitting threads, and a significant crack in the exhaust clamp. The crack was approximately 1.5 inches and deemed not recent.
Operational Context
LCC procedures required pilots to calculate remaining fuel using the most pessimistic consumption rate (6.1 gph for the Cessna 152) and confirm via fuel gauges and visual tank inspection. The Director stated that the accident CFI had checked the tanks and estimated 12 gallons of fuel based on Hobbs time from full tanks, and noted gauges at just below half. The CFI's first flight of the day had lasted 1.1 hours from full tanks; a second flight of 1.4 hours followed without refueling. The accident flight ended after 0.7 hours. The Director noted that an appreciable amount of fuel was seen leaking from the cowling after the crash, raising the possibility of in-flight leakage, but first responders did not detect fuel or odor at the site.
Summary
The investigation found no pre-impact mechanical failures that would have precluded continued operation. The engine could be rotated by hand. The loss of engine power occurred in conditions conducive to carburetor icing at glide and cruise power, but the relative humidity was 32 percent. The NTSB did not state a probable cause for this accident.