Accident Summary
The airplane experienced a complete loss of power from the left engine approximately 20 minutes into a flight that had departed at maximum gross weight and climbed to 9,500 feet mean sea level. The pilot heard a loud "pop" and the left engine surged once. After turning back toward lower terrain, the pilot attempted to restore power per checklist items but was unsuccessful, then completed the shutdown and feather checklists. While heading to the closest airstrip, the airplane could not maintain altitude at best single-engine rate of climb airspeed and began to drift down. The pilot determined he lacked sufficient altitude to reach any nearby airstrip or clear mountainous terrain, and elected to land on a beach at a recreation lake. During the landing rollout, the aircraft encountered moderately sized rocks, collapsing the nose and left landing gear.
Engine Examination
The left engine was removed and installed on a test stand. The only discrepancy found was a fractured fuel injector line for the No. 6 cylinder injector nozzle. The fracture was completely through the line near the manifold end at a brazed joint between the line and a larger diameter ferrule. No support clamps were observed on this line between the manifold and the injector nozzle, while support clamps were present on the injector lines to the remaining five cylinders. After replacing the fractured line with a serviceable line, the engine was started, accelerated to full power, and met all specifications.
Metallurgical examination of the fractured fuel injector line revealed fatigue failure from multiple origin sites on the line's outer surface. No material defects or mechanical damage were found at any origin site that could have contributed to crack initiation. No evidence of clamps was found along any point on the line length.
Maintenance History and Compliance
Airworthiness Directive (AD) 93-02-05 applied to this engine and mandated compliance with Lycoming Service Bulletin (SB) 342A. The provisions require a one-time inspection and recurring inspections of the fuel injector lines at each 100-hour inspection, at each overhaul, and after any maintenance where lines were disconnected, moved, or loosened. The line inspection involves checking for cracks, dents, or other unserviceable wear indicators. The SB requires that any line found without clamps supporting the line run must be replaced, and that each line must be clamped, with specific clamping points noted on a diagram for each engine model. The engine was last inspected on July 14, 2000, 23 hours prior to the accident.
Operational Factors
The fuel injection system on this engine is a constant flow type; a leak in any one line reduces flow to other cylinders, resulting in an excessively lean condition. Based on the pilot's report of conditions at the landing site and METAR data from the closest aviation observation station, density altitude on the surface was calculated at 4,700 feet. The outside air temperature at the site and the estimated temperature at cruise altitude were outside the temperature envelope for a positive rate of climb on the aircraft's single-engine climb performance chart. According to the aircraft manufacturer, temperature lines on the charts are limits and no extrapolation can be made for points outside those lines.