History of Flight
On November 11, 2011, at 1615 mountain standard time, a Cessna 337G, registration N337LC, was destroyed when it impacted the ground shortly after takeoff from runway 20 at San Luis Valley Regional Airport/Bergman Field (ALS), Alamosa, Colorado. The airplane was operated under 14 CFR Part 91 by LAMP Ministry LLC. The pilot, the sole occupant, sustained fatal injuries. Visual meteorological conditions prevailed, and no flight plan was filed. The intended destination was Harriet Alexander Field (ANK), Salida, Colorado.
Witnesses at the airport reported seeing the pilot start both engines, but did not observe taxi or takeoff. Another witness south of the accident site saw the airplane traveling east at low altitude, then heard what he thought was an engine shutting off, followed by two pops. A third witness in a car saw the airplane lose altitude and nose dive toward the ground, disappearing behind trees.
Personnel Information
The accident pilot had over 3,650 total flight hours, including 565 hours in the Cessna 337. He had flown to Alamosa that morning with another ministry pilot to retrieve the aircraft after its annual inspection. The ministry pilot noted the accident pilot was in good spirits and displayed strong aeronautical knowledge and flying skills. His last bi-annual flight review was in June 2010 in the Cessna 337. He held Commercial Pilot certificates for single and multi-engine airplanes and an instrument rating. His most recent FAA medical certificate (Second Class) dated June 6, 2011, required corrective lenses for near and intermediate vision. Between October 2010 and November 2011, he flew the accident aircraft 124.1 hours according to tachometer times.
Aircraft Information
The 1976 Cessna Skymaster 337G (serial number 33701672) was a twin-engine airplane with engines in tandem (front and rear), retractable landing gear, and a belly-attached cargo pod. The aircraft had been at Alamosa since October 15, 2011, for its annual inspection, completed on November 1, 2011. The accident flight was the first after inspection. Airport personnel added 35.1 gallons of fuel to the right wing tank prior to takeoff.
Recovered journey logs (starting 1999) showed the aircraft was regularly flown in Canada until December 2005, with a gap until October 2010. The accident pilot was the only pilot listed from October 2010 onward. The annual inspection entry on November 1, 2011 recorded front engine total time (TT) of 1769.2 hours (114.5 since overhaul), rear engine TT 1420.9 hours (114.6 since overhaul), and propeller TTs of 605.2 hours each. Individual engine logbooks for front and rear engines were also recovered but fire-damaged.
Meteorological Information
Local witnesses described mild weather with variable light wind. METAR data from nearby stations indicated clear skies and light winds.
Wreckage and Impact Information
The accident site was at N37°24.631', W105°52.349', elevation 7,544 feet, about 0.89 miles south of the departure end of Runway 20. The aircraft impacted a level cow pasture on a heading of approximately 070° in a wings-level, 45-degree nose-down attitude. No ground contact marks were found before the main wreckage. A post-impact fire consumed most of the fuselage, including the cockpit, and portions of both wing roots. The rear propeller showed no evidence of power at impact; the fuel valve to the rear engine was closed. The forward engine showed evidence of power at impact. Main landing gear uplocks and downlocks were not engaged, but impact damage precluded confirmation of gear position. Flight control cables were confirmed continuous from the cabin floor to each control, but full continuity could not be assessed due to fire damage. The left main wheel and tire exhibited damage consistent with a propeller blade cut. The flap actuator was found in the retracted position.
Detailed examinations at a salvage facility revealed that the rear engine cowling had propeller cuts that aligned with damage to the left main gear. The main landing gear legs were in an intermediate position with wheels oriented upward. The nose gear appeared retracted. Both fuel selector valves functioned normally; the rear fuel strainer was clear. The front fuel strainer was not located. All cockpit engine controls were in the full forward position.
Engine and Propeller Examinations
The front engine (IO-360-G, serial number 244582-R) exhibited no pre-impact anomalies. The propeller showed S-bending and leading edge damage. The mixture control cable was near the lean position. The throttle fuel control throttle plate was near idle. The rear engine (IO-360-GB, serial number 813007-R) had its propeller and crankshaft flange separated. Blade A was bent aft with gouges; blade B had chordwise scratches. The rear engine fuel pump showed thermal damage but no pre-impact anomalies. Both engines' spark plugs exhibited normal operating signatures.
Medical and Pathological Information
An autopsy revealed no pre-existing medical conditions that could have contributed to the accident. Toxicology tests on the pilot were negative.
Performance Calculations
Actual aircraft weight at the time of the accident could not be determined. Using the lightest weight from the Pilot's Operating Handbook (4,000 pounds), normal rate of climb at 7,000 feet pressure altitude and 0°C with the belly pod was 672 feet per minute. Single-engine climb rates (with rear engine operating) were 142 feet per minute; with front engine operating, 99 feet per minute. Rate of climb was reduced 110 feet per minute with landing gear extended and 240 feet per minute with gear in transit.
Additional Information
The airplane wreckage was released to the owner's representative.