Accident Overview
On July 7, 2017, at approximately 0830 Pacific daylight time, a Cessna 177RG airplane, registration N7532V, was substantially damaged during a forced landing shortly after takeoff from Nut Tree Airport (VCB) in Vacaville, California. The private pilot, who was also the registered owner and operator, was not injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight and was originating at the time, destined for Rio Vista Municipal Airport (O88) in Rio Vista, California. Visual meteorological conditions prevailed, and no flight plan was filed.
Pilot Report
According to a statement provided to the NTSB investigator-in-charge, the pilot reported that prior to departure all engine runup checks indicated normal operation. After takeoff and during the initial climb at about 200 feet above ground level, the engine "wheezed" and then provided minimum power. Approximately 30 seconds later, the engine ceased to provide power or thrust, necessitating a forced landing straight ahead to an open field. During the landing, the left wing and fuselage were substantially damaged. The pilot reported that the airplane had 30 gallons of fuel on board at takeoff. During recovery, personnel drained between 18 and 20 gallons of fuel, with roughly equal amounts from the left and right fuel tanks.
Post-Accident Examination
The airplane was equipped with a Lycoming IO-360-A1B6D fuel-injected reciprocating engine. A postaccident examination by representatives from the NTSB and FAA revealed that all accessories, including fuel and oil lines, remained secured and attached to the engine. Continuity for the mixture and propeller controls was established from the cockpit to the engine controls. However, the throttle control handle was observed bent downward about 70 degrees during impact. Despite attempts to bend it back to near its original position, full travel could not be attained; estimated movement was about 2 inches. The upper spark plugs were removed and exhibited normal wear signatures. Hand-rotation of the crankshaft yielded thumb compression on all four cylinders, and spark was obtained on all ignition leads when the crankshaft was rotated. Air pressure applied to both wing fuel vent lines passed through unobstructed.
Engine Run Attempt
Prior to an engine run attempt, an external fuel source was attached to the left wing fuel inlet port. Due to propeller damage, the propeller was replaced with a serviceable unit. The airframe fuel pump was actuated to prime the engine. After starting, the engine was run at various power settings for about 5 minutes before being secured with the mixture control. During the run, when the magneto switch was placed to the right magneto position, the engine lost power. The reason for this anomaly was not determined during the examination. The magneto and ignition switch were retained for further analysis.
Ignition System Examination
A subsequent examination of the ignition switch by an NTSB investigator using an ohmmeter to establish continuity at various switch settings found no evidence of malfunction. On July 28, 2017, at an FAA-certified repair station under the supervision of an FAA airworthiness inspector, a certified magneto technician inspected and tested the airplane's Dual Magneto D4LA-2000 (part number 10-382555-11, serial number 8016457). The technician reported that the magneto achieved a coming-in speed of 70 rpm at a 5mm gap (150 rpm maximum allowable). When speed was increased to 3,000 rpm and spark gap opened to 10mm, no missing was observed in either the right or left position. The technician concluded that the magneto was clean and functioned normally.
Conclusion
The accident investigation did not determine a definitive cause for the loss of engine power. No probable cause was specified by the investigating authorities.