History of Flight
On February 26, 2008, at 1315 Pacific standard time, an experimental single-engine Bartle Lancair IV-P airplane, registration N811HB, experienced a loss of engine power while on final approach for runway 18 at French Valley Airport (F70), Murrieta/Temecula, California. The owner/pilot operated the airplane under 14 CFR Part 91 as a personal flight. The commercial pilot and two passengers were seriously injured; one other passenger received minor injuries. The airplane sustained structural damage to the entire fuselage during an off-airport landing. Visual meteorological conditions prevailed, and no flight plan had been filed for the local area flight that originated about 1300 from F70.
The pilot stated that the airplane had about 52 hours of total time. This was his first "big" trip in the airplane, which he had built. The flight departed from Independence, Oregon, for Southern California the day before the accident, landing about 2.5 hours later at Ontario International Airport (ONT), Ontario, California. On the accident day, he refueled at ONT and flew to John Wayne-Orange County Airport (SNA), Santa Ana, California, and then to F70. The pilot met his family and friends at F70 with the intent of taking them flying. He loaded the first group and flew them around the area for about 10 minutes, making an uneventful landing. He offloaded the passengers, checked the fuel and oil, and reloaded another group. He reported having about 35 gallons of fuel onboard.
The pilot stated that the second flight was uneventful, flying around the area for about 15 minutes. The downwind and base legs of the landing approach were normal. As the airplane turned onto final, the engine lost power. The pilot stated that the engine "just quit, there was no sputtering or surging." He switched fuel tanks, activated the fuel boost pump, and cycled the mixture, but was unable to restart the engine. Realizing they were short of the runway, he prepared for an off-airport landing. He chose an open area, left the landing gear down, and about 20 feet above the ground selected full flaps and activated the speed brakes. The airplane contacted the ground at 70 knots, the landing gear collapsed, and the airplane slid across hilly desert terrain and came to a stop upright. The pilot reported that no circuit breakers had tripped prior to the engine failure.
Responding personnel reported that the wings were not compromised and there was no fuel leaking. They estimated about 25 gallons of fuel remained on board.
Personnel Information
A review of FAA airman and medical records revealed that the 52-year-old pilot held a commercial pilot certificate with ratings for airplane single and multiengine land, and instrument airplane. He had been issued a third-class medical on May 12, 2006, with the limitation that he shall wear corrective lenses. The pilot reported his total flight hours as 2,245.1 hours.
Aircraft Information
The airplane was a 2007 experimental Bartle Lancair IV-P, serial number LIV-311. An experimental Teledyne Continental Motors engine, TSIO-500-EXP, serial number TC5169, was installed by Performance Engines of La Verne, California. A Light Speed Engineering (LSE) Electronic Ignition System, consisting of two Plasma III capacitive discharge ignition (CDI) modules with direct crank sensors, serial numbers 43019 and 43032, had been installed.
Engine Examination and Electrical System Testing
A Safety Board investigator examined the engine visually and found no anomalies other than impact damage to the oil sump and propeller assembly. Rotating the crankshaft did not produce a spark from the ignition coils. Inspection revealed two 12-volt batteries mounted on the firewall, with a fuse box adjacent to the outside battery. Recovery personnel reported that during retrieval they disconnected the battery and removed the fuses to prevent fire.
The investigator examined the fuses, identifying them as automotive type, with three fuses rated at 5 amps and three rated at 20 amps. Two of the three 5-amp automotive fuses had blown. The investigator inserted an intact 5-amp fuse into one of the empty ignition fuse slots. With the crankshaft rotated, spark was obtained from the ignition coils.
The pilot/builder stated that he designed the ignition system's electrical circuit to provide electrical redundancy. The owner's wiring diagram for the airplane showed that both the left and right Plasma III CDI units were interconnected through their own individual 5-amp circuit breaker to a common bus bar. The bus bar then split through two branches to two separate independent batteries. Each branch consisted of a 5-amp automotive fuse in series with an IRSQ04 Schottky diode.
Investigators tested the ignition system for a short circuit between the common bus bar and airplane ground with a continuity tester; no short circuit was identified. A diode functionality test showed no anomalies. The current draw from both CDI units was measured at simulated engine rpm using a simulated ignition pulse system provided by the manufacturer. Results: 300 rpm – 0.9 A, 600 rpm – 1.8 A, 1200 rpm – 2.9 A, 1800 rpm – 4.1 A, 2400 rpm – 5.3 A, 3000 rpm – 5.7 A. According to the airplane kit manufacturer, the TSIO-550 engine produces maximum 350 horsepower at 2,600 rpm. The ignition system manufacturer stated that the measured combined current was within normal limits.
To test wiring functionality, investigators replicated the ignition system wiring on a test bench using two 40-watt automotive lamps in place of the CDI units. Power was supplied by a variable power supply (PSU) for the left ignition circuit and a 12-volt battery for the right ignition circuit. Current draw was measured at the input terminal of each lamp. As voltage was incrementally varied at the PSU, at an increment of 0.1 volts the right ignition circuit drew 4.7 amps and the left drew 0.02 amps. At a voltage differential of 0.68 volts, the right circuit drew 7 amps and the left drew no current. Shortly thereafter, both automotive fuses blew, extinguishing the lamps.
According to the ignition manufacturer, the recommendation for wiring the dual ignition system to independent power sources required a direct current flow-path to each battery without a common bus bar or serially connected Schottky diodes.
An automotive manufacturer fuse data sheet states: "The current rating of a fuse is typically derated 25 percent for operation at 25-degree Celsius to avoid nuisance blowing. For example, a fuse with a current rating of 10 amps is not usually recommended for operation at more than 7.5 amps in a 25-degree Celsius ambient temperature." The data sheet also stated that "Similarly, if that same fuse were operated at a very high ambient temperature of 80-degree Celsius additional derating would be necessary."
Additional Information
According to FAA Advisory Circular AC 20-27F, Certification and Operation of Amateur-Built Aircraft, "Amateur builders are free to develop their own designs or build from existing designs. We do not approve these designs and it would be impractical to develop design standards for the wide variety of design configurations, created by designers, kit manufacturers, and amateur builders."