N507RV

HISTORY OF FLIGHTOn September 20, 2015, about 1706 Pacific daylight time, an experimental amateur-built Bryon S Graves (Vans Aircraft) RV-7A, N507RV, nosed over during an off-airport landing following a loss of engine power near Byron Airport, Byron, California. The airplane was registered to the pilot/builder and operated by him under the provisions of 14 Code of Federal Regulations Part 91. The private pilot and passenger were not injured. The airplane sustained substantial damage to the vertical stabilizer, right wing and lower airframe structure during the accident sequence. The local flight departed Byron about 1650. Visual meteorological conditions prevailed and no flight plan had been filed.

The pilot stated that after an uneventful preflight inspection and engine run-up, which included a magneto check, his intention was to fly to a practice area north of the airport and perform aerobatic maneuvers. He departed, and after executing two rolls and leveling off at 4,500 ft mean sea level (msl), the engine began to "sputter", and the airplane's Vertical Power VP-200 display indicated that the ignition system had reverted to backup mode. The pilot turned the magneto switch from left to right, and then back to both, and also switched the fuel selector valve to the opposite fuel tank, with no noticeable change in engine operation. He initiated a return to the airport, and stated that having descended to about 3,500 ft msl the engine lost all power.

The pilot declared an emergency on the airport's common traffic advisory frequency, and performed a forced landing into an alfalfa field about 2 miles northeast of the airport. During the landing flare he maintained full airplane nose-up elevator input in an effort to keep the nosewheel from touching the ground. The airplane began to fishtail on the main landing gear. Once the airspeed reached about 30 knots the nose dropped, the nosewheel made contact with the soil, and the airplane immediately nosed over. Both the pilot and passenger released their harnesses and repositioned themselves within the inverted cabin. The airplane was equipped with a sliding canopy, which had become impinged against the soil, and unable to open; the pilot began to kick at its Plexiglas sides. About 20 to 25 minutes after the accident he was able to open a hole large enough to exit, and emergency response personnel reached the site about 10 minutes later. AIRCRAFT INFORMATIONThe airplane was equipped with a four-cylinder normally aspirated, fuel injected experimental engine, constructed utilizing Superior Air Parts components. It was built by Eagle Engines, and marketed as an Xtreem 360, model number IO-360-B1BC3, serial number 6D081429. The engine was equipped with an FAA certified Champion Aerospace LASAR electronic ignition system, and a Whirlwind two-blade constant-speed composite propeller.

The airplane was completed in 2009, and first flown in March of that year. At the time of the accident, the airplanes tachometer indicated a total time of 311.6 hours. AIRPORT INFORMATIONThe airplane was equipped with a four-cylinder normally aspirated, fuel injected experimental engine, constructed utilizing Superior Air Parts components. It was built by Eagle Engines, and marketed as an Xtreem 360, model number IO-360-B1BC3, serial number 6D081429. The engine was equipped with an FAA certified Champion Aerospace LASAR electronic ignition system, and a Whirlwind two-blade constant-speed composite propeller.

The airplane was completed in 2009, and first flown in March of that year. At the time of the accident, the airplanes tachometer indicated a total time of 311.6 hours. ADDITIONAL INFORMATIONThe airplane was equipped with an Advanced Flight Systems combination electronic flight instrument and engine monitor. The unit was capable of storing engine and flight parameters in non-volatile memory, at 5 second intervals.

The data for the accident flight was downloaded and reviewed, and revealed an increase in engine speed to about 1,800 RPM approximately 4 minutes after engine start, with a corresponding increase in fuel flow and manifold pressure. The rise was consistent with the pilot performing a magneto check, and lasted about 30 seconds; however, the data resolution prevented an accurate determination of the exact engine speed drops during the check.

About 11 minutes and 30 seconds after takeoff, having reached a GPS altitude of almost 5,000 ft, the manifold pressure dropped from 25 to 15 inches of mercury (inHg) and the fuel flow dropped from 12 to 7 gallons per hour. For the next 90 seconds the airplane began to descend. During that period the engine speed remained at 2,400 RPM as the exhaust gas temperatures rose about 200 degrees F, accompanied by a reduction in cylinder head temperatures of about 75 degrees F. With the airplane now at 2,000 ft, the engine speed dropped to 1,400 RPM, as the manifold pressure increased to 28 inHg. The descent continued as both the exhaust gas and cylinder head temperatures decreased, until the recording ended 2 minutes later. Oil temperature and pressure remained relatively constant throughout the flight. TESTS AND RESEARCHEngine Examination

Post-accident examination revealed no evidence of catastrophic engine failure, and the engine crankshaft could be manually rotated smoothly by the propeller hub. All fuel lines were intact, and remained attached at their respective fittings. All spark plugs were of the aviation-grade, massive electrode type, were free of mechanical damage, and exhibited light-grey and brown deposits, and normal wear signatures consistent with a short service life.

Ignition switch operation and electrical continuity was confirmed through to the wiring harness forward of the firewall.

The magneto-to-engine timing was checked utilizing a Champion Aerospace T-300 SyncroLASAR timing system. The right magneto appeared set to the correct timing, however during engine rotation, the left magneto top dead center (TDC) light remained illuminated on the T-300, and the BKR/PT light did not turn on. According to the LASAR system maintenance manual, such a condition indicated a failure of the left magneto.

The left magneto was then removed from the engine, revealing that its steel drive gear had become detached, and was found loose within the accessory case. Examination of the gear revealed that it remained attached to the rotor shaft end, but the shaft had fractured at the main magneto bearing. The fracture surfaces revealed a generally cup-shaped curvature, with uniform granular features, and no indication of "beachmarks" or propagation lines typically associated with fatigue. The engine's accessory drive gear teeth all remained intact, and one tooth on the separated magneto gear exhibited a 3-mm-long gouge to its top land surface.

Ignition System Operation

The LASAR Ignition system was developed and manufactured by Slick Aircraft Products/Unison Industries until September 2008, when the product line was purchased by Champion Aerospace. The model installed was certified for use in a Lycoming 180 horsepower IO-360 engine.

The system utilizes an electronic controller interfaced to a set of traditional magnetos, and operates in either "automatic" or "backup" modes. In automatic mode, when the ignition switch "BOTH" position is selected, the controller receives engine parameter inputs including manifold pressure and crankshaft speed, and adjusts the ignition timing, spark duration, and spark energy based on an internal software map. In this mode, a series of relays are energized within the magnetos, electrically isolating their contact points from the ignition coils. One "sensor" magneto (left in the accident airplane) contains a Hall Effect switch, which provides timing and speed reference to the controller.

The system switches to traditional magneto ignition (backup) mode when the controller detects a fault, or when the ignition switch is moved to the "LEFT" or "RIGHT" position. Under these circumstances, the internal relays de-energize, and the magneto reverts to the fixed ignition timing angle utilizing its contact points and ignition coil. The controller also switches an annunciator output, which in the accident airplane was connected to the VP-200 display and configured to present a "backup mode" indicator.

During preflight magneto checks, as the ignition switch is moved between BOTH and either the RIGHT or LEFT position, the system reverts to backup mode, with RPM drops equal to that observed in a traditional magneto system. In order to check and adjust the magneto timing following maintenance, the specialized T-300 SyncroLASAR timing system is required.

Magneto Maintenance

The pilot reported that about 20 flight hours prior to the accident, he had been experiencing uneven engine operation when in backup mode, with symptoms including high RPM drops of about 180-200 rpm during magneto checks. After conferring with technical support at Champion Aerospace, he sent the magnetos to a repair facility for a 500-hour inspection and maintenance. Records revealed that the repair shop performed the inspection in accordance with the L-1503E overhaul manual, which was appropriate for the LASAR ignition system. As part of the maintenance, the contact and cam assemblies were replaced in both magnetos and the coil was replaced in the right magneto. Once complete, the pilot reinstalled the magnetos and performed the engine-to-magneto timing adjustments utilizing the T-300. He reported that the engine roughness had now been resolved, and that all preflight magneto checks for the remaining flights leading up to the accident resulted in normal engine RPM drops.

Magneto Examination

Both magnetos, along with the LASAR control unit, and ignition and control harnesses were examined by the NTSB investigator-in-charge and technical representatives from Champion Aerospace at the Champion facility in Liberty, South Carolina. A complete examination report i...