Aviation Accident Summaries

Aviation Accident Summary LAX00LA293

BAKERSFIELD, CA, USA

Aircraft #1

N24VW

Barclay/Vincent MURPHY SR 2500

Analysis

During an emergency landing the left wing of the airplane struck an irrigation standpipe, and the airplane was destroyed in a post impact fire. The pilot reduced the power to descend and circle to land at a dirt airstrip. When he advanced the throttle to arrest the airplane's descent there was no corresponding power increase. He conducted the emergency procedures, but was unable to restart the engine. He overflew the airstrip and attempted an emergency landing in a cornfield. Review of the airplane's power plant logbook revealed that an overhauled engine had been installed on the experimental airplane in March 1999. The last entry was December 8, 1999, when the engine was test ran, and the fuel injection system was adjusted according to manufacturer's specifications. No further entries were found in the airframe or power plant logbooks. During the engine examination the throttle valve was found jammed in the closed position. Investigators also found the idle speed stop screw backed off from the throttle shaft arm about 1/8 inch. No further mechanical anomalies were noted.

Factual Information

HISTORY OF FLIGHT On August 11, 2000, at 1900 hours Pacific daylight time, a Barclay/Vincent Murphy SR 2500, N24VW, struck a standpipe while attempting to land on an access road near Bakersfield, California. The amateur-built airplane, owned and operated by the pilot under the provisions of 14 CFR Part 91, was destroyed in a post impact fire. The pilot and two passengers sustained serious injuries and a third passenger was fatally injured. One of the passengers subsequently died from her injuries. Visual meteorological conditions prevailed for the personal local flight that had departed from a dirt airstrip adjacent to the access road at an earlier time. No flight plan had been filed. WITNESS INFORMATION A deputy from the Kern County Sheriff's Department interviewed witnesses. A compilation of witnesses stated that they were having a church barbeque at a private residence where the airstrip was located. The pilot had offered to take the three passengers around the area to look at some of the local farms. Three other witnesses located 100 yards, 1/4 mile, and 1/2 mile from the accident site saw the airplane rocking back and forth from wing tip to wing tip. They believed that the pilot was having problems maintaining a straight and level flight attitude. One witness saw the airplane strike the ground in a right wing low attitude and cartwheel after impact. The owner of the property from where the airplane had taken off stated that he saw the airplane on approach to the airfield and believed that the pilot intended to land. He stated that the airplane was off the centerline while at a low altitude. He heard the engine accelerate and saw the airplane begin to gain altitude. He then heard the engine begin to "pop and sputter without gaining altitude." He indicated that the airplane appeared to be too high to land at the dirt strip. As the airplane continued down a dirt access road, he saw it collide with an irrigation standpipe. A Federal Aviation Administration (FAA) inspector interviewed the pilot. The pilot indicated he had been flying for about an hour and this had been his third flight of the day. At the time of the accident he had just reduced the power setting in order to descend. The pilot advanced the throttle full forward so he could arrest the rate of descent and circle to land. He stated that the engine failed to respond and continued to run at idle power as the propeller windmilled. He moved the mixture and propeller controls forward, and adjusted the position of the throttle. He then verified that both fuel valves were in the open position and verified the ignition/magneto switch was in the both position. The pilot stated that he was unable to restart the engine, and his descent continued. He overflew the airstrip and attempted an emergency landing in a cornfield. WRECKAGE AND IMPACT INFORMATION The airplane was inspected on scene by an FAA inspector. The inspector reported that the fuselage had been damaged by fire from the engine firewall to the tail section. The cockpit instruments were unreadable due to the fire damage. The two rear passenger seats were found about 10 feet from the tail section of the airplane. The two front seats remained in place in the forward portion of the cockpit. The tail section separated from the airplane and was lying next to the right rear side of the airplane. The propeller and spinner remained attached to the engine crankshaft. One blade of the propeller appeared to be undamaged and the other blade was bent towards the cambered side at the tip. The FAA inspector observed that the left wing had struck a metal irrigation standpipe during the descent to landing. AIRCRAFT INFORMATION The Safety Board investigator conducted a review of the airplane construction, airframe, and power plant logbooks. The airplane was built by the owners from a Murphy Super Rebel (SR) 2500 kit, serial number 024, purchased from the Murphy Aircraft Company in Chilliwack, British Columbia, Canada, in February 1999. Review of the aircraft construction logbook disclosed that the initial Experimental Category airworthiness certificate was issued under 14 CFR Part 21.193 on March 17, 1999. The special airworthiness certificate was issued on December 4, 1999, and the maiden flight occurred on December 9, 1999. The initial 25-hour test period was completed on January 8, 2000. The next condition inspection was due in December of 2000. On March 28, 1999, an engine overhaul was completed and total time was reported as 2,161.08 hours. On December 6, 1999, the engine was ground run for 15 minutes at 1,000 rpm to check for leaks. The next entry stated the owner found "some" nuts and bolts loose and tightened them. On December 7th and 8th, 1999, the engine was started and test run, with a warm up at 1,500 rpm, per Teledyne Continental Motors (TCM) Overhaul Test Run Standard Acceptance Test (72-70-14). On December 8th the fuel injection system was adjusted according to TCM bulletin SID 97-3 and TCM manual X30593A. The engine was returned to service with a total time of 2,163.00 hours and a tachometer time of 2.0 hours. ENGINE EXAMINATION The power plant was examined on September 1, 2000, under the supervision of the Safety Board investigator, with a representative from TCM, who was a party to the investigation. The examination took place at KL Aviation in Bakersfield. The investigators conducted a visual inspection of the engine. The top spark plugs were removed and examined. According to the Champion Aviation Check-A-Plug chart AV-27, the spark plugs displayed coloration consistent with normal operation. The rocker covers were removed. The valves and valve train were intact. Manual rotation of the crankshaft produced thumb compression in all six cylinders in the proper firing order, and valve train continuity was established. Both magnetos were thermally damaged by the post impact fire and could not be operationally tested. The fuel pump was removed and inspected. The drive gear and drive coupling were intact and the pump was manually rotated with no discrepancies noted. The throttle and throttle valve were in were jammed closed. The throttle valve linkage to the metering unit was bent about 90 degrees. This was attributed to impact forces sustained during the accident sequence. The idle speed stop screw was found about 1/8-inch off the throttle shaft arm. No further mechanical anomalies were noted.

Probable Cause and Findings

Adjustment by other maintenance personnel of the idle speed stop screw. The idle speed stop screw was backed off from the throttle shaft arm, not allowing the butterfly valve to operate properly, which resulted in the butterfly valve remaining closed during a power input via the throttle control linkage during the approach to landing phase.

 

Source: NTSB Aviation Accident Database

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