Aviation Accident Summaries

Aviation Accident Summary WPR09LA056

Lompoc, CA, USA

Aircraft #1

N6461E

CESSNA 172

Analysis

While on final approach for landing, the airplane impacted a power line about 1/3 mile from the runway threshold. Witnesses reported seeing the airplane approaching the power line at a "very slow" speed, about 50 feet above the ground. The airplane passed between the upper and lower wires of the power line, impacted the lower wires, then collided with the ground in a flat, cultivated field. No evidence of any preimpact discrepancies was found during examination of the airframe. Although several anomalies were noted with the engine's ignition system, they would not have prevented the engine from operating and producing power. The minimal damage to the propeller suggests the engine was operating at a low power setting at the time of ground impact. The throttle was found in the idle position, and since no mechanical reason for a loss of power was found, it is likely the pilot intentionally reduced power. He did not have a current medical certificate or biennial flight review; his previous medical certificate expired in July 2007, and his previous biennial flight review expired in September 2007. Toxicological evaluation detected hydrocodone (a prescription narcotic painkiller) and dihydrocodone (a prescription narcotic painkiller and metabolite of hydrocodone), but no blood was available for testing, and it was not determined when the pilot might last have taken medication or whether he could have been impaired by its use.

Factual Information

On December 10, 2008, about 1440 Pacific standard time, a Cessna 172, N6461E, collided with a power line and impacted terrain in a field about 1/3 mile short of the threshold of runway 25 at Lompoc Airport, Lompoc, California. The airplane, which was owned and operated by the pilot, was substantially damaged. The private pilot, the sole occupant, was killed. Visual meteorological conditions prevailed, and no flight plan was filed for the 14 Code of Federal Regulations Part 91 local personal flight. The airplane departed from the Lompoc Airport at an unknown time. According to two witnesses, who were interviewed by local authorities, they were working in the field near one of the power poles when the airplane impacted the power line. They first noticed the airplane as it was traveling west over the field at a "very slow" speed about 50 feet above the ground, east of and approaching the power line that runs north/south across the field. The airplane passed between the upper and lower wires of the power line and impacted the lower wires. The airplane then descended and collided with the ground. Two other witnesses, one located about 500 feet southwest of the accident site and the other located about 1/2 mile east of the accident site, reported that they initially observed the airplane flying eastbound and then saw it make a "sharp right turn" to head westbound. The closer witness stated that when the airplane turned it hit the power line's lower wires and crashed in the field. The other witness stated that as the airplane turned its left wing clipped the power lines. According to local authorities and Federal Aviation Administration (FAA) inspectors who responded to the scene of the accident, the airplane came to rest nose down on a southwesterly heading about 380 feet west of the power line. The power line's lower wires and support cable were lying on the ground west of the power poles. A piece of wire cable was found wrapped around the airplane's left main landing gear; the piece was determined to be part of the support cable from the power line. The accident site was located in a flat, cultivated field, which extended to the east and west of the power line. There were orange marker balls on the power line's uppermost wire. The airplane was recovered from the accident site to a storage facility where it was further examined under the supervision of an National Transportation Safety Board investigator by representatives of the airframe and engine manufacturers. No evidence of any preimpact discrepancies was found during examination of the airframe. The throttle control was in the idle position; the mixture control was in the full rich position; and the carburetor heat control was in the off position. Control continuity was established from the cockpit controls to the carburetor for the throttle and mixture. The fuel tank selector was found in the "BOTH" position. Recovery personnel reported that they drained about 8 to 9 gallons of fuel from the airplane. The fuel was light blue in color and had no visible contamination. The propeller remained attached to the crankshaft propeller flange. One blade was bent aft about 45 degrees approximately 6 inches outboard from the propeller hub. The opposing blade had minimal damage. During examination of the engine, the propeller was used to manually rotate the crankshaft. Continuity was established throughout the engine and valve train. Thumb compression was obtained on all six cylinders. When the crankshaft was rotated, the left magneto produced spark on all six ignition harness leads with impulse coupling engagement. The right magneto did not produce spark on any of the six ignition leads with no impulse coupling engagement. The ignition leads were undamaged and improperly routed. The left magneto was routed to all upper spark plug positions and the right magneto was routed to all lower spark plug positions. Both the magnetos were further tested and inspected at a local engine overhaul shop. The ignition leads were removed from the right magneto and a test set was used on a test bench. The impulse coupling did not engage. At approximately 600 rpm, spark was visible from all six test leads. The ignition leads were removed from the left magneto and a test set was used on a test bench. During the first run the impulse coupling engaged and spark was visible from all six test leads at approximately 1,000 rpm. The left magneto rotation was slowed to 350 rpm and the impulse coupling would not engage. The right and left magneto impulse couplings were disassembled. The springs showed signs of wear and the pawls were loose on their rivet attachments. The spark plugs were all tested successfully in a pressurized test stand. Examination of the airplane's maintenance records revealed that it received its most recent annual inspection on December 12, 2007, at an airframe total time of 4,580.8 hours and a tachometer time of 301.8 hours. At the time of the annual inspection, the engine, a Continental O-300-A-3, had accumulated 3,012.8 hours total time and 230.7 hours since major overhaul. The most recent maintenance entry was dated November 3, 2008, and stated that the airplane was stripped and repainted at a tachometer time of 309.9 hours. At the time of the accident, the airplane had been flown 9 hours since the annual inspection and 1 hour since it was repainted. The pilot, age 77, held a private pilot certificate with a single engine land airplane rating. His most recent third-class FAA medical certificate was issued on July 13, 2005, with the limitation: must wear corrective lenses. This medical certificate expired on July 31, 2007. The most recent biennial flight review recorded in the pilot's logbook was conducted on September 2, 2005; this biennial flight review expired on September 30, 2007. The most recent entry recorded in the pilot's logbook was dated June 18, 2005, and indicated the pilot had accumulated 793.4 hours of flight time. Time sheets for the airplane dating from April 14, 2005, to January 13, 2008, were used to determine the remainder of the pilot's flight time. During the second half of 2005, the pilot flew 10.6 hours, in 2006 he flew 12.8 hours, in 2007 he flew 2.3 hours. In 2008, the pilot made one flight of 1.2 hours on January 13, 2008. According to FAA records, the pilot purchased the airplane in 1996. The airplane's maintenance records indicated the airplane accumulated about 240 flight hours from October 1996 to the date of the accident. Therefore, the pilot's time in the accident make and model of airplane was estimated to be 240 hours. An autopsy of the pilot was conducted by the Santa Barbara County Sheriff-Coroner's Bureau. The cause of death was determined to be multiple blunt-force trauma. The autopsy report noted evidence of attempted resuscitation and the following other significant conditions: atherosclerotic cardiovascular disease, chronic obstructive pulmonary disease, and hypertension. Toxicology tests were conducted by the FAA's Toxicology and Accident Research Laboratory. Atropine was detected (unquantified) in liver. Dihydrocodone was detected at 0.11 ug/mL in liver and hydrocodone was detected at 0.4 ug/mL in liver and 0.095 ug/mL in kidney.

Probable Cause and Findings

The pilot's failure to maintain clearance from the power line. Contributing to the accident was the pilot's lack of recent experience.

 

Source: NTSB Aviation Accident Database

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