Pomona, CA, USA
N7342P
Piper PA-24-250
While on approach for the destination airport, the pilot reported engine problems, and attempted to land in a field short of the airport. During the forced landing, the left wing contacted the ground, and the airplane tumbled through an impact sequence. During the postaccident engine examination, investigators noted debris and corrosion inside the carburetor and the main jet passage. The airframe and engine inspection revealed no further mechanical anomalies that would have precluded normal operation. A Safety Board metallurgist examined the carburetor and debris/particles. The examination identified that the debris/particles were most likely a combination of lead and soil that had built up over time. The corrosion indicated prolonged exposure to water. The particles probably caused a restricted flow of air-fuel mixture in the main jet that eventually resulted in a reduction or loss of engine power once the particulate contamination had built up to a significant amount. There were no entries in either the airframe or engine logbook indicating that the carburetor had ever been overhauled in its 46-year history. The carburetor manufacturer issued a service bulletin regarding the overhaul of the accident airplanes' carburetor. The recommended time for the overhaul was either at the engine manufacturer's time between overhaul, or every 10 years the carburetor was in service, whichever came first. While service bulletins are not mandatory, had the carburetor been inspected at the manufacturer's recommended intervals, the corrosion and debris may have been identified and source of the fuel system contamination corrected. Investigators noted that the airplane had not been equipped with a shoulder harness restraint system. The fatal injuries for the pilot and front seat passenger were caused by head and upper torso trauma associated with the upper body not being restrained during the impact sequence. The airplane manufacturer had issued Service Bulletin No. 980, Shoulder Harness Installation, in 1995, for the accident make and model airplane. The pilot/owner had purchased the shoulder harness restraint system kit for his airplane, but had not installed them. The still packaged shoulder harnesses were found in the debris field by the investigation team.
HISTORY OF FLIGHT On August 17, 2005, about 1950 Pacific daylight time, a Piper PA-24-250, N7342P, impacted flat terrain at the Spadra Ranch facility for California Polytechnic State University, Pomona, California. The pilot/owner operated the airplane under the provisions of 14 CFR Part 91 as a personal flight. The airplane sustained substantial damage. The pilot and one passenger were fatally injured. A passenger seated in a back seat sustained serious injuries. Visual meteorological conditions prevailed for the local area flight, and no flight plan had been filed. The flight departed Zamperini Field Airport (TOA), Torrance, California, at an undetermined time. The flight's destination was Chino Airport (CNO), Chino, California. A witness in his backyard heard an airplane's engine 'sputtering and cutting out.' When he looked up he saw the accident airplane flying 'really low' in an easterly direction. He did not see any smoke or fire coming from the airplane. The airplane made a turn northbound, and then returned to a southbound heading. As the airplane continued to circle he could no longer hear the engine. The witness reported that the airplane was "going down" and gliding towards a field. He lost sight of the airplane behind the tree line and then heard it crash. He responded to the accident site and observed the rear seated passenger standing on the passenger side wing. The witness could smell gas and told the passenger to "get away." The passenger told the witness that they were headed towards Chino, but did not indicate what had happened. The National Transporation Safety Board investigator-in-charge (IIC) reviewed communications between the pilot and Brackett airport (POC) Air Traffic Control Tower personnel. At 1948, the pilot made the initial call to POC. A minute later the pilot reported an engine failure near San Antonio College (Mount Sac), about 5.5 miles from the airport. At 1950, the controller calls emergency equipment after he receives no response to his radio communications to the pilot. The controller further reported in his personnel statement that he coordinated with Pomona Air 1 to locate the airplane. The POC controller last observed the position of the accident airplane utilizing DBRITE (Digital Bright Radar Indicator Tower Equipment) about 3 miles southwest of the airport. PERSONNEL INFORMATION A review of Federal Aviation Administration (FAA) airman records revealed the pilot held a private pilot certificate with an airplane single and multiengine land ratings. The pilot held a third-class medical certificate issued on September 27, 2004. It had the limitations that the pilot must wear corrective lenses. The aeronautical experience listed in this report was obtained from a review of the airmen FAA records on file in the Airman and Medical Records Center located in Oklahoma City, Oklahoma. These records indicated a total time of 3,200 hours, with 50 hours logged in the last 6 months. AIRCRAFT INFORMATION The airplane was a 1961 Piper PA-24-250, serial number 24-2521. A review of the airplane's logbooks revealed a total airframe time of 3,760.60 hours at the last annual inspection. An annual inspection was completed on August 6, 2004. The entry for the annual inspection stated in part that the mechanic had to tighten some of the electrical leads on system. There were no other discrepancies identified during the annual inspection. The tachometer read 3,841.32 at the accident scene. The airplane was equipped with a Textron Lycoming O-540-A1D5 engine, serial number L-18544-40. Total time on the engine at the last annual inspection was 3,760.60 hours. An engine field overhaul had been completed on June 24, 1993, with an engine total time of 1,098.2 hours. A Marvel-Schebler, MA-4-5 carburetor, serial number R-41-9230, had been installed on the airplane. Service Bulletin MSA-3 Revision 1 dated November 18, 1991, titled Overhaul Periods for Float Carburetors, as issued by Precision Airmotive, LLC, indicated that the accident airplane's carburetor should be overhauled at the engine manufacturer's specified time between overhaul or 10 years in service or last overhauled, whichever occurs first. There were no airframe or engine logbook entries of compliance with Service Bulletin MSA-3 Rev. 1. WRECKAGE AND IMPACT INFORMATION The airplane impacted in a fallow field (Spadra Farm Field) owned by the State of California - Cal Poly Pomona University. The accident site was on the west side of Lanterman State Hospital in Pomona. Responding officers from the Cal Poly-Pomona Police Department noted a strong odor of fuel from the airplane when they arrived on scene. Officers also reported that the pilot and front passenger remained inside the airplane and that both occupants were wearing their "lap seatbelts." The rear seat passenger was outside of the airplane when the officers arrived, and they rendered assistance until the passenger was transported to a local area hospital. The passenger relayed to an officer that they had departed from the Torrance airport en route to Chino. The passenger did not indicate the nature of the emergency that precipitated the accident. Investigators from the Safety Board, the FAA, Piper, and Textron Lycoming, parties to the investigation, responded to the accident site and examined the wreckage. The wreckage was at a Global Positioning System (GPS) coordinates of 34 degrees 02.023 minutes north latitude and 117 degrees 49.215 minutes west longitude. The debris path was along a magnetic bearing of 057 degrees. The first identified point of contact (FIPC) was on a magnetic heading of 118 degrees, and the airplane came to rest upright 122 feet from the FIPC. The empennage partially separated from the aft cabin bulkhead and remained intact, and next to the cabin area. The engine remained attached to the engine mounts, firewall, and airframe; however, it was canted in a nose down attitude with the aft portion of the engine propped up against the instrument panel. The cockpit area of the airplane had been breached during the accident sequence. Three feet of the outboard section of the left wing came to rest about 45 feet from the main wreckage. The aft portion of the airplane had separated along the aft baggage door line and was slightly perpendicular to the fuselage. The propeller assembly remained connected at the crankshaft flange. Both blades were bent near the hub and folded aft. The carburetor had been displaced from the engine; however, it remained intact. After the carburetor was removed, the throttle lever was manually actuated with a discharge of a steady stream of fuel from the accelerator discharge tube. The carburetor was disassembled and investigators noted contaminates at the bottom of the carburetor bowl. The float assembly remained in place and was not damaged. Investigators visually inspected the airplane's fuel tanks and observed fuel in both right fuel tanks, which they estimated to be about 3/4 full. The left fuel tanks had been breached; however, the fuel bladder material was slick to the touch. MEDICAL AND PATHOLOGICAL INFORMATION The County of Los Angeles Department of Coroner, Los Angeles, California, conducted an autopsy on the pilot on August 21, 2005. The cause of death was listed as multiple blunt force trauma. The TC FAA Forensic Toxicology Research Team, Oklahoma City, Oklahoma, performed a toxicological analysis from samples obtained during the autopsy. The tests for carbon monoxide and cyanide were not performed. The results of the analysis of the specimens were negative for volatiles and tested drugs. According to the airplane manufacturer, when the airplane was delivered new in 1961, it had not been equipped with a shoulder harness restraint system. The airplane manufacturer indicated that a mandatory Service Bulletin No. 980 titled Should Harness Installation, dated January 18, 1995, existed for the accident make and model airplane, as well as several other models of Piper airplanes. During the on scene inspection, investigators found brand new uninstalled shoulder harnesses in the debris field. The autopsy report for the pilot noted the following injuries under "Anatomical Summary": A. Multiple blunt force trauma: 1. Abrasions/lacerations, face, neck, chest, abdomen and extremities 2. Multiple fractures, mandible/maxillae, sternum, ribs (left number 2 through number 12; right number 2 through number 5), T2-3 vertebrae. 3. Atlanto-occipital dislocation 4. Lacerations, aorta, left lung and liver The front seat passengers' injuries were listed in part under the "Anatomical Summary" as: B. Multiple blunt force trauma: 1. Abrasions/contusions/lacerations, head, face, neck, chest, abdomen and extremities. 2. Multiple fractures, basal skull (hinge-type), sternum, right ribs, and left tibia-fibula 3. Contusions/lacerations, brain and right lung 4. Subdural hemorrhage TESTS AND RESEARCH Investigators examined the wreckage at Aircraft Recovery Service, Littlerock, California, on August 19, 2005. Flight control continuity was established during the airframe examination, with no discrepancies noted with the airframe during the examination. Investigators noted that the carburetor exhibited signs of previous water contamination as evidenced by rust and corrosion deposits inside the carburetor bowl, fuel pump, and gascolator bowl. Foreign object debris was also found in the main jet passage and carburetor bowl. According to the engine manufacturer's representative, the steel drain plug in the carburetor bowl had been severely corroded on the interior surface. Sediment was found in carburetor bowl and debris was found in the main fuel jet passage. The top spark plugs were removed. All of the spark plugs were secure at each position with their respective leads attached. The spark plug electrodes were clean with no mechanical deformation. The spark plug electrodes were gray in color, which corresponded to normal operation according to the Champion Aviation Check-A-Plug AV-27 Chart. The vacuum pump, rear mounted, remained secure at its mounting pad. The pump was removed and examined. The drive remained intact and the rotor/vane assembly remained intact and was undamaged. The oil filter and suction screen were secured at their respective mountings, and were removed for further examination. Both the oil filter and suction screen were free of contamination. Investigators established mechanical and valve train continuity through manual rotation of the engine. Thumb compression was obtained on all cylinders in firing order. The engine rotated freely and the valves moved approximately the same amount of lift in firing order. The cylinders were removed and examined. The combustion chambers were not mechanically damaged with no evidence of foreign debris ingestion or detonation, or evidence of valve to piston face contact observed. Investigators were not able to establish magneto to engine timing due to displacement of the left magneto from its mounting pad. Portions of the magneto flange remained secured at its mounting pad. The magneto was manually rotated and produced spark at all posts. The right magneto remained secured at its mounting pad and when manually rotated produced spark at all of its posts. Carburetor Examination The carburetor, main jet needle, and four debris particles were shipped to the Safety Board Materials Laboratory, Washington, D.C., for further examination. The senior metallurgist noted black debris on the surface of the main jet. The main jet, the black debris, and deposits were analyzed using an X-ray energy dispersive spectroscopy (EDS). The EDS spectrum results from the clean portion of the main jet contained major elemental peaks of copper and zinc, consistent with brass alloy. The EDS analysis of the black debris from the main jet surface contained a major elemental peak of lead, and minor elemental peaks of silicon, aluminum, magnesium, carbon, chorine, potassium, calcium, titanium, iron, copper, and zinc. The EDS analysis of one of the debris particles yielded similar spectrum results as the black debris from the main jet. The senior metallurgist attempted unsuccessfully to remove the drain plug from the carburetor bowl. He disassembled the carburetor and noted that the examination of the bottom portion of the carburetor bowl port for the drain plug contained a layer of granular-like debris particles. The EDS spectrum results for the debris particles contained a major elemental peak of aluminum, and minor peaks of carbon, oxygen, chlorine, lead, silicon, iron, copper, and zinc. ADDITIONAL INFORMATION The IIC released the wreckage to the owner's representative on January 30, 2006.
A loss of engine power during the landing approach due to fuel starvation caused by debris and corrosion in the carburetor assembly. A factor contributing to the accident was the failure of the owner to comply with the manufacturer's service bulletin regarding overhaul of the carburetor.
Source: NTSB Aviation Accident Database
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