N56626Piper PA-28-235 · 1973

On May 9, 2010, at 1028 Pacific daylight time (PDT), N56626, a Piper PA 28-235, collided with trees and terrain approximately 8 miles northeast of the Livermore Municipal Airport, Livermore, California. The pilot was operating the airplane under the provisions of Title 14 Code of Federal Regulations Part 91. The private pilot and passenger, who also held a private pilot certificate, were fatally injured. The airplane sustained substantial damage. Witness information indicated that instrument meteorological conditions prevailed at the accident site. The pilot departed in visual flight rules (VFR), requested and received flight following after departing from Auburn Municipal Airport, Auburn, California, about 0945, and was destined for the San Carlos Airport, San Carlos, California.

According to family members of the pilot, the pilot and passenger were visiting family in the Auburn area and wanted to return to their home in San Carlos for an afternoon meeting.

A witness that lives near the accident site was outside when the accident occurred. She heard the airplane but did not see it due to fog. She stated that the airplane sounded lower than most that fly in the area, and the engine sounded normal. She then heard what she believed was the sound of the airplane's impact with terrain.

The pilot was in communication with Northern California Terminal Radar Approach Control (TRACON). According to Federal Aviation Administration (FAA) air traffic control information, the pilot had requested a flight following clearance to San Carlos Airport, and the pilot was authorized to fly at an altitude of the pilot's discretion. There were no distress calls from the pilot.

A Safety Board Air Traffic Control specialist completed a plot of the radar data for the accident airplane. The plot showed a flight track from the northeast to the southwest at about 3,000 feet. In order to reach San Carlos, the airplane would have crossed over an area of hilly terrain that rose to about 2,300 feet. When the track reached the hilly terrain, the radar targets showed a descent to 2,600 feet and a turn to the south-southeast. The last radar target was at 2,799 feet at 1028. The accident site was about 10 miles southeast of the straight-line path from Auburn to San Carlos.

The pilot, age 75, held a private pilot certificate for airplane single-engine land, and a third-class airman medical certificate issued December 4, 2008, with limitations that she must wear corrective lenses. Review of the pilot's logbook showed that she had 983 flight hours, with 751 hours in the accident airplane. The pilot had flown 3 hours in the past 90 days, 2 hours in the past 30 days, and 1 hour over the past 24 hours.

The passenger, the pilot's husband, was also a rated pilot with a current medical; however, family members indicated that he no longer flew as pilot-in-command.

The four-seat, low-wing, fixed-gear airplane, serial number 28-7410016, was manufactured in 1973. It was powered by a Lycoming Engines O-540-B4B5 250-hp engine, and equipped with a Hartzell HC-C2YK-1BF fixed-pitch propeller. Review of copies of maintenance logbook records showed an annual inspection was completed on April 1, 2010, at a recorded tachometer reading of 3,171.74 hours. The tachometer read 3,175.65 hours at the accident site. The airplane was equipped with a Garmin (Apollo) CNX 80 global positioning system integrated avionics unit, and maintenance records showed that the main software had been upgraded on April 19, 2010.

According to a representative from Lockheed Martin Flight Service, no weather services were provided. Additionally, there was no record of a weather briefing being obtained from either DUAT provider.

A Safety Board meteorologist completed a weather study. The closest official weather observation station was Livermore, California. At 1053, an aviation routine weather report (METAR) was reporting the following conditions: wind from 210 degrees at 7 knots, 190 degrees variable to 250 degrees; visibility 10 statute miles; clouds few 2,200 feet, broken 4,000 feet; temperature 14 degrees Celsius; dew point 9 degrees Celsius; altimeter, 30.02 inches of Mercury.

The National Weather Service (NWS) Surface Analysis Chart for 1100 PDT depicted a shortwave trough in northern California extending from near the California/Oregon border out into the Pacific Ocean north of Mendocino, California. Station models in and near the San Francisco, California Bay Area indicated generally a westerly flow with overcast skies to the west of the accident site. Light rain was reported north of the accident site.

A region mosaic of composite reflectivity data from WSR-88D stations indicated light rain was likely falling in limited areas of the San Francisco Bay Area. These radar data give no indication of severe weather in northern California at this time.

The closest WSR-88D weather radar to the accident location was KMUX located in the Santa Cruz Mountains south of the San Francisco Bay Area. The radar was located approximately 40 miles south of the accident site at an elevation of 3,469 feet. At this distance and a radar tilt of 0.53°, hydrometeors above the accident site were detected between approximate altitudes of 4,700 and 8,800 feet (assuming a standard refraction of “1.33”). Highest reflectivities in the immediate area of the accident site are 20-25 dBz, corresponding to light precipitation, which had an observed movement to the east through the area before the accident.

Radar imagery at 1013 PDT indicated light precipitation passed through the accident airplane’s eventual flight path near the accident site about 12-15 minutes prior to the airplane. Although unconfirmed, it is likely that falling precipitation reached flight altitudes. Radar imagery at 1025 PDT indicated no precipitation was falling at the accident site near the accident time.

The first identified point of impact was an area of 50-foot tall trees, at an elevation of 2,412 feet mean sea level. Pieces identified from the left wing were located in the area of the trees. The debris path continued in a direction of about 100 degrees magnetic, with additional pieces of the left wing. The first identified ground impact was approximately 110 yards from the trees. The debris field continued with large sections of the left and right wings, the main wreckage and empennage, and the engine. The length of the overall debris field was approximately 290 yards.

The Contra Costa County Coroner completed an autopsy on the pilot. The cause of death was reported as multiple blunt impact trauma.

The FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed forensic toxicology on specimens from the pilot. The toxicology report stated no carbon monoxide or ethanol was detected. Drug screening showed that fluoxetine, norfluoxetine, and quinine were detected. FAA toxicology staff indicated records accompanying the specimens noted that the blood provided was “cavity blood.” FAA toxicology staff also indicated that the blood was not tested for the presence of quinine.

The airframe was examined. Both wings were in multiple pieces. The left wing consisted of a circular indentation 12 inches from the inboard of the wing root that ran from the leading edge and pushed the skin aft to the spar. A 2-foot section of the flap remained attached to this section. The next section was 6 feet in length and contained the remainder of the left flap, the left landing gear, and a 3-inch inboard section of the aileron. Two smaller pieces of leading edge were identified with two circular indentations, similar in size and shape to the tree branches found at the site. Moving outboard from this section the leading edge and trailing edge of the wing had separated into two pieces, and the remainder of the aileron had separated. The tip tank had separated from the wing. The right wing had separated into four sections. The largest section was the inboard portion of the wing that extended outboard to the tip tank. The flap and aileron remained attached. A 4-foot outboard leading edge panel of the wing had separated and was crushed. The tip tank had separated from the wing and was found in two pieces. There were no circular indentation marks on this wing. All control surfaces were accounted for.

The control cables were traced to the ailerons and all separations were broomstrawed. The flap control surfaces appeared retracted and there was no damage on the trailing edges. Control cables were traced from the cockpit attach points and then aft. All cables were still secure at their attach points.

The engine was examined. Mechanical continuity was obtained via manual rotation of the propeller. Thumb compression was obtained on all cylinders and the valves produced the same amount of lift. Manual rotation of the magnetos produced spark at all posts. The engine driven fuel pump was not found. The spark plugs were examined and all electrode gapping was similar. Spark plugs 2, 4, and 6 were oil coated. There was no evidence of catastrophic malfunction or fire. The cylinders were borescoped and there was no evidence of foreign objects or detonation. The carburetor remained secured at the mounting pad and the respective control arms attached. The carburetor was removed and then disassembled. Approximately 3 ounces of fuel remained in the bowl and was consistent in color and smell to 100 low lead (LL). No evidence of water was found. The floats were intact and secure on their mountings.

Examination of the recovered airframe and flight control system components revealed no evidence of pre-impact mechanical malfunction.