WPR17FA013

A loss of airplane control for reasons that could not be determined due to the extensive impact and fire damage to the airplane.

The private pilot and the pilot-rated passenger were making a local personal flight in the airplane in visual flight rules conditions so that the passenger could assist the pilot in becoming familiar with avionics components that had recently been installed. The new avionics components were upgrades of the previously-installed combination communication, ground-based navigation, and GPS navigation units. No flight testing of the airplane was conducted after the installation of the new avionics, nor was any required. The airplane was only flown once in the period between the avionics installation and the accident flight. That flight was conducted by the pilot who was the passenger on the accident flight and was uneventful. According to acquaintances, both pilots were experienced in the accident airplane make and model. The pilots planned to fly to a practice area east of the airport, but the details of their plans were not known. Following a normal takeoff, the airplane began a turn to the east at an altitude of about 500 ft and climbed at a normal speed and rate for about 3 1/2 minutes. The airplane reached a maximum radar-indicated altitude of about 3,400 ft, where it leveled off for about 8 seconds. It then entered a descending left turn, and the descent rate and airspeed increased continuously. Analysis indicated that the average descent rate was about 5,000 ft per minute (fpm), and the maximum rate was about 10,000 fpm. During the descent, the speed increased from about 120 kts to nearly 250 kts, which was significantly above the airplane's never-exceed speed of 203 kts. During the descent, the pitch attitude decreased from about 5° airplane nose up to nearly 30° airplane nose down, and the total heading change was about 70°. The high descent rate, airspeed, and nose-down pitch attitude were consistent with an uncontrolled descent. About 30 seconds after the descent began, the airplane struck high-tension powerlines and then impacted terrain. The airplane was highly fragmented by impact with the line, ground impact, and a post-impact fire altered or consumed much of the remaining structure and other evidence. All flight control surfaces were accounted for; however, flight control continuity could not be confirmed due to the extent of the damage. No evidence of an in-flight fire or a bird strike was observed in the wreckage. Further, the two occupants were both capable of flying the airplane, any incapacitation would have had to affect both. Although ethanol was detected in the passenger's tissues, the levels varied widely, consistent with post-mortem ethanol formation; therefore, the ethanol did not contribute to the accident. Thus, it is unlikely that a flight control malfunction or failure or pilot incapacitation contributed to this accident. It is possible the recent avionics installation may have resulted in physical control interference or mechanical failure; while no direct evidence of this was found, the condition of the wreckage precluded elimination of that possibility. Also, although there were no reports of any previous problem with the airplane's electronic flight control system, it is possible that an uncommanded or inadvertent control input via the autopilot or electric trim may have occurred and led to the loss of control. No direct evidence of an electronic flight control system malfunction was found; however, the condition of the wreckage precluded elimination of the possibility.

HISTORY OF FLIGHT On October 25, 2016, about 1220 Pacific daylight time, a Textron Aviation (formerly Beechcraft) A36 Bonanza, N364RM, was destroyed when it impacted powerlines and terrain during a steep descent near Pittsburg, California. The private pilot and pilot rated passenger received fatal injuries. The airplane was registered to Accretion LLC and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed for the local personal flight that departed from Buchanan Field Airport (CCR), Concord, California, about 1215. According to persons familiar with one or both occupants, the airplane had recently undergone the installation of a new avionics' suite, and the accident flight was the second flight since the avionics upgrade. The purpose of the flight was for the passenger to assist the pilot in becoming familiar with the new avionics. They were reportedly planning to fly to a known practice area east of CCR. Coroner's forensic evidence indicated that the pilot was in the left seat for the flight, and that the passenger was in the right seat. CCR fuel records indicated that the airplane was fueled with 37.0 gallons of 100LL aviation gasoline on the day of the accident flight. Review of Federal Aviation Administration (FAA) air traffic control (ATC) audio communications and ground tracking radar information indicated that the airplane departed from CCR runway 19R, made a left turnout shortly thereafter, and that there were no further communications from the airplane. The airplane continued to climb in a relatively straight track to the east, until about 4 ½ minutes after the start of the takeoff. The airplane reached its maximum altitude of about 3,600 ft, and then commenced a left turn and a steep descent. The airplane struck high tension powerlines and then the sloped face of a ravine. The accident site was in rolling open hills about 8 miles east of CCR. There were no eyewitnesses to the accident, and it was initially reported as a grass fire. Responding personnel determined that it was an airplane accident, but by that time the fire had been burning for a while. The wreckage was highly fragmented, and the post impact fire consumed much of the airplane. The wreckage was examined on scene, and then recovered and subjected to additional examination. PERSONNEL INFORMATION Efforts to locate the pilot logbooks for both persons on board were unsuccessful. According to persons who knew the pilots, both were well-experienced, and familiar with the accident airplane make and model. Pilot FAA records indicated that the pilot held a private pilot certificate with airplane single-engine land and instrument airplane ratings. His most recent FAA third-class medical certificate was issued in May 2015. According to information provided by the pilot on his most recent FAA medical application, he had about 1,775 total hours of flight experience. Passenger FAA records indicated that the passenger held airline transport pilot and flight instructor certificates, with airplane single- and multi-engine land, and instrument airplane ratings. His most recent FAA first-class medical certificate was issued in March 2016. According to information provided by the passenger on his most recent FAA medical application, he had about 7,035 total hours of flight experience. AIRCRAFT INFORMATION FAA information indicated that the airplane was manufactured in 1995, as manufacturer's serial number E-2957. The pilot's company had owned the airplane for about 10 years. The airplane was equipped with a Continental Motors IO-520 series piston engine that was field converted to a TIO-550 series engine via Supplemental Type Certificate (STC) SE02881AT. The engine was also modified with the installation of a Tornado Alley brand turbonormalizer system via STC SA5223NM. Those modifications, as well as the installation of Osborne-brand wingtip fuel tanks, were accomplished in September 2007. Maintenance records were recovered at the accident site. According to the recovered maintenance records, the most recent annual inspection was completed in May 2016, at which time the airplane had accumulated about 2,626 total hours in service. The engine maintenance records indicated that, at the time of the annual inspection, the engine had accumulated about 2,382 total hours in service, and about 681 hours since major overhaul. The most recent avionics upgrade had been accomplished at Westover Field / Amador County Airport (JAQ) Jackson, California. According to the owner of the avionics shop that accomplished the installation, the airplane arrived the week of October 11, 2016, and the maintenance was completed on October 19, 2016. Ground tests were satisfactory, and no flight testing was required or conducted. On October 20, 2016, at the request of the airplane owner, the accident passenger took possession of the airplane and flew it solo from JAQ back to its base at CCR, a distance of about 64 miles. The pilot who flew the accident passenger to JAQ to retrieve the accident airplane reported that the accident passenger encountered an anomaly during his preflight inspection, and although he considered leaving the airplane at JAQ, he decided to fly it to CCR. That flight was the first flight of the airplane after the avionics installation, and the accident flight was the second post-installation flight. The accident passenger did not specify the nature of the anomaly to the drop-off pilot. The avionics installer reported that the accident passenger advised him that the new avionics equipment operated satisfactorily, except for a complaint about sidetone volume. The details of the avionics installation activity are documented under ADDITIONAL INFORMATION. METEOROLOGICAL INFORMATION The CCR automated terminal information service (ATIS) that was current at the time of the airplane's taxi-out included wind from 170° at 9 knots. When the airplane was in the runup area, the ground controller advised the pilots that the winds were from 170° at 14 knots, with gusts to 27 knots. The 1220 CCR automated weather observation included wind from 180° at 12 knots, visibility 10 miles, scattered clouds at 4,200 ft, overcast layer at 11,000 ft, temperature 68° C, dew point 52° C, and an altimeter setting of 30.07 inches of mercury. COMMUNICATIONS The communications between the airplane and the CCR ATCT ground and local control positions were recorded and provided to the investigation. The communications from the airplane were accomplished by both the pilot and the passenger. There were no communications regarding any significant problems. The first communication from the airplane was from the pilot to the ground controller about 1204:40, for taxi instructions. The full length of the departure runway (19R) was not available, but the communications indicated that the available length was acceptable to the pilot for the departure. Based on the radio communications, an engine runup was conducted prior to the takeoff. The airplane switched to the local controller (LC) about 1212:20, and the pilot advised that he was ready for takeoff on runway 19R and requested a left crosswind departure from the airport traffic area. The airplane was cleared for takeoff about 1212:34, but then that takeoff clearance was cancelled when the pilot requested a "minute" for an unspecified reason. The passenger then asked for a "radio check," and the LC responded with "loud and clear." About 1213:50, the pilot again announced he was ready for takeoff, and the airplane was cleared for takeoff about 3 seconds later. About 6 seconds after that, the pilot acknowledged the takeoff clearance; that was the last recorded communication from or to the airplane. Except for the left crosswind turnout request, there were no communications regarding the intended route of flight