Pittsburg, CA, USA
N364RM
BEECH A36
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 or destination. WRECKAGE AND IMPACT INFORMATION Powerlines Two of the individual lines on the powerline were damaged, consistent with the airplane striking the line just before it impacted the ground. The powerlines were oriented roughly perpendicular to the flight path, and consisted of 6 separate lines, arrayed as 3 vertically-stacked lines on either side of the support tower. According to a PG&E representative, the tower was 170 ft high, the highest lines were at a height of 165 ft (at the tower), and the vertical separation between lines was about 16 ft. Investigators estimated the horizontal separation of the lines to be about 40 ft. Although no powerlines were severed by the airplane, two were damaged. The first powerline along the flight track exhibited three discontinuous/separate damage sites, over a span of about 25 ft. The second powerline exhibited three discontinuous/separate damage sites, over a span of about 12 ft. The lines were composed of 7 steel support strands, wrapped with 54 aluminum conductor strands. The powerline manufacturer's "rated strength" of the lines was cited to range from 26,000 to 32,300 lbs. Line damage and airplane debris was consistent with the airplane striking the lines about 130 ft from the tower; line catenary sag was estimated to be about 5 ft at the strike location. The airplane struck the middle line of the first array along the flight track, and the lower line of the second array. Point calculations based on the damage locations, but which did not account for airplane dimensions or attitude, indicated a flight path angle of about 21º below horizontal. A second, similar array of 6 more powerlines was situated just beyond, and parallel to, the struck set. None of those powerlines were damaged. Debris Field The struck powerlines were located about 300 ft prior to (short of) the ground impact point. About 50 fracture-separated fragments of the airplane were scattered below the powerlines, and in the field between the powerlines and the ground impact site. A segment of a wing tip tank rib remained wrapped around one of the powerlines. The debris field fragments were primarily from the empennage or right wing, with some later fragments from the left wing. None of those fragments contained any evidence of smoke or thermal distress. The fragments were catalogued in a database, recovered, and re-assembled in a two-dimensional layout at the recovery facility. The plane of the vertical stabilizer and rudder cut/tear line was approximately parallel to the plane defined by the lateral and longitudinal axes of the airplane, consistent with the airplane being approximately wings level (either upright or inverted) at the time of the powerline strike. The plane(s) of the wing, horizontal stabilizer and elevator fragment cut/tear lines were irregular and inconsistent with one another, with no clear pattern observed. The outboard left-wing damage appeared consistent with it becoming separated during the powerline strikes, but the section was found in the main wreckage area. Main Wreckage Ground scar and wreckage distribution were consistent with the airplane striking the ground in a relatively steep trajectory, approximately perpendicular to the ravine face. The main wreckage was very tightly contained, approximately within the area of a circle about the diameter of the wing span. The overall main wreckage distribution was generally consistent with the airplane striking the ravine face approximately upright, and then coming to rest inverted, consistent with a nose-over during impact. The left aileron remained attached to the left wing, but the right aileron was fracture-separated from the right wing, consistent with powerline impact. The aileron trim actuator extension was consistent with a trim setting of about 4° left aileron trailing edge down (TED). The rudder and left and right elevators were fracture-separated from their respective stabilizers and were almost all found in the debris field between the powerlines and the impact site. No measurements of the left or right elevator trim actuators were possible due to impact and/or thermal damage. The airplane was not equipped with cockpit-controlled rudder trim. Both flaps remained partially attached to their respective wings. All evidence was consistent with a flap extension of 0° (flaps up/retracted). On-site and post-recovery examinations of the airplane indicated that all primary flight control surfaces were present at the time of the powerline strike and/or ground impact. Due to severe impact disruption, and damage and/or consumption by fire, only a coarse approximation of flight control continuity was able to be accomplished. No pre-impact anomalies were observed. The nose and main landing gear actuator configurations were consistent with the landing gear being retracted at the time of impact. Although some components or fragments of components were able to be identified, impact and thermal damage precluded the determination of the integrity, functionality, or settings of any portions of the fuel system. Portions of flight, navigation, and engine instruments, electrical switches, circuit breakers, and avionics devices, were observed in the wreckage, but due to damage, no information regarding the integrity, functionality, operational status, or indications/settings of any of those systems or subsystems was able to be determined. The engine had separated from the airframe, and was located at the bottom of the ravine, about 15 ft downslope of its impact location. The engine sustained significant impact damage, and thermal damage consistent with the post impact fire. Most accessories were fracture-separated from the engine. No evidence of any pre-impact engine or engine component failures was observed. No direct information regarding the engine functionality or operational status was able to be determined. All three propeller blades were recovered at the main wreckage site. Two blades were fracture-separated from the propeller hub, which was fractured into numerous pieces. All three blades displayed relatively minimal shape deformation, and all three were missing about ¾" to 1-1/2" from their tips. No evidence of any pre-impact failure of the propeller or its system components and controls was observed. No evidence consistent with in-flight fire, in-flight structural failure, catastrophic engine failure, or a bird strike was observed. Refer to the NTSB public docket for detailed accident site and wreckage examination information. MEDICAL AND PATHOLOGICAL INFORMATION Pilot The 67-year-old pilot reported the following to the FAA that he had hypertension and high cholesterol treated with valsartan and atorvastatin respectively. These medications are not considered impairing. The Coroner's Division of the Office of the Sheriff, Contra Costa County, California, performed an autopsy of the pilot. The autopsy cited the cause of death as multiple blunt force injuries. The autopsy was inconclusive for significant natural disease due to the level of trauma. NMS Labs performed toxicological testing at the request of the coroner and identified 57 ng/g of pseudoephedrine in liver. The FAA's Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed toxicological tests and detected atorvastatin and valsartan in liver tissue. Bupropion and a metabolite were detected in liver and muscle tissue. Pseudoephedrine is a sympathomimetic often used to treat nasal congestion. It is not generally considered impairing. Bupropion is a prescription antidepressant that is also indicated for use as an aid to smoking cessation. It carries a boxed warning about the risk of significant neurocognitive effects and the potential for suicidality. There is also a dose dependent risk of seizure with the drug. Passenger The 58-year-old passenger reported no significant conditions or medications to the FAA. The Coroner's Division of the Office of the Sheriff - Contra Costa County, California performed an autopsy of the passenger. The autopsy cited the cause of death as multiple blunt force injuries. The autopsy was inconclusive for significant natural disease due to the level of trauma. NMS Labs performed toxicology testing at the request of the coroner and identified 0.074 gm
A loss of airplane control for reasons that could not be determined due to the extensive impact and fire damage to the airplane.
Source: NTSB Aviation Accident Database
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