Preliminary Reports
Fuel Starvation Implicated in King Air Crash
Beech King Air C90, July 26, 2018, Lecanto, Florida—A mechanic found about 30 gallons of fuel in each of the airplane’s wing tanks but none in the nacelle tanks that directly feed the engine, according to the NTSB's preliminary report. While the airplane returned to its base at the Williston, Florida Municipal Airport following brake-system maintenance at the Brookville-Tampa Bay Regional Airport, its left engine surged in the vicinity of the Crystal River Airport. The pilot entered a “wide right downwind” for Crystal River’s Runway 27 while attempting to troubleshoot the problem; however, the left engine stopped during the turn to base and the right engine lost power while turning final. Unsure of the airplane’s ability to glide to the runway, he chose to make a forced landing in a field where the right wing struck a tree during the landing roll. The solo pilot was uninjured.
He reported having added 20 gallons of fuel to each wing tank before departing on the 53-nautical mile flight but subsequently flying a more circuitous route to avoid scattered thunderstorms lingering in the area. The FAA inspector who responded to the scene advised that in this model, fuel moves from the main tank in each wing to a smaller tank in the engine nacelle, and thence to the engine. Gravity maintains sufficient fuel flow until the quantity in the main tanks drops to around 28 gallons, after which it’s necessary to activate electric transfer pumps. The mechanic who examined the airplane found the transfer pumps off; when activated, fuel flowed normally from the wing to the nacelle tanks.
Swiss Authorities Cite Apparent Spin in Tri-Motor Tragedy
Junkers Ju-52/3mg4e, Aug. 4, 2018, Piz Segnas, Switzerland—A brief preliminary report by the Swiss Transportation Safety Investigation Board suggests that the 1939-model Junkers tri-motor entered a spin after initiating a left turn over the basin southwest of Piz Segnas. All three crewmembers and 17 passengers were killed when the vintage airliner hit the western slope of the mountain at an elevation of 2,540 meters (8,330 feet) in a near-vertical descent. The pilots, aged 62 and 63, were former airline captains with more than 30 years’ experience as Swiss Air Force reservists and “hundreds of hours” in the Ju-52. Switzerland, like much of northern Europe, was in the grip of a heat wave at the time, with temperatures as high as 35 degrees Celsius (95 Fahrenheit) reported at lower elevations, and unofficial reports suggest the possibility of strong, gusty winds in the vicinity.
This was the first fatal accident and only the second accident of any kind in the 35-year history of operator Ju-Air, which has offered charter and sightseeing flights in a fleet of vintage Ju-52s since 1983. (A landing undershoot in 1987 caused aircraft damage but no serious injuries.) After voluntarily suspending operations during the early phase of the investigation, Ju-Air was allowed to resume flights on August 17 under conditions including higher minimum cruise altitudes, installation of GPS-based data recorders, and a requirement that all passengers and crew remain belted in throughout the flight.
Nine Fatalities Confirmed in Rescue Helicopter Wreck
Bell 412EP, Aug. 10, 2018, near Mount Yokote, Gunma Prefecture, Japan—A rescue helicopter carrying seven public employees plus a pilot and mechanic working for the aircraft operator hit trees while inspecting mountain trails in central Japan. The trails were scheduled to be opened to hikers the following day. Rescue efforts ultimately involving about 160 people, including police officials and members of the Self-Defense Forces, reached the site on foot the following morning and found no survivors. Witnesses reported that the helicopter had been flying extremely low, with one also citing “unusual” engine sounds.
The casualties included two members of a prefectural disaster management unit and five firefighters. The helicopter, which was owned by the prefectural government, was operated under contract by Tokyo-based Toho Air Service, which also conducts scheduled commuter flights as well as on-demand construction, conservation, and news-gathering missions. Four Toho employees were killed in the November 2017 crash of an Airbus AS332L, also in Gunma Prefecture.
Caravan Collides With Cow
Cessna 208B, Aug. 26, 2018, Pieri Airport, South Sudan—No human injuries were reported after the airplane struck a cow that wandered onto the grass runway during the Caravan’s takeoff roll. Scene photographs show extensive damage forward of the firewall, including collapsed nose gear, near-complete destruction of the propeller and cowlings, and crushing of the engine and accessories. The purpose of the flight has not been reported, but there were no initial reports of passengers on board.
This was the airplane’s second collision with a large animal. Almost exactly seven years earlier, on Sept. 8, 2011, it struck a Topi antelope during the landing roll at Kenya’s Musiara Airport. Damage in that incident was considered minor and the airplane was returned to service.
Final Reports
Air-tour Engine Failure Traced to Fuel-p ump Spacer
Bell 206, April 4, 2016, Pigeon Forge, Tennessee—The loss of engine power that caused an air-tour helicopter to crash onto a forested ridgetop, killing the pilot and all four passengers and igniting a significant wildfire, was triggered by lubrication failure along the splined drive shaft that operated the engine’s fuel pump. The NTSB ound that an incorrectly sized spacer allowed grease to escape from the drive gear-drive shaft junction, resulting in severe wear to both components. The Board was unable to determine whether that spacer was installed during the fuel pump’s previous overhaul, conducted some eight years and 1,078 flight hours prior, or earlier.
Eleven different thicknesses of spacers are available; according to the maintenance manual, the choice is determined by measurements made during the shaft-to-pump assembly process. The installed pump was about twice the thickness of that installed when the pump was manufactured and showed evidence of frictional damage.
The NTSB was unable to determine why the pilot was unable to make an autorotative landing but cited the helicopter’s certification and operation without a crash-resistant fuel system as having contributed to the subsequent fire.
Air Ambulance Crash Attributed to Spatial Disorientation Following Autopilot Disconnect
Pilatus PC-12, April 28, 2017, Amarillo, Texas—The catastrophic crash of an air-ambulance flight just after takeoff was caused by the pilot’s spatial disorientation after the autopilot disengaged in instrument conditions during climb. In a finding of probable cause, the NTSB noted that while turbulence might have imposed accelerations in excess of the unit’s 1.6g load limit, the accident airplane also had a documented history of unexpected autopilot disconnects. The pilot and two medical crewmembers were killed when the airplane crashed a mile and a half from the airport while descending at 17,000 fpm. The flight was intended to pick up a patient in Clovis, New Mexico, for transport to Lubbock, Texas.
The airplane took off at 11:44 p.m. using the transponder code assigned on its previous flight. The pilot leveled off between 800 and 1,000 feet above ground level after being alerted to this by the tower controller, then resumed climbing after the controller acknowledged radar contact with the correct code. After being handed off to departure control, the pilot transmitted “with you at 6,000” (2,400 feet above the ground), then disappeared from radar less than a minute later. Investigators found stretched filaments indicating that the “autopilot disengage” caution indicator was illuminated at the moment of impact, suggesting that the disconnection had occurred within the preceding 30 seconds (after which the caution light would have automatically extinguished).
Performance studies incorporating airport surveillance radar data, weather observations, and measurements at the accident site estimated that the PC-12 rolled out of a 42-degree right bank at 4,100 feet msl, reaching a pitch attitude of 23 degrees nose-up to climb at 6,000 feet per minute. After briefly stabilizing, it rolled into a left bank that reached 76 degrees while pitching 42 degrees nose-down. A simulation of the loads imposed on the pilot’s vestibular system during these events found that the “apparent” pitch attitude would have remained between zero and 15 degrees, while the “apparent” roll attitude would have stayed within five degrees of neutral.
Descriptions of flight conditions by other crews operating in the area varied widely. Several reported no or light turbulence, while the pilot and first officer of a Boeing 737 described moderate to heavy turbulence during their climb. The operator’s maintenance staff had attempted to address instances of unanticipated autopilot disconnection on two occasions in 2017, replacing the autopilot computer on March 2 and the autopilot trim adapter on April 26, two days before the accident, and the same day that footage of an unexpected disconnect was captured by the operator’s chief pilot.
Company procedure was to engage the autopilot at or above 1,000 feet above ground level. The 57-year-old pilot had flown 5.9 hours IFR, 2.6 of them at night, since completing an instrument proficiency check on Dec. 21, 2016.
No Injuries After Citation Compressor Failure
Cessna Citation 560, Jan. 26, 2018, 185 miles north of Brisbane, Queensland, Australia—The aircraft landed safely after “a loud noise from the rear of the airplane” and the smell of smoke prompted the crew to issue a PAN-PAN call and request an immediate descent and return to Brisbane. Two pilots and six passengers were on board the flight to Townsville, Queensland, operated by the Queensland state government’s Public Safety Business Agency.
Borescope examination and a tear-down found that one blade had separated from the low-pressure boost rotor of the left engine’s cold section, lodging in the trailing edge of the front inner low-pressure compressor stator. The failure was traced to fatigue cracks, with no evidence of any foreign object impact. The failed rotor was original to the engine, which had flown for 3,126.6 hours and 3,122 flight cycles since its manufacture in 2001. In 2009 it was reworked in accordance with the manufacturer’s Service Bulletin 7595, intended to reduce the risk of this type of failure. The engine had been operated for 27.2 hours since being installed on the incident aircraft on Oct.25, 2017.