Preliminary Reports
Nine Fatalities in Dominican Gulfstream Crash
Gulfstream GIV-SP, Dec. 15, 2021, Santo Domingo, Las Americás International Airport, Dominican Republic - All nine on board were killed when the airplane went down during an attempted emergency diversion to the Santo Domingo--Las Americás International Airport shortly after departure from the La Isabela airport in Higuero. Initial accounts indicate that one of the two pilots reported an unspecified problem with the aircraft when requesting the diversion. The other victims were alternately described as either seven passengers or six passengers and a flight attendant. The chartered jet’s intended destination was Orlando (Florida) International Airport. As of this writing, details of the nature of the in-flight anomaly have not been disclosed.
Caravan Destroyed in Texas Mid-air
Cessna 208B, Dec. 21, 2021, near Fulshear, Texas - Both pilots were killed and both aircraft destroyed when a scheduled cargo flight from Houston’s Bush Intercontinental Airport to Victoria, Texas, struck a powered paraglider about 50 miles southwest of its point of departure. Witnesses reported seeing the Caravan in a near vertical nose-down descent; the owner of the property where it crashed described it bouncing up 30 feet after impact. Media photographs confirm the near-total destruction of the Caravan, while “deputies later recovered part of the [paraglider’s] equipment nearly 10 miles away.” As of this writing, the NTSB has not released its preliminary report.
Four Fatalities in Air Ambulance Approach Accident
Learjet 35A air ambulance, Dec. 27, 2021, El Cajon, California - A Learjet air ambulance crashed onto a residential street in El Cajon while maneuvering to land on Runway 27R at Gillespie Field, killing both pilots and both flight nurses on board. The aircraft was returning to base at the end of a short positioning flight after delivering a patient to Santa Ana-John Wayne International Airport in Orange County. The accident occurred at 19:14 local time, nearly two and a half hours after sunset and two hours after the end of civil evening twilight. Prevailing weather at the airport included 3 miles visibility in mist and a broken ceiling at 2,000 feet; archived radar imagery shows rain showers in the vicinity. No ground injuries were reported, though power lines were knocked down and the post-crash fire damaged one house and a vehicle.
After executing a GPS approach to the 4,145-foot Runway 17, the pilot requested an overhead visual approach to 5,342-foot Runway 27R. The tower controller instructed him to cross the airport to the south and enter a left downwind, then cleared the Learjet to land. Radar track data archived on FlightAware show that the circling maneuver was flown at altitudes of 725-775 feet msl, less than 400 feet above the airport’s elevation of 388 feet. The pilot asked the tower controller to turn up the runway lights and was told they were already at 100 percent. About 75 seconds after receiving the clearance, the pilot was heard “cursing and then screaming.” The jet entered a steep descent in the vicinity of the base-to-final turn.
Final Reports
Error Deemed Likely in Norwegian Gear-up
Beeechcraft 200 Super King Air, April 9, 2018, Stavanger-Sola Airport, Norway - A King Air 200 transporting medical isotopes to a hospital landed gear-up, causing damage to the airplane’s nosewheel, fuselage skins, both propellers, and the trailing edges of both flaps. No one was injured. The crew reported a slight left bank after touchdown, to which the captain responded by touching the gear handle to make sure it was down. He later acknowledged having “retracted the handle in a reflex action,” then quickly placing it down again.
The crew claimed that this resulted in the landing gear retracting after touchdown, but investigators failed to find corroborating evidence. They concluded that the landing gear was either in transit or completely retracted during the landing.
Overlooked Exhaust Damage Leads To Engine Failure
Garlick Helicopters UH-1H, April 17, 2018, Talbingo, New South Wales, Australia - Multiple fractures of the exhaust diffuser’s inner struts due to high-cycle metal fatigue caused a sudden engine failure during an external load flight, requiring the pilot to make a forced landing into trees. No one on the ground was hurt, but the pilot suffered serious injuries that were likely made more severe by his not having used the helicopter’s upper-body restraints. A post-accident teardown by Honeywell, the engine’s manufacturer, found that “the exhaust diffuser cracking and material loss from the inner core would have been visible during the most recent Phase Inspection performed 20.8 hours before the accident. Visual indications of cracking were likely present during the preceding phase inspection(s) as well.” After reviewing the helicopter’s maintenance records, the Australian Transport Safety Bureau (ATSB) concluded that the cracking went undetected through at least two scheduled phase inspections performed by licensed aircraft maintenance engineers (LAMEs) and no fewer than 34 daily preflight inspections conducted by four different individuals.
The accident occurred on the twelfth in a series of brief long-line flights (about five minutes round trip) to move components of a disassembled drill rig used in geotechnical survey work in support of a proposed hydroelectric project. Following a brief hold while the ground crew prepared the drill rig motor for lifting, the pilot began “a very slow approach” to the lift site, only to be advised that additional time was needed to check the rigging. To minimize rotor wash on the ground crew, he began to climb. Downloaded GPS data showed that the helicopter had reached an altitude of 200-250 feet agl at an airspeed of 20-25 knots when “the pilot heard a loud mechanical ‘screaming’ noise and started planning for a forced landing.” An audible alarm was followed by the yaw accompanying power loss. Witness reports of smoke emanating from the engine bay were confirmed by ground-based cameras at the site.
To avoid endangering ground personnel near the site’s helipad, the pilot instead made an autorotative approach to the Yarrangobilly riverbed to the southwest, jettisoning the hoist line and then flaring as the helicopter reached the trees. The helicopter came to rest nose-down on the riverbank. Members of the ground crew extinguished a small fire in the engine bay, extricated the pilot, and administered first aid until emergency responders arrived on the scene. The pilot subsequently confirmed he could not maintain the necessary view of the ground while wearing the aircraft’s upper torso restraints—a point confirmed by a survey of other Australian vertical reference pilots—and the ATSB confirmed that the nature of the mission required operating the helicopter in the “avoid” region of its height-velocity diagram.
The exhaust diffuser’s inner struts are critical engine components supporting the rear of the power turbine assembly via the number 3 and 4 bearings. Failure of the struts allowed the power turbine to move aft far enough for the rear tapered section of the power turbine’s drive shaft to make contact with the rear shaft of the compressor assembly, which rotated in the opposite direction. The resulting friction and deformation of the rear compressor shaft then brought the compressor assembly into contact with the walls of the engine case, causing catastrophic engine failure. Following the accident, the operator’s maintenance contractor was acquired by another company that instituted computer--based trend maintenance and improved vibration testing. A joint hazard assessment by the site and helicopter operators also formalized risk management practices for mountain flying and external lift operations, including assuring access to emergency landing sites.
Engine Fire Traced to Incorrect Lock Washer
Airbus Helicopters AS355F1, Bourne End, Buckinghamshire, United Kingdom, March 2, 2021 - Failure to replace the serrated lock washer supplied with the clamp with the correct folding-type lock washer called out under a separate part number led to the fracture of the V-band clamp securing the right engine’s inboard exhaust nozzle. The nozzle then separated from the engine’s exhaust collector and became lodged in the fuselage’s exhaust duct, blocking it and diverting exhaust gases back into the engine bay and cowling. Subsequent examination found that several of the teeth on the serrated lock washer had broken, allowing the clamp to loosen; fracture signatures on its bracket were consistent with low-load, high-frequency propagation of a pre-existing fatigue crack.
The helicopter was working on a film set. The day’s shooting began with several takes of a ground shot in which an actor boarded the ship with the engines running. Only the left engine was started for this sequence, and it was then shut down while the pilot and film crew prepared for an aerial filming sequence. After restart, recorded images show some smoke drifting from the exhaust duct with the helicopter on the ground, intensifying as power was increased for takeoff. Shortly after it lifted into a 20-foot hover, the film crew’s aerial coordinator radioed the pilot to advise of smoke emanating from behind the cockpit. Though engine indications remained normal, the pilot made an immediate precautionary landing, shutting down both engines as the aerial coordinator reported that the smoke was increasing.
Flames became visible 10-15 seconds later and the pilot reacted to the FIRE RH warning light by discharging the right engine’s fire bottle, which extinguished the flames. The right engine and gearbox had been removed, repaired, and reinstalled 2.6 flight hours earlier due to elevated chip detector readings. Follow-up inspection found that the right engine’s vibration level was close to its service limit due to damage to the compressor module bearings, and it was subsequently replaced. Excessive vibration was cited as a likely factor in the clamp’s failure. The manufacturer responded by clarifying the helicopter’s maintenance manual, to explicitly require installation of the correct washer.