Preliminary Reports

Post-reception Crash Kills Newlyweds and Pilot

Bell 206B, Nov. 4, 2018, Uvalde, Texas—Twenty-four-year-old newlyweds Will and Bailee Ackerman Byler were killed when the helicopter transporting them from their wedding reception hit the top of a hillside five miles east of the venue. Pilot Gerald Green, a 76-year-old ATP with more than 24,000 hours of flight experience, also died in the crash. The flight was the first leg of the couple’s honeymoon, taking them to San Antonio to board an airline flight. The accident site was about 100 feet below the top of a 1,450-foot hill. Skies were clear with at least 10 miles’ visibility but no moon. 

Freighter Pilot Incapacitated by Carbon Dioxide

Cessna 208B, Nov. 23, 2018, Bakersfield, California—Improperly packed dry ice appears to have caused a Federal Express feeder pilot to lose consciousness while awaiting takeoff clearance. The airplane’s cargo of 41 large boxes included a combined 36 kg (80 pounds) of dry ice, well below the limit of 76 kg (167 pounds)  established by FedEx for its Caravan fleet, and the shipment was signed off by the company’s dangerous goods representative on that basis.

After starting the airplane and taxiing to Runway 30R, the pilot experienced “strong sleepiness” and difficulty breathing; he stopped the airplane in the run-up area and closed his eyes. After he failed to respond to communications from air traffic control for some 25 minutes, he was revived by a firefighter who found him “with his head rolled back and his mouth open.” The firefighter shut down the airplane’s engine and electrical system. The pilot was taken to a hospital after regaining enough coherence to climb out of the airplane unassisted.

The responding FAA inspector found “numerous boxes labeled ‘Dry Ice’ positioned behind the pilot and stacked to the ceiling of the upper cargo pod.”  The refrigerated cargo was inside thermal bags filled with dry ice pellets; “the bags were loosely closed and taped.” 

Six Fatalities in Brazilian Mountains

Agusta AW109SP, Nov. 24, 2018, Itapeva Peak, Campos de Jordão, São Paulo, Brazil—A helicopter belonging to the pharmaceutical company Cristália disappeared on a flight from Itapira to Campos de Jordão. An emergency locator transmitter signal helped firefighters locate the wreckage in a forest near the peak of Itapeva about eight hours after its expected 11 a.m. arrival time. There were no survivors. 

In addition to pilots Antonio Landi Neto and Juliano Martins Perizato, the six casualties included board vice chairman Kátia Stevanatto Sampaio and her husband Paulo, architect Leticia Telles, and builder Ronoel Sholl. Weather conditions in the area were described as having been rainy, foggy, and windy for most of the day.

Interim and Factual Reports

Landing Excursion Involved Bald Tires, Wet Runway

Learjet 25, Sept. 22, 2016, San Juan, Puerto Rico—The Venezuelan-registered Learjet that ran off the left side of San Juan’s Runway 9 had no measurable tread on three of its four main gear tires, according to an NTSB factual report. Tread on the right outboard tire was measured at 1.17 mm (less than 0.05 inches). 

Following a “smooth” touchdown, the airplane began to hydroplane as it slowed through 80 knots and veered into the grass off the left side of the runway. As it crossed the intersecting taxiway the left main gear collapsed, causing the airplane to spin 180 degrees and come to rest in the grass. There were no injuries to either of the two pilots or the single passenger.

A U.S. Customs agent interviewed by investigators reported heavy rain at the time. The passenger said it was raining “profusely,” with two to four inches of standing water on the runway and taxiway.   

Overtorqued Nut Implicated in Leicester FC Helicopter Accident

Agusta AW169, October 27, 2018, Leicester, United Kingdom—The failure sequence that caused the helicopter to crash moments after takeoff was apparently initiated by excessive torque on the castellated nut at the actuator end of the tail rotor actuator control shaft. Leicester City FC owner Vichai Srivaddhanaprabha, two pilots, and two members of his staff were killed when the aircraft went down just outside Leicester’s football stadium.  In a Special Bulletin published on December 6, Britain’s Air Accidents Investigation Branch detailed the results of its examination of the helicopter’s tail rotor drive system, which determined that separation of the shaft from the actuator lever mechanism rendered the aircraft uncontrollable.

The shaft is normally fastened to the lever mechanism by a connecting pin and pin carrier held in place by a castellated nut secured with both a split (cotter) pin and safety wire. The nut and the pin carrier, originally separate components, were found loose in the tail cone friction-welded together; there was no evidence of the cotter pin. Its remains were subsequently found in the threaded end of the control shaft. The threads of both shaft and nut were undamaged. The corresponding nut at the opposite end of the control shaft “was found to have a torque load significantly higher than the assembly value,” and the associated duplex bearing was without grease and jammed by metallic particles. The bearing cages were fractured and the inner surfaces of the races showed significant damage, particularly the inboard race. Burned grease and heat discoloration were visible on the bearing end of the shaft.

As reconstructed by the AAIB, the failure sequence began with frictional heat welding the overtorqued nut at the shaft’s actuator end to the pin carrier, shearing the cotter pin. This allowed the tail rotor actuator control shaft to rotate in its housing, effectively unscrewing itself from the nut until contact between the shaft and lever was lost.

An Alert Service Bulletin prescribing procedures for one-time precautionary inspections of AW169s was issued by the manufacturer on November 5 and extended the following day to the AW189 series, which uses a similar tail rotor control system. Those inspections were made mandatory by an EASA Airworthiness Directive issued on November 7. Subsequent Emergency ASBs issued on November 21 and 30, first for expanded one-time and then for repetitive inspections of the castellated nuts and duplex bearings, were also made mandatory by concurrently issued ADs.

Final Reports

Gear Collapse Traced to Stuck Valve, Procedural Error

Piaggio P180 Avanti II, Jan. 31, 2014, Springfield, Illinois—After a metal particle of unknown origin jammed the directional valve in the landing gear’s hydraulic system in the “gear up” position necessitated an emergency gear extension, the pilot’s decision to re-engage the airplane’s hydraulic system allowed the gear to retract at the end of the landing roll.  In its finding of probable cause, the NTSB noted that the airplane’s flight manual required the hydraulic system to be turned off before a manual gear extension and “did not include a provision for the hydraulic system to be re-engaged” afterwards. 

The pilot acknowledged having reactivated the hydraulics to have the use of power-assisted brakes and nosewheel steering while landing on a snow-covered runway.  However, during the landing roll the nosewheel steering remained inoperative and the brakes were only marginally effective. Investigators were unable to determine whether the gear retracted because the pilot moved the emergency gear selector valve back to the gear-up position (which he denied) or because line pressure in the emergency hydraulic system dropped below the threshold required to prevent the down locks from releasing. There were no injuries to any of the five on board.

Fuel Contamination Brings Down R66

Robinson R66, Nov. 14, 2016, Hokonui Hills, Southland, New Zealand—A loss of main rotor rpm has been attributed to contaminated fuel, but the exact source of the contamination remains unclear. The pilot responded to a low-rpm warning at an altitude too low to accommodate normal recovery techniques by attempting a run-on landing into a recently plowed field. The helicopter bounced and pitched forward, breaking the main rotor blades and severing the tail boom. The engine continued to run until the pilot shut it down; he escaped with minor injuries.

The Transport Accident Investigation Commission (TAIC) found partially dissolved fine sediment in the engine fuel pump filter housing, fuel hose assembly, and engine fuel nozzle. However, no contamination was found in the helicopter’s main fuel tanks or the series of vehicles and transport tanks used by the operator to refuel the aircraft in remote locations. Analysis by the Defence Technology Agency determined that the particles were primarily “silicon and aluminium with varying quantities of other metal elements…[whose] appearance and composition…strongly suggest that they are an aluminoslicate clay material. Clays are common components of most soils.”

Investigators identified a number of routes by which contaminants might have entered the fuel system, including the filler nozzle on the support truck, the flush-mounted filler port located adjacent to the step used to inspect the main rotor head, and a filler spout stored under that step.  The operator frequently performed “hot refueling” with the engine and main rotor turning in dusty environments. 

While the accident helicopter was conducting spray operations, the TAIC noted that similar contamination risks apply in any operation involving remote refueling via an extended supply path.

Runway Excursion Caused by Engine Oil Leak

Fairchild SA227 Metro III, Nov. 2, 2017, Winnipeg, Manitoba –Steady leakage past a faulty air-oil seal in the left engine allowed oil pressure to drop below the level required to operate the propeller governor, causing the twin-engine turboprop to veer off the right side of the runway during the landing roll. The two pilots suffered minor injuries. 

Near the end of a ferry flight from Manitoba’s God’s River Airport, the crew noted the low-pressure warning but, after consultation with company maintenance, chose not to shut the engine down rather than risk a single-engine approach and land without hydraulic steering.  The TSB report noted that this was contrary to the quick reference handbook’s procedures for low oil pressure indications, and recommended that Transport Canada review the corresponding emergency procedures in the airplane’s flight manual.