Business Aircraft Accident Reports: February 2023

 - February 1, 2023, 10:11 AM

Preliminary Reports

Two Killed in Nebraska Approach Accident, Piper PA-46-500TP, Nov. 9, 2022, Bignell, Nebraska

The 505-hour pilot and his sole passenger were killed when their single-engine turboprop slammed into the bank of an irrigation reservoir during an attempted ILS approach to Runway 30 of the North Platte Regional Airport. Prevailing weather included three-mile visibility under a 300-foot overcast and an eight-knot crosswind from 030 degrees. Airmets were in effect for IFR conditions and low-level wind shear, but not icing. The Part 91 business flight originated in Lincoln, Nebraska, at 8:32 local time, climbing to a cruising altitude of 16,000 feet.

The pilot requested the ILS approach to Runway 30 after checking in with Denver Air Route Traffic Control Center (ARTCC). The controller issued an initial vector of 230 degrees and cleared the flight to descend to 7,000 feet with a right turn to 280 degrees, followed by a descent to 5,000 feet and clearance for the approach with instructions to maintain 5,000 feet until established on the localizer. In the same clearance, without waiting for a readback, the controller told the pilot to change to the North Platte advisory frequency and report cancellation of his instrument flight plan. By the time a controller position change had been completed, radar contact had been lost and the relieving controller reported the flight overdue. At about that time, a resident three miles southeast of the airport called the local fire department to report smoke rising from a field. The debris field was just 50 feet in diameter.

ADS-B position data showed that during the last minute of the flight, its rate of descent increased from 500 feet per minute (fpm) to 3,000 fpm, reversed to a 2,000-fpm climb, and then abruptly entered a 5,000-fpm descent. The flight instructor who’d trained the pilot in the accident airplane said that he’d purchased it about three weeks earlier and received 10 hours of ground instruction and 15.1 hours in the cockpit. The pilot’s logbook, recovered from the wreckage, showed that he claimed 24.5 hours in the accident airplane with a career total of just 5.2 hours of actual instrument time, 1.0 of which came in high-altitude instruction during his transition training.

Autopilot Malfunction Suspected in Rescue Crash, Fairchild SA227-AT, Nov. 15, 2022, Pewaukee, Wisconsin

A Part 135 charter transporting 53 crated rescue dogs came down on a golf course after the pilots responded to a discrepancy between the autopilot and flight director. Only minor injuries were reported to the two pilots and several dogs. Volunteers responded quickly, transporting people and dogs alike to shelter.

The flight from New Orleans was inbound on a coupled ILS approach to Runway 10 at Waukesha County Airport. The autopilot appeared to capture the localizer and glideslope, but the pilots noticed that the flight director indicated a climbing right turn. When they disconnected the autopilot to continue the approach manually, the airplane immediately rolled right. Both pilots got on the controls, succeeded in leveling the aircraft, and increased power, but it struck the ground in a nearly wings-level attitude. Both wings were separated by collisions with trees before it came to rest.

In-flight Break-up Claims Four, Cessna 208B Grand Caravan EX, Nov. 18, 2022, Snohomish, Washington

The four members of a flight-test and data collection team were killed when the Caravan’s right wing detached during a series of planned maneuvers. The accident took place on the third day of baseline data collection in support of an initiative to expand a supplemental type certificate (STC) for a Cessna 208B drag-reduction system. The purpose of the accident flight was to complete the previous day’s test card recording the airplane’s stall behavior at an aft center of gravity, which had been suspended when one of the crew members began to feel ill.

The right-seat pilot from the previous day, who was not on board the accident flight, reviewed radar track data and surmised that the crew was likely performing the next-to-last scheduled maneuver, a 30-degree left bank at 96 knots indicated airspeed with landing flaps, prop full forward, and the engine producing 930 foot-pounds of torque.

The radar track showed that the flight departed Renton, Washington, at 9:25 Pacific time, climbed to 9,700 feet, and for about 45 minutes performed a series of maneuvers between 6,500 and 10,275 feet. At 10:17 it returned to 9,700 feet and began turning left. At 10:19, after a nearly 360-degree turn, the track made a sharp left 180-degree turn and began descending at an initial rate of 14,000 feet per minute, which decreased to 8,700 fpm at the last radar hit. Witnesses described seeing a plume of white smoke when the airplane broke up, and security camera footage recorded it spinning down in a nose-low attitude.

The debris field spanned 1,830 feet of a grass farm field. The right wing was found 580 feet from the main wreckage with its strut still attached; fragments of the right flap were scattered through the debris. The left wing was separated but adjacent to the fuselage with its flap retracted.

Final Reports

Multiple Shortcomings Revealed by B.C. Helo Investigation, Bell 206B, Sept. 24, 2019, Campbell River, British Columbia, Canada

Though the immediate cause of the accident was an in-flight deformation of a main rotor blade following an apparent disruption of engine power, the Transportation Safety Board (TSB) investigation also identified significant discrepancies in the operator’s installation of a replacement engine, testing and approval of aftermarket main rotor blades, and Transport Canada’s medical certification procedures. The TSB also called out serious deficiencies in the operator’s safety culture. The 16,200-hour commercial pilot was killed when the helicopter descended vertically into a building less than four minutes after taking off on a planned 22-nm flight to deliver supplies to a client’s cabin.

The flight departed the operator’s base at 11:00 local time on an easterly heading, turning southeast and climbing to 615 feet after crossing the coastline. At 11:02:50 it began to descend at a rate of 400 fpm and 87 knots groundspeed, accelerating to 92 knots and turning right at an altitude of 417 feet. After climbing to 620 feet during the turn, it began descending at an initial rate of 1,950 fpm and 63 knots groundspeed. During the next nine seconds groundspeed dropped to 54 knots. The helicopter departed controlled flight at an altitude of 200 feet and the main rotor struck the tail boom, separating a section of the tail boom cover. Surveillance camera footage showed that the main rotor blades were bent or deformed and not turning during its final descent, and metallurgic examination of engine debris was consistent with a flame-out prior to impact.

The 1981-model helicopter was imported to Canada from South America in 2017 and underwent extensive maintenance and refurbishment, including installation of a replacement Rolls-Royce M250-C20B engine that had previously been installed in a Hughes 369 and then a Bell 206B3. The replacement engine was fitted with a Bendix fuel-control system that included one three-cubic-inch and one six-cubic-inch accumulator but no double check valve. The engine installation manual called for two six-cubic-inch accumulators with a double check valve to “dampen fuel system instability due to torsional vibrations inherent in the two-bladed rotor system of the Bell 206 series of helicopters.”

Company records showed that on September 18, the same pilot had to compensate for a 20 percent reduction in main rotor rpm. Following inspection of the fuel system and an uneventful test flight, maintenance personnel contacted Textron, learned that the existing fuel system configuration was incorrect and ordered replacement parts.

They arrived the day of the accident but had not yet been installed, and the company’s chief pilot had advised his colleagues that the helicopter was unairworthy in the interim. However, the accident pilot, who was one of the operator’s corporate officers, nevertheless chose to dispatch it for the short flight. Neither the troubleshooting work nor the test flight were recorded in the aircraft’s journey log as required by regulation.

In January 2019, the original aluminum main and tail rotor blades were replaced by composite blades manufactured under a U.S. STC subsequently approved by Transport Canada. The investigation found damage to both blades with “characteristics of different failure mechanisms, namely fiber breakage, ply separation, delamination, and debonding.” Microscopic examination of the debris concluded that one main rotor blade had sustained significant undetected fatigue damage prior to the accident. The fatigue testing performed during the certification process relied on the “no-growth” standard of showing that damage sustained in service will not propagate before the component is retired. However, the blade manufacturer’s threat assessment “contained little quantitative assessment and stress/load data recorded” to determine the extent of damage arising from flaws assumed to be either pre--existing, or incurred at random locations, according to the TSB. The observed damage to the accident main rotor blades included a V-shaped fracture suggesting in-flight overstress from alternating torsional loads.

Post-mortem examination of the pilot found more than 75 percent obstruction of all four major coronary arteries. The pilot, whose age was given only as “more than 70 years,” had not advised his Civil Aviation Medical Examiners of several factors relevant to his physical fitness to fly, including elevated blood glucose and cholesterol, his use of more than one anti-hypertensive medications, and elevated liver enzymes.

He was known to be a smoker and overweight, and ascribed persistently elevated blood-pressure readings to “white-coat syndrome,” the tendency for anxiety to increase blood pressure during a medical exam. The TSB concluded that his risk of an incapacitating medical event was more than 5 percent per year, but that there was no direct evidence that incapacitation contributed to the accident.