N62069Beech U-8F

On June 16, 2021, at 1905 mountain daylight time, a Beech U-8F airplane, N62069, was substantially damaged when it was involved in an accident near Goodland, Kansas. The pilot sustained minor injuries. The airplane was operated by Bemidji Aviation Services Inc. as a Title 14 Code of Federal Regulations Part 135 cargo flight.

The pilot stated that, while starting the right engine, he heard a loud bang and noticed flames coming out of the right wing. An airport surveillance video captured flames from the right wing for about 1 second. The pilot shut down the right engine with the mixture control and egressed the airplane.

Examination revealed that the outboard 12 ft of the right wing was heavily damaged, with the forward spar deflected significantly aft and the right-wing leading edge curled aft. The outboard aft fuel bladder for the right wing was removed and observed to be in a degraded condition, with indications of fire damage. Electrical wiring to the navigation light was chafed and conductor was exposed in two locations. The outboard aft fuel bladder and wiring bundle from the right wing were both submitted to the National Transportation Safety Board Materials Laboratory for examination.

The fuel bladder was constructed of nitrile butadiene rubber and was brittle in several areas, with multiple holes. A sample from the edge of one of the holes examined using a Fourier Transform Infrared spectrometer indicated degradation due to oxidation, with the embrittlement consistent with physical aging of the bladder material.

The right wing wire bundle contained several areas where the insulation for the wires was chafed. One chafed area of the wiring for the navigation lights showed evidence of electrical arcing and welding. Electrical damage to the conductor surface indicated that the wire was energized at the time the damage occurred.

The operator maintained the airplane with a maintenance manual accepted by the Federal Aviation Administration. The manual contained a continuous care inspection guide that required a routine inspection of the entire airplane every 60 flight hours, as well as eight more detailed inspections of specific portions of the airplane every 480 flight hours.

On May 22, 2021, about 50 flight hours before the accident, a detailed inspection occurred that required following areas be checked:

1) Fuel Tanks, Vents, and Pumps – Check cells for leaks, plugged vents, pumps for leakage.

2) Fuel Caps and O-Rings – Check fuel caps and O-rings for fit and seal.

3) Fuel Quantity Transmitters – Check for leakage or visible damage.

4) Plumbing – Check for chaffing, leakage and damage, and proper attachment.

5) Electrical Wiring and Equipment – Check for security, chaffing damage and attachment.

On July 9, 2019, the airplane was involved in a similar accident that the NTSB investigation attributed to an explosion of the outboard left wing due to electrical arcing and ignition of fuel vapors. Following the most recent wing explosion accident, the operator instituted several maintenance protocols to aid in detection of a fuel leak, including top-off of the fuel system in conjunction with the wing inspection procedure checklist or unscheduled fuel system maintenance.

On July 9, 2019, about 0813 mountain daylight time, a Beech 65 airplane, N62069, experienced a left wing explosion during takeoff roll from the Sidney Municipal Airport (SNY), Sidney, Nebraska. The airline transport pilot was not injured, and the airplane sustained substantial damage to the left wing. The airplane was registered to and operated by Bemidji Aviation Services, Inc., as a Title 14 Code of Federal Regulations Part 91 positioning flight. Day instrument meteorological conditions prevailed at the time of the accident, and an instrument flight rules flight plan was filed. The flight was originating from SNY, and destined for Denver, Colorado.

According to the operator, the pilot had topped off the outboard fuel tanks prior to departure, and the airplane contained about 230 gallons. While taxiing and advancing the engine throttles, the stall warning horn sounded so he pulled the circuit breaker as a corrective action which stopped the stall warning horn. The pilot thought the stall warning horn was in error and no further action was taken before the takeoff. During the takeoff roll, the pilot heard a loud bang and observed significant damage to the outboard left wing. Initially he thought maybe the airplane struck an animal, or the airplane impacted a pothole on the runway. While taxiing back to the ramp, the pilot noted a small amount of smoke coming from the top of the left wing. The pilot taxied the airplane to the corner of the ramp, performed an abbreviated shutdown of the airplane, grabbed a fire extinguisher, and evacuated. The pilot did not observe any additional smoke or fire and did not discharge the fire extinguisher.

Postaccident examination of the airplane by a Federal Aviation Administration inspector and personnel from the operator revealed fire and thermal damage near the wing root area to include melted and burned wiring. After the accident as a precaution, the airplane was defueled by the operator, and in order to determine if a fuel leak was present, fuel was added to the outboard left wing during the examination. After fueling with 15 to 25 gallons of fuel, fuel began leaking from the top of the left wing fuel sending unit. Safety wire on the fuel sending unit screws was removed, and the fuel sending unit screws were found loose. The screws were tightened and fuel stop leaking from the sending unit. A hole was cut in the wing skin to examine the melted and burned wiring. A wiring harness was found pinched between a metal clamp and a wing rib. The clamp was removed and metal to metal contact was noted between exposed wiring and the wing rib. Due to the thermal damage, the wiring harness could not be separated to determine if the stall warning system could be functionally tested.

On February 22, 2019, the airplane was involved in an accident that required the replacement of the outboard left wing. According to the operator's director of maintenance, the electrical wiring in the wing was not inspected during the wing replacement. In addition, during recent maintenance at an unknown time, the inboard left fuel sending unit was replaced. The most recent continuous airworthiness inspection was completed on June 26, 2019.

On February 22, 2019, about 0945 central standard time, a Beech 65 airplane, N62069, impacted terrain near Colby, Kansas, while maneuvering for a precautionary landing. The commercial pilot was not injured, and the airplane sustained substantial damage. The airplane was registered to and operated by Bemidji Aviation Services, Inc., as a Title 14 Code of Federal Regulations Part 91 positioning flight. Day instrument meteorological conditions prevailed at the time of the accident, and an instrument flight rules flight plan was filed. The flight was originating from Shalz Field Airport (CBK), Colby, Kansas, and destined for Denver, Colorado.

According to the pilot, shortly after takeoff, he noticed the crew hatch door, located next to the left front seat, had unexpectedly opened. The pilot attempted to close the door, without success. While focusing on trying to close the door, the pilot "wasn't able to fully control the airplane normally (mainly [in] heading and pitch)," so he initiated a precautionary landing back to CBK. While maneuvering at a low altitude to stay in visual flight rules conditions (overcast ceiling at 300 ft), the airplane's airspeed decreased, and the wing tips were dipping back and forth. The pilot retracted the landing gear and applied full engine power to try and gain airspeed. The pilot was unable to gain airspeed, the airplane was losing altitude, and he knew the airplane was going to impact terrain. Prior to the impact, the pilot kept the wings level, and the nose in a slightly pitch up attitude. The airplane then impacted the snow-covered terrain with the landing gear retracted.

Postaccident examination of the airplane by the operator revealed the left wing and left aileron were bent. No evidence was noted that the crew hatch door malfunctioned during the flight.