Mark Huber is an aviation industry veteran who has worked in the flight training, aircraft sales, aircraft component, and airport development businesses. He has flight time in more than 50 different and diverse aircraft, including helicopters, aerobatic aircraft, vintage warbirds, jet fighters, business jets and turboprops, and transport-category aircraft. He has jumped out of several of these—on purpose—with a parachute. His defense and aviation journalism has been published in a variety of national and international periodicals.

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Mark Huber

An errant washer is being blamed for the emergency landing of a Bristow Sikorsky S-92A. The Norwegian Safety Investigation Authority (NSIA) has concluded that the washer was probably introduced into the aircraft’s main gearbox (MGB) during maintenance and eventually became lodged standing on edge in the oil passageway, reducing the flow of oil in the return oil channel.
According to the NSIA, the washer likely had been present for nearly 500 flight hours before the event occurred on Sept. 25, 2020, triggering cockpit warnings for MGB loss of oil pressure and rising oil temperature. The crew declared an emergency but continued the flight for another 25 to 30 nm to the airport at Sola, the intended destination. Upon landing, visual evidence revealed a significant oil leak on the left side of the MGB.
NSIA believes that the washer entered the MGB when the generator was removed from the flange on the accessory module—a procedure done 487.35 flight hours before the incident. Post-incident investigation located the washer in the oil passageway after the input module had been disassembled. The safety agency recommended that the Norwegian Civil Aviation Authority follow up on the operator’s procedures and routines related to foreign object debris in connection to gearbox maintenance.

News and information on safety procedures and concerns.

Errant Washer Triggers S-92 Main Gearbox Leak, Emergency Landing

Norwegian authorities blame emergency S-92 landing on maintenance

An errant washer is likely to blame for the emergency landing of a Bristow Sikorsky S-92A, the Norwegian Safety Investigation Authority (NSIA) has concluded.

Errant Washer Triggers S-92 MGB Leak, Emergency Landing

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