Russian investigators believe the crew of a Yakovlev Superjet 100 thought the aircraft was experiencing an air-data system fault relating to airspeed, rather than a highly-improbable angle-of-attack discrepancy, before the jet fatally dived into a forest about 6min after take-off.

Simulations of the flight have led test pilots to conclude that the Gazpromavia crew – flying from Lukhovitsy to Moscow on 12 July last year – perceived an air-data disagreement warning as indicating unreliable airspeed.

Unknown to the crew, the aircraft’s behaviour was actually due to its angle-of-attack sensors having been wrongly installed during maintenance. Such a scenario was considered so unlikely that the flight manual did not contain a procedure to address it, says the Russian Interstate Aviation Committee.

As the crew attempted to climb, with autopilot and autothrottle engaged and the flaps retracted, the aircraft instead transitioned to a descent as the horizontal stabiliser started countering the apparently-high nose-up attitude, to prevent a stall.

The first officer, who was flying, instinctively pulled on the control column which disengaged the autopilot, before the captain took over and momentarily managed to arrest the descent.

According to the inquiry, the autothrottle was switched off and both pilots remarked that the airspeed was unreliable. Investigators believe the captain, in response to the airspeed uncertainty, increased thrust and tried to increase pitch.

But the disconnection of the autothrottle meant the aircraft accelerated unchecked, exceeding overspeed thresholds. The combination of angle-of-attack protection and overspeed protection meant the aircraft not only responded by entering a dive, but also deployed spoilers which resulted in loss of lift. The situation was unrecoverable.

Gazpromavia crash RA-89049-c-Interstate Aviation Committee

Simulation using an ‘electronic bird’ test rig in August and October last year indicated that the crew’s interpretation of the unreliable air data as a speed issue, rather than an angle-of-attack error, “predetermined” their actions – including the thrust increase which led to the overspeed.

The simulations also demonstrated that the crew could have brought the aircraft back under control and landed by reducing the engine thrust – the ensure the airspeed remained below the maximum operating threshold – and by switching the flight-control system to direct law.

But the inquiry also carried out simulation experiments, with the participation of 10 pilots from various Russian airlines, to determine the time needed to carry out the procedures for ‘unreliable speed’ indications.

These experiments showed that, from the point that the problem emerged, the time required for crews to perform the tasks and eventually switch the aircraft into direct law was more than seven minutes.

Crews also had “difficulty” in recognising the failure, given that – like the pilots involved in the accident – they were presented with intermittent indications of air-data disagreement, says the inquiry.

“At critical stages of flight, climbing after take-off, the [simulation] crews’ increased psycho-emotional stress was observed, as a result of which the pilots had difficulty finding a procedure in [the quick-reference handbook] and performing it,” it adds.

Gazpromavia wreckage-c-Interstate Aviation Committee

None of the three crew members on board the aircraft (RA-89049) survived after the aircraft crashed near the village of Apraksino.

Investigators state that recommendations for crew actions have since been developed and included in the emergency procedures section of the Superjet 100’s flight manual. The inquiry’s final report into the accident also underlines the need for strict compliance with maintenance procedures when replacing angle-of-attack sensors.





Source link

Posted in
Uncategorized
Related Posts
Limousine Comments are Closed

Plan the perfect NYC Memorial Day weekend

Pack only what you need and avoid overpacking to streamline the check-in and security screening…

News Comments are Closed

LA’s worst traffic areas and how to avoid them

Consider using alternative routes, such as Sepulveda Boulevard, which runs parallel to the 405 in…

France outlines plans to order 52 more Dassault Rafale fighters from 2027 onwards in budget expansion

France could significantly expand its future commitments for the Dassault Aviation Rafale fighter, having disclosed…

Hybrid Air Vehicles locks in ‘innovative defence contractor’ as customer for three Airlander 10 hybrid airships

An undisclosed customer has secured reservations for three Hybrid Air Vehicles (HAV)-produced Airlander 10 aircraft…

United Aircraft tests Il-114-300’s navigation capabilities in mountainous Siberian terrain

Russia’s United Aircraft has undertaken a series of flight tests with the Ilyushin Il-114-300 turboprop…

Saab discussing extra production hub to support Ukrainian Gripen E purchase

Saab is already looking at ways of significantly increasing production of its Gripen E fighter…

Denmark, Germany and NATO among sales prospects for GlobalEye surveillance aircraft, Saab chief executive says

European interest in Saab’s GlobalEye surveillance aircraft is continuing to build, as the Swedish company…

Ukraine exploring purchase of Bell AH-1Z attack and UH-1Y utility helicopters

Ukraine has signed a letter of intent with rotorcraft manufacturer Bell exploring the purchase of…

Italy plans to restore lapsed maritime patrol capability with six-aircraft buy

Italy has outlined plans to acquire six new maritime patrol aircraft capable of performing anti-submarine…

Stockholm Arlanda takes advantage of ‘EoR’ concept to increase parallel approach efficiency

Stockholm Arlanda is claiming to be the first European airport to introduce a concept intended…

Norway presses ahead with defence helicopter acquisitions, as talks continue with UK on ASW assets

Norway continues to analyse the options for a future anti-submarine warfare (ASW) helicopter to equip…

Airbus Helicopters open to H225 Super Puma’s return for oil and gas operations

Airbus Helicopters is seeing renewed interest in its H225 Super Puma for offshore operations, almost…

Post a comment

Your email address will not be published.