MAK: SSJ-100 crashed near Kolomna due to problems with angle of attack sensors
On Friday, August 30, the Interstate Aviation Committee (IAC) presented an interim report on the crash of the SSJ-100 aircraft in the Kolomensky district of the Moscow region during a test flight on July 12.
According to the document, the plane crash was caused by malfunctions or incorrect installation of sensors.
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The crew noticed that the sensors were not working correctly.
According to the report, during takeoff, the crew noticed that the angle of attack sensors (AOA) were behaving abnormally.
The co-pilot reported: “Look, we have a high angle of attack.” The PIC (aircraft commander) responded: “Is the angle of attack sensor not working?
The conditions for the first activation of the angle of attack limiting function arose precisely during the process of retracting the mechanization – this is demonstrated by the nature of the change in the deflections of the elevator and stabilizer.
Also, according to the report, during the process of shifting the stabilizer “to a dive”, the pitch angle value decreased from five degrees for pitching up to 3.5 degrees for diving. After that, the aircraft began to descend.
At the same time, the angle of attack sensor readings showed a discrepancy during the flight a week before the incident in the Moscow region. After the flight, the pilots reported a malfunction.
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The speed limit was exceeded during the flight.
In addition, the speed limit was exceeded during the flight, as evidenced by the sound of a warning signal. However, none of the crew members discussed this sound.
The second pilot did not switch the radio station when reporting to the Domodedovo airport dispatcher about the unreliable speed indication, as a result of which the dispatcher did not receive the information. Subsequently, the dispatcher never received a single message from the crew.
When the speed is exceeded, the onboard systems release the interceptors and raise the nose of the aircraft to reduce it, but due to the increased load on the SSJ-100 engines, this could not be done. The interceptors reduced the lift, causing the aircraft to lose altitude. The pilots switched the engines to takeoff mode and tried to pull the aircraft up with the control stick, at this point the elevators were set to descend. A few seconds later, the aircraft banked to the right.
A few seconds before the crash, the engines were switched to idle mode. At a speed of 365 knots, the plane hit the ground.
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Technician Admits to Incorrect Sensor Installation
On July 24, it became known that a technician at the Lukhovitsky Aviation Plant’s Civil Aviation Maintenance and Repair Center admitted to incorrectly installing angle-of-attack sensors.
The specialist mistakenly installed two sensors at the wrong marks, which is confirmed by the aircraft debris found.
On July 16, experts and the commission determined the priority version of the SSJ-100 crash near Kolomna. Preliminary, the catastrophe is not related to the operation of the engines.
The Superjet 100 of Gazprom Avia crashed in the afternoon of July 12 in the Kolomensky district of the Moscow region during a test flight. The airliner, built in 2014, crashed in a forest while taking off from Lukhovitsy, where the P.A. Voronin Aviation Plant is located in Vnukovo. The three pilots on board did not survive. Three hours before the crash, the plane was undergoing maintenance.
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