The aircraft developer sent such a letter, in particular, to the airline "Rossiya" (part of "Aeroflot"). It is currently the largest operator of SSJ-100 aircraft in Russia.
In particular, according to RBC, which had a copy of the letter, the aircraft manufacturer recommends that operators pay special attention to "aligning the holes and marks on the overlay with the mark on the fuselage skin and reinstalling the overlay only on the area of the fuselage skin from which it was removed" when replacing angle of attack sensors.
Also, companies performing maintenance on SSJ-100 aircraft should not allow one specialist to replace two or more sensors. At the same time, "operators are recommended to carry out double quality control and completeness of work when performing work to replace angle of attack sensors". The authenticity of the letter was confirmed by "Yakovlev".
Earlier, on July 12, an SSJ-100 crashed in the Moscow region during a test flight after repairs. Several possible versions of the crash were put forward: from engine and system failure to birds entering the engines from the outside. Also, among the causes of the disaster, Izvestia sources cited the incorrect installation of angle of attack sensors during maintenance.
According to sources, one of the technicians at the Lukhovitsky aircraft plant, where the aircraft was undergoing maintenance, installed two of the four sensors with a deviation of approximately five degrees, in violation of the operating manual. During the climb, these sensors gave unreliable readings.
This led to the untimely activation of the protection system, which protects the aircraft from entering stall modes. The system received unreliable sensor readings and automatically directed the SSJ-100 into the ground. The pilots did not have time to recognize this equipment failure and could not manually stop the stall protection system to avoid the crash. Similar information about the possible causes of the crash from their sources in the aircraft building environment was received by RBC journalists.
There is no official confirmation of this information, nor is there any refutation. The results of the investigation into the causes of the disaster have not yet been summarized.
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