Russian investigators probing the Aeroflot Sukhoi Superjet 100 crash at Moscow Sheremetyevo a year ago are still awaiting results of specific fire and structural analyses before releasing their final findings about the accident.
But the Interstate Aviation Committee says some of the work – including US manufacturer Curtiss-Wright’s assessment of fire-protection units – has been held up by restrictive measures imposed during the coronavirus crisis.
The inquiry is yet to complete research into the probability of fire occurring and spreading after the aircraft lands, which is being carried out by St Petersburg’s university for the state fire service.
It is also awaiting the results of assessment into the collapse of the aircraft’s landing-gear and damage to the fuel tanks in the wing, and analysis of compliance with design requirements of landing-gear struts and attachment points.
This work will be carried out by the investigators once they receive the results of undercarriage load modelling being performed by French aerospace firm Safran.
While returning to Sheremetyevo, after a lightning strike on 5 May last year, the aircraft bounced on landing. Its landing-gear failed during the impact and the subsequent damage to the engines and fuel tanks led to a severe fire as the jet came to a halt, resulting in 41 fatalities.
The Interstate Aviation Committee says it is trying to finish the inquiry promptly, but the need to comply with local and federal coronavirus restrictions at its Moscow headquarters is “significantly affecting” the completion time.
Investigators have completed the analysis of wreckage and flight-recorder information, as well as mathematical modelling of the flight – including assessment of Superjet aerodynamics and performance following external disturbances.
The inquiry has looked into Aeroflot Superjet crew training and simulator capabilities, and previous instances of switching of the aircraft’s flight-control mode to direct law, as well as cases of hard landings.
Investigators are looking into the psychological and personal characteristics of the crew, but full details were only submitted by the carrier at the end of February, the inquiry says.
As well as the routine examination of air traffic control and meteorological data, several devices and units with non-volatile memories, which might hold additional flight information, have been removed from the aircraft.
Structural lightning-strike analysis has been carried out in co-operation with Sukhoi, Aeroflot and Rosaviatsia, and research has also been undertaken into the weather radar, electronic engine-management system, avionics, power supplies, fuel controls and shut-of valves, flight controls and radio equipment.