The operation of the SSJ100 with the put off engine fault was carried out by the Yakutia airline in full compliance with the flight operation documentation certified and approved by the aviation authorities.
Thrust reversal deactivation according to MMEL (Master Minimum Equipment List) is based on the conclusion drawn about the absence of the influence over the operational safety and is consequently included into the flight operation documentation in a form of corresponding instructions concerning the peculiarities of the aircraft operation in this configuration. The thrust reversal has a function of partial declination of the engine efflux to the opposite of the aircraft trajectory and performs an auxiliary braking function aimed at the landing gear brakes resource saving.
The standard procedure for the modern passenger aircraft configuration with deactivated thrust reversal either for one, or for both engines, according to MEL provides the corresponding corrections of the aircraft performance data that are given in the Pilot Operating Handbook. This allows the cockpit crew to operate the aircraft safely and to prepare for landing under different weather conditions after precise evaluation of the necessary landing distance.
The cockpit crew received the information from the ground service that the runway surface friction coefficient was higher than 0.4 and therefore, the pilots took the reasonable decision to perform landing according to the procedure described in the flight operation documentation. However, the true condition of the runway surface was characterized by almost twice lower surface friction coefficient – which required an individual decision concerning the possibility of the landing under the abovementioned circumstances. The cockpit crew was not provided with that information and for that reason they could not prevent the overrunning. Therewith, the aircraft was sufficiently damaged while it continued rolling over the runway surface that is being under reconstruction.
Source: Sukhoi.Civil.Aircraft.Company
