Certification flights of the SJ-100 regional jet are underway at Zhukovsky, with the latest phase focusing on aircraft behavior beyond operational speed and Mach number limits, according to the United Aircraft Corporation’s press office.
During these tests, flight test specialists from Yakovlev PJSC and the Russian Aviation Register assessed the SJ-100’s safety when recovering from unintentional pitch and roll excursions that resulted in speeds exceeding the maximum operating limits (VMO and MMO). The aircraft’s integrated flight control system (FCS), developed by KRET, is responsible for managing these scenarios.
VMO (Maximum Operating Limit Speed) is the highest indicated airspeed (in knots) permitted during flight.
MMO (Maximum Operating Mach Number) is the maximum allowable Mach number, representing the ratio of the aircraft’s speed to the speed of sound under current conditions. Exceeding either limit can result in structural damage or system failure. VMO is used as the upper limit for indicated airspeed, while MMO applies at higher altitudes where the speed of sound varies with altitude.
Test results demonstrated that the FCS reliably prevents the aircraft from exceeding these operational limits, regardless of crew input, by automatically maintaining speed and Mach number within certified boundaries. If atmospheric conditions cause the aircraft to approach these limits, the system autonomously returns the aircraft to safe operating parameters.
The FCS algorithms, developed by Yakovlev and validated by TsAGI (Central Aerohydrodynamic Institute), are designed so that releasing the sidestick is sufficient to restore normal flight. The sidestick then returns to a neutral position in both pitch and roll axes, stabilizing the aircraft.
Three prototype aircraft are involved in the certification program. Aircraft 97021 is equipped with SaM146 engines and partially Russian avionics. Aircraft 97012, powered by PD-8 engines, is used for new engine certification. The fully import-substituted aircraft, 97023, also with PD-8 engines, is undergoing certification of Russian avionics.
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