RuAviation

In the production centre of PJSC Yakovlev in Komsomolsk-on-Amur are frequency tests of the SJ-100 aircraft with the s/n 97003, which are the final stage before the start of flight tests of the aircraft and are designed to eliminate the possibility of dangerous aeroelastic resonance oscillations. This is reported in the Notes of aircraft builders Telegram channel.

During the tests there is a collection of experimental data on the vibrations of all elements of the airframe, which is necessary to predict the behaviour of the aircraft in the occurrence of flutter. For this purpose, a prototype equipped with all standard on-board systems and units is being used.

Flight 97003 is the third prototype aircraft with full replacement of foreign components with Russian ones. In order to obtain reliable information about the aircraft and ensure its safety, the frequency test programme includes three main phases of inspections.

Investigation of the aircraft vibrations in free flight conditions. At this stage, special attention is paid to unit connections and the quality of the aircraft assembly. The operation of rudders and ailerons is also checked, and their evaluation in abnormal situations is carried out.

Remote control system tests. In this stage, the operation of all aircraft control paths, including sensors, actuators and other units and aircraft systems is tested. The aircraft response and the behaviour of the autopilot algorithms under the influence of rudders and ailerons in flight are analysed.

Landing gear testing. This stage is aimed at preventing the shimmy effect during takeoff and landing – automatic wheel oscillation caused by the instability of straight rolling. Shimmy is manifested in the intense yaw motion of the wheels in lateral and longitudinal directions, which is a consequence of the interaction between the runway, pneumatics, wheel stand and the aircraft airframe.

All stages of frequency testing are aimed at confirming the safety and reliability of the import-substituted SJ-100 97003, which is an integral part of type certification. Successful completion of the tests ensures that the aircraft will be safe to operate and resistant to flutter and shimmy phenomena.