RuAviation

The second prototype of the MC-21-310 medium-range airliner (tail number 73057, serial number MC.0013) has successfully completed ground frequency testing at the Irkutsk Aviation Plant. The tests evaluated the performance of the electrical power system, hydraulic system, integrated flight control system, landing gear, and avionics. This was reported by the press service of the United Aircraft Corporation (UAC).

During the tests, engineers analyzed the response of various aircraft systems to vibrations across a range of frequencies. Special attention was given to the integrated flight control system and landing gear.

“At present, we are conducting ground frequency tests of the landing gear and integrated flight control system. These tests are part of additional certification procedures required for any aircraft. We are determining the frequency characteristics and safe operational modes for future flights,” said Anton Chmil, lead MC-21 design engineer.

“Frequency testing for medium-range airliners such as the MC-21 typically takes several weeks to two months. The duration depends on the number of systems under evaluation and the scope of certification requirements. For the MC-21, considering the integration of new domestically produced systems, the testing cycle may be longer compared to similar procedures for foreign models,” a source at the Gromov Flight Research Institute told Aviation of Russia.

According to the source, the tests involve inducing structural vibrations at various frequencies, recording vibration parameters, and assessing system performance. After each phase, the collected data is analyzed and compared with regulatory requirements set by aviation authorities, including EASA and Russian FAR-128. These regulations require manufacturers to analyze the dynamic characteristics of the airframe and control systems and to submit test results for compliance assessment.

Frequency testing is one of the most labor-intensive stages of certification. Completion of this phase confirms the operability of domestic components within the aircraft and allows the program to proceed to flight testing.

“The tests must cover all primary operational modes, including various landing gear and wing configuration settings. The results are compiled into a report submitted to the certification authority for approval to begin flight testing. Without a positive conclusion from these tests, the aircraft cannot advance to the next stage of certification,” the source explained.