Tests continue on MC-21 tailplane

The engineers are looking to determine the residual strength of a repaired torsion box (TsAGI)

Russia’s Central Aerohydrodynamic Institute (TsAGI) is conducting fatigue tests on the composite tailplane torsion box of the Russian Irkut MC-21-300 airliner, the institute’s press office reports.

The upper panel of the torsion box was deliberately damaged and subsequently tested for residual strength. By applying loads the engineers studied crack propagation from the damaged area. The torsion box successfully withstood all the loads applied. The damage was then repaired, and the part was put through bending deformation tests. “The experimental data will help the engineers determine the residual strength of a repaired torsion box,” TsAGI says. “A total of 60,000 cycles will be performed at 50% of the design load.”

Previously, the MC-21’s tailplane torsion box, produced by ORPE Technologiya and assembled at Aviastar SP, went through endurance tests at TsAGI equivalent to 60,000 flights. That stage of the MC-21-300 testing program was completed in August 2017. The Central Institute of Aviation Motors (CIAM) then conducted a dynamic strength (birdstrike resistance) test, as well as a hail resistance test to simulate reference certification conditions. The test article was subsequently returned to TsAGI for further testing.