Russian analysts have verified the strength of the Yakovlev MC-21’s replacement vertical fin, which is being constructed from domestically-produced composites.

The change is part of United Aircraft’s efforts to substitute imported components and reduce its reliance on foreign suppliers.

Composite materials for the MC-21’s manufacture, in particular, have been subject to international sanctions. The MC-21’s structure is 30% composite.

“One of the most labour-intensive works was the creation of our own composite materials for the wing and tail of the aircraft,” says the Moscow-based Central Aerohydrodynamic Institute.

MC-21 domestic composite test-c-TsAGI

Source: Central Aerohydrodynamic Institute

Russia’s aerospace industry has had to source domestic composites for the MC-21 fin

It has conducted research to confirm the strength of the composite fin, using a dedicated rig fitted with mechanical and hydraulic systems to impose loads and collect data.

The institute says an initial cycle of endurance testing simulated 10,000 flights which, it adds, the find “withstood without damage”.

Reserachers also stress-tested the structure, up to normal design limits, before inflicting loads 1.5 times higher.

“It is unlikely that the airliner will encounter [such loads] in reality, but it must withstand them,” says static and thermal strength department deputy head Viktor Tsygankov.

“If the aircraft cannot cope with such a load during testing, then its design is modified and strengthened.”

But he states that the domestically-built MC-21 fin “successfully passed all strength tests”.

Yakovlev will use the data as part of the certification programme. Static testing will also be carried out on a domestic horizontal stabiliser, as well as other components including floor structures, doors, and the windshield.