RuAviation

Composite Materials Development and Manufacturing Challenges

During the Innoprom-2025 industrial exhibition held July 7-10 in Yekaterinburg at the Yekaterinburg-EXPO Exhibition Center, significant attention focused on domestic aerospace industry development under import substitution policies and manufacturing technology modernization. A key presentation addressed composite materials implementation in the MC-21-310 aircraft. Anatoly Gaidansky, First Deputy Managing Director of Yakovlev Design Bureau and Director of the Engineering Center, delivered a comprehensive overview of the airliner’s composite structures, detailing achievements, testing progress, and weight optimization challenges associated with transitioning to domestically-produced materials.

The localization process for composite structure materials presented several technical challenges that required modifications to certain aircraft design parameters. These changes demanded additional attention to balancing technical specifications with operational performance characteristics of the MC-21. Despite identified challenges, Yakovlev Design Bureau and AeroComposite JSC continue systematic efforts to adapt and improve structural solutions based on accumulated experience and existing constraints.

According to Gaidansky, the majority of composite structures in the MC-21-310 concentrate in the detachable wing section. Significant composite content includes panels, spars, internal wing structural framework, and all high-lift devices. Composites also feature in the empennage – vertical stabilizer, horizontal stabilizer, and control surfaces – as well as various fairings, including wing-fuselage fairings and flap track fairings. All these components exist as prototype specimens currently undergoing comprehensive testing, including successfully completed static tests.

Gaidansky explained that engineers developed and manufactured two wing box prototypes measuring up to 72 feet (22 meters) in length with chord dimensions up to 21 feet (6.5 meters). One prototype completed static testing to ultimate loads. Fatigue testing continues on specialized test rigs in a purpose-built TsAGI (Central Aerohydrodynamic Institute) facility, enabling durability and reliability assessment.

“We are currently implementing design modifications to the detachable wing section to realize accumulated experience from recent years in terms of weight reduction. We expect to remove several hundred kilograms specifically from the wing structure, plus some weight reduction from the empennage and wing-fuselage fairings,” Gaidansky stated.

He noted that previously, vertical stabilizer and horizontal stabilizer panels for the MC-21-310 were manufactured from polymer composite materials in Obninsk, with final assembly conducted at Aviastar-SP in Ulyanovsk. Currently, both composite component manufacturing and empennage assembly concentrate at the KAPO-Kompozit facility in Kazan. This consolidation enables better quality control and innovation implementation in manufacturing processes. Obninsk served as one of the former composite component production centers, but with the transition to more centralized manufacturing, this production capacity relocated to Kazan.

Gaidansky identified thermoplastic polymer composite materials as an important development direction in aviation composites, capable of multiple reprocessing cycles without strength characteristic degradation. He estimates that modern composite utilization could reduce passenger airliner weight by 15-20% compared to traditional aluminum and magnesium alloys, directly impacting fuel efficiency and operating costs. Thermoplastic composites are planned for load-bearing structures, wing leading edges, ribs, and fastening elements, significantly expanding technological capabilities and improving repairability.

JetOS Real-Time Operating System Development

Civil aviation development directly correlates with flight safety enhancement, onboard system reliability, and aircraft operational efficiency improvement. Aviation standards requirements for onboard system functional software development represent a critical factor in this context. The State Research Institute of Aviation Systems (GosNIIAS), in collaboration with the Institute for System Programming and Institute of Applied Mathematics of the Russian Academy of Sciences, develops the domestic JetOS real-time operating system for aviation onboard systems. Since 2024, JetOS integration proceeds with the multifunction display developed by Ulyanovsk Instrument Design Bureau for the MC-21 aircraft.

Primary JetOS development directions and contemporary cybersecurity and resource optimization challenges receive annual discussion at the OS DAY conference. In 2025, “Isolated Execution Environments” served as the central theme, where GosNIIAS representatives provided detailed presentations on ARINC 653 standard implementation – the basic JetOS interface ensuring spatial and temporal application separation. The presentation included modular architecture descriptions, application interaction services, and error handling procedures, guaranteeing correct and safe operation of multiple software components on a single hardware platform. Despite ARINC 653’s original aviation focus, its principles successfully apply to any mission-critical systems with high safety and resource separation requirements.

Prototype Aircraft 73057 Acceptance Testing

Acceptance testing commenced for prototype MC-21 aircraft serial number 73057 (MS.0013) in the final assembly shop at Irkutsk Aviation Plant. This airliner underwent modernization under the import substitution program, including replacement of key systems with domestic equivalents. Modifications include a comprehensive flight control system with domestic actuators and cockpit controls, electrical power system, landing gear with domestically-produced wheels and tires, and fuel quantity sensors.

The MC-21 EPS represents the first application of variable frequency networks in Russian civil aviation. This solution simplifies generator design, reduces weight, and extends service life by eliminating constant speed drives – complex units in both design and maintenance, positioned between the engine and generator. Through integrated automatic diagnostics and operational reconfiguration capabilities during failures, the system ensures uninterrupted power supply to priority consumers, significantly enhancing functional safety and airliner reliability.

Upon completion of acceptance testing, aircraft 73057 will transfer to the Irkutsk Aviation Plant flight test station for factory development testing, followed by ferry flight to Zhukovsky for certification flight testing integration.

Lightning Protection Ground Testing

Lightning protection ground testing continues at Yakovlev Design Bureau’s Flight Test and Development Complex at Ramenskoye Airfield using aircraft 73051, which features replacement of imported onboard wiring with Russian equivalents.

Lightning protection testing captures induced voltages in wiring systems and evaluates onboard system resistance to high-intensity electromagnetic field exposure. These studies identify and promptly eliminate potential vulnerabilities in electrical systems, ensuring aircraft safety and reliability under thunderstorm conditions.

Flight Testing Activities

During July 2025, prototype MC-21 aircraft with serial numbers 73054 and 73055 completed 15 flights totaling 34 hours 42 minutes. Aircraft 73054 serves for domestic Traffic Collision Avoidance System (TCAS) accuracy evaluation, while 73055 conducts electrical power system (EPS), inertial navigation system (INS), air traffic control (ATC) transponder, radio communication range, and antenna-feeder system assessments.

Within this flight program, aircraft 73055 completed two airway flights: one under factory development testing (FDT) and another under additional certification testing (ACT). The crew included an Aviation Register test pilot. Flights proceeded along low-traffic routes in the central region. The aircraft flew from Zhukovsky to Syktyvkar and return. Flight testing evaluated domestic inertial navigation systems, Traffic Collision Avoidance System (TCAS), weather radar, and communication/radio navigation equipment performance. Testing also assessed aircraft transponder operation when interfacing with standard ATC system monitoring equipment.

For comprehensive TCAS evaluation, July 23 featured a “paired” flight of prototype MC-21 aircraft 73054 and 73055 with mutual TCAS verification, including domestic radio navigation system assessment (GNSS receivers, VOR/DME, ADF) compared with aircraft 73054 equipped with similar but imported equipment. All domestic systems operated normally, demonstrating stable and reliable performance across various modes. Such testing ensures flight safety and represents an integral component of aircraft certification preparation.

Traffic Collision Avoidance System testing using two identical prototype aircraft follows strictly regulated methodology. During “paired” flights, aircraft execute maneuvers at various altitudes and distances, simulating potential approach situations under real conditions. TCAS monitors mutual positions and alerts crews of necessary course or altitude changes to prevent collision. Post-flight ground analysis evaluates system activation accuracy and timing.

Aircraft 73056 Emergency Evacuation Testing Preparation

Prototype MC-21 aircraft serial number 73056 remains at Yakovlev Design Bureau’s Flight Test and Development Complex (Zhukovsky), with limited information available recently. According to Aviation Russia sources at Gromov Flight Research Institute, this aircraft currently undergoes preparation for passenger emergency evacuation testing using domestic emergency slides, requiring door modifications since original doors featured imported inflatable slides. This aircraft incorporates maximum-density cabin configuration for 211 passengers. Similar testing occurred in November 2024; however, complete compliance with the import-substituted MC-21-310 version requires full configuration matching. Following door and slide modifications, ground certification testing for emergency aircraft evacuation will continue.

Technical Specifications and Program Outlook

The MC-21 program demonstrates significant progress in domestic aviation technology development, particularly in composite materials application and avionics systems integration. Weight optimization efforts target several hundred kilograms reduction through design refinements based on accumulated operational experience. The transition to thermoplastic composites promises 15-20% weight reduction compared to traditional metallic structures, directly impacting fuel efficiency and operational economics.

JetOS real-time operating system development represents a crucial milestone in domestic avionics autonomy, providing ARINC 653 compliance for mission-critical applications. The integration with domestic multifunction displays and other avionics components establishes foundation for comprehensive Russian civil aviation systems architecture.

Comprehensive flight testing programs validate domestic system performance across multiple aircraft variants, ensuring safety and reliability standards compliance. Lightning protection testing, TCAS validation, and emergency evacuation procedures represent essential certification requirements for commercial operation approval.

The MC-21 program’s systematic approach to import substitution while maintaining international certification standards demonstrates Russian aerospace industry capability to develop competitive commercial aircraft using domestic technologies and manufacturing capabilities.