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Gökbey’s Challenging Test Campaign Begins

by Cem AKALIN

Issue 92

The grueling test campaign of GÖKBEY will be conducted with three prototypes over the next two years. The first prototype – P1 soared at 6am with its much-anticipated debut flight June 29, 2019 .

The T625 Multi-Role Helicopter Program was initiated to cater to the light-weight class helicopter requirements both for military and private users worldwide. It was launched upon the decision of the Defence Industry Executive Committee dated on June 15th, 2010. The Turkish Light Class Utility Helicopter (TLUH) Program was signed between the SSB and Turkish Aerospace which was awarded the amount of US$687.3 million in a contract dated June 26th, 2013. On September 6th the contract became effective and the kick-off meeting was held on October 11th, 2013.

In conjunction with the contract effective date, the System Requirements on September 15th, 2015, Preliminary design on October 20th, 2016 and the Dynamic Systems Critical Design on December 28th, 2016 were completed according to the program schedule.  The potential end-users (government agencies) submitted their requirements for this helicopter to Turkish Aerospace during this period. 

The numerical name of T625 was designated for the platform that is comprised of the helicopter’s six-ton gross weight, ‘2’ representing the two engines and ‘5’ representing the number of main rotor blades.  In 2017, the first mock-up of the T625 Multi-Role Helicopter was debuted at IDEF’ 17 held in May 2017. The first international demonstration was actualized at the Paris Air Show in June of 2017.

Test Campaign to be Completed Along with 3 Test Prototypes 

Within the scope of the project, the Critical Design Phase was completed on September 29, 2017. As of October 2017, the first prototype design was finalized, and the manufacturing process was initiated by Turkish Aerospace. The Rotor System Test Preparation Review, as well as the first bladed engine run-up tests of the T625 Multi-role Helicopter prototype, was successfully completed between August 17th and 31st, 2018. The first hover flight of the T625 Multi-Role Helicopter for testing of the rotor system, engine, flight control, system and transmission were accomplished with the P0 prototype on September 6th, 2018 with the participation of an official delegation. The comprehensive test campaign was initiated by Turkish Aerospace following successful hover flight as of September 6th, 2018. The ground test activities and system verification tests forged ahead during this time period. According to Turkish Aerospace, it was carried out within 50 hours of system verification tests over the P0 prototype. Concurrently, the production of the P1 prototype was also completed during this period. As a result of these activities, the required structural retrofitting was reflected in the platform by Turkish Aerospace.

Within the scheduled program, 3 prototypes in total will be manufactured for the test campaign (flight and ground tests), system verification and optimization. To qualify for a particular type of certification, the helicopter must be in compliance with the 1956 safety requirements and successfully perform over a hundred helicopter and system level tests. 

P1 Prototype has Accomplished its Maiden Flight on 29th June

On May 2st, 2019, Turkish Aerospace President & CEO Temel KOTİL said that “The production of the second prototype (P1) was completed recently. We are aiming for it to make its maiden flight within two weeks” during a press meeting at IDEF’19. Within the same month following this encouraging statement, the first bladed engine run-up of the second prototype (P1) fed by GPU (Ground Power Units) was successfully accomplished on May 20th, 2019. The first flight was expected to occur on June 18th, but the flight was postponed. On June 29th, the P1 Prototype successfully accomplished its debut flight early in the morning at 06:00am with the completion of the necessary permissions obtained from the General Directorate of Civil Aviation (SHGM). During this flight, the P1 climbed up to 50ft and ran around 500 meters on a straight line, lasting a total duration of 45 minutes. With this flight, the GÖKBEY certification flights were officially launched.

The P1 prototype to be utilized in the flight and ground tests will incorporate the necessary system and structural retrofitting according to the verification tests over the P0 prototype. According to the test campaign schedule, the flight envelope’s maximum speed, altitude and load factors will be expanded gradually with the P1 Prototype. Besides, more than 500 sensors mounted on the P1 fuselage, wings, main rotor mast, tail rotor, landing gears and different parts of the platform will relay critical information to the program system room, and all exceeded limits will be monitored in real-time and analyzed by the design team. The payload in particular and analytical data analysis to be collected during the ground and flight tests will be utilized for the optimization of the weight or the structural retrofit over the P3 prototype. Furthermore, the P2 prototype, which will support the P1 prototype during the tests, is still being manufactured at the facilities. According to Turkish Aerospace executives, the system integration of the P2 prototype is expected to be completed in August 2019 and is scheduled to enter into the test campaign in September 2019. Within the scope of the program, over 1500 hours of flight and ground tests are expected to be conducted with the prototypes. While the testing processes and the Technical Data Package are intended to be finalized in 2020, the type CS-29 certification and EASA certification processes are aimed to be completed in 2021. the T625 GÖKBEY is expected to be in service in 2021 according to the statement by Prof. İsmail DEMİR, during the Turkish Defense Industry Summit on December 13th, 2018,

The aircraft incorporates several new technology features to provide the highest levels of safety and operational advantages. Within the scope of the program, critical systems such as transmission, rotor, and landing gears as well as aerostructures and avionics systems are designed from scratch at Turkish Aerospace facilities in Ankara, Turkey. 

A new generation, advanced aerodynamic indigenous rotor design will provide excellent performance in the most demanding operating environments. The T625 GÖKBEY design also benefits from extensive use of composites, advanced airframe aerodynamics, next-generation widescreen digital glass cockpit design and state-of-the-art avionics for maximum situational awareness. 

Under the Turkish Light-Weight Utility Helicopter (TLUH) Program, Turkish Aerospace has completed design, development and manufacture of an indigenous twin-engine 5-ton class light utility helicopter with a takeoff weight of 6 tons and powered by two CTS800-4AT turboshaft engines, 1373shp each, enabling the aircraft to perform in hot & high environments and perform safely in a one engine loss condition for Category-A certification. The unique TS1400 Turboshaft engine, which is going to replace the CTS800-4AT in the serial production period, currently has been in development by TEI since 2017. The preliminary prototype of the turbojet core to be utilized on the TS1400 engine was successfully tested for the first time on a test bench on June 11, 2018. The SSB announced this success via its official twitter account; “Under our Turboshaft Engine Development Project, production of the preliminary prototype of the core motor which constitutes the main core of the TS1400 engine was completed and the first ignition test was successfully performed.” The TS 1400 Turboshaft Engine development project consists of five stages which are as follows; the development of the core engine, prototype engine stage, mature engine stage, certificated engine stage and integrated engine stage. TEI is to design, develop, produce and certify two 1400shp turboshaft engine (TS1400, ITAR-free) prototypes. 

The T625 GÖKBEY is designed for IFR and VFR single-pilot operations, night operations and flight in known icing conditions. The geometry of the helicopter is optimized for maximum aerodynamic performance with retractable landing gears hence providing efficient fuel consumption leading to better range and endurance. Thanks to the auxiliary fuel tank, the range of the helicopter surpasses the 950km range accompanied by five-hour endurance.

The T625 GÖKBEY has a five-blade main rotor and a four-blade tail rotor to minimize vibration and noise. Both the main and tail rotor hubs are fully articulated with elastomeric bearings. Both rotor systems are driven by a transmission system, which consists of the three-stage main gearbox, having the capability of operation for 30 minutes in the event of loss of lubrication. With regard to the main gearbox and tail rotor, Turkish Aerospace and Italian company Avio Aero signed an agreement for the manufacturing of several parts of the main gearboxes and tail rotor for the GÖKBEY at Paris Air Show’ 19.  

It also incorporates a state-of-the-art, four-axis, dual redundant automatic flight control system to improve helicopter stability, handling and reduce the pilot workload in-flight.

Aselsan’s Modular Avionic Touch-Screen Environment (MATE) 

The new generation smart cockpit of the T625 GÖKBEY and all its avionics systems were developed by Aselsan, demonstrating competitive and innovative solutions in the global aviation market with this new generation smart cockpit.

The new generation smart cockpit MATE (Modular Avionics Touchscreen Environment) consists of two wide touchscreen (8x20 inches) Integrated Mission Displays and two touch screen (8x10 inches) data entry Touch Command Control Units. MATE was developed to be compatible with the civil aviation standards of the European Aviation Safety Agency (EASA) and the General Directorate of Civil Aviation (SHGM) enabling pilots to control all avionics systems on the helicopter via the touchscreen cockpit displays. The navigation, communication, identification for friend or foe, electronic warfare and EO/IR systems of the helicopter were designed by Aselsan as well.

The T625 GÖKBEY Utility Helicopter’s flight and mission management software was also developed by Aselsan. This software enables the helicopter to navigate Performance Based Navigation up to the level of RNP 0.3 (Required Navigation Performance 0.3) in all civil airspaces all over the world. The unique digital map and Helicopter Terrain Awareness and Warning System (HTWAS) software enables pilots to perform safe flights in extreme conditions.

The T625 GÖKBEY Helicopter is designed to offer a superior payload and diversified configurations to end-users. The T625 GÖKBEY can accommodate a maximum of two crew, namely a pilot and co-pilot, and up to 12 passengers. The extensive cabin space can also be customized according to the requirements of the end-user such as Search and Rescue, Passenger & Cargo Transportation, V.I.P., Firefighting, Air Ambulance, and Off-shore operations