manufacturing agreement with Zhong-Ou International Group to produce the EC135 luxury helicopter in Zhejiang Province, China. In October 2015, a letter of intent between Airbus Helicopters and Ecopark was signed for the establishment of a final assembly line (FAL) in Qingdao Province, China; a related $1.1 billion order for 100 Chinese-assembled H135s was announced in the same month. The majority of assembly work on the type remains at Airbus Helicopter's Donauwörth facility. Construction of the FAL started in May 2017, and it was opened for production on 17 April 2019. In January 2016, it was announced that the Ural Works of Civil Aviation (UWCA), a division of Rostec, had signed an agreement to build the H135 under licence at the firm's facility in Yekaterinburg, Russia. In May 2016, it was reported that Russian production of the H135 was anticipated to begin in 2017, following the receipt of Russian type certification; in addition, Russian manufacturers may be incorporated in the global supply chain. Two variants, the EC135 T3 and EC135 P3, were developed with improved high altitude and hover performance. Changes include repositioned air intakes to the engines, wider blades being installed on the main rotor, and changes to the fenstron anti-torque tail device. The EC135 T3 was introduced to service in December 2014. In December 2020, the H135 helicopter family EASA has certified a new Alternate Gross Weight (AGW). With the new AGW, the maximum takeoff weight has been increased up to 265 lb (120 kg) and payload. This modification can also be used to increase range by up to 75 nm or endurance by up to 40 minutes under standard conditions. The new AGW is available as an option and can be applied retroactively to all Helionix-equipped H135s. Airbus certified a new single-pilot IFR Helionix cockpit for its H135 helicopters in December 2020. The modified cockpit allows customers to choose whether to remove the copilot side of the instrument panel to increase the field of view or keep it to install specific STC equipment. Design The H135 is a twin-engine rotorcraft. It can be alternatively powered by a pair of Turbomeca Arrius 2B or Pratt & Whitney Canada PW206B engines, dependent on customer's preference (which gives either a T or a P, respectively, in the variant name). The main rotor is of a four-bladed, hingeless fiber-composite design; progressive improvements to the main rotor have increased its performance and reduced