Airbus has recently completed a major test phase with the A400M airlifter refueling helicopters. The test campaign allowed the completion of many certification requirements and development objectives and moves the A400M a significant step closer to being fully cleared for rotary-wing refueling operations.
The trials took place over France’s western coast and involved a tanker-configured company A400M testbed and two Airbus H225M Caracal helicopters from the Armée de l’Air et de l’Espace (AAE, French air and space force). During the course of the tests, 81 “wet” contacts were conducted, during which 6.5 tonnes of fuel was transferred.
The A400M's initial refueling trials with helicopters revealed wake turbulence issues, requiring some fixes and inevitably incurring a delay to fielding of the capability. Building on the results of dry and wet contacts that were performed in 2019 and 2020 to validate the cure, the latest campaign focused on clearing the refueling envelope, and involved contacts being made at altitudes between 1,000 feet and 10,000 feet, and at speeds as low as 105 knots. The tests also involved the two Caracals being refueled simultaneously.
The campaign also involved some night contacts—a tricky operation given the need to fly in close formation at low altitudes, and keeping the tanker and receiver(s) within their restricted common performance envelope. Further nighttime trials are required before military certification can be released for helicopter refueling, which is expected to be achieved before the end of the year.
The ability to provide tanker support for helicopters is a key selling point for the A400M, with particular application to long-range combat search and rescue (CSAR) and special forces transport roles, both of which are performed by the AAE’s Caracals. Already possessing an impressive 700-nautical-mile range, the use of air-to-air refueling can extend the H225M’s mission endurance by up to 10 hours. French Caracals currently refuel from the Lockheed Martin KC-130J, which was bought to urgently provide the capability in the light of the delay in clearing the A400M for the role.
The A400M has already demonstrated its ability to pass fuel to a wide range of fixed-wing types, including Rafale, Typhoon, Tornado, and F/A-18 fighters, and large aircraft such as the C295, C-130, and the A400M itself. A total fuel capacity of 50.8 tonnes is accommodated in the aircraft’s wing and center wing box tanks, while an additional 11.4 tonnes can be carried in two roll-on, roll-off auxiliary tanks installed in the main hold. A useful feature is that these additional tanks can be used solely for fuel offload, separate from the aircraft’s own fuel system. This, in turn, permits different types of fuel to be carried to match varying receiver requirements.