Airbus A400M

8th December 2021

Airbus A400M user+1@localho Wed, 12/08/2021 - 21:17

The Airbus A400M Atlas is a medium lift military cargo aircraft powered by four Europrop International (EPI) TP400-D6 engines. Airbus markets the A400M as a multi-role tanker-transport capable of carrying more than the Lockheed Martin C-130J yet still being able to operate from austere runways as a tactical transport. The aircraft can transport loads up to 37 tons or 81,571 lbs. The Atlas also be quickly reconfigured to act as an aerial refueling aircraft with the addition of two hose and drogue under-wing refueling pods as well as a centerline hose and drum unit. As of November 2021, a total of 103 aircraft were in service across Europe and Asia.

Program History

In 1979, the Air Force leadership of Germany, the UK and France began to discuss the need for a new perspective airlifter to replace the C-130 Hercules and Transall T-160. The Future International Military Airlifter (FIMA) group was created in 1982 for this purpose and comprised A rospatiale, British Aerospace, Lockheed and Messerschmitt-B lkow-Blohm (MBB). In 1987, Alenia Aermacchi and CASA joined the program. However, political disagreements and divergent requirements caused Lockheed to leave the group in 1989. FIMA was subsequently renamed as the Future Large Aircraft Group (Euroflag) in 1991 and was based in Rome. Seven nations signed a memorandum of understanding (MoU) for a feasibility study regarding the future large aircraft (FLA) in 1993: Germany, France, Italy, Portugal, Turkey, Belgium and Spain. Studies for the FLA slowly progressed throughout the 1990s as European nations intermittently reassessed their participation in the program. Design requirements focused on creating an aircraft to bridge the gap between tactical transports like the Lockheed C-130 and strategic airlifters like the Boeing C-17.

In September 1994, the participating nations agreed to transfer industrial responsibility from Euroflag to Airbus (first Airbus SAS later Airbus Military). In July 1997, the UK announced its intent to join the program which was followed by the FLA RFP in September. Airbus made its final RFP submission in January 1999. On May 16, 2000, the UK became the first nation to authorize the procurement of the A400M with an initial commitment for 25 aircraft. In December 2001, OCCAR signed the A400M development and procurement contract pending the parliamentary approval of each individual government. A total of seven European nations would proceed with the procurement of the A400M as both Portugal and Italy withdrew from the program.

In May 2003, the development and production contract came into force with 180 A400Ms on order with the following national commitments:

  • UK: 25
  • France: 50
  • Germany: 60
  • Spain: 27
  • Turkey: 10
  • Belgium: 8 (including one aircraft for Luxembourg)

The fixed price development contract was valued at 20 billion at the time or approximately $29 billion in inflation adjusted dollars. Both Malaysia and South Africa joined the program in 2005. However, South Africa opted to leave the program in 2009 due to rising costs but Denel remained a part of the A400M supply chain up until 2019. EPI began assembly of the first engine in 2007 which underwent flight testing on a modified C-130 test bed in 2008. A total of five prototypes were built to support the development program, the first of which took flight on Dec. 11, 2009, from Airbus Seville Spain facility.

Engine Development & Configuration

Among the first major hurdles to the program was the decision to develop an indigenous turboprop. The FLA studies group examined four main propulsion configurations including two turbofans, four turbofans, four turboprops and four propfans (contra-rotating propellers or CRPs). The study found turboprops and propfans offered lower weight, better tactical/austere airstrip performance and lower landing distance as well as take-off distance at the cost of lower MTOW performance and cruising speed (100.9 tons for four turbofans vs. 92.7 tons for four turboprops). Ultimately, turboprops were chosen over propfans due to noise and technological availability concerns. Initially, Airbus evaluated the Turboprop International SNECMA M138 which was based on an M88 core, Pratty & Whitney (P&W) Canada modification of the PW150 and Rolls Royce Deutschland s BR700-TP.

The M138 won in December 2000 and became the TP400, but in February 2002, Airbus reopened the engine competition after deciding the engine did not meet its weight and performance specification. EPI adapted the TP400 to a three-shaft configuration from a two-shaft design with input from Rolls Royce. The new engine was designated as the TP400-D6. P&W reentered the competition with its PW180 12,000 SHP turboprop which Airbus reportedly found to be 20% cheaper than EPI s bid. Airbus ultimately selected EPI in May 2003 and U.S. media at the time alleged P&W lost as a result of French political pressure.

Features and Variants

Airbus A400M relative performance compared to other transports in the light (MTOW from 25,000 to 100,000 lbs.), medium (MTOW 100,000 to 400,000 lbs.) and heavy class (MTOW >400,000 lbs.). All cost figures have been inflated in local currency prior to conversion to U.S. dollars when appropriate.

Credit: Aviation Week

Airframe

Composite materials constitute more than 30% of the A400M s airframe and facilitate weight reductions which improve fuel economy and range. The largest single carbon fiber sheets incorporated into the aircraft are the wingskins, which measure 62 ft. long. Aluminum is also extensively used throughout the airframe to further reduce weight. The A400M Atlas features a payload capacity approximately twice that of the Super Hercules at 81,571 lb. and a maximum takeoff weight of more than 300,000 lb. The cargo bay has an area of 340 m^3 which can accommodate a maximum of 116 troops in a transport configuration enabling the Atlas to accommodate nearly all military vehicles other than main battle tanks. The cargo hold can also accommodate a total of nine standard 463 cargo pallets as well as 54 troops relative to the maximum of eight pallets in the C-130J-30.

The Atlas can land on an unprepared airstrip, with a California Bearing Ratio (CBR) of 6, with a length of just 3,000 ft. while holding a 60,000 lbs. (27.2 ton) payload. For benchmarking purposes, most strategic transports like the C-5 typically require more than 5,000 ft. to land with higher loads and must be operated from paved runways with a higher CBR.

Engines

The A400M s four Europrop International TP400-D6 engines produce more than 11,000 shaft horsepower (SHP) each, which enables the Atlas to achieve a cruising speed and altitude of Mach 0.72 (475 mph) and 37,000 ft. respectively. This compares to the 4,700 SHP on the Rolls Royce AE 2100 powering the C-130J. The TP400-D6 features eight propeller blades with a diameter of 17.5 ft. and each engine weighs 4,189 lbs. (1,900 kg) dry. Workshare amongst EPI consortium members includes: 32.2% Safran, 25% for Rolls Royce, 22.2% MTU and 20.6% for ITP.

The A400M uses a unique contra-rotating propeller (CRP) arrangement. While CRPs have been used for decades to cancel out torque and produce additional power on aircraft such as the Tu-95 Bear, typically CRPs have been mounted over a single piston as a self-contained unit. The A400M was the first aircraft to implement the CRP effect across a pair of engines on each wing, which Airbus calls Down Between Engines (DBE), through the gearbox as opposed to a stack of CRPs over a single piston unit. This increases airflow over the center of the wing, improving fuel efficiency and lift. DBE reduced the effects of prop-wash and torque which enabled designers to reduce the tail area thereby lowering drag.

Refueling System

The A400M has a baseline capacity for 111,995 lbs. (50,800 kg) of fuel, which can be supplemented further with Cargo Hold Tanks (CHT). Note, the 50,800 kg figure is the total fuel capacity of the aircraft not the fuel-offload total i.e., a portion of the fuel must be reserved for the A400M itself. The two hose and drogue underwing refueling pods can provide up to 400 gallons per minute (1,200 kg or 2,645 lbs.) while the centerline unit can sustain 600 gallons per minute. Compared to boom mounted aerial refueling systems, drogue and hose systems offer greater compatibility with the majority of aircraft types (including non-Western platforms) at the cost of a lower fuel transfer rate. In comparison, the A330 MRTT s boom can transfer 1,200 gallons of fuel per minute.

A basic video system is embedded in the rear the aircraft to assist with aerial refueling, but operators can elect to install a more comprehensive aerial refueling kit with three video cameras as well as an associated computer system. Additionally, the aircraft features a nose mounted refueling probe. As part of the tactical series of upgrades, the A400M has been upgraded to be able to refuel helicopters.

Upgrade Programs

Retrofit Programs

Both to address teething problems discovered in operation and to more quickly field the planned series of tactical transport upgrades, A400Ms have been produced in six production batches through 2022 of varying capability and readiness standards. Between 2017-2019, A400M participating nations and Airbus launched the Global Re-baselining Review (GRB) to stabilize the program and implement a pathway to correct concurrency issues through a two-stage retrofit program. The first stage was announced in 2016 and was concluded in December 2020, covering the UK, France and Germany. The second-stage announced was in July 2019 covers the remaining nations through 2023.

Among the most pressing issues which hampered the A400M s initial entry to service include the aircraft s power gearbox (PGB) and aluminum alloy fuselage sections. An assortment of teething problems was also identified with the helicopter aerial refueling system and tactical series of proposed upgrades. As of the time of this writing, Airbus believes it has made significant progress in addressing these issues.

In January 2015, a cracked input pinion plug, a component supplied by Avio Aero as part of the PGB, caused the engine of a UK A400M to shut down in flight. As a result, a series of regular checks were mandated that affected flight operations. EPI fielded an interim solution in 2016 (entered into production with Batch 4 aircraft in 2017) to reduce the frequency of these checks to once every 600 hours. In 2017, Airbus and EPI developed the Pack 2 enhancement which reduced vibration as well as reinforcing the longevity and reliability of the PGP. The EASA certified Mod Pack 2 in March 2018 and all new build engines since January 2019 have received the upgrade and existing aircraft had been retrofitted.