Airbus is determined to launch a hydrogen-powered and non-polluting aircraft by 2035. A huge step has been taken towards this goal for the development and testing of the aircraft's hydrogen-powered engine.

Since airplanes run on petroleum-based fuel, known as kerosene, they have negative environmental impact on our planet. That's why the aviation industry is looking for ways to reduce or even zero its carbon footprint. The way to achieve this goal is for engine makers to produce more efficient and environmentally friendly engines powered by sustainable fuels.

European aircraft manufacturer Airbus is ambitious to launch an aircraft that produces non-polluting gas emissions by 2035. In line with this goal, Airbus is making plans to build a hydrogen-powered aircraft within the scope of the program called ZEROe.

CFM International, partnership by the world's largest engine manufacturers GE and Safran with 50% shares, has taken action to meet Airbus' hydrogen engine needs. Under the agreement between the two companies, CFM International will modify the combustor, fuel system, and control system of a GE PassportTM turbofan to run on hydrogen.

This developed engine will be mounted along the rear fuselage of an Airbus A380, which will be equipped with liquid hydrogen tanks, and flight tests will be conducted. The purpose of placing the engine in this part of the A380 is to enable the easy monitor of the performance of the hydrogen engine separately from the emissions of the A380's own engines and the white condensation traces left behind by the engines called contrails.

The fact that the A380 has a large amount of internal space to carry the hydrogen tanks to power the developed engine and all other equipment necessary for test engineers makes it the best fit for these tests. It was also decided to connect the engine in alignment with with the upper part of the fuselage so that it would not be affected by any interference while cruising.

The A380, chosen as the test bed, is MSN 001, the first A380 prototype coming off the production line. It was designed and built entirely for testing. In addition to being the first A380 to meet the sky, it played a key role in the A380's flight test program until the certification process was completed. After it obtained its type certificate, the A380 remained active and was used for other tests in the following years.

Airbus has plans to conduct the first zero-emission flight under the ZEROe program in 2026. As a result, it would not be wrong to say that the A380, which will be used as a test bed, will start test flights soon.

What is a Flying Test Bed?

Each new aircraft engine developed by engine manufacturers undergoes complex, rigorous ground and flight tests before becoming a commercial product. Airplanes that perform flights where engines are tested in the sky are called flying test beds in aviation.

In aviation history, the use of aircraft as a test bed dates back to the 1940s. After the Second World War, the Avro Lancastrian bombers were adapted to be used as test beds by British engine manufacturer Rolls-Royce. These planes had four piston engines. During test flights, Rolls-Royce replaced two of the aircraft's engines with newly developed RB.41 'Nene' turbojet engines. If the tested engines had a problem in the sky, the airplane would be able to continue flight with its other two piston engines. In the 1950s, companies such as de Havilland and Armstrong Siddeley also began using the Lancastrian as a flying test bed.

Which modifications are made to the airplane for the test bed?

In order to use an airplane as a test bed, only removing the existing engines and replacing them with newly developed engines to be tested is not enough. Due to the nature of the work, other modifications are required for such airplane in order to safely perform any tests in the sky.

The handling of the airplane’s kilometers of wiring is an important part of the process. This is critical not only for ensuring the safe operation of the engine in the aircraft, but also for collecting the necessary data from the engine during testing. Structural changes such as the removal of winglets on the Boeing 747, which is used as a test bed by General Electric, are a good example of the situation.

Four-engine airplanes, like the Avro Lancastrian and 747, are much better suited to be used as test beds as they offer greater contingency in the event of an emergency or a failure. For this reason, many major engine manufacturers use the Boeing 747 as a test bed for flight testing of their new engine designs.

Test Beds of Giant Engine Manufacturers

Ohio-based engine maker General Electric is one of them. The 28-year-old Boeing 747-400 (N747GF) has started to make test flights of engines developed by General Electric, after serving in the Japan Airlines fleet for approximately 16 years. The world's largest aircraft engine, the GE9X, designed to power the Boeing 777X family aircraft, also used on this test bed for the first time in 2018.

Rolls Royce, major British manufacturer of aircraft engines, is using two different versions of the 747 to test its new engines. The older of these planes (N787RR) is the 42-year-old 747-200 (N787RR). Started to serve in the Cathay Pacific fleet in 1980, the plane arrived in Iceland in 1999 to join the Air Atlanta fleet. In 2005, it was started to be used as a test bed at Rolls Royce.

This airplane, which is also used to test the engines powering the Boeing 787 Dreamliner, recently took a part in the flight tests of a Rolls-Royce Trent 1000 engine using 100% sustainable aviation fuel.

Rolls-Royce's other test bed, the 22-year-old 747-400 (N747RR) retired from the Australian Qantas fleet after its commercial services since 2000 and started to be used as a flying test bed within Rolls Royce in 2019.

On the other hand, Pratt & Whitney progresses a little differently for engine testing than its rivals. In addition to two 747SPs, the short-bodied version of Boeing 747s, it also uses the Dornier Do328‑300 JET and de Havilland Dash 8-100 turboprop aircraft for such test flights.

The 41-year-old C-GTFF-registered 747SP joined the Pratt & Whitney family in 1998 after commencing service at Korean Air in March 1981. C-FPAW, on the other hand, began flying at the Canadian engine manufacturer in 2009 after it began flying passengers in China in 1980. The company bases its test airplanes at Canada's Montréal-Mirabel Airport (YMX)