Countdown to A350F first flight: Preparing for the sky

For the team preparing the Airbus A350 Freighter (A350F), the upcoming first flight is the result of five years of detailed planning, component and demonstrator testing. As they progress from the 'Virtual First Flight' milestone to the real thing, we sit down with Laurent Bussiere, Lead Flight Test Engineer for the A350F programme – who explains how they are bringing this new freighter flight testing programme to life.

A350F MSN700 Rollout

Why does the A350F need a full flight test campaign given that it is derived from the A350-1000? 

It would be easy to assume that a freighter built on the A350-1000 needs little new testing. But Laurent explains: “The A350F presents unique dimensions due to the freighter’s specific fuselage configuration – which is equivalent to an A350-900 forward fuselage [length] mated to an A350-1000 rear fuselage [length] and A350-1000 wings. In turn, this creates a new aerodynamic model which affects flight control,  while the new geometry for the landing gear affects ground maneuvering.”

He adds: “It’s not an A350-1000 and it’s not an A350-900, but rather it’s between both. So we need to look at the behavior of the whole system with this unique model. That's why we go into the development simulator to prepare for the first flight and the subsequent 400 flight-hour flight test campaign.”

Flying before flying: the Virtual-first-flight programme 

Before the real aircraft ever leaves the ground, the crews push it to the limits virtually in the development simulator. This is called the "Virtual First Flight" (VFF) and is the latest milestone for the programme. Its overall purpose is to:

• Clear the aircraft’s new systems
• Validate flight control laws 
• Involve the entire crew of the first two aircraft (MSN700 and MSN701) 
• Evaluate aircraft behaviour under specific systems failure combinations. “This allows the team to assess failure criticality, determine appropriate reactions, and decide whether existing A350-1000 procedures, on which those of the freighter variant are based, need to be adapted,” says Laurent.

Moreover, it ramps-up the excitement amongst the teams and observers alike, since it indicates that actual flight tests are approaching soon.

A350F first flight rehearsal in simulator

Connecting the simulator to real avionics

The VFF for the A350F consists of 13 simulation sessions lasting approximately five hours each. These sessions utilise a development flight test simulator connected to real aircraft avionics systems test benches, including the actual flight controls and digital engine control systems. 

“Everything is already connected,” enthuses Laurent. “This VFF setup is 90% representative of the physical aircraft. The only significant variable left to prove in the sky is the freighter’s specific aerodynamic model.”

On the ground, in the weeks before first flight

On the ground, preparation is also underway before the first flight. 

Ground vibration testing

Ground vibration testing, completed in June, measured how the real airframe reacts to mechanical vibration, building the structural model the team will rely on once the aircraft is airborne.

 Read the full GVT story here

A350F Ground Vibration Test

Preparing the anemometry testing for flight data calibration

This involves using a trailing cone to calibrate the aircraft's pitot-static system which measures airspeed, altitude, and Mach number.

The team is currently preparing to ensure full readiness for the freighter campaign by undertaking pre-verification tests on MSN59 (an A350-1000). “The trailing cone deployed behind the aircraft gathers clean air data and compares measurements with the aircraft’s own internal air data instruments,” explains Laurent.

Testing fire and smoke detection systems

Using smoke generators on the ground initially is critical in the A350F's preparation and test planning. “If a fire or smoke propagation is detected in the large cargo area, the operational procedure requires depressurising the cargo deck to extinguish the fire, which may require the aircraft to operate and fly at 20,000 feet,” explains Laurent.

To test the installed detection systems, the smoke propagation and procedural execution without actual fire, smoke generators will be deployed both on the ground and during flights.

Preparing to open up the flight control laws  – from “Direct Law” to “Normal Law”

The initial flight profile will be executed entirely in “Direct Law” [manual control], which is a basic flight control mode, rather than “Normal Law”, [ie. with flight envelope and stability protections] because 10% of the derivative aircraft's aerodynamic characteristics are still treated as an unverified model. To prepare the five-person crew – comprising two pilots, one Test Flight Engineer (TFE), and two FTEs – there was a dedicated simulation session at the start of September. 

A350F first flight rehearsal in simulator

“We not only prepared the first flight profile and learned all the tasks we have to perform during this flight, but we also trained on how to react in case there is any issue during this first flight,” explains Laurent.

Fitting new FTI station 

Both MSN 700 and MSN701 are being fitted with a new FTI station design located in the forward courier area right behind the pilots. While the software remains identical, the physical hardware layout of the FTI in the A350F has been heavily modified to leave as much space free for unobstructed cargo operations on the main deck. To this end all associated recording computers and electronics have been consolidated onto a single specialised pallet located in the lower deck/forward cargo area.  The FTEs seated there will appreciate its large LED screens – and a modern graphical user interface (GUI) with scalable/moveable windows. 

A350F FTI

Working closely with the European Union Aviation Safety Agency (EASA)  on the flight plan. 

“EASA is already actively involved in monitoring, reviewing, and approving the official flight test plan,” notes Laurent. “EASA pilots and flight test engineers are scheduled to participate directly as onboard witnesses during performance flights and they will become extensively involved in the formal certification phase planned in 2027.”

Nine months, two flight test aircraft, one goal

The global certification campaign plan, which targets an overall duration of around nine months, will utilise two complementary test aircraft equipped with different specialised flight test instrumentation (FTI) setups: 

~ MSN700 will focus on aerodynamic performance, handling qualities, and autopilot systems, and it has been equipped with a specialised tail skid and bumper to protect the structure during takeoff performance tests. MSN700 will clear the flight control laws first so that MSN701 can fly in normal law during its first flight.

~ MSN701, meanwhile, will focus on system-related testing, including air conditioning and comprehensive fire and smoke testing. The latter will eventually permit MSN700 to fly with real cargo on board. MSN701 will also perform the hot and cold weather campaign.

Testing cargo operations 

“In terms of cargo operation – which is the A350F’s entire ‘raison d'être’ – we are focusing on maturity right from the start,” stresses Laurent. 

“Our target is to be able to load and unload various representative containers and payloads every day after flight.” 
Laurent notes that part of the flight testing will also go to some operators so they can try out their own ULDs and pallets, “with their own way how to load or unload the aircraft, just to check also the maturity with them”.

A350F HTP Load testing

The tip of the iceberg: the team behind the flight test crew

While the "guys in the orange suits" get the visibility, quips Laurent, he is quick to credit the massive, invisible web of support: "It's teamwork. With the design office, the programme team, the blue-collar manufacturing teams, the ground crews and many more. The flight test crew is just the tip of the iceberg."