Test programme and certification
Before reaching series production, Airbus aircraft programmes undergo a complex, rigorous flight test and certification campaign. Once approved and certified, the aircraft is cleared for take-off for the entirety of its lifetime. This extensive process is detailed in the paragraphs below, with specific examples from Airbus’ A380 and A350 XWB.
Airbus’ 21st century flagship A380 was certified by the two major international governing bodies – the European Aviation Safety Agency (EASA) and the U.S. Federal Aviation Administration (FAA) – in December 2006, following a programme that began more than five years earlier and ultimately comprised more than 2,600 flight hours with a fleet of five test aircraft.
To ensure the A350 XWB’s reliability from the moment it entered commercial service in January 2015, Airbus implemented one of the most thorough test programmes ever developed for a jetliner. Lasting just over 14 months, which is an industry record, the A350-900 flight test and certification programme comprised a five-aircraft fleet that performed over 2,600 flight hours in total – with Type Certification received from EASA and FAA in September and November 2014, respectively.
Structural static tests
In preparation for first flight clearance, a new-production jetliner – such as the double-deck A380 and new-generation A350 XWB – undergoes structural static tests that include: Flight Test Installation (FTI) calibration test, maximum wing bending at limit load, ailerons and spoilers functioning test during max wing bend, fuselage pressure test, and fatigue tests and flight cycles simulation.
Fatigue testing examines how the aircraft structure responds to stress over a long period of time and during different stages of its operations, such as taxiing on the runway, take-off, cruising and landing. To re-create these conditions, a combination of loads is placed on the airframe and activated by computer-operated hydraulic jacks.
As an example, the A380’s fatigue testing lasted 26 months and was conducted to 2.5 times the design service goal. Testing accumulated a total of 47,500 flight cycles: 2.5 times the number of flights that an A380 would make in 25 years of operations. A 16-hour flight was simulated in just 11 minutes. The tests pushed the aircraft structure to its limits to identify any necessary design improvements. Final test and preparation for flight is a phase that includes calibration of the gauges, cabin pressurisation testing and testing of navigation systems.
Flight test campaign
An aircraft’s flight test campaign is designed to assess general handling qualities, operational performance, airfield noise emission and systems operation in normal mode, failure scenarios and extreme conditions – culminating with certification by airworthiness authorities.
For the A380 extreme weather trials, Airbus flew the double-deck jetliner from Northern Canada to the desert heat of the Gulf and hot and high altitudes of Ethiopia and Colombia; while the A350 XWB’s evaluations included cold weather testing in Iqaluit, Canada; high altitude evaluations in La Paz, Bolivia and a hot weather campaign in Al Ain, United Arab Emirates.
In addition, the A350 XWB became the first Airbus aircraft to visit the McKinley Climactic Laboratory in the U.S. state of Florida. At this unique location the jetliner was subjected to a range of climactic conditions ranging from 40 deg. C. to negative-40 deg. C in a climate controlled hangar.
Further certification flight testing is dedicated to water ingestion trials, low speed take-off tests, flutter and rejected takeoff and landing. In addition to the wake vortex trials – air turbulence created behind the aircraft at takeoff – required for certification, Airbus continues to perform an extensive series of tests and measurements in this area.
Certification is a regulatory obligation, with all aircraft, their engines and propellers certifiable. The “Type Certificate” – issued to signify the airworthiness of an aircraft manufacturing design – is followed by the “Airworthiness Certificate,” which authorises aircraft operations in a certain countries or regions.
The certification process covers the complete development process of a new aircraft. It includes various phases:
- Detailed design review,
- Test review and participation in laboratory,
- Test review and participation in flight (designed to take into account modifications in light of the results),
- Aircraft operators (closely involved in design definition, development and service introduction).
The competent authorities in each geographical jurisdiction control the certification process. Today, the two main aircraft certification systems are:
- For the United States, FAR 25 regulations,
- For the European Union, JAR 25 regulations.
Each authority has the right to require specific conditions, while an aircraft manufacturer must always plan in advance for certification by importing countries.
In addition to flight test success, further highlights of the A380’s entry into service included airport compatibility trials, with a total of 38 airports visited around the globe demonstrating the aircraft’s ability to operate just like existing large aircraft.
For the A350 XWB, a global route-proving tour – one of the final steps toward certification – took this highly-efficient jetliner to 14 major airports on four different trips, flying approximately 81,700 total nautical miles in 180 flight hours.
Another important aspect of A380 and A350 XWB testing was the Early Long Flights (ELF) programmes, which went above and beyond certification requirements. For these evaluations, a cabin-equipped flight-test aircraft was operated on simulated commercial services with real “passengers” – comprised of Airbus employees – and actual airline flight crews to evaluate cabin systems in typical operating conditions.