We have all heard that the aircraft we fly in are ‘safe’ because they go through gruelling tests before taking to the skies. But just how brutal are these tests? Well, very.

First, let’s look at tests for the the engine, the heart of an aircraft.

According to engine manufacturer Rolls-Royce, the most “exciting” test for an aircraft engine is the ‘Fan Blade Off Test’ as the company has to ensure that the engine is at its maximum thrust and rotational speed when the fan blade “breaks”.

“Effectively, what we are doing is artificially breaking that fan blade off the engine for which we need a small explosion and then catching (the parts) in the casing that is outside,” explains Peter Johnson, Head of Marketing for Fleets, Rolls-Royce.

The test is done to check if the pieces of a broken blade will be caught successfully by the fan case, preventing them from going further inside the engine and causing an explosion. During the test, which costs millions of pounds, one engine is destroyed.

“European Aviation Safety Agency (EASA) sets out all the tests that we have to complete. We also do our own testing to make sure that everything is working as we want it, and the engines perform at the level we want them to,” he says.

Nothing is left to chance. Not even a bird hit. For this test, EASA specifies the weight of the bird, the speed of the bird and also where it goes into the front end of the engine. “We have to broadly do two sets of tests — one with a large bird and the second a medium-sized bird test where you have to fire six or seven smaller birds that give quite a big shock to the fan system, the first part of the engine that they will hit,” Johnson points out.

Extreme conditions

The rest of the aircraft too goes through similar gruelling tests. Given that aircraft produced by both Airbus and Boeing criss-cross the globe daily, sometimes taking off from an airport in sub-zero temperature and landing in the middle of a desert in West Asia, it is imperative that these machines undergo specific tests to handle these extreme weather conditions. Commonly called the cold soak and hot and high tests, these see an aircraft being powered up, including its systems and engines, under extreme conditions.

For the Airbus A-380 extreme weather trials, Airbus flew the aircraft from Northern Canada to the desert heat in the Gulf and in the high altitudes of Ethiopia and Colombia, while the A-350 XWB (ExtraWidebody) evaluations included cold weather testing in Iqaluit, Canada, high altitude evaluations in La Paz Bolivia and a hot weather campaign in Al Ain in the United Arab Emirates.

There’s more

The two manufacturers also have a fatigue test which examines how the main aircraft structure responds to everyday operationsover a long period of time. This covers different stages of an operation, such as taxiing, take-off, cruising and landing.

Then there is also the flutter test or flight vibration test to examine the behaviour of an aircraft structure when subjected to aerodynamic disturbances throughout the flight envelope.

At the first flight of the Boeing 787-10 in South Carolina recently, Captain Craig Bomben, Vice President, Flight Operations, Boeing, said the pilots flying the first flight would have been in the aircraft for the past week (before the first test flight) doing taxi tests.

“Teams start preparing for the first flight months ahead with engineering teams in a simulator to develop the profile of the flight and test systems,” he pointed out.

Boeing also did the Service Ready Operational Validation (SROV) for Boeing 737 MAX with launch customer Southwest Airlines taking the MAX to several airports in the airline’s system to simulate real-life conditions. The Boeing 737 MAX is Boeing’s first new aircraft in the second century of its operations (Boeing completed 100 years in 2016).

Using the MAX test airplane over a six-day period, pilots from Southwest and Boeing flew routes from Love Field in Dallas to cities including Albuquerque, Denver, Chicago, Austin and Phoenix. Southwest’s maintenance and ground crews at each airport got hands-on experience, doing everything from towing and fuelling the airplane, to conducting fit checks of ground support equipment and performing maintenance.

Incidentally, a few years ago Boeing performed SROV activities with the 787, taking the Dreamliner to Japan for similar exercises with ANA.