Aircraft certification

In our research on Space Law, we wanted for this new Space Legal Issues article focus on aircraft certification. The recent crash of an Ethiopian Airlines plane casts doubt on the certification methods of airliners. These long and laborious procedures have been proven, but the crash of two Boeing 737 Max in a few months, calls into question their effectiveness.

Should the methods of certification of airliners be reviewed? The question arises after two successive accidents on Boeing’s latest aircraft, the 737 Max, which claimed the lives of three hundred and forty-six people. Since March 12, 2019, the plane has been grounded, and the air sector is facing a systemic crisis: the American supervisory authority, the FAA (Federal Aviation Administration), and Boeing, are accused of having put on the market a faulty device.

Long and thorough test phases – Aircraft certification

The aircraft certification phase takes time: between the very beginning and the end, the procedure extends over at least five years. The certification tests actually start from the beginning of the launch of a new aircraft program: in the case of the A380 for example, these tests began in 2002, when the first elements were manufactured. The inaugural flight only took place in 2005, and the aircraft was put into service two years later, in October 2007, at Singapore Airlines.

We do not certify the aircraft directly as such in one piece, we first test the different parts one by one, on the ground or on other aircraft”. For a new engine, the test engineers install it on the wing of an aircraft already in service, and check that it works well. It will only be installed on the new device once these tests are completed. “The plane itself is tested in a wind tunnel to verify that it is stable and balanced. All this is verified also in simulator. Then we get closer to the final version”. The prototypes (they were five in the case of the A380) then make tests of rolling, take-off at low altitude, before moving to more and more complex flights. “In the long term, we test the device in more and more extreme conditions: cold, hot, rain, thunderstorm, lightning… The goal is to test all the cases in order to reach an optimal safety for the passengers”.

Are there failures? “It’s very rare, because a large part of the parts have already been validated, we know what we expect, and we especially need to verify that the behaviour of the aircraft corresponds to the projections”. This test phase is now much less risky than in the past: “Thirty or forty years ago, test pilots were practising a risky profession where their intuition counted much more than today, where simulations predict very well the reality”. Nevertheless, sometimes, the test phases lead to changes that were not planned. During the first flights of the A380, the landing gear did not fit properly, and had to be modified.

Tests conducted by manufacturers under the control of independent authorities

A significant proportion of new aircraft are self-certified by manufacturers. A number of things do not need to be verified or validated: for example, all systems already certified and reused in a new aircraft (throttles, flaps…) have been validated on a previous device”. “On the other hand, the evolutions and innovations must be the subject of an additional certification by the regulatory authorities: the new sensors, the new flight controls, the new flight laws (which protect the aircraft, including actions of the pilots, in order to maintain it in stable flight”. These certifications can be local, conducted by a country. In China, aircraft produced and operated in this country are allowed to fly, but the manufacturers do not even try to get the European or American certificates, because these devices have absolutely no reliability required.

On the other hand, concerning aircraft certification, other certifications have the value of opening up access to all skies: these are the labels issued by the FAA (Federal Aviation Administration for the United States of America) and EASA (European Union Aviation Safety Agency for the European Union). These are extremely reliable certificates that have a high degree of trust. Typically, if the American authority certifies an airplane, this aircraft will also be accepted on the European territory. And everything, absolutely everything, is subject to certification. There are hundreds of standards for the smallest part, the least nut, the way to tighten the nut. When it was desired to remove the ashtrays armrests, it had been necessary to re-certify the entire seat while this modification was not about a vital equipment. No part without certification explains that this procedure is extremely expensive in time and therefore in money: one imposes a precision and obligations disproportionate compared to most other industries.

Revocable certifications in case of problems

Despite this amount of checks, there are still problems with aircraft entering service. The Boeing 787 Dreamliner was banned from flying for three months in 2013, because of the overheating of its lithium batteries, which threatened to catch fire, and spread the fire to the rest of the aircraft. But since then, the corrections made by the engineers have made this aircraft a model of reliability: no serious accident to report.

Other cases are more dramatic, like that of the 737 Max, the latest version of the Boeing single-aisle aircraft, whose first flight took place in 1967. This new aircraft, put into service in 2017, was built to nearly four hundred copies, but it is forbidden since March 12, 2019. Most countries of the world have withdrawn its certificate after two accidents that killed all people on board: the Lion Air 610 flight on October 29, 2018, which crashed in the Java Sea, and Ethiopian Airlines Flight 302, on March 10, 2019, which crashed near Addis Ababa. In both cases, the aircraft dipped shortly after take-off and the pilots failed to regain control. “These two accidents are a systemic crisis for the airline industry in the United States of America, because they directly challenge Boeing and the FAA. Boeing for having built a failed aircraft, and the FAA for failing to properly control the evolutions on this aircraft”.

At the heart of the problem: the new Boeing-designed flight control system called the Maneuvering Characteristics Augmentation System (MCAS). The 737 Max carries larger reactors, which had to be advanced and raised, to avoid being too close to the ground. But the centre of gravity of the aircraft was changed, and Boeing added an anti-stall safety system. But this system is based on a single probe, which sometimes sends misinterpretations, and orders the aircraft to prick forward. It is this system, which the pilots did not know how to deactivate, which would be at the origin of the crashes.

Also, the American manufacturer is also accused of wanting to minimise the changes made on the 737 Max, compared to the older generation of this aircraft. “The more change there is, and the more the companies have to incur training costs for their pilots”. After the first report of the Ethiopian investigators on April 4, Boeing took note that this device was involved and promised swift changes.