is often referred to aerospace sector as one of the safer of the world. Could we talk about 99% safety? If chance didn't exist and all events occurred according to their probability, an aircraft that was 99% safe would fail for 7 hours a month, which is too risky. If the safety level rises to 99.99% the possibility of failure is reduced to 5 minutes per month, which starts to be a considerable value. But how are these levels achieved?
The aeroplane is, without a doubt, the safest means of passenger transport available, but there is a long process to get to that point.
There are many factors that contribute to achieving this very low risk. However, a good example of this dedication to safety would be the a large number of tests to which an aircraft is subjected before its maiden flight.
Perhaps the most basic step can be found in the very materials with which they are made.
If we take a titanium rivet as an example, the base material must be supplied to the rivet manufacturer by a supplier who is himself approved by the final aircraft manufacturer. Subsequently, once a batch of rivets has been produced, some of its units must be tested by the manufacturer itself to verify that they meet the required standard.
But this is not where it stops. Whoever receives the rivets, before fitting them to their part, will also need to test some rivets from the batch with the aim of ensuring that the product retains its properties after transport and has not been tampered with or exchanged for another of worse characteristics during the process.
And of course, all of these steps are documented with the aim of ensuring adequate traceability of each element involved in the aircraft's manufacture.
This will occur with all materials, and in all their forms, that end up being part of the finished aircraft product. To all of this, we must add the workers, the designs, the manufacturing and testing machinery, shall have been approved for the functions they perform, raising industry quality standards.
At this point, the properties of each element can be considered verified, but what is done now with the assemblies? In this case, the testing chain continues, with the possibility of to test the different sets that are manufactured. Not only is their resistance and integrity assessed, but their resistance to corrosion or their behaviour as electrical insulators is also checked, in the case of surface parts.
A striking case would be the wing bending test. In this test, cables are placed along the entire extrados and intrados, and the maximum deflection the wing reaches in each direction is checked. If the rivet from the previous example ends up in a wing, its resistance will be tested again, to which the quality of its placement and tightening is now added.
Another option is that they are carried out Aircraft part testing that by their function they are seen exposed to high demands, as would be the case for engines. Some of the more curious tests carried out on an engine are water ingestion, bird strike, or the “blade-off” test.
The first tests the engine's operation while a large amount of water is projected into its intake. This test simulates a situation typical of heavy rain during take-off and landing phases, in which a large amount of water is ingested by the engine, or even during flight.
The second indicated test assesses the damage caused by the impact of a projectile, similar in size and weight to a large bird such as a goose, on the engine blades. This situation is common at some point during the aircraft's lifespan, mainly during take-off or landing phases.
The third is a somewhat different test. In it, nothing is introduced into the engine, but rather one of its own blades is forced to fracture, and it is checked whether the engine withstands the passage of the blade through it without losing its integrity or generating a fire in the process.
When all the aircraft's components are deemed suitable, a crucial moment arrives: the first flight. In it, the aircraft will leave the ground under its own power for the first time and its flight performance will be tested. Multiple test flights will follow, during which the aircraft's response to certain manoeuvres will be evaluated, as will how the installed electronic systems function and their behaviour in the event of system or engine failures.
A large amount of data is collected from these flights, such as loads on the fuselage, wings, wing root, and landing gear. Once the manufacturer is satisfied with all corrections made for any detected defects, the aircraft will be submitted to the competent authority for final certification.
But there is still one last step before passengers can be loaded on board: the Evacuation drill. According to European regulations, aircraft with more than 44 passengers must be able to be fully evacuated within a maximum of 90 seconds.
Not only that. To force the situation, the test must be carried out in darkness with half of the emergency exits blocked. Participants as passengers should represent a heterogeneous sample of the population and not have recently received training on the matter. In this trial, to cite an example of considerable magnitude, the A380, with its 873 passengers, managed to pass the test in just 78 seconds.
As you might expect, all these trials represent a considerable additional cost during the manufacturing and certification process of any aircraft. However, no one will doubt its necessity. Otherwise, how could aeroplanes be the safest mode of transport in the world?
