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Aircraft general knowledge
8.3 Aircraft structure
At the beginning of the history of flight, the focus was on making structures that
could fly. Durability and strength calculations were based on static calculations
that the structure should be able to last.
They had not thought much about metal fatigue and corrosion.
They had operation time / number of flights on components, and then they had
to be replaced. The philosophy was that they would scrap the plane when it was
no longer safe to use it. So, the plane had security in the strength of the structure
until scraping.
Here you can see a static test of an airplane.
8.3.1 Safety by Design
In the 50s, the Fail-safe philosophy was introduced.
People now thought about safety in the structure. It was "safety by design." The
meaning was that there was a back-up in the structure.
One of the changes was that instead of 2
large bolts to attach the wings, 16 smaller
bolts are now used.
When it is made this way, you can tolerate
the 4 bolts breaking. There is a back-up in the structure.
The various parts of the aircraft were inspected regularly, and intervals for
inspection and replacement were set.
This led to today's methods of construction and maintenance, which are a
combination of the "Safe life" and "Fail Safe" philosophies.
Flyveteori PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 681
