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Certification stress/strength tests

Serve to prove the basic structural strength of all primary structure parts of the aircraft, such as wing, fuselage, empennage etc.

• the tests are carried out by the manufacturer under the supervision from the LAA
• the tests are carried out by simple loading methods
• the tests are carried out until the calculated limit stress/load is achieved, while the visual checks and measurements of the deformation are carried out too.

The concept of the tests

• Each structure has therefore to pass a system of strength tests covering the requirements of the regulations to at least the calculated loads.
• The tests are carried out at normal temperatures, therefore various additional coefficients are applied to the results to cater for the specific thermal properties of composites as deemed necessary.
• With the wings the ultimate strength (loading to destruction) tests are preferred to ascertain the actual strength reserves of the airframe. Often the failed critical points of structures are appropriately strengthened and the tests are repeated to find eventual other critical points. Cooperation with the Institute of Aerospace Engineering of Brno University of Technology takes place here.
• The tests results are in case of failures compared to the design calculations and thus they serve to precise design calculation methods.