An alternative is to develop major (or “heavy”) inspections at certain intervals to check the structure and replace suspect components.
At Cirrus we chose to test for a useful life of 12,000 flight hours – about 60 years of average use. Most of our major structures, however, have been tested for twice this lifetime. At Cirrus we also chose to demonstrate that the structure is good for this design life without the need for any interim, heavy inspections – with their associated cost and inconvenience.
At Cirrus we expect that, as real-life aircraft approach 12,000 hours, a further round of testing, analysis, and inspections will determine how to extend the useful life.
Other manufacturers use different combinations of life and inspections. For example:
All of these approaches produce sound, strong airplanes – probably the best general aviation airplanes ever produced. Different engineering approaches, though, produce different trade-offs. At Cirrus we prefer the simple, uncomplicated approach – which we believe offers the highest level of convenience and economy for our customers.