Maintaining aircraft airworthiness to ensure the fleet's safe operation
and maintain its readiness is critically dependent on accurate modelling
and reliable predictions of fatigue crack growth. In this process a
knowledge of the representative initial discontinuity sizes that cause
fatigue crack nucleation and early growth in aircraft is essential. Here
the effective pre-crack size of aluminium alloy 2024, from samples of
aircraft production material and tested under aircraft spectra, are
considered.