Foundation of damage tolerance principles in-service for the RRJ-95
aircraft structural components
Abstract
Fatigue cracks initiated from holes in several zones and structural
components of the RRJ-95 aircraft frames were investigated. Using the
method of quantitative fractography the crack growth duration in the
brackets of the in-service airframe and in the wing panels during
full-scale bench tests was estimated the spacing of meso-beach-marks
(MBM) and fatigue striations. The applied program of bench test
consisted of blocks of variable loads that were equivalent to the wing
loading in flight and reproducing schematized flight-cycle. It was shown
that the duration of fatigue crack propagation in several structural
components of the RRJ-95 aircraft frames was approximately the same as
for the crack nucleation duration. The total lifetime is sufficiently
long for cracks in the structural components to be detected and reliably
monitored with a large operating time interval between adjacent
inspections.