Appendix 7 Figure A7-6: Conditional Probability of Fracture Calculation The POF calculation is described here following a Monte Carlosimulation process. A large sample of holes should be simulated (see App. 1, 3 (e)). Each hole simulation in the sample follows the flowchart below to determine if it :
fractures before part certified life / succeeds to reach part certified life / is detected with a crack.
st star artt Is therea manufacturing anomaly?
Success ye Is therea manufacturing anomaly?
Success yes s n noo Notes :
- each r equires a random pick from the pertinent
random variable distribution
-(1) record the number of cycles at fracture or detection for each hole Conditional prob.of fracturebefore Ncycles number of fracturedholes beforeNcycles = total sample size Whatsize « a0 »?
Geta0 anomaly life from “AvsN” curve (see fig. A7-7) Cyclesat inspection(s) ?
Is thereone or more inspection(s) ?
Is anomaly detectable at inspection(s) using applicable PODcurve?
Any inspection during anomaly life ?
Get anomaly size at inspection(s) from “AvsN” curve (see fig. A7-7) Fracture(1) Success Fracture(1) Detection(1) yes no no no yes yes a0anomaly life > part certifiedlife ?
What size « a0 »?
Get a0 anomaly life from “AvsN” curve Cyclesat inspection(s) ?
Is thereone or more inspection(s) ?
Is anomaly detectable at inspection(s) using applicable PODcurve ?
Any inspection during anomaly life ?
Get anomaly size at inspection(s) from “AvsN” curve - Fracture(1) Success Fracture(1) Detection(1) yes no no no yes yes a0 anomaly life > part certifiedlife ?
Appendix 7 Figure A7-7: a0 Anomaly Life & Anomaly Size at Inspection(s) Calculations from “AvsN”Curve a N just above threshold anomaly size inspection a0 anomaly size at inspection a N just above threshold anomaly size inspection a0 anomaly size at inspection A vs N Curve a0 anomaly life 40