(a) The defect data for several line replaceable units (LRU) of an aircraft cabin
temperature control system gathered over a 12-months period

(i) Using the MS Excel application or otherwise, construct the Weibull Probability
Plot for each of the LRU in the given aircraft cabin temperature control system.
The cumulative distribution function may be estimated using the median rank
method.

(ii) For each of the Weibull Probability Plots drawn in (a), construct the best-fit
straight line(s) connecting failure data points, and estimate the shape parameter
and scale parameter for each best-fit straight line(s).

(iii) For each LRU, analyse the failure patterns exhibited from the plotted graph and
evaluate the suitability of implementing Hard-Time (HT), On-Condition (OC)
maintenance and Condition Monitoring (CM) maintenance.

(b) Discuss the latest industrial trend in applying the following maintenance concepts on
commercial aircraft systems. Illustrate your discussion with specific, relevant aircraft
examples.
(i) On-condition Maintenance
(ii) Prognostic Maintenance & Health Monitoring