A k-out-of-n:G system and a system with components subject to soft and hard failures are both inspected non-periodically. For the k-out-of-n system, components fail “silently” (i.e. are hidden), and the entire system fails when (n-k+1)st component fails. For the system with hard-type and soft-type components, hard failures cause system failure, while soft failures are hidden and do not cause immediate failure of the system, but still reduce its reliability. Every system failure allows for an opportunistic inspection of hidden soft-type components in addition to the scheduled inspections. The available maintenance types are replacement and minimal repair. For hard-type components, the maintenance decision is determined by the optimal age before replacement. For the soft-type components with hidden failures, we do not know their age, and so decide on the appropriate type of maintenance using the optimal number of minimal repairs before replacement. The hidden nature of soft-type component failures precludes the use of a tractable analytic expression, so we use simulation and genetic algorithm (GA) to jointly optimise the non-periodic policies on maintenance and inspection and to ensure these incur minimal expected total cost over a finite planning horizon. Due to increasing computational complexity associated with the number of inspections and maintenance policies to be evaluated, the genetic algorithm presents a promising method of optimisation for complex multicomponent systems with multiple decision parameters.