Optimal Cost-Effective Maintenance Policy for a Helicopter Gearbox Early Fault Detection under Varying Load

Table 5

The optimal maintenance cost under different maintenance policies.

Policy	Optimal parameters		Expected average cost
	Bayesian (HSMM)	0.71		—	113.59
Bayesian (HMM)	0.28	—	121.72
Aged-based replacement	—	17.24	140.23