Maintenance Program Basic Objectives
Maintenance Programs Should have the following five basic objectives:
To ensure realization of the design level of safety and reliability of the equipment;
To restore safety and reliability to their design levels when deterioration has occurred;
To obtain the information necessary for the adjustment and optimization of the maintenance program when these inherent levels are not met.
To obtain the information necessary for design improvements of those items whose design reliability proves inadequate; and
To accomplish these goals at a minimum total cost, including maintenance costs and the costs of residual failures.
Maintenance Program Simplified Objectives
We could simplify it further and say that there are 2 essentials features of a modern Maintenance Program. In other words there are only two reasons why we should “have” to do maintenance.
To Ensure Safety of Operation
To Ensure Economic Effectiveness
Foundation of Reliability Driven Maintenance Programs
Both MSG-2 and MSG-3 Maintenance Programs are considered Reliability-based maintenance programs, as such they are based on the following general principles.
a) A failure is an unsatisfactory condition.
There are two types of failures: functional and potential. Functional failures are usually reported by operating crews. Conversely, maintenance crews usually discover potential failures.
b) A potential failure is an identifiable physical condition, which indicates that a functional failure is imminent.
c) The consequences of a functional failure determine the priority of a maintenance effort. These consequences fall into the following general categories:
1/ Safety consequences
2/ Operational consequences, which involve an indirect economic loss as well as the direct cost of repair;
3/ Non-operational consequences, which involve only the direct cost of repair; or
4/ Hidden failure consequences, which involve exposure to a possible multiple failure because of the undetected failure of a hidden function.
d) In a reliability-based maintenance program, scheduled maintenance is required for any item whose loss of function or mode of failure could have safety consequences.
e) If preventative tasks cannot reduce the risk of such failures to an acceptable level, the item requires redesign to alter its failure consequences.
f) Scheduled maintenance is also required for any item whose functional failure will not be evident to the operating crew, and therefore reported for corrective action.
g) In all other cases the consequences of failure are economic, and maintenance tasks directed at preventing such failures must be justified on economic grounds.
h) All failure consequences, including economic consequences, are established by the design characteristics of the equipment and can be altered only by basic changes in the design.
i) Safety consequences can, in nearly all cases, be reduced to economic consequences using redundancy.
j) Hidden functions can usually be made evident by instrumentation or other design features.
Notes
The feasibility and cost effectiveness of scheduled maintenance depend on the inspectablility of the component, and the cost of corrective maintenance depends on its failure modes and design reliability.
The design reliability of equipment or components will only be achieved with an effective maintenance program.
This level of reliability is established by the design of each component and the manufacturing processes that produced it.
Scheduled maintenance can ensure that design reliability of each component is achieved, but maintenance alone cannot yield a level of reliability beyond the design reliability.
Sofema Aviation Services www.sassofia.com (SAS) and our Partner SofemaOnline www.sofemaonline.com (SOL) offer both classroom based and online regulatory training course compliant with EASA Regulations. For additional details please see the websites or email office@sassofia.com or online@sassofia.com
Tags:
Aircraft Reliability, EASA Compliant Large Aircraft Maintenance Programs
