A review of all maintenance man hours shows that over the life of the aircraft up to 20 hours of maintenance is delivered for each flying hour of aircraft utilization, of course this increases over time, a new aircraft requires considerable less maintenance than more mature aircraft. How do we know these man hours are invested wisely?
Delivering āmoreā maintenance does not necessarily bring the most effective outcome rather we should consider are we doing the ācorrectā maintenance. This is a question which we are able to answer using reliability data and analysis.
In essence we can consider maintenance as either planned or unplanned, unplanned arising from defects and damage in service.
Reliability is designed into the aircraft and the two reasons we perform maintenance in a MSG environment is in respect of either safety or economic benefits. We may in fact consider a significant part of this as preventative maintenance, means to preempt failure by timely maintenance activity, and to reduce the incidence of in service failure.
It was understood many years ago that the majority of component maintenance did not actually benefit the fundamental reliability of a component in service. A small number of components require continuous attention, typically associated with lubrication and changing of and lubricants, all activities typically designed to prolong component life.
Different categories of component
Components whose reliability is considered independent of age
These components may be susceptible to infant mortality. Typically these components will not benefit from regular maintenance, with the exception of failure finding tasks.
Hard life or components which will wear-out due to use
Landing Gear and Control Actuators are examples of this category, to ensure that we remove these components at the optimal time. These components may also be susceptible to infant mortality. These components may benefit from lubrication tasks. Effective management of reliability is important for this category.
Components whose inherent reliability levels requires scheduled maintenance activity
Systems containingĀ filters and Oil would be examples of this group adequate maintenance whilst not eliminating the failure may increase component life and reduce the cost of restoration if this is an option.
Components which deteriorate with age
Wheels are a good example of this group, we know for a fact that they will wear out and require replacing, assuming that the aircraft is being used of course. Otherwise they will be subject to age related wear.
Behaviour plays a part for example careful landing and not using excessive braking will prolong the life of the wheels. Routine maintenance may be required to check serviceability for example Tyre Pressures.
Sofema Aviation Services www.sassofia.com offers Aircraft Reliability and Aircraft Maintenance Planning Training. Please visit the web site or email office@sassofia.com for further information.
