Coming to Grip with Aircraft Maintenance Check Packaging

The concept of a maintenance check used to be earlier a very basic concept- There were different level of checks, call them what you may A, B, C, D etc. and each check was allotted an Interval at which it must be repeated mostly by the OEM and during each of these checks you would perform a set of maintenance checks with each check becoming progressively more complex.

The problem with this methodology was that as a maintenance planner it does not give you much flexibility in terms of determining your ground time since you had no control over the type of tasks that you can include in a given check.

Of course with the advent of new concepts like MSG-3 logic, the output of the entire exercise of developing a baseline maintenance program involving industry, OEM, Regulators and other stake holders yielded in a set of maintenance tasks with varying intervals. Now the operator/CAMO has the opportunity to package these tasks as they want (however ensuring that the individual limit on each task is not exceeded)

A maintenance package, to put it simply, consists of a set of scheduled maintenance tasks that need to be done at a given maintenance check event.

The way an operator will plan and package these tasks essentially depends upon the aircraft and ground time availability.

There are two basic methods of check packaging

1.      The Block check is focused on the principle of grouping tasks which require frequent repetition under a single check i.e. A1, A2, C1, C2 etc. This method produces a small number of relatively large work packages. The disadvantages of this method is that ground times are longer and not uniform as each check normally incorporates all the work covered in preceding checks, plus the tasks assigned at that letter check interval.

Advantages:

-         Simplifies planning of work packages

-         More efficient sequencing of long jobs.

-         Total access/open-up time is minimized.

-         Additional time to incorporate SBs, Non routine etc.

-         More time to respond to findings based on inspections.

Disadvantages:

-         Sporadic Manpower Requirements

-         Longer Ground times.

-         Operators with smaller fleet may have higher impact to fleet operations.

2.      The phased check also called equalized or segmented check- apportions tasks to smaller packages that may be accomplished more frequently than the packages in a block check. For example, right engine tasks may be accomplished in one check while left engine in another check. An operator, for example may phase or segment portions of its heavy maintenance tasks equally over the appropriate number of C checks. The objective of this subdivision is to even out the maintenance workload over time and shorten the length of each period of down time. Peaks and valleys in man power requirements are minimized by moving tasks from one check pack to another.

Advantages:

-         Reduces ground time

-         Increases airplane availability by reducing downtime

-         Reduces sporadic manpower.

-         Reduces manpower required for a given check.

-         Flexible

Disadvantages:

-         Scheduling & Management of this type of checks is quite complex and increases the amount of time and manpower needed to plan checks.

-         Limited time for accomplishment of major jobs.

-         Limited time to attend to non-routine maintenance.

-         Setup and access may be redundant.

One can also have a semi equalized check system where the A check are equalized however the major checks C and above are planned as Block level.

The decision of which check packaging type to follow ultimately depends on the operator based on their resources and fleet availability. Let us say an operator which has a night halt every day has a fixed aircraft availability and this is more suited to an equalized check. On the other had if the aircraft availability for maintenance is variable then it is advisable to follow a block check philosophy. At the end of the day the decision of appropriate check packaging will go a long way towards optimization of maintenance costs.