Subtopic: Applying Technology to your Fleet – Step #2
The next step after determining the operating conditions within the aircraft is to review the aircraft from the fleet level. This is if you are considering an aircraft wire life extension program. This fleet level assessment examines utilization; basically, it evaluates the fleet’s variability (age, service history, and service locations). This is necessary as aircraft used differently will show different aging patterns and test results from one aircraft may not be applicable to another aircraft.
Understanding fleet utilization provides the necessary information to logically group the aircraft. Just as grouping of aircraft zones reduced the number for testing, the logical grouping of fleet aircraft identifies partitions for the selective sampling. This process ensures the validity and applicability of risk assessment results.
Suppose there is a fleet that has been in production for a number of years. The fleet consists of multiple squadrons with different service lives (and locations). Utilizing Lectromec’s fleet analysis algorithm, four distinct groups are created. Within each of these groups there is some variability in terms of service received and age, but it is not large enough as to warrant partitioning into small groups.
While the analysis could be labor intensive, these partitions are easily determined with Lectromec’s fleet analysis algorithms, which built the groups to minimize intragroup variability. The algorithms have been designed such that, if a target number of groups is desired, then the relative loss of confidence interval is determined (versus the ideal group selection). This provides a huge advantage over standard manual assessments that may ignore the factors impacting fleet groupings.
If you are interested in wire life extension, you may want to read Lectromec’s When Should you Consider a Life Extension Program? articles.
After the groups have been created, the next step is to determine which aircraft within these groups should be selected for testing. The aircraft within these groups that are typically selected are those that are most available for wire removal (e.g. depot level maintenance). As for the number to be selected from each group, typically 5-15% of the aircraft needs to be selected for testing.
The wires removed from the selected aircraft are tested to examine their current condition and to make projections on remaining wire life (as discussed in a previous article). But these steps are only half of the process; the likelihood of failure must be combined with the failure severity to determine the risk to the aircraft. The next article in this series will discuss the process for assessing the risk of failure.