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Component Reliability - Batch Problem
A Batch problem refers to a group of components that are experiencing similar problems. Unlike a “Poor Design” issue, batch problems affect only a portion of a component population. There are several possible causes of batch problems:
1. Material change: Manufacturers sometimes use multiple suppliers for “piece parts” used to build their products. Repair shops often change suppliers for availability or economic
reasons. Theoretically, these “piece parts” are interchangeable. But,sometimes there are small
differences that can (and do) cause reliability issues once the component is installed on an
aircraft.
2. Process change: Sometimes, manufacturers and repair shops change the way they do
things. A new test fixture may cause alignment problems during assembly. A wave-soldering
machine may have been repaired and not properly calibrated – causing poor solder joints
and/or heat damage. The sequence of manufacturing events may change – resulting in
hidden damage or improperly fastened assemblies. Regardless of the change, the end result
is poor reliability.
3. Modifications with unintended consequences: Occasionally, a modification fixes one
problem but creates a different problem. If this happens, you probably will not be aware
of the problem until quite a few components have been modified – unless the modification
renders the component completely inoperative. As more and more modified components are
installed on your fleet, you will notice an increase in pilot reports and/or component removal
activity. If you cannot quickly connect the dots – and stop the modification plan – your batch
problem will turn into a fleet-wide issue.
Batch problems are known to cause significant reliability issues. These types of problems can be easily misdiagnosed. Because the early stages of a batch problem affect only a small portion of the total component population, the problem may be completely overlooked – or viewed as a group of rogue components. As the batch problem grows, and pressure builds to “get it fixed”, a knee-jerk reaction for drastic action (modification, retrofit, fleet campaign, etc) sometimes takes over.
Batch problems can be identified several ways. Depending on the source of the problem, you may be able to identify batch issues by serial number, date of manufacture or date of repair. You should always try to pinpoint when the problems originated – and share this information with your repair shop and/or manufacturer. They may be able to correlate a process or material change with the timeframe that you began to experience problems.
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