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Fleet Reliability - The Initial Technical Analysis
Once an ATA alert notice is generated, the first question you need to answer is: Is this alert due to a legitimate reliability issue? At this point, you are not looking to identify root cause. You are simply trying to determine if the increase in activity is the start of an actual problem – or is simply a statistical spike. To do this, you must try to formulate a problem statement. Gather your data and try to answer the following questions:
1. What specific problems are being reported?
a. Are all of the reported problems the same – or different?
b. How many occurrences of each type of problem?
2. How does the problem present itself?
a. A warning light or status message
b. A noise or vibration
c. Weak, sluggish or erratic operatio
d. Unexpected operation
e. Operation ceases unexpectedly – or fails to operate at all
f. Intermittent or hard-failure?
3. How many aircraft are experiencing the problem(s)?
a. Is it a chronic problem on only one or two aircraft?
b. Are most aircraft in the fleet affected by the problem?
4. When is/are the problem(s) occurring?
a. On the ground (at the gate, or during taxi)?
b. At takeoff or landing?
c. During flight?
d. During maintenance checks?
If you cannot define one or two specific problem statements after answering these questions, your alert is probably just a statistical spike – because there is no common failure mode occurring during the reporting period.
If a problem is apparent, try to define it as specifically as possible. This will help you identify root cause much quicker – and implement a successful solution. Here is an example of a strong and a weak problem statement:
1. During the reporting period, two aircraft experienced a total of fourteen APU
auto-shutdowns. Aircraft 911 had eleven shutdowns (seven shutdowns occurred along with
a low oil pressure light). The shutdowns occurred after landing while the aircraft was taxiing
to the gate. Aircraft 909 had three shutdowns (with an associated inlet door message).
These shutdowns occurred during preflight checks before the first flight of the day (on
three successive mornings).
2. During the reporting period, fleet 9 experienced fourteen APU shutdowns.
A strong problem statement sets the course for a detailed and focused root-cause analysis. With the first problem statement, your root-cause analysis only needs to identify what fixed the two chronic aircraft. The second problem statement is so open-ended that it is nearly impossible to decide where to begin.
In summary, a fleet alert notice does not always mean that a legitimate reliability issue exists. It simply means that higher than normal activity has occurred with the affected system. Therefore, an initial analysis should seek to answer: What, When and How Many? These questions will lead to a detailed problem statement – if a legitimate reliability issue exists.
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