By Jack Hessburg
Last month, we discussed my definition of maintenance — the management of failure. OK. Just how does one manage failure? Most will agree that failure is a frequent surprise. It seems that failures always occur at inopportune times.
It is possible, however, to manage the failure of airplane systems and components. There are two strategies available to do this:
• Manage the consequences of failure
• Avoid the failure
Three techniques, in use since the early '50s, permit managing the consequences of failure:
First, a coded fault report is radioed to the destination station. This is an unrefined form of failure management as it permits line mechanics an awareness of what is coming to them. It provides time for all organizations to plan an effective corrective action or at least plan alternative handling of the passengers, should the fault be serious enough to cause a flight cancellation.
Today, in order to facilitate the process, mechanics employ such documents as Fault Reporting Manuals (FRM) and Fault Isolation Manuals (FIM).
Mechanics are further supported by maintenance control centers. These help direct the mechanic's work and provide expert technical backup. They are staffed by experienced mechanics who "have been there, done that."
Another way to manage failure is the use of a Minimum Equipment List (MEL). The MEL permits safe continued operation of an airplane with inoperative equipment until a repair can be made. This is done by limiting the operation of the airplane or by the transfer of function to another or redundant system.
The third solution is contingent upon the reliability program mandated by FAR 121. Reliability programs collect a large body of data. Statistical analysis of this data against defined performance standards permits identification of problem areas. This, in turn, allows development of a fix.
But, all of these solutions are managing the consequences of failure, they are really not managing failure.
The more elegant and effective strategy is the second previously mentioned strategy — avoid the failure.
Consider the following: If there is a method that permits watching a system deteriorate toward a failure, a failure can be avoided. This puts the maintenance organization in front of the airplane. The concept is the foundation of a maintenance process called condition monitoring.
Condition monitoring involves watching the deterioration of a component as it trends toward a failure. Analyzing selected operating characteristics of the device does this. The information is compared against known standards. The results alert the maintenance manager to the impending failure of a device. Repair or replacement can be scheduled before failure occurs.
Now carry the application of engine condition monitoring a step further. Suppose it is possible to get the airplane to talk to maintenance while it is operating; not just the engine but all of the important systems and components. Current transports have Built-in Test Equipment (BITE). BITE monitors the operating parameters of a device but also analyzes the data to arrive at failure information. This information is translated into failure reports from individual units. This is further combined with information from other systems by a maintenance computer. The resulting reports provide evidence of both failure and the deterioration of the component — allowing the maintenance manager to decide what to do with the real or incipient failures .
Effective condition monitoring has several benefits. It minimizes delays and cancellations. It can be used to schedule repairs at a convenient time. It is possible to better control inventories and manpower. And, very importantly, it can provide the mechanic direct assistance when troubleshooting the airplane.
So there you have it. It is possible to manage failure thus assuring the availability of safe reliable transportation. Maintenance is truly the management of failure. The opportunity to maximize revenue exists when the airplane remains available rather than being removed from service. Knowledgeable mechanics working with the assistance of maintenance engineers avoid costly repairs and schedule interruptions. They "pick their fights" and keep airplanes safe and available. Everybody wins — the traveling public, the maintenance organization, and the bookkeeper.