Welcome to the third part of a four-part series that explains what constitutes maintenance from an FAA perspective and what are the differences between the elements that make up maintenance?
This article provides an overview of replacing aeronautical parts.
REPLACEMENT OF PARTS
The replacement of parts is the removal and/or installation of parts on a product or article, and therefore, logically a maintenance task. However, there are some specific tasks that require further explanation.
Removing and Reinstalling the Same Part
While not addressed in the FAR’s (the FAR’s use the term “replacement”), reinstallation of the same part that was removed would still be classified as maintenance. If this was not the case, you could remove an entire engine, reinstall it and not call the action maintenance. Without classifying it as maintenance, there would be no requirement to record the activity, and no need to follow the manufacturer’s instructions! The word “replacement” should not interpreted as changing the part out for something new, but rather the placement, or installation, of a part on a product.
Components Designed for Simple Removal and Replacement
Removal and replacement/reinstallation of some parts designed to be easily exchanged, such as those with quick disconnects, may not be considered maintenance; even more so if it does not require any form of hand tools. This includes obvious things like removing a fuel cap or opening an access panel with quick release latches to facilitate fuelling of the aircraft. However, this can also include more complex actions like replacing a medical oxygen bottle. But this becomes complicated. For example, if the component is part of a critical aircraft function such as avionics component, then the replacement/reinstallation of the component be considered maintenance even though the component is mounted in a tray and only secured with thumb screws (i.e., not requiring tools to remove it). The same would apply for the removal and reinstallation of fuses, control yokes, and certain doors on helicopters and/or aircraft, even though designed for easy removal without tools.
Per the MSG-3, “function” is the normal characteristic of an item, and “functional checks” are a quantitative check to determine if one or more functions of an item perform within specified limits.
Classification of Functional Checks
Functional checks are not one of the defined elements of maintenance. While logically, they may seem to be a form of inspection, they really should be classified under the element of maintenance from which they are called out. For example, when performed as a check after a part replacement, the functional checks are part of the part replacement element of maintenance; when performed after a repair, then they are part of the repair. Specifically, if a maintenance procedure calls for a functional check, then that check is part of that maintenance procedure and must be completed by, or at the very least performed under the supervision of, a mechanic or entity authorized to perform the maintenance procedure.
An operational check flight is a type of functional check. When prescribed in the Instructions for Continued Airworthiness, a mechanic can provisionally approve an aircraft for return to service limited to the performance of an operational check flight. A pilot can then perform the flight. A mechanic may or may not need to accompany the pilot on the flight depending on what needs to be checked, but no unnecessary persons should be allowed on the flight. After the flight, the mechanic can make any necessary adjustments, call for the operational check flight to be repeated, or finalize the maintenance procedure and approve the aircraft for return to regular service.
An operational check is a task to determine that an item is fulfilling its intended purpose. Checks that are part of a pilot’s pre or post-flight procedures, as defined in the Aircraft Flight Manual (AFM), are operational checks and not functional checks and are therefore not items of maintenance. Similarly, Extended Operations (ETOPS) verification flights, which are required after maintenance on a primary system, are also a form of an operational check. Verification is accomplished by the flight crew and not observed by maintenance. And finally, AD’s sometimes prescribe “checks” and specifically authorize pilots to perform them. In these cases, these would be considered operational checks and not items of maintenance.
Inclusion of Checks in Inspection Programs
Since functional checks are not classified as inspections, they should not be considered part of the manufacturer’s inspection program. Only checks that are specifically called out for in the inspection program should be classified as inspections.