A component of an aircraft removed and changed at fixed intervals estimated in elapsed flight hours, after which the removed part is taken for service and reused afterward.
How a Rotable Works
Rotables are components or parts of the aircraft required to be 'rotated' at regular periods in time. Rotables are aircraft components that are issued and recorded on an airline's database. It is also a removable and repairable part (in-house or by a vendor) to be used again. Expendable (throw-away) parts are the general opposites of rotables.
The stock of rotables is to be kept in the stores of airlines or operating companies. The manufacturer supplies a recommended scale of rotables. However, for major components that companies can't keep in stock, such as an engine, a due date for replacement would be ascertained. Therefore, the operating company could demand a new engine two weeks before the pre-determined date of replacement.
To cater to unforeseen circumstances that affect the engine, a couple of whole engines could also be on the list of components on a recommended scale for an airline. There is another set of replaceable aircraft components that only when damaged affect the existing part or item. Such items would not be normally made available in the stores, and they are demanded from the manufacturer only when it is fundamental to change them. A list of components is linked to every aircraft called the minimum equipment list (MEL).
Examples of Rotable
Rotables are required to be built, calibrated, and installed with care. The failure of a rotable compartment could have dire consequences with the replacement of these compartments at regular intervals. Rotables can be utilized many times by repairing them.
For example, the plane's tires will be replaced when an aircraft completes a certain number of landings; let's assume 250 landings. The tires will be removed, repaired, retreaded, etc. then placed back on the plane. There could also be a need to replace a tire when unusual damage occurs before it completes its set number of landings. Similarly, is the case with other items such as oil filter, and many other components.
Expendable Parts vs. Rotables
Expendable parts are serviced components utilized in the repair and overhaul of the serviced airframe. Any serviced engine and other rotable components that are presumed to have no potential to be used again and miscellaneous equipment and items utilized during the repair and service process are expendable parts. Expendable parts have the potential for an overhaul or reuse but are usually presumed to as expended for various reasons.
However, rotables follow the Federal Acquisition Regulations (FAR) or the original equipment recommendations by the manufacturer. These rotables can be frequently and economically reinstated to a serviceable condition over time, approximating or exceeding the life of the flight item to which they are linked.
Rotables are based on anticipated failures calculated by manufacturers and the planning guidelines completed as the management chooses. The significant difference between expendable parts and rotables is that rotables can be repaired repeatedly, whereas companies throw out expendable parts upon use.