A rotable is an aircraft component built to be repaired and reused: it is removed from the aircraft, overhauled or repaired, certified for service again, and fitted to the same or another aircraft, over and over across its life. Because rotables travel in a loop rather than a straight line, the logistics that move them, and the time each leg takes, decide how long an aircraft waits for a replacement.
Rotables, Consumables, and Expendables: Three Kinds of Parts
Operators and manufacturers draw the lines a little differently, so check how your own stores system classifies a part number. The working distinction is straightforward.
| Category | What it is | Typical examples | When it fails |
|---|---|---|---|
| Rotable | A repairable, serial-numbered component with a tracked history | Actuators, starters, generators, hydraulic pumps, avionics units, landing-gear components | Removed, repaired or overhauled, certified, and returned to stock |
| Consumable | Used up or replaced at set intervals, and not repaired | Filters, seals, gaskets, fasteners, lamps | Discarded and replaced |
| Expendable | Replaced rather than repaired, but often still traceable | Certain fittings, bearings, and small assemblies | Replaced; the old unit is scrapped |
The Loop: How a Rotable Moves
- Removal. A unit fails or reaches its limit. Maintenance removes it and tags it unserviceable.
- Replacement. A serviceable unit comes from the operator's own stock, a component pool, or an exchange program and is shipped to wherever the aircraft is. This leg is often urgent.
- Return of the removed unit. The removed unit, known as the core, goes back to the supplier or repair shop, usually within a window set by the exchange agreement.
- Repair or overhaul. An approved facility evaluates the unit, repairs it, and tests it.
- Certification. The unit leaves with a release certificate stating who certified it and what work was done.
- Back to stock, ready to start the loop again.
Two Legs, Two Kinds of Urgency
| Leg | Why time matters | What it needs |
|---|---|---|
| Serviceable unit to the aircraft | The aircraft may be on the ground, and every hour has a cost | Direct transport, careful handling, the release certificate riding with the part, and a named receiver |
| Core back to the supplier or shop | Exchange terms usually set a return window, and a late, damaged, or incomplete core can affect credits or fees | Secure packing for an unserviceable unit, the removal tag, and clear return instructions |
The outbound leg is the one everyone worries about. The core-return deadline is the one that tends to show up on an invoice. Terms differ by contract, so read yours before the first exchange, not after.
The Paperwork That Defines a Rotable
A rotable's value lies in its documented history, and a sound part that arrives without the right records may be unusable. Four kinds of paper matter most.
- An authorized release certificate on serviceable units, such as Transport Canada's Form One, EASA Form 1, or FAA Form 8130-3, showing who certified the part and under what work.
- A removal or unserviceable tag on the core, describing the fault, the removal date, and the aircraft hours or cycles. Some shops will not evaluate a core without it.
- Traceability data: part number, serial number, and, for life-limited parts, the time or cycles already accumulated.
- Exchange documents: the order, the return instructions, and an authorization number if the supplier issues one.
A courier does not certify anything. Its job is to keep the paperwork with the right unit and deliver both in the condition they left. Our guide to the paperwork that travels with an AOG part covers the outbound side in more detail.
Packing a Core for Return
- Treat it as a valuable item, not scrap. A core damaged in transit can be rejected or cost more to repair.
- Cap or plug open ports and fittings, and contain any residual fluids. Fluids can bring dangerous goods rules into play.
- Use the original shipping container if you have it, or a rigid, cushioned crate that keeps connectors and mounting points from carrying weight.
- Attach the tag, keep a copy, and photograph the unit before sealing the package.
- Put the return authorization and return address on the outside of the package.
Where Montreal Fits In
McGill University's aerospace institute describes Montreal as the world's third-largest centre of aerospace manufacturing, with aircraft makers, engine and systems suppliers, and repair shops within a short drive of each other. For rotables, that means many exchange and core-return legs are short, and a courier based by the airport in Dorval can run a core to a shop and an exchange unit back within hours. Longer legs follow the cross-border and hand-carry routes.
Frequently Asked Questions
What is the difference between a rotable and a consumable?
A rotable is repairable and tracked by serial number, so it is repaired and reused many times. A consumable is used up or replaced at set intervals and is not repaired. Each operator classifies individual part numbers in its own stores system.
What is a core return?
In an exchange, the operator receives a serviceable unit and sends the removed unit, called the core, back to the supplier or repair shop. The exchange terms usually set a return window and may adjust credits or fees if the core is late, damaged, or incomplete.
Who pays for shipping in a rotable exchange?
It depends on the contract. Some exchange agreements include shipping in one direction, while others leave it with the operator. Check the terms before you book a courier, and confirm who is authorized to release the unit and sign.
Why do rotables need serial-number traceability?
Airworthiness depends on a unit's history: what work was done, by whom, and how many hours or cycles it has accumulated. A unit without traceable records generally cannot be installed, whatever its physical condition.
Can a courier ship a rotable that still contains fuel or oil?
Residual fluids can trigger dangerous-goods rules, so the unit may need to be drained or packed to specific requirements and declared at booking. See our dangerous goods basics.
Plan the Whole Loop, Not Just One Leg
Treat a rotable exchange as a loop with a deadline on every leg: outbound for the aircraft, return for the core, and the repair turnaround in between. Agree in advance who collects, who signs, and where the paperwork travels. For the urgent outbound leg to a grounded aircraft, see our guide to AOG parts delivery for MRO teams.
Rush Expedited Courier moves exchange units and cores for operators and repair shops from Dorval, around the clock. Tell us the part's size, whether it is serviceable or unserviceable, and both addresses through our aircraft parts courier service page or the quote form.
See also: delivering heavy and oversized aircraft parts and Montréal's aerospace cluster and parts logistics.