Quick Summary
- What it is: A classification system for aircraft parts based on how they are used, maintained, replaced, and tracked.
- Why it matters: Determines pricing, inventory strategy, paperwork, repair options, and regulatory oversight.
- Who uses it: Parts distributors, maintenance planners, purchasing teams, and regulators.
- Key drivers: Part function, repairability, traceability requirements, and life-limits.
Plain-English Definitions
1. Rotable
A rotable is a part that:
- can be removed, repaired/overhauled, and reinstalled
- retains value over many cycles
- usually has its own identity, history, and paperwork
Examples:
- starter generators
- wheels & brakes
- actuators
- avionics modules
Rotables form the backbone of an operator’s rotable pool and are often exchanged or loaned.
2. Expendable
An expendable is:
- not normally repaired
- cheaper to replace than repair
- still traceable, but not tracked individually like rotables
Examples:
- sensors
- switches
- some probes
- small electrical components
Expendables are replaced during troubleshooting without major paperwork burdens.
3. Consumable
A consumable:
- is used up during maintenance
- has no life beyond the immediate task
- is not serialized
- is not repaired or returned to stock
Examples:
- oils and fluids
- adhesives and sealants
- filters
- O-rings
- hardware (nuts, bolts, rivets)
Consumables represent a large portion of maintenance spend, but low individual value.
Why This Matters
The part type affects everything:
- Pricing: Rotables are expensive core assets; consumables are cheap but high volume.
- Inventory strategy: Rotables require pool planning; consumables require reordering discipline.
- Repair economics: Only rotables go through formal overhaul/repair cycles.
- Paperwork: Rotables get full trace; expendables get simpler tags; consumables often just get batch trace.
- Cash flow: Rotable pools and exchanges impact deposits, cores, and reserves.
How This Works Operationally
- Maintenance event occurs
- Technician identifies required part type.
- Repair vs replace decision
- Rotables → repaired/overhauled.
- Expendables → replaced outright.
- Consumables → used as needed.
- Traceability requirements
- Rotables → serialized tracking.
- Expendables → batch trace.
- Consumables → proof of lot certification (usually).
- Inventory strategy
- Rotables → managed carefully, often pooled.
- Expendables → purchased in moderate quantities.
- Consumables → purchased in bulk with auto-replenishment.
Example Scenario
A landing gear strut actuator fails.
- It’s a rotable item.
- Shop visit estimate: $18,000 repair or $32,000 replacement.
- Operator chooses exchange:
- Pays a flat exchange fee + returns core.
- Keeps aircraft flying with minimal downtime.
- Consumables (seals, fluids) are used during installation.
Common Misunderstandings
- “Consumables don’t matter.”
Incorrect — consumables can represent millions in annual spend for large fleets. - “Expendables are unimportant.”
Many avionics faults require expendables (probes, sensors) to diagnose issues. - “Rotables always get repaired.”
When the market price drops, it may be cheaper to buy serviceable units.
Related Topics
- Core returns
- PMA parts
- Pooling strategies
- Repair vs replace economics
- Serialized asset tracking