Glossary
Maintenance, engineering and commercial terms used throughout A-Sync.
Airworthiness and compliance
AD (Airworthiness Directive) - a mandatory instruction from a regulator to correct an unsafe condition on a type of aircraft or component. Not optional, and always has a compliance deadline.
SB (Service Bulletin) - a manufacturer's recommended action. It becomes mandatory only if a regulator makes it so through an AD.
CAMO (Continuing Airworthiness Management Organisation) - the organisation, or the team within it, responsible for keeping aircraft airworthy: the maintenance programme, ADs, and the decisions behind deferrals.
Maintenance programme - the approved schedule of what must be done to an aircraft and when, expressed in flight hours, cycles or calendar time.
Due item - one instance of a requirement falling due on one aircraft or component, with a deadline calculated from utilisation.
MEL (Minimum Equipment List) - the approved list of equipment that may be unserviceable while the aircraft still flies, with conditions and a time limit.
Deferral - a decision to postpone rectifying a defect under the MEL, within its category limit.
ETOPS - approval for extended operations away from a diversion airport. Carries additional maintenance and readiness conditions.
CRS (Certificate of Release to Service) - the statement that maintenance was carried out correctly and the aircraft is fit to fly. Only a certifier issues one.
Life limit - the maximum hours, cycles or calendar time a part may remain in service before it must be removed, regardless of condition.
Aircraft and components
Registration - the aircraft's tail number.
MSN (Manufacturer's Serial Number) - the permanent serial number of an airframe.
ESN - the equivalent serial number for an engine.
APU (Auxiliary Power Unit) - the small onboard turbine providing power on the ground.
Configuration - the named positions on an aircraft and what is fitted to each.
Fitment - installing or removing a component from a position.
Utilisation - accumulated usage. FH is flight hours, FC is flight cycles.
Rotable - a component that is removed, repaired and returned to service rather than discarded.
Cannibalisation (ROB) - taking a serviceable part off one aircraft to keep another flying, creating an obligation to restore the donor.
Off-wing - a component that is not currently installed.
Stores and materials
Stock line - a quantity of one part, in one warehouse, in one condition, with its own batch or serial number.
Serviceable / unserviceable - whether a part is fit to install.
Shelf life - the date after which a part may not be used, regardless of use.
Batch / lot - a production run identifier for non-serialised parts.
Reservation - a claim on stock for a specific task, before picking.
Kit - a pre-picked set of parts staged for a scheduled check.
Cycle count - a physical stock check of part of the warehouse. Blind, so the counter cannot see the expected figure.
Ownership class - who owns the stock: own, customer-owned, consignment, pool or loaned-in.
Consignment - supplier-owned stock held on your premises, paid for when used.
Core - the unserviceable unit returned to a supplier in exchange for a serviceable one.
AOG (Aircraft on Ground) - the aircraft cannot fly until the part arrives. The highest priority there is.
Certificates and records
EASA Form 1 / FAA 8130-3 - authorised release certificates. The document proving a component was released by an approved organisation.
CoC (Certificate of Conformity) - a manufacturer's statement that an item conforms to its specification.
Records package - a bundle of airworthiness records assembled for a customer or for delivery of an aircraft.
Back-to-birth traceability - an unbroken record of a life-limited part from manufacture onward.
Dirty fingerprint - informal term for the signed record that a specific person did a specific job.
Shop and quality
Shop visit - a component or engine's stay in the workshop, from induction to release.
Workscope - the agreed list of what will be done during a shop visit.
Induction - formally receiving a component into the shop.
Finding - something discovered during work that was not in the agreed workscope.
MRB (Material Review Board) - the body that decides what happens to non-conforming material.
Scrap - condemning a part so it can never return to service.
SMS (Safety Management System) - the framework for reporting, investigating and acting on safety occurrences.
Occurrence - a reported safety event.
SDR (Service Difficulty Report) - a report to the regulator about a significant failure or defect.
Planning and execution
Work package - a group of tasks planned to be done together, usually during one visit.
Task card - the instruction for one job, and the record that it was done.
Sign-off - the signature recording that a step was performed, by whom.
Independent inspection - a second person verifying safety-critical work.
Handover - the structured transfer of work in progress between shifts.
Capacity - the man-hours available, against the man-hours planned.
Commercial
Quotation - a priced offer of work to a customer.
Work order - the authorised job, and the thing costs accumulate against.
Landed cost - the true cost of a part once freight, duty and handling are included.
AR / AP - accounts receivable (owed to you) and accounts payable (owed by you).
Aging - how long an invoice has been outstanding, grouped into bands.
Credit note - a document reducing what a customer owes.
Lease - an agreement to operate an aircraft or engine owned by someone else.
Redelivery - returning a leased asset at the end of a lease, in the condition the contract requires.
Power by the hour - a support arrangement charged per flight hour rather than per repair.