A glossary of continuing airworthiness terms

The document kept with the aircraft in which every flight is recorded after it happens: times, counter readings, landings and the technical state — NIL or a reported defect. It is the source of the flight time used to compute maintenance due points, and the first evidence that the aircraft was operated as the records say.

More Electronic techlog The techlog entry: what it has to contain

A technical logbook kept in a computer system instead of on paper. The regulation does not require paper — it requires a record system that meets the conditions set out in AMC1 ML.A.305: a backup kept separately from working data, legibility for the whole retention period, protection against unauthorised change, access control and a written procedure for when the system is unavailable. Acceptance of the system is issued by the operator’s authority.

More Electronic techlog The electronic techlog and Part-ML: what a record system must do

The entry stating that no defect was found after a flight. It is the opposite of an empty field: an empty field means “nobody answered”, while NIL means “somebody checked and reports nothing”. That is why an entry with neither NIL nor a described defect is an incomplete entry.

More Electronic techlog The techlog entry: what it has to contain

The way to correct an error in a record that must not be edited: instead of changing the original entry, you add a record that undoes its effects and then enter the correct one. All three events stay in the register, so you see not just the final state but also what was corrected and why.

More Electronic techlog

Time counted from the moment the aircraft moves from its parking position under its own power until it stops after the flight. It is longer than airborne time because it includes taxiing, and it is usually the basis for accruing hours in the maintenance programme and in training records.

More Electronic techlog The techlog entry: what it has to contain

Time accrued in proportion to engine speed, so it grows more slowly than block time at low RPM. Many maintenance programmes tie part of their tasks to this counter rather than to block time — which is why both counters must be kept independently and one must never be converted into the other.

More Electronic techlog The techlog entry: what it has to contain

The set of lighter continuing airworthiness requirements for smaller aircraft not used in commercial air transport, covering among other things the maintenance programme, records, maintenance and the airworthiness review. It exists so that general aviation does not have to run on a regime written for airlines.

More Electronic techlog The electronic techlog and Part-ML: what a record system must do

Requirements for an organisation managing continuing airworthiness: structure, personnel, procedures, management system and record keeping. It applies to the organisation rather than to the aircraft — Part-ML says what has to happen to the machine, Part-CAMO says how the outfit doing it has to be organised.

More Maintenance tracking

The point of the regulation that sets out what the continuing airworthiness records of an aircraft must contain: a record of every flight, a record of maintenance referencing the release to service, the status of the maintenance programme, of directives and of life-limited parts, accuracy and currency of records, no editing after certification, and retention periods.

More Electronic techlog The electronic techlog and Part-ML: what a record system must do

Material issued by the Agency alongside the rule itself. An AMC describes a way of meeting a requirement that is accepted as adequate — you may comply differently, but then you have to demonstrate it. GM provides explanation and examples. For an electronic logbook the key one is AMC1 ML.A.305, because it spells out the conditions for a computerised system.

More The electronic techlog and Part-ML: what a record system must do

The organisation that manages continuing airworthiness: it looks after the maintenance programme, due dates, airworthiness directives and bulletins, keeps the records and is responsible for the aircraft remaining airworthy. It is not the same as a workshop — CAMO manages and documents; maintenance is performed and released by a maintenance organisation.

More Maintenance tracking

An organisation that holds continuing airworthiness management and maintenance of lighter aircraft under a single approval. For smaller operators it is often more practical than maintaining two separate approvals, because the same organisation keeps the records and performs the work.

More Who it is for

Two ways of running flight training: an ATO operates under an approval and can deliver a wide range of training, while a DTO operates on a declaration and covers a narrower scope, typically non-professional licences and basic ratings. For technical records the difference is secondary — both have many pilots on one aircraft and the same need for an attributable signature.

More Who it is for

The document confirming that the aircraft records demonstrate its airworthiness. It is issued after an airworthiness review, which consists of a records review and a physical survey of the aircraft. The certificate is valid for a year and — if the aircraft has stayed in a controlled environment — it can be extended, typically twice by one year; after that a full review is performed.

More Maintenance tracking The ARC and the airworthiness review: an operator's calendar

The basic certificate of an aircraft, issued when it enters service and remaining valid as long as the conditions for keeping it are met. It is the ARC that confirms those conditions are still met — which is why the ARC is the one with a date to watch in the calendar.

More Maintenance tracking The ARC and the airworthiness review: an operator's calendar

The document issued after maintenance, stating that the work was carried out in accordance with the requirements and that the aircraft may return to service. It is issued by certifying staff or a maintenance organisation — not by a software system and not by CAMO.

More Maintenance tracking

A document issued by an aviation authority in response to an identified unsafe condition, mandating specific actions by a stated deadline. It is mandatory by law — there is no “is it worth it” assessment, only the question of whether it applies to a given airframe.

More Bulletins and ADs ADs, SBs and SLs: what is mandatory and what is advisory

A manufacturer publication describing a recommended modification, inspection or change to maintenance practice. It is not mandatory in itself: it becomes mandatory only when an airworthiness directive, the maintenance programme, the airworthiness limitations section, a condition of the airworthiness review or a deliberate CAMO decision makes it so.

More Bulletins and ADs ADs, SBs and SLs: what is mandatory and what is advisory

A manufacturer publication of an informational nature: a clarified procedure, an explanation, a warning about an observed phenomenon. It usually imposes no obligation, but it is often the basis of a later bulletin or directive — which is why it belongs with the rest of the documents rather than in an inbox.

More Bulletins and ADs ADs, SBs and SLs: what is mandatory and what is advisory

The document setting out which maintenance actions are performed on a specific aircraft and at what intervals — with hour, calendar and cycle limits, tolerances and references to manufacturer documentation. It belongs to the operator and is subject to revisions.

More Maintenance tracking Tolerances without drift: how to compute inspection due points

The permitted usage before a maintenance action is due or before a part is withdrawn from service, expressed in hours, cycles, calendar time, or several of these at once. When limits appear together, the rule written in the maintenance programme applies: whichever comes first, or whichever comes later.

More Maintenance tracking Tolerances without drift: how to compute inspection due points

A part for which the manufacturer has set a hard life limit — once reached, the part is withdrawn from service regardless of its condition. The limit carries no tolerance, and the installation history of such a part is among the first documents examined during an airworthiness review and when an aircraft is sold.

More Maintenance tracking Tolerances without drift: how to compute inspection due points

The margin defined in the maintenance programme within which an action may be performed after its planned due point without breaching the programme. What matters most is what the next due point is counted from: if it is counted from the actual compliance date, the schedule drifts forward and after a few years the “100 h” inspection really happens every 115 hours.

More Maintenance tracking Tolerances without drift: how to compute inspection due points

A list of tasks and documents ordered by remaining margin — how many hours, cycles or days are left. It is the basic maintenance planning tool: it answers which aircraft will stop first and whether that can be reconciled with the season.

More Maintenance tracking Tolerances without drift: how to compute inspection due points

The data entered when an electronic system goes live: current counter readings, the maintenance programme tasks, and the dates and counter states of the last compliances. Flight history is not migrated — you carry over the state from which counting starts, together with a note on which document it came from.

More Pricing From paper to electronic records without losing history

A period during which records are kept both on paper and in the electronic system, with paper prevailing in case of divergence. It serves two purposes: catching differences before they become a problem, and building the evidence base for the conversation with the authority about leaving paper behind.

More Security From paper to electronic records without losing history

The set of documents presented during an audit or an airworthiness review: the flight register for a period, task statuses and compliances, the status of directives and bulletins, components with installation history, defects and aircraft documents. Its value rests on two things — completeness, and whether it can be read without the system that produced it.

More Security The ARC and the airworthiness review: an operator's calendar