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Glossary

A320 Family (A320 FAM)

Means Airbus A318, A319, A320 and A321 aircraft.

A Check

The most frequent regular check carried out on an aircraft (apart from daily/pre-flight check). Typically performed every eight to 12 weeks and often generically referred to as a Light Maintenance check. These checks can be sequentially numbered with, for example, a “2A” check includes a few more tasks than a “1A” check.

Aircraft Availability

The time for which an aircraft was available for flight service, usually referred to in percentage terms.

Aircraft On Ground (AOG)

When an aircraft has been grounded and is unable to fly for technical reasons it is referred to as an AOG. An urgent request is sent out for parts or components or engineering assistance to enable the aircraft to be repaired and put back into service in the shortest possible time.

Aircraft Phase-In

When an aircraft (new or used) is first delivered to an operator, the airline itself (or its maintenance partner) must record all details of Part Number, Serial Number, Maintenance Planning Document (MPD) schedule for all components within its maintenance planning and control system. This will also include details of the Flight Hours (FH)/Flight Cycles (FC) undertaken to date by each component, plus the lives already consumed on all installed life limited parts (LLP’s). An Aircraft Phase-In is a particularly extensive task in the case of a used aircraft requiring a large amount of time and resources.

Aircraft Phase-Out

The reverse of Phase-In, performed when an aircraft is sold (or leased) to another operator. The previous operator (or its maintenance partner) must extract all the Phase-In data which must have been continuously updated to reflect all the lives consumed and maintenance events which have taken place throughout the time in service with the previous operator/s. In addition, this term is also used to describe the physical work performed on the aircraft and its engines and components in order to meet the Lease Agreement Return Conditions (if leased) or the Sales Agreement Acceptance/Delivery Conditions (if sold).

Airworthiness Directive (AD)

Issued by one or more Airworthiness Authorities, this is a legally-binding requirement for work to be done on a specific aircraft, or engine, or component (type, model, or serial number/s). The work may involve modification, inspection, or other preventative measures, and may involve a one-off task or a task that needs to be repeated. ADs always have a threshold expressed in Flight Hours (FH) and/or Flight Cycles (FC) and/or Calendar Time (by which time the task must have been performed).

Approved Standard

Indicates a manufacturing/design/ maintenance/quality standard approved by the relevant Authority.

Auxiliary Power Unit (APU)

A small gas turbine engine, usually mounted at the tail of an aircraft, which provides additional power for services (e.g. electrics, hydraulics, air conditioning and engine starting). Normally used only whilst the aircraft is on ground with the main engines shut down. Not permitted to be used at some airports (mainly for environmental reasons).

Avionics

Modern passenger aircraft are highly automated and are often referred to as being “computerized”, and as having “glass cockpits” (as opposed to the “old-fashioned needles on dials” type of instrument). The numerous electronic units including the various computers themselves, plus items such as interfaces, display generators, sensors, signal distributors, etc. are all generically referred to as avionics.

C Check

Next most frequent check after an A check. Typically performed every 12 to 18 months. These checks are also sequentially numbered with, for example a “2C” check including rather more tasks than a “1C” check, and so on.

Component Maintenance

Component maintenance means bringing unserviceable components of the operator’s aircraft into a serviceable (airworthy) condition. This maintenance can be performed internally or externally and comprises of one or a combination of the following tasks: repair, overhaul, test, modification, inspection and re-certification. The incorporation of ADs etc. is also part of the component maintenance services. Component maintenance services comply with the airworthiness requirements of the operator’s authority and are in accordance with vendor or manufacturer requirements or the relevant Component Maintenance Manual (CMM).

Component Management

Component Management comprises Repair Cycle Management, Inventory Management, Component Technical Management and Warranty Management. In addition, this service is performed to improve reliability (component history reports analysis, analysis of suggested modifications, etc.) and to secure the availability of interchangeable and qualitatively equal components.

Consignment Stock

Consignment stock means an onsite stock at the operator’s main base or another specified location. The components remain under the ownership of Tunisair Technics. In order to ensure aircraft are not delayed for technical reasons, the consignment stock comprises the most critical components that are likely to be required.

Component

Means a rotable or repairable part (re-usable). Aircraft components whose maintenance intervals are scheduled separately to the maintenance intervals of the aircraft itself.

Cycle

Cycle means one take-off and subsequent landing of the aircraft. Cycle is often used as a charging basis for wheels,tyres and brakes, but it is also a measurement of the length of time an item is in service before maintenance and/or exchange becomes necessary.

Deferred Defect Rectification

Faults or defects found on an aircraft which do not need immediate action and can be deferred for repair to a later date. This deferred defect status is only given for a strictly limited period of time and rectification must take place before that time has elapsed.

EASA (European Aviation Safety Agency)

While national authorities continue to carry out the majority of operational tasks – such as certification of individual aircraft or licensing of pilots, EASA, the European Aviation Safety Agency ensures common safety and environmental standards at the European level. Responsibilities include drafting safety legislation and providing technical advice to the European institutions and the member states; inspections; safety and environmental type-certification of aircraft, engines and parts; approval and oversight of aircraft design organizations worldwide and of production and maintenance organizations outside the EU; data collection, analysis and research to improve aviation safety.

Engine Condition Monitoring (ECM)

Today engine workshop visits are normally scheduled on the basis of “On Condition”. To establish the condition of an engine while installed (“on-wing”), various parameters are regularly monitored and plotted graphically for comparison against norms stored using special PC software. By comparing actual parameters with previous values, and comparing those against the stored norms, it is possible to predict engine removal with some accuracy since it is the gradual deterioration of various parameters affecting overall engine performance and efficiency which are being monitored. When used together with complementary techniques such as analysis of lubricating oil samples or particles lodged in filter elements, plus the use of borescopes to view various internal parts whilst the engine is still installed, the planning of engine servicing can be predicted quite accurately.

Engine Engineering

The analysis and preparation of customized work scopes for the customer’s engine. This also covers key activities like inspections after disassembly, the preparation of a tailor-made reliability program and repairs development.

Engine Fleet Management

Engine fleet management includes engine trend monitoring (analysis of the performance of an engine on-wing), trend analysis and recommendations for on-wing maintenance actions. The key objective of engine fleet management is in determining the most appropriate removal plan for every single engine.

Engine Maintenance

The off-wing maintenance that is performed in a workshop. This includes the overhaul and repair of complete engines, modules, accessories and QEC; the engine's component repairs; the engine and accessory testing; the incorporation of Service Bulletins, Airworthiness Directives, campaigns and modifications and also the management of the entire repair cycle.

Engine Management

Engine management comprises the management of the shop visit, engineering activities (mentioned above), engine fleet management, on-wing/field team assistance (24hrs/365day), warranty management (including special reports, occurrences analysis with customers and the OEM), data management, engine changes, transportation and the access to Maintenance Operation Center (MOC) 24 hours a day, 365 days a year.

Federal Aviation Administration (FAA)

The airworthiness authority of the USA.

Fleet Technical Management

Tasks such as scheduling maintenance work, evaluating Airworthiness Directives (ADs) and Service Bulletins (SBs), monitoring maintenance costs and reliability, arranging the escalation of maintenance intervals, etc. are referred to as technical fleet management. This can also be referred to as a maintenance partner carrying engineering responsibility for a fleet.

Flight Hour (FH)

Basic unit for measuring length of time in service/before maintenance becomes due. The flight hour (FH) represents one hour of flight.

Ground Time

Expression used to define the total time an aircraft will spend (start to finish) undergoing a defined maintenance check.

Heavy (or Major) Maintenance

See D Check and HMV.

Heavy Maintenance Visit (HMV)

The maintenance “visit” (or ground time) for performing a D Check (or similar major work).

Integrated Airline Solutions (IAS)

Tunisair Technics total offering. Click here for further details.

Integrated Component Services (ICS)

Tunisair Technics total component offering. Click here for further details.

Integrated Engine Solutions (IES)

Tunisair Technics total engine offering. Click here for further details.

Integrated Maintenance Services

The maintenance services delivered to the airline by a maintenance partner such as Tunisair Technics. The services may be carried out by the maintenance partner or outsourced to other reliable suppliers but the maintenance partner will oversee and “integrate” all aspects of the services provided to the airline.

Integrated Service Provider

A maintenance partner who is responsible for providing all technical services for an airline. The services may be carried out by the maintenance partner or outsourced to other reliable suppliers but the maintenance partner will oversee and “integrate” all aspects of the services provided for the airline.

Inventory Technical Management

The technical management of the component stock to support an airline's fleet.

Landing Gear (LDG)

The complete assembly of legs, struts, wheels, brakes, steering gear, etc. that allows the aircraft to move and steer on the ground. A “ship set LDG” is one set of all the units required by one aircraft

Light Maintenance

See A Check.

Line Engineer

A licenced certified engineer who performs the Line Maintenance functions.

Maintenance Operations Control (MOC)

An office at a maintenance provider (or airline) open 24 hours/365 days, staffed with qualified technical specialists and equipped to communicate both verbally and by written message with technicians and pilots of aircraft away from base, both while airborne and on ground.

Modification

Modification means the alteration of an aircraft/aircraft component in conformance with an approved standard. Such modification can be initiated by the Authorities (Airworthiness Directives – mandatory) or by the Vendors or other market participants (Vendor Bulletins, Service Bulletins, etc. – non-mandatory).

C of A for Export

MRO

Maintenance, Repair and Overhaul.

MRO Provider

Maintenance companies who hold Airworthiness Authority approvals for the maintenance and repair of specific aircraft, engine, and component types/models.

N1 Vibrations

N1 relates to engine low pressure rotor speed, i.e. how fast the first set of turbine blades in a jet engine are turning.

Original Equipment Manufacturer (OEM)

An original equipment manufacturer (frequently abbreviated “OEM”) is a company that builds products or components that are used in products sold by another company.

Rotable/s (Components)

Aircraft components whose maintenance intervals are scheduled separately to the maintenance intervals of the aircraft itself.

Serviceable

Means certified release to service in accordance with the applicable requirement.

Technical Snags

Damage, problems or faults of a technical nature.

Turn Around Time (TAT)

The time taken (usually an average, expressed in days) between the arrival of a component, engine or aircraft (usually for overhaul) and the time at which the overhaul will be completed and unit released ready for service.

Type Courses

Also known as type training. These are technical courses for a specific aircraft type, e.g. Boeing B737-300 or A320 training.

Work Scope

Official document (usually part of the contract between a maintenance provider and an aircraft operator – or owner) precisely defining the tasks to be performed during a specific aircraft ground time (or engine shop visit).

Not to be confused with IATA Pool which functions on the basis of component rental for subscribers.

Pooling is today an established concept that delivers optimized component availability at minimum cost. It generates economies of scale on smaller fleets and guarantees homogeneous standards to operators of large fleets.