ISTAT Definitions

DER, Designated Engineering Representative

A DER is a person approved by the FAA to certify specific repairs or modifications to specific systems as covered under his/her capability authorization. There is no directly comparable designation within EASA.

PMA, Parts Manufacture Approval

A Parts Manufacturer Approval (PMA) is an FAA design and production approval for aircraft parts. It is only issued after the FAA has (1) reviewed the design of the part to assure that it is safe and meets the requirements of the FAA regulations and (2) reviewed the production quality system to make sure that there is a system in place to verify that each part that is manufactured meets the FAA-approved design. The operator/owner is ultimately responsible for ensuring the safe operation of the Aircraft upon which PMA parts are installed. There is not a directly comparable approval process in the EASA regulations.

QEC, Quick Engine Change

A QEC kit is a collection of components and accessories such as pumps, generators, thrust reverser, nose cowl, wiring harnesses and fluid lines installed onto a bare engine to speed the eventual installation of the entire power plant onto an aircraft. See also "Engine." The actual makeup of the QEC kit will usually depend on the type of aircraft that the engine will be used on, and may also be different for different engine positions on the same aircraft. With the QEC kit installed, the power plant is sometimes then called a "QEC Unit."

Engine Table Inspection

A Table Inspection may be made by the owner/operator of the engine immediately after an engine has been disassembled, and prior to any cleaning. The intent of the table inspection is to detect potential or probable mechanical discrepancies with the internal hardware and permit the maintenance provider and engine owner/lessor to decide upon the final workscope The results of this inspection may warrant a change to the initial workscope.

Type Certificate

A Type Certificate pertains to aircraft, aircraft engines and propellers. EASA / FAA issues a Type Certificate when the applicant (normally the manufacturer) submits the type design, test reports, and computations and proves to EASA / FAA's satisfaction that the product meets the applicable requirements of the European Commission Regulations / FARs regarding airworthiness, noise and emissions. The Type Certificate is kept at the manufacturer's facility and is the basis for issuing airworthiness certificates to all aircraft (or engines or propellers) subsequently manufactured according to the same type design. (See EASA EC-1702/2003 and FAR 21). Type Certificates may also be issued for products manufactured in foreign countries with which the United States has an agreement for the acceptance of these products if the country of origin certifies that the product meets airworthiness, noise and emission standards equivalent to the US standards, and the manufacturer submits the appropriate supporting technical data.

ETOPS, Extended (Twin Engine) Operations

A brief history: As aviation technology evolved, regulations also evolved to address the safety of commercial aircraft operations in areas remote from airports where an aircraft in distress could make an immediate emergency landing. In the US, the first rule-making was in 1936, with updates in 1953, 1961, 1985 and 1988 with rules regarding two-engine aircraft and specified time and/or distance limits from suitable diversion airports. The 1985 rules introduced the acronym "ETOPS" (Extended-Range Twin-Engine Operations), allowing two-engine aircraft to operate on routes up to 120 minutes from an adequate airport after demonstration of specific levels of in-service experience and systems reliability. Over time, additional standards were established for longer diversion times of 138 minutes (an increase of 15% over the 120-minute rule), 180 minutes, and 207 minutes (15% beyond 180 minutes). Some of the rules aimed at two-engine aircraft have been extended to three- and four-engine aircraft on the basis that all long-range passenger-carrying aircraft, regardless of the number of engines, needed a viable diversion airport in the case of onboard fire, medical emergency, or catastrophic decompression. Nevertheless, the acronym "ETOPS" is still operative, although it is now defined simply as "Extended Operations". Moreover, diversion times up to and beyond 240 minutes may be permitted in certain area-specific or city-pair-specific circumstances. EASA has similar rules for two-engine aircraft (depending on passenger capacity and maximum takeoff weight) for diversion times of 60 minutes, 90 minutes, 180 minutes and beyond 180 minutes. EAA also uses the acronym "LROPS" for Long Range Operations, that proposes to extend some of the provisions for two-engine aircraft to aircraft with three and four engines. Note also that there is more to ETOPS than just reliable aircraft and engines. There are operational challenges with limited navigation and communications infrastructure in the north and south polar regions as well as the southern Atlantic and southern Indian Ocean where there may be few suitable diversion airports and where weather reporting and forecasting and field conditions can be problematic. There are other concerns to be addressed, including maintenance, maintenance training, ETOPS-qualification for maintenance persons, engine condition monitoring, oil consumption monitoring, APU starting after cold-soak in flight, dispatch, flight planning and flight monitoring, fuel-freeze risks on long polar flights, protection and recovery of stranded passengers and so on. References for digging deeper into ETOPS: FAA Advisory Circular 120-42B "Extended Operations (ETOPS) and Polar Operations" dated 13 June, 2008. EASA AMC 20-6 rev 2 "Extended Range Operation with Two-Engine Aeroplanes ETOPS Certification and Operation" dated 23 December, 2010. ICAO Convention on International Civil Aviation, Annex 6 Part I "Operation of Aircraft, International Commercial Air Transport"

Chapter 11

A chapter of the U.S. Bankruptcy Code which provides the rules whereby a debtor is allowed to file for court protection. Such protection enables the debtor to continue its operations while undergoing reorganization. Chapter 11 also allows a creditor to protect its interests.

Chapter 7

A chapter of the U.S. Bankruptcy Code which provides the rules whereby a debtor or creditor may petition the court for the appointment of a trustee or receiver to supervise the orderly liquidation of a business.

Inspection, General Visual

A collective term which includes the External Surveillance Inspection, the Internal Surveillance Inspection, and the Walk-Around Check.

ACARS, Aircraft Communications Addressing and Reporting System

A communications system that automatically reports via radio when an aircraft is out of the gate, off the ground, back on the ground, and at the gate again, thus automatically collecting data on flight cycles, flight time and block time. During flight the system may also monitor and report on aircraft and engine performance.

Non-Recourse Loan

A debt security in which only the equipment used as security is available as remedy to the creditor. The creditor is not able to look through to all of the borrower's assets. See also Recourse Loan below.

ETC, Equipment Trust Certificate

A debt security issued by a trust and secured by a mortgage, lease, mortgages, or leases, over a single asset or group of assets. ETC's may be split into several tranches (slices with unique levels of seniority and typically unique interest and repayment terms and ratings).

Service Bulletin, SB

A document issued by the manufacturer to notify the owner or operator of an aircraft (or engine or other device) of recommended (or required by Airworthiness Directives) modifications, substitution of parts, special inspections/checks, reduction of existing life limits or establishment of first-time life limits and conversion from one engine model to another. Service Bulletins may or may not be FAA-approved.

FDR, Flight Data Recorder

A fire and crash resistant black box (painted orange) which records the basic flight dynamics of the aircraft, such as airspeed, "G" loads, acceleration, altitude, attitude and direction. In addition, all of the operations of critical aircraft systems, such as control surfaces, pilot control inputs, engine, hydraulic, electrical systems etc. are recorded. The FDR can usually be located in the tail area of the aircraft and has a location radio transmitter.

Appraisal

A formal valuation of property made by a competent authority. See special section in this handbook for discussion of types of appraisals.

NDB, Non Directional Beacon

A ground-based radio navigational aid, typically operating on a frequency between 190 kHz and 535 kHz, which may be tuned by the pilot on his ADF (which see). The needle on his ADF indicator points to the station. Formally the primary radio navigation aid before the advent of the VOR system (which see), it is now used mostly to locate an NDB equipped airport during an instrument approach.

Rotorcraft

A heavier-than-air aircraft that depends principally for its support in flight on the lift generated by one or more rotors.

Capital Lease

A lease in the U.S. is classified as a capital lease if it meets any of the following criteria: The lease transfers ownership to the lessee at the end of the lease term. The lease contains an option to purchase the property at a bargain price. The lease term is equal to 75% or more of the estimated economic life of the property (with exceptions for used property that is already near the end of its useful life). The present value of minimum lease rental payments is equal to 90% or more of the fair market value of the leased property.

Net Lease

A lease which provides that all costs in connection with the use of the equipment are paid by the lessee and are not part of the rental, e.g. taxes, insurance and maintenance are paid directly by the lessee. Note that most capital leases, leveraged leases and direct finance leases are net leases.

Leveraged Lease

A leveraged lease involves at least three parties: lessor, lessee and a lender. The lessor owns the equipment and will generally provide a portion of the purchase price while borrowing the remainder, usually on a non-recourse basis, from the lender. The lessor thereby enhances his ability to purchase and own the asset using the capital of a third party.

NDT, Non Destructive Testing

A maintenance procedure to determine the condition of an area or part of an aircraft or component by means of tests that do not affect the function or serviceability of the item being tested. Some commonly used NDT methods include visual, radiographic, magnetic particle, ultra-sonic, dye penetrate, and eddy-current inspections.

Rebuild

A maintenance process whereby an aircraft, engine, propeller, appliance or component part is disassembled, cleaned, inspected, repaired as necessary, reassembled and tested to the same tolerances and limits as a new item, using either new parts or used parts that either conform to new part tolerances and limits or to approved oversized or undersized dimensions. See FAR 43.2.

MSG3 Maintenance Program

A maintenance program developed in accordance with the principles developed jointly by the FAA and Airlines for Air Transport America (ATA) and compiled by the Maintenance Steering Group (MSG). The results of the MSG analysis form the main body of the Maintenance Review Board (MRB) report, which is then certified by FAA or EASA as the minimum acceptable requirements in an operator's maintenance program. The program is designed around historical and assumed probability of failure rates and takes a top down approach by reviewing the effect of system failures, rather than individual component failures, upon the operation of the Aircraft. The effect of a system failure upon the safety of the Aircraft will determine the type and frequency of each task to be accomplished to each component. The operator is responsible for completing each task at the required interval and it may not necessarily be completed in conjunction with other tasks (as with a block maintenance program). However operators will normally complete those tasks that exhibit a common compliance interval at the same time leading to creation of a check sequence. Revisions to the program, as issued through the Maintenance Planning Document, reflect an annual review of data reflecting changes to component failure rates .The primary advantage of MSG3 is to improve Aircraft availability and reduce costs. For commercial Aircraft EASA and FAA will only now accept proposed maintenance programs based on MSG3 standards.

Airworthiness Directive, AD

A mandatory order issued by the FAA, EASA, or any other National Aviation Authority usually applying to specific types of aircraft, engines or appliances, when an unsafe condition exists and that condition is likely to exist or develop in other aircraft, engines or appliances of the same design. An AD usually requires some maintenance action (possibly only an inspection), within some specified time in order to ensure continued safety and airworthiness, and no aircraft may be operated in contravention of the requirements or limitations of an AD. All Large Aircraft registered in an EASA Member State are required to only comply against those Airworthiness Directives issued by EASA. The Agency will, unless extenuating circumstances apply, normally elect to re-issue those Non-EU Member State (Foreign State of Design) ADs automatically unless it has already issued its own AD on the same subject, in which case different compliance data may apply.

Assembly

A number of parts, subassemblies, or any combination thereof joined together to perform a specific function and which can be disassembled without destruction of designed use. (The distinction between an assembly and a subassembly is not always exact. An assembly in one instance may be a subassembly in another where it forms a portion of an assembly.)

Maintenance, On Condition

A primary maintenance process having repetitive inspections or tests to determine the condition of units, systems, or portions of structure with regard to continued serviceability. Corrective action is taken when required by the item's condition. For example, a hydraulic component may be tested regularly to determine its internal leakage rate, but refurbishment is required only when the rate exceeds a specified limit.

Maintenance, Hard Time

A primary maintenance process under which an item must be removed from service at or before a previously specified time in order to perform some required actions such as inspection or refurbishment.

Maintenance, Condition Monitored

A primary maintenance process under which data on the whole population of specified items in service is analyzed to indicate whether condition monitored maintenance allows failures to occur, and relies upon analysis of operating experience information to indicate the need for appropriate action. some allocation of technical resources is required. Not a preventive maintenance process, Note - Failure modes of condition-monitored items do not have a direct adverse effect on operating safety.

ECMP, Engine Condition Monitoring Program

A program permitting the non-invasive monitoring of various engine parameters on a repetitive basis in order to analyse the performance of the engine while in flight. Among many parameters typically recorded are N1 & N2 speed, fuel flow, vibration and EGT. Data is typically analysed using propriety software issued by the engine manufacturer which permits the setting of various 'alert levels' and defect resolution guide.

RVSM, Reduced Vertical Separation Minimum

A program to reduce the vertical separation between airways above Flight Level 290 (29,000 feet) from the previous 2,000-ft minimum to 1,000-ft minimum in order to increase airspace capacity. An implementation schedule for various regions of the world has been established by ICAO. Both the individual operator and the specific aircraft type require approval before conducting flights in RVSM airspace.

Program, Maintenance

A program, either acceptable or approved by airworthiness authorities, which defines a logical sequence of maintenance actions to be performed as events or pieces of a whole which, when performed collectively, result in achievement of the desired maintenance standards. The program may be originated by the manufacturer or the operator. A "Block Maintenance Program" is one which allocates major structural inspections and/or maintenance tasks into groups, or blocks, which permit convenient, economical and effective accomplishment. A program of recurring C-Checks and D-Checks may be a block maintenance program. See also phased maintenance program below. A "Continuous Airworthiness Maintenance Program" is a compilation of the individual maintenance and inspection functions utilized by an operator to fulfill its total maintenance needs (see Advisory Circular AC120-16C and FAA publication 8300.9). The authorization to use continuous maintenance programs is documented in the operator's Operations Specifications. The basic elements of a continuous airworthiness maintenance program are: Aircraft inspection Scheduled maintenance Unscheduled maintenance Engine, propeller and appliance repair & overhaul Structural inspection program / airframe overhaul Required inspection items Maintenance manuals A "Phased Maintenance Program" (sometimes called an "equalized" or "segmented" program) is one where some of the maintenance effort is apportioned to smaller packages that may be accomplished more frequently than the packages in a block maintenance program. Usually, the objective of this subdivision of effort is to even out the maintenance workload over time and shorten the length of each period of down-time. Note that the distinction between "block" and "phased" programs is not very clear. Different airlines and different air authorities have adopted many variations, so these terms do not have unique meanings applicable to all circumstances. For example, the C-Check might be divided into phases while the D-Check is left intact, or the D-Check might also be divided into phases, and the number of phases could be large or small. Moreover, different airlines have adopted different lettering and numbering terminologies to designate their checks. A "Progressive Maintenance" program is one which provides for the complete inspection of an aircraft within each 12 calendar months, consistent with the manufacturer's recommendations and other regulatory requirements. In practice, this primarily applies to small aircraft, although FAA Order 8300.9 Section 5 says the progressive inspection system "is particularly adaptable to larger multiengine aircraft and aircraft operated by companies and corporations where high utilization is demanded." See also FAR 91.409(d).

Investment Tax Credit (ITC)

A provision of the tax code designed to stimulate investment in capital equipment by allowing a percentage of the purchase price to be credited directly against taxes due.

Advisory Circular (AC)

A publication of the FAA to inform the aviation public of non-regulatory material of interest. Unless incorporated into a regulation by reference, the contents of an AC are not binding. An AC is issued to provide guidance and information in its designated subject area or to show a method acceptable for complying with a related Federal Aviation Regulation. EASA does not have directly comparable publications.

ADF, Automatic Direction Finder

A radio navigation system the receives a signal from a ground Non-Directional Beacon (see NDB) and displayed on the pilot's ADF indicator. The needle on the indicator points towards the selected station, thus giving the pilot the bearing to the station relative to the aircraft's heading.

Item, Repairable

A replaceable part or component, commonly economical to repair, and subject to being rehabilitated to a fully serviceable condition over a period of time less than the life of the flight equipment to which it is related. Examples include many engine blades and vanes, some tires, seats, galleys.

Renewal Option

A right whereby the lessee may renew a lease for an additional period after the original termination date. The rent for the renewal period is usually set at a lower rate than in the initial period.

PTC, Pass Through Certificate

A security issued by a trust in the asset-backed market representing an undivided interest in a pool of debt securities. A PTC allows the bundling of multiple separate or groups of assets in a single transaction. A PTC may include notes issued in separate leveraged leases.

Tax Lease

A single-investor or leveraged lease in which the lessor has satisfied certain Internal Revenue guidelines, retaining the tax benefits (such as investment tax credits and depreciation) associated with ownership. These tax benefits may be passed through to the lessee in the form of lower rental payments. The lease may require special indemnity by the lessee for any of the lessor's benefits lost or subject to recapture.

TCAS, Traffic Alert and Collision Avoidance System

A system intended to alert flight crews of the existence of nearby aircraft and to provide warning of imminent collisions. There are four categories of TCAS; TCAS I is a proximity warning system that advises pilots of the presence of nearby aircraft and is mainly used in General Aviation. TCAS II is intended to warn pilots of an impending collision, and it commands vertical avoidance maneuvers. TCAS III and TCAS IV, both designed to provide horizontal clearance,were never certified, due to accuracy issues. TCAS II Version 7.01 is the proposed future standard and incorporates upgrades permitting reversible resolution advisories. Both the FAA and EASA are expected to make the installation of this system mandatory in both new and used Aircraft by 2015.

EFIS, Electronic Flight Instruments System

A system that replaces the conventional electro/mechanical cockpit gauges with computerized cathode tubes or liquid crystal displays combining a number of gauges. Multiple pages can be accessed for navigation and aircraft system information.

Discounted Cash Flow

A technique for assessing the present value of future payments which takes into account the time value of money.

CVR, Cockpit Voice Recorder

A unit that records pilot's conversation and cockpit background noise for a minimum of 30 minutes onto an endless loop of magnetic tape or digital media, and is primarily intended to be used by accident investigators. The CVR unit is crash-proof and normally equipped with an independent radio transmitter.

Inspection, Walk Around Check

A visual check conducted from ground level to detect obvious discrepancies

Inspection, External Surveillance (Structural)

A visual check that will detect obvious unsatisfactory conditions/discrepancies in externally visible structure. It may also include internal structure which is visible through quick opening access panels/doors. Work stands, ladders, etc., may be required to gain proximity.

Inspection, Internal Surveillance (Structural)

A visual check that will detect obvious unsatisfactory conditions/discrepancies in internal structure. This type of inspection applies to obscured structure and installations which require removal of fillets, fairing, access panels/doors, floor-boards, liners, insulation blankets etc.

GPS, Global Positioning System

A worldwide radio-navigation system using a constellation of 24 US Department of Defence satellites as reference points enabling the receiver to compute position, velocity and time with very high precision.

Cost, Direct and Indirect

Although there is not an "official" definition from any regulatory body, aircraft direct operating costs (DOCs) is customarily categorized as follows: Flying Operations Crew Salaries & Expenses Fuel & Oil Insurance Maintenance Direct Labor & Materials Maintenance Burden Depreciation & Rentals Landing Fees & Airport Handling Charges (sometimes) The major categories of indirect operating costs include: Aircraft Servicing Traffic Servicing Servicing Administration Reservations & Sales Advertising & Publicity General & Administrative.

Airworthiness Certificate

An Airworthiness Certificate is issued by the FAA for an individual aircraft when it is satisfied that the aircraft conforms to the Type Certificate and is in a condition for safe operation. The Airworthiness Certificate is issued to the registered owner, and is transferred with the aircraft. It remains in effect as long as the aircraft is maintained (or altered) according to the appropriate FAA regulations and continues to be registered in the United States. (See FAR 21). An Airworthiness Certificate is issued by the Aviation Authority of an EASA Member State when it is satisfied that it conforms to the Type Certificate and is in a condition for safe operation. The nonexpiring Airworthiness Certificate is only valid for as long as the Airworthiness Review Certificate (ARC) is in force. The validity of the ARC is 12 months and may be issued by the operator of the Aircraft, if appropriately approved, or the incumbent national air authority (NAA). It is mandatory for the original C of A and the ARC to be carried within the Aircraft at all times.

LROPS, Long Range Operations

An EASA term for the proposed extension of some provisions of two-engine ETOPS to apply to three-engine and four-engine aircraft. See the ETOPS entry in this glossary.

EETC, Enhanced Equipment Trust Certificate

An EETC (usually referred to as a "double-ETC") provides an additional liquidity reserve (usually supplied by a rated bank) to pay interest for a specified period of time after a default within an ETC (which see above). Like an ETC, an EETC may be split into several tranches.

MEL, Minimum Equipment List

An approved list of items which may be inoperative for flight under specified conditions and/or specific limited periods of time. Use of the MEL is authorized by the airline's Operations Specifications. Regulatory authorities, like the FAA in the US, require certain systems and equipment to be operative for multi-engine aircraft operations. The MEL provides for deviations from these requirements when the manufacturer or operator has proven that the aircraft may safely operate without certain items, sometimes under certain conditions. For example, a four-engine aircraft with electrical generators on each engine might be safely dispatched if one generator is known to be inoperative, in which case the MEL would state that a minimum of three generators must be serviceable. The standards could be higher for twins in ETOPS operations compared to nonETOPS operations. The pilot in command is responsible to assure that the missing or inoperative equipment is allowed for in the MEL and noted in the on-board maintenance logbook. Depending on the criticality of the component, there may be time limits to operating a commercial aircraft before correcting the problem. The limit can vary from mandatory correction at the next maintenance facility for a navigation/radio component to a week or more for an escape slide provided the door is clearly placarded.

ILS, Instrument Landing System

An electronic system for providing flight path guidance to landing aircraft. Guidance consists of a localizer for lateral guidance and the glide slope for vertical guidance. Range from the touchdown zone is provided by the outer and middle electronic markers. There are several categories of ILS approaches. Most fall into Category 1, with the lowest decision height (DH) in this group set at 200 feet above the touchdown point and a minimum visibility of 1,800 feet runway visual range (RVR). The most severe category, reserved for aircraft and airports with very precise computer controlled guidance systems, is Category 3c with both the minimum DH and RVR set at zero feet.

Engine, Shop Visit

An engine removal is classified as a "shop visit" whenever the subsequent engine maintenance performed prior to reinstallation entails one of the following: Separation of pairs of major mating engine flanges (other than solely for shipment), Removal/replacement of a disk, hub, or spool. Sometimes the definition is specifically tailored, as in some Airworthiness Directives that say, "For the purpose of this AD, an engine shop visit is defined as input to an engine repair shop where the low pressure turbine module is removed" ... or "the front and rear flanges of the combustion case are separated" ... or "any major module is separated" ... or "the inlet gearbox is exposed."

Inspection, Detailed

An intensive visual examination of a specified detail, assembly, or installation. It searches for evidence of irregularity using adequate lighting and, where necessary, inspection aids such as mirrors, hand lens, etc. Surface cleaning and elaborate access procedures may be required.

Item, Rotable

An item that can be economically restored to a serviceable condition and, in the normal course of operations, can be repeatedly rehabilitated to a fully serviceable condition over a period of time approximating the life of the flight equipment to which it is related. Examples include avionics units, landing gears, auxiliary power units, major engine accessories.

Item, Time Limited

An item which must be inspected, tested or reconditioned at specified intervals of time (hours, cycles or calendar) in order to ensure continued airworthiness. Not the same as Item, Life Limited, listed separately.

Item, Life Limited

An item which, when listed on the aircraft, engine or propeller type certificate data sheet or the manufacturer's instructions for continued airworthiness, must be permanently removed from service and discarded before a specified time (e.g. hours, cycles or calendar limit) is achieved. Among the most significant life-limited items for appraisal purposes are engine disks and shafts.

Wet Lease

An operating lease that provides crew, fuel and maintenance services in addition to the aircraft itself.

Bargain Purchase Option

An option given to the lessee to purchase leased equipment at lease expiry for a price which is significantly lower than the expected fair market value of that equipment at the end of the lease.

Part - New/New Surplus

Any part that has never been installed on an aircraft or engine. Such parts are assumed to have all required certifications and to be unaffected by age when properly stored according to regulatory requirements and standard industry practice.

Part, Overhauled

Any part that has undergone disassembly, inspection and/or check to an extent necessary to determine that it is in satisfactory condition to operate one complete overhaul period. Includes parts that have no defined overhaul period, but that have been inspected, bench checked and repaired if necessary, to ensure that condition and operation are within prescribed limits for installation on an aircraft, engine or other component without operational limitation. Overhauled parts must be accompanied by all documentation required by the FAA.

Part, Serviceable

Any part that is acceptable for immediate use on an aircraft. Such parts may have been previously installed on an aircraft and removed in serviceable condition, or may be a new or previously unserviceable part that has undergone a shop visit for bench check or overhaul. Serviceable parts must be accompanied by all documentation required by the FAA.

Part, As Removed

Any part that is removed from an aircraft and has not been subjected to a bench test or inspection. An As Removed part must be inspected and tested in an approved manner before it an be declared serviceable and installed on an aircraft or engine unless it is installed on an aircraft or engine within the same operator's fleet and was in operable condition prior to its removal.

DER Repair

Approval from the FAA via a Designated Engineering Representative of the engineering data relating to the modification or repair of a system or component on an FAA registered aircraft. The approval basis may be based on acceptable and or approved data provided by the operator or the OEM, depending upon the scope of approval sought.

Life, Economic Useful

As it pertains to an aircraft or engine, the economic useful life is the period of time over which it is (or is expected to be) physically and economically feasible to operate it in its intended role. Periodic maintenance and repair will usually be required in order to preserve safety and efficiency during the economic useful life.

Time, Block

Block time is the time from the moment an aircraft first moves for the purpose of flight until the moment it comes to rest at the destination; sometimes called block-to-block time. Push-back time is considered as part of Block Time.

GPWS and EGPWS

Equipment installed in an aircraft to automatically provide a timely and distinctive warning to the flight crew when the aircraft is in potentially hazardous proximity to the earth's surface. Typically a GPWS is based on downward-looking radar that senses the aircraft's altitude above the ground and the rate of change of that altitude. EGPWS systems typically include forward looking features and stored mapping databases to give the crew additional warning time and greater awareness of terrain elevations for a wide area around the aircraft.

Extended Overwater Operations

Flight operations over water at a horizontal distance of more than 50 nautical miles from the nearest shoreline. These are operations for which the regulations require certain communications equipment, as well as various items of emergency and water survival equipment (life rafts and emergency flotation devices, for example). Note that the distance is specified from the shoreline, not necessarily from an airport.

Time, Flight

Flight time is the duration of the airborne portion of a flight, sometimes called wheels-off to wheels-on time. It is always less than block time (see above). Note that FAR 1 appears to equate Block Time and Flight Time, but this is not generally accepted.

Operating Lease

For financial accounting purposes, a lease which does not meet the criteria of a capital lease (see separate entry). Also used generally to describe a short-term lease whereby the user can acquire the use of an asset for a fraction of its useful life. It is not common, but the lessor may pay for maintenance and insurance.

EROPS, Extended Range Operations

Generally, flight operations at a distance more than 60 minutes flying time with one engine inoperative from a suitable airport. "EROPS" now has virtually no official standing except within Canada where certain communication, navigation and emergency requirements pertain to all aircraft in extended-range operations, regardless of the number of engines. In the U.S. and many other countries, the requirements have evolved into "ETOPS" (listed separately below) with rules that apply only to twin-engine aircraft operating beyond the 60-minute distance.

Owner Trustee

In a leveraged lease, the party who holds title to the equipment for the benefit of the equity participants. The owner trustee issues trust certificates to the equity participants, maintains the register, acts as the agent for such certificates, and makes appropriate filings to perfect and protect the lenders' interest in the collateral.

EGT Margin

In a turbine engine, the difference between the EGT limit (or EGT red line) and the engine's actual EGT when producing maximum thrust at the full rated take-off power setting The actual EGT should be lower than the EGT limit, and the magnitude of this difference (the EGT margin) is indicative of the time remaining before normal deterioration of the engine will require removal for restoration.

ACMI Lease

In an ACMI lease, the lessor (who may be another airline) provides the aircraft, one or more flight crews, maintenance for the aircraft, and insurance (usually hull and third party liability). The lease may set a minimum guaranteed number of block hours per month. Typically an ACMI lease may be for a few months or a few years. See also Wet Lease and Dry LeaseAPPRAI.

Item, Expendable

Items for which no authorized repair procedure exists, and for which cost of repair would normally exceed that of replacement. Expendable items include nuts, bolts, rivets, sheet metal, wire, light bulbs, cable and hose. For financial accounting purposes, expendable items are normally considered to be consumed when they are issued, so they are then not carried as inventory assets.

Pitot-Static System

On a simple aircraft some of the flight instruments (airspeed indicator, altimeter and vertical speed indicator) are driven by air pressures derived from the passage of the aircraft through the air. These pressures are sensed by the pitot tube and static ports. The pitot tube is an openended, forward-facing tube to sense the "ram" air pressure required to operate the airspeed indicator. The static ports are usually small, flush holes on the fuselage sides that sense static pressures for the altimeter and rate of climb indicator. These sensors, indicators and their connecting tubing constitute the pitot-static system.

Asset Based Finance

Secured asset financing, with credit emphasis on the ownership of, or lien on, such assets as accounts receivable, inventory, machinery and equipment.

Supplemental Type Certificate (STC)

See also Type Certificate. An STC is issued by the FAA to grant approval for an alteration of a product by a major change in the type design, where such a change is not great enough to require a new application for a Type Certificate. The STC is kept by the applicant and is then the basis for issuing or retaining airworthiness certificates to all aircraft (or engines or propellers) subsequently modified in the same way. In the case of alterations by the original manufacturer, approval is normally in the form of an amendment to the original Type Certificate, rather than an STC. (See FAR 21). For all Aircraft registered to a EASA member state all Supplemental Type Certificates must have received EASA approval confirming applicability and compliance prior to installation. Instructions for Continued Airworthiness (ICAs) must form part of the STC and must, for new commercial Aircraft, conform to MSG3 program requirements. In most cases EASA will accept FAA previously approved STCs but reference to the appropriate regulations is required.

EMPG, Engine Maintenance Planning Guide

The EMPG is issued and revised by the Engine Manufacturer and is based on the principle of on-condition maintenance, relying on extensive visual/dimensional build group and piece part inspections and a soft time policy on particular build groups and components. The objective of the guide is to achieve a cost effective method to achieve optimum levels of engine performance and reliability.

FMS, Flight Management System

The FMS is the general name given to the system, which consists of a number of individual automated avionic systems, relating to the navigation, performance and automation of flight. Control and data input is typically effected through the Central Display Unit (CDU) which also illustrates routings and performance limitations. Data is transferred between the various systems typically using an ARINC 429 data bus.

FADEC

The Full Authority Digital Engine Control (FADEC) unit consists of a number of modules which manage the operation of the engine and accessories throughout its operating range. The unit normally consists of one active and standby channel, which then swap over at each engine start. A permanent dedicated alternator powers the unit until aircraft power is available.

Type Certificate Data Sheet

The Type Certificate Data Sheet is the part of the Type Certificate setting forth the limitations prescribed by the applicable airworthiness regulations and any other limitations and information found necessary for type certification. Type Certificate Data Sheets may be viewed and downloaded from the FAA and EASA websites.

Utilization, Aircraft

The average daily flying hours or block hours for an aircraft or a fleet of aircraft. May also be expressed in hours per year or hours per month.

Engine

The basic engine assembly plus its essential accessories as supplied by the engine manufacturer. These include those units and components which are used to induce and convert fuel/air mixture into thrust/power; to transmit power to the propeller shaft, if any, and accessory drives; to supplement the function of other defined systems external to the engine; and to control and direct the flow of internal lubrication. The nacelle and the reverser are excluded. See also definition of QEC.

Overhaul

The disassembly, inspection and/or check of an aircraft, component, engine or appliance to an extent necessary to determine, as substantiated by service experience and accepted practices, that it is in satisfactory condition to operate one complete overhaul period. It shall include the replacement, repair, adjustment or refinishing of such parts as required, which, if improperly accomplished would adversely affect the structural strength, performance, flight characteristics or safety of the aircraft involved. See FAR 43.2 and also "rebuild" defined below.

Balloon Payment

The final payment, which is substantially larger than the other payments, of an amortized term loan or lease. Less commonly, balloon payments may also occur periodically during a lease term.

Hot Section Inspection (HSI)

The inspection and restoration of the hot section items of an engine (principally the combustion and turbine sections), usually at a predetermined time/cycle limit. A hot section inspection is not necessarily considered an "engine shop visit" (see separate listing) if no major disassembly or repairs are required.

Maintenance, Scheduled

The maintenance performed at defined intervals to retain an item in a serviceable condition by systematic inspection, detection, replacement of worn out items, adjustment, calibration, cleaning, etc.

Time Between Overhauls, TBO

The maximum time that an item is permitted to operate between overhauls. TBOs are usually expressed in flight hours, cycles, or calendar increments.

Time, Total

The operating time that an aircraft, engine or component has accumulated since new. Unless otherwise stated, this is usually total flight time, rather than total block time.

Repair

The restoration of an airframe, powerplant or appliance to a condition for safe operation after damage or deterioration. A "Major" repair is one that, if improperly done, might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics or other qualities affecting airworthiness.

Purchase Option

The right to buy leased property at the end of the lease term. In the U.S., if the tax characteristics of a true lease are to be protected, the purchase option may not be at a price less than the asset's fair market value at the time the right is exercised.

Engine Performance Restoration, PR

The services performed during an Engine Shop visit in which, at a minimum, the compressor, combustor and high-pressure turbine are exposed and subsequently refurbished. For those refurbished modules the time and cycles since PR are then re-set to zero.

EGT, Exhaust Gas Temperature

The temperature of the exhaust gasses in a turbine engine.

Fly By Wire

The term "Fly by Wire" relates to the transmission of a control input by electrical cabling rather than mechanical controls. In the flight deck, transducers translate the physical displacement of a control input into an electronic signal which is transmitted via various flight control computers to electrically controlled, hydraulically actuated power control units attached to the flight control surface. This type of control system is also used by the powerplant to control thrust through the FADEC unit (Full Authority Digital Engine Control).

Burden, Maintenance

Those maintenance labor and material costs not considered to be direct maintenance costs, but which contribute to overall maintenance program costs through overhead operations, administration, record-keeping, scheduling, controlling, planning, supervision, tooling, test equipment, facilities, etc.

Dry Lease

Traditionally in aircraft and marine leasing, an agreement that provides financing only for the equipment itself, and does not extend to personnel, maintenance, fuel and provisioning necessary to operate the craft. Corollary in marine leasing is a bare boat charter. See also "wet lease."

Recourse Loan

Unlike a non-recourse loan (which see above), the creditor has a right to all of the borrower's assets not otherwise pledged.

VOR/DME

VHF Omnidirectional Range with Distance Measuring Equipment. A primary aid to radio navigation. When tuned to a VOR/DME (frequency range 108.00 - 117.95 MHz) the pilot's VOR indicator can indicate the heading to fly along the radial to the station and by using the DME the aircraft's position on the radial. Using a second VOR for triangulation, a course can be flown without having to fly directly to a station.

Registration Certificate

With certain exceptions for foreign aircraft, aircraft with temporary authorizations, or aircraft of the armed forces, no aircraft may be operated without a Registration Certificate that is issued to its owner by the FAA. The Registration Certificate is also the basis for assigning a U.S. identification number ("N-Number"). Generally, the Registration Certificate remains effective until the aircraft is sold, exported, destroyed or scrapped. Note that this definition pertains specifically to the U.S. but comparable regulations apply in most other jurisdictions. Outside the US, The Aviation Authority of each country is responsible for issuing and cancelling the registration certificate of each Aircraft. The aircraft need not have in force a Certificate of Airworthiness in order to receive a Registration Certificate. If the owner or operator of the Aircraft changes then these details must be amended on the certificate. It is mandatory for this Certificate to be carried in the Aircraft at all times.