ATA 21 · ATA 38 · ATA 49 — Filters, cores and consumables
ATA 21, ATA 38 and ATA 49 — Filter elements and heat exchanger cores
Three chapters, one product type: an element or a core that is replaced on a service interval and takes the aircraft out of the dispatch calculation when it is not on the shelf. Air conditioning filters and heat exchanger cores (ATA 21), potable water filters (ATA 38) and APU oil system elements (ATA 49) are presented on one page because a programme buys them the same way.
- ATA 21
- ATA 38
- ATA 49
ATA 21
ATA 21 — Air conditioning
The air conditioning chapter is a consumables chapter. Heat exchanger cores and air filters are replaced on a fixed interval or when a pressure drop or contamination limit is reached, which makes availability and lead time more important than unit price. Both item families are covered here.
- 21-21 recirculation
- 21-51 cooling pack
- 21-51-03-05 (B737NG heat exchangers)
Heat exchangers and cores
The cooling pack exchanges heat in two stages, and the core is the part that fouls and degrades. Unit and core are quoted against the part number in the illustrated parts catalogue for the installed pack.
Air cycle machine heat exchanger
Pack-level exchanger, quoted by part number.
Primary heat exchanger core
First-stage cooling against ram or fan air.
Secondary heat exchanger core
Second-stage exchanger downstream of the compressor.
Condenser and reheater
Water separation stage components.
Precooler
Engine bleed air pre-cooling.
Seals and associated hardware
O-rings and seals supplied with or separately from the core.
Cabin recirculation air filters
The recirculation filter protects the cabin air path and is typically a high-efficiency element with a defined service interval.
Cabin recirculation HEPA filter
High-efficiency element for the recirculation air path.
Recirculation fan filter element
Element for the recirculation fan intake; cabin-specific.
Filter housing and retainers
Housing hardware where the element alone is not the item consumed.
Avionics and equipment compartment ventilation filters
Equipment bay ventilation keeps the electronic compartments within their cooling envelope; contamination in this path shows up as an overtemperature fault rather than as a filter fault.
Equipment compartment ventilation filter
Element for the equipment bay ventilation path.
Filter assembly
Complete assembly where the housing is replaced with the element.
Filter cartridge
Cartridge-format elements for specific installations.
Part numbers — ATA 21
Listed for identification. Availability, condition and the approval basis applicable to the item are confirmed on quotation.
Aircraft coverage — ATA 21
Chapter-level coverage is broad; applicability of a specific part number is narrower and is governed by the approval document for that part number.
Boeing
737 (classic and NG), 757
Airbus
A319 / A320 / A321
Applicability
Declared per part number — confirm against the aircraft type and model
Related to ATA 21
- Element or assembly? — Some filter housings are not PMA articles. The page explains the difference.
- Quote a filter or core — Send the part number and aircraft type for availability and documentation.
ATA 38
ATA 38 — Water & waste
Water system filters are replaced on a service interval that is easy to miss, and a blocked element shows up as a passenger complaint rather than a maintenance message. The items are small, low value and specific to the aircraft and the installation, which is the pattern across this chapter.
- 38-10 potable water
- 38-30 waste
Potable water filters
Filters are fitted at the point of use in the galley and each lavatory, and are quoted by the part number of the element and the aircraft type.
Water filter element
Element for the galley or lavatory potable water line.
Stainless steel water filter
Stainless element for installations that specify it.
Filter assembly
Complete filter where the housing is replaced with the element.
Filter seals and O-rings
Sealing elements for the filter installation.
Water system consumables
The adjacent items quoted with the filter rather than ordered after it.
Lavatory water system components
Components in the lavatory water path.
Galley water system components
Components in the galley water path.
Water and waste system hardware
Fittings and hardware for the water and waste systems.
Part numbers — ATA 38
Listed for identification. Availability, condition and the approval basis applicable to the item are confirmed on quotation.
Aircraft coverage — ATA 38
Chapter-level coverage is broad; applicability of a specific part number is narrower and is governed by the approval document for that part number.
Airbus
A300, A319 / A320 / A321, A330 / A340 — filter tasks are commonly grouped under 38-10
Boeing
737 — lavatory water filters, one per lavatory, in the potable water system
Applicability
Confirm the element against the aircraft type and the installation
Related to ATA 38
- ATA 11 & 25 — Galley, lavatory and cabin content — The surrounding cabin service content.
- Quote a filter element — State the aircraft type, part number and quantity required.
ATA 49
ATA 49 — Auxiliary power
APU oil system filters are a small, high-turnover item with a hard service interval, and an unavailable element is enough to take an APU out of the dispatch calculation. The chapter is otherwise dominated by components that require an OEM or repair route rather than parts supply, so the offering here is deliberately narrow.
- 49-90 APU oil system
APU oil system filters
Elements and the associated sealing components, quoted by part number against the APU model installed.
APU oil filter element
Oil system element for the installed APU model.
Filter assembly
Where the housing is replaced with the element.
Seals, O-rings and washers
Sealing components for the filter installation.
APU consumables and standard hardware
Adjacent items quoted with the element.
Fasteners and hardware
Standard fasteners supplied as standard parts, not as approved articles.
Plumbing and connection hardware
Fittings and hardware in the oil system path.
Part numbers — ATA 49
Listed for identification. Availability, condition and the approval basis applicable to the item are confirmed on quotation.
Aircraft coverage — ATA 49
Chapter-level coverage is broad; applicability of a specific part number is narrower and is governed by the approval document for that part number.
Boeing
737 — APU oil system filters
General
Applicability is declared per part number against the installed APU model
Related to ATA 49
- ATA 21 / 38 / 49 — Filters and cores — The other filter family we carry.
- Quote an APU filter element — Send the part number, APU model and quantity.
Questions we are asked
Is a filter element quoted as a PMA part?
A filter element that replaces an OEM element on an approved installation is normally an approved article, but not every element we supply sits in that category. Each offer states the approval basis that applies to that item.
Do you supply the heat exchanger core on its own, or only the complete unit?
Both positions exist depending on the part number and on whether the core is a separately identified item in the illustrated parts catalogue. State which you need and we will confirm before quoting.
How often is a potable water filter replaced?
The interval is set by the operator maintenance programme for the type, not by the filter. We supply the element against the part number; the interval comes from the applicable maintenance documentation.
Which APU models are covered?
Applicability follows the part number rather than the aircraft type, because more than one APU model can be installed on the same type. State the APU model as well as the aircraft type when requesting a quote.
Send the part number, get a real answer
Availability, condition, lead time and the documentation that ships with the item are confirmed against the specific part number — not assumed from the chapter.