A life-limited part (LLP) is a part that must be permanently removed from service when it reaches a mandatory limit in cycles, hours or calendar time. The type certificate holder sets that limit, and the operator must be able to prove, at any moment, how much life each LLP has used and how much remains. An ATA Spec 2000 Chapter 9-5 RFID tag can carry the identity of the part, so every reading points to the right record. The tag does not replace the official records or the release certificate.
What is a life-limited part
The FAA definition is in 14 CFR 43.10: a life-limited part is “any part for which a mandatory replacement limit is specified in the type design, the Instructions for Continued Airworthiness, or the maintenance manual”. The same section defines life status as “the accumulated cycles, hours, or any other mandatory replacement limit” of the part.
EASA uses equivalent wording. The guidance material to point M.A.305 of Part-M (EASA Easy Access Rules for Continuing Airworthiness) describes an LLP as a part that the maintenance programme requires to be permanently removed from service when, or before, a mandatory life limitation is reached. The applicable parameter can be flight hours, flight cycles, landings, calendar time or another utilisation unit.
Typical LLPs
| Area | Examples | Usual limit |
|---|---|---|
| Engine | Disks, spacers, hubs, shafts, high-pressure casings, non-redundant mounts | Flight cycles |
| Landing gear | Structural gear parts with a published life limit | Cycles or landings, per the manufacturer’s data |
| APU | Parts with a published life limit | Per the manufacturer’s data |
The engine examples come from 14 CFR 33.70. That rule says engine LLPs are rotor and major static structural parts “whose primary failure is likely to result in a hazardous engine effect”, and requires a maximum number of flight cycles for each one. An error in that count is a safety problem, not only an administrative one.
What the regulations require in the records
Both the FAA and EASA require the operator to keep the current status of each LLP. Neither one asks for a specific format.
| Regulation | What it requires | Retention |
|---|---|---|
| 14 CFR 91.417(a)(2)(ii) | “The current status of life-limited parts of each airframe, engine, propeller, rotor, and appliance” | Transferred with the aircraft when it is sold |
| 14 CFR 121.380(a)(2)(iii) | Same requirement for Part 121 air carriers, kept in the system described in their manual | Transferred with the aircraft when it is sold |
| 14 CFR 43.10 | Control of LLPs removed from a product, so they are not installed after their limit | The mark, tag or record moves with the part when it is transferred |
| EASA Part-M M.A.305(d) and (e) | Current status of each LLP, with the life accumulated against the applicable limit, plus “an in-service history record for each life-limited part” | Detailed records kept until superseded, never less than 36 months |
The EASA guidance material adds what “current status” means: for each part, the life limitation, the total life accumulated in each applicable parameter and the remaining life before the limit.
43.10: how a removed LLP is controlled
Section 43.10(c) lists methods to control a removed LLP. The method must “deter the installation of the part after it has reached its life limit”. The options include a record keeping system, a tag or record attached to the part, non-permanent or permanent marking, segregation and mutilation. For the record and tag options, the data must include the part number, serial number and current life status, and it must be updated each time the part is removed.
Section 43.10 does not say that an RFID tag is that record. If you want to use an RFID tag as part of a 43.10 method, write that into your procedures and confirm acceptance with your authority.
Back-to-birth traceability: what it really means
“Back-to-birth” (BtB) is the market term for documented traceability of an LLP from manufacture to its current status. It is not a regulatory term.
The IATA Guidance Material and Industry Framework for LLP and TCC Traceability Documentation (Edition 2, September 2026) is explicit:
- It quotes the FAA position that “the regulations do not require back to birth records in order to determine the life status of life-limited parts provided that the operator can determine the part’s life status with sufficient certainty using available documentation”.
- It quotes the EASA FAQ: “The term ‘back to birth’ is not used in European regulations”. The requirements are in M.A.305(d) and (e).
- It replaces “BtB” with a new term, Current Status Confirmation (CSC), because BtB misinterpretation “can lead to unnecessary documentation demands, delays, and increased costs without improving safety”.
What the regulations do require is continuous traceability of the part identity, its life limit and its in-service history. According to IATA, the in-service history record should start with the identification of the part: part number, serial number and a verifiable starting point. It is then supported by installation and removal records, shop visit reports, ADs, modifications and service bulletins.
In the market, buyers and lessors still ask for full trace packages, because, as IATA notes, the value of an LLP “is directly dependent on the ‘remaining life’ of the LLP”. No verified status means no verified value.
Why a gap in the records makes a part unusable
An LLP without a demonstrable current status cannot be installed. The rules require that you know the life accumulated against the limit. If you cannot show it, you cannot show that the part is below its limit.
Common gaps:
- Missing installation or removal data. A period with no record of where the part flew breaks the cycle count.
- Installation on different engine or aircraft types. The IATA document asks for a full installation history when the remaining life depends on the types on which the part was installed.
- Identity errors. A wrong digit in a serial number links the part to another history. IATA dedicates a section to data errors that affect TSN, CSN or part identity.
- Lost operator records. After a repossession or bankruptcy, the records may not be available. IATA describes a reconstruction by an authorized organization, with the result submitted to the competent authority, which “may require additional maintenance or inspection if not satisfied with the substantiation”.
Most of these gaps start with a part identity typed wrong or a movement not recorded. That is where Spec 2000 RFID helps.
Where Spec 2000 Chapter 9-5 RFID fits
ATA Spec 2000 Chapter 9-5 defines how part data is written to passive UHF RFID tags. If you are new to it, start with our guide to ATA Spec 2000 Chapter 9-5.
For an LLP, a Chapter 9-5 tag can carry:
- Identity in a locked birth record: manufacturer CAGE code, part number, serial number and date of manufacture. FAA AC 119-2A, paragraph 8.3, states that operators should not be able to change birth record data once installed. The exception is a maintenance activity that changes the part number.
- A life cycle record, when you need one. Dual-record tags add a rewritable record for data after delivery. The IATA airline requirements for OEMs warn that updating tag data “is expensive and error-prone for operators and avoided when possible”.
The 2023.1 revision of Chapter 9 also updated the section on embedded life parts; check the detail in your own copy.
To compare formats and memory sizes, see our post on Spec 2000 RFID tag types and AC 20-162.
What the tag does not do
| The tag can | The tag cannot |
|---|---|
| Identify the part with its PN and SN without typing | Replace the records required by 91.417, 121.380 or M.A.305 |
| Link a reading to the correct record in your system | Replace the authorized release certificate |
| Carry a life cycle record as a complement | Be the primary record of life status, unless your authority accepts it |
| Speed up receiving, inventory and removal checks | Replace the part marking required by 14 CFR Part 45 |
AC 20-162B treats the tag as ancillary marking, not a substitute for Part 45 marking. IATA states that high-memory tags with maintenance history are “not currently supported by airlines communities”. One of the conditions IATA lists to change that is that regulators accept the tag history as a primary record. For release certificates, read our post on Spec 2000, EASA Form 1 and FAA 8130-3 for that topic.
The practical rule: identity on the tag, life status in your system of record.
How to apply RFID to LLP tracking
- List your LLPs and their records. Start from the LLP listings in your continuing airworthiness record system. Note which parts already have a Spec 2000 tag from the OEM.
- Decide the tag format per part. A single-record birth tag covers identification. Use a dual-record tag only if a life cycle record on the part adds value to your process.
- Check tag qualification. AC 119-2A, paragraph 5.5.1, says tags on aircraft parts should be certified by the manufacturer to SAE AS5678B or AS6023 for their operating conditions. LLPs in engines and landing gear see extreme conditions.
- Write and validate the birth record. Check the encoded PN and SN against the part marking and the release certificate before you lock the record.
- Read at every movement. Read the tag at receiving, installation, removal, shop induction and shipping. Record the reading in your system with the life status.
- Reconcile. Compare tag readings with the records at audits and lease transitions. Any mismatch is a data error to correct before the part moves.
- Keep the manual fallback. AC 119-2A, paragraph 9.5, says operators must default to manual procedures if the RFID system fails.
LLP checklist
- Each LLP has PN, SN, limit, accumulated life and remaining life in the record system.
- Each LLP has an in-service history record with a verifiable starting point.
- Installation history covers every engine or aircraft type when the limit depends on it.
- The tag birth record matches the part marking and the release certificate.
- Removed LLPs are controlled with a 43.10 method or your authority’s equivalent.
- The mark, tag or record moves with the part when it is transferred.
- Your procedures say what the tag is for, and what it is not.
How Spec2000 RFID fits
Spec2000 RFID is software to read, write and manage ATA Spec 2000 RFID tags. It reads EPC and USER memory with automatic ATA decoding, writes tags following the Spec 2000 protocol with real-time data validation, and scans multiple tags at once. You can export the data for audit and compliance reports.
For engine components, the use case is the control of rotatable engine parts with tracking of cycles, hours and operating condition. The software works with our own readers and tags: a USB desktop reader for shop workstations that connects directly to the browser without drivers, and a Bluetooth portable reader for cabin, ramp and warehouse.
Frequently asked questions
Is back-to-birth traceability a legal requirement?
No. The FAA and EASA require the current status of each LLP and the records that support it. According to IATA, the FAA has stated that back-to-birth records are not required if the life status can be determined “with sufficient certainty”. Buyers and lessors may still ask for full trace in contracts.
Can an RFID tag replace the LLP records?
No. The records required by 14 CFR 91.417, 121.380 and EASA M.A.305 stay in your record system. A Spec 2000 tag identifies the part and can carry a life cycle record as a complement.
Should I write cycles and hours to the tag?
Only if your process needs it. A dual-record tag allows a rewritable life cycle record, but IATA warns that updating tag data is expensive and error-prone. For most LLPs, a locked birth record and the life status in your system is the safer setup.
Does a Spec 2000 tag replace the EASA Form 1 or FAA 8130-3?
No. The authorized release certificate is a separate document. The tag can help you link the part to its certificate, but it is not the certificate. See our post on release certificates and Spec 2000.
Conclusion
LLP tracking depends on one thing: an unbroken link between the physical part and its life status. The regulations put that status in your records. A Spec 2000 Chapter 9-5 tag puts a locked identity on the part, so every reading points to the right record. Use the tag for identity and the record system for life.
If you want to see how Spec 2000 tags work with your engine and landing gear parts, request a demo.