Quick summary. Federal aviation rules do not require back-to-birth records for a life-limited part. That phrase comes from lease agreements and asset appraisals, not from Part 43. What the regulation does require is a record that establishes current life status with, in the FAA’s own words, a high degree of certainty. Knowing which of those two standards a seller is failing decides whether a used engine module is a bargain or a paperweight.

Operators running 737 Classics, ATR 42/72s and Dash 8s buy modules and piece-part engines because a full shop visit costs more than the airframe is worth. The module arrives with a stack of paper, and a buyer without an in-house records team has to answer one question: is this stack enough? That is not a matter of taste. It maps onto four specific pieces of published regulation.

Need a part shipped to your region? Submit an RFQ on Aviatrading and reach verified sellers worldwide.

What the regulation actually says

Two rules carry the weight. 14 CFR 43.10 governs what happens to a life-limited part once it comes off a product. It defines a life-limited part as any part for which a mandatory replacement limit is specified in the type design, and life status as the accumulated cycles, hours or other mandatory limit. Paragraph (c) lists the ways a person removing such a part may control it: a record keeping system, a tag or record attached to the part, a non-permanent marking showing life status, a permanent marking, segregated storage with records, mutilation beyond repair, or another method approved by the FAA.

Paragraph (d) is the one that matters to a buyer. Each person who removes a life-limited part and later sells or otherwise transfers it must transfer with the part the mark, tag or other record showing life status. A module offered with no life-status record attached is not a documentation gap in the soft sense. It is a transfer that did not meet 43.10(d).

14 CFR 91.417(a)(2) covers the other side: what the operator has to hold. Six items, and every one of them becomes a line on a purchase checklist. Total time in service of the airframe, each engine, each propeller and each rotor. The current status of life-limited parts. Time since last overhaul of everything overhauled on a time basis. Current inspection status. Current status of applicable airworthiness directives, including the method of compliance, the AD number and the revision date. And copies of the major alteration forms. Paragraph (b)(2) adds that these records are retained and transferred with the aircraft when it is sold. Nothing in either rule uses the phrase back-to-birth records.

Where “back-to-birth” really comes from

On 18 July 2009 the FAA Office of the Chief Counsel answered a query from Phoenix Heliparts. The reply, signed by Rebecca MacPherson, Assistant Chief Counsel for Regulations, states plainly: “We agree with you that the regulations do not require ‘back to birth’ records.” What the rules require instead is a record system sufficient to show, with a high degree of certainty, the current status of life-limited parts. The letter goes further: an audit trail tracing a part back to its origin is required only where the operator’s records are so incomplete that an accurate determination of elapsed time could not be made.

That is a narrower test than the market applies. Lessors, appraisers and most Western MRO acceptance departments ask for back-to-birth records because they are cheap to demand and expensive to fake. The regulator asks only that the number on the disk sheet be defensible. Both standards are real. They are enforced by different people, and a buyer who confuses them either overpays for paper or accepts a module no shop will touch.

The practical consequence for an operator on a developing-market AOC: your authority will look at current life status, while your future exit buyer, your lessor and your insurer will look for back-to-birth records. If you intend to run the module until it is scrapped, the regulatory standard is the one you must meet. If the engine is an asset you may resell or return, budget for the commercial standard, because a module with an interrupted trace loses a large share of its residual value at exactly the moment you want to realise it.

The teardown package, document by document

This is the file to ask for before money moves. Each row maps to a published requirement rather than to an industry habit, which makes it a list you can defend in a negotiation.

Document	What it proves	Requirement it maps to
Engine or module log card, trace sheet	Total time in service of the engine or module	14 CFR 91.417(a)(2)(i)
LLP status sheet (disk sheet)	Cycles and hours accumulated on every life-limited part	14 CFR 91.417(a)(2)(ii)
Tag, mark or record from the removing party	Life status physically travelled with the part	14 CFR 43.10(c) and (d)
Maintenance release or serviceable tag	Returned to service by a certificated person	AC 20-62E paragraphs 9.g and 10.a
AD status list with method of compliance	No open mandatory action inherited with the module	14 CFR 91.417(a)(2)(v); AC 20-62E 10.b
Last shop visit report, time since overhaul	What was done, what was deferred, what was left as-is	14 CFR 91.417(a)(2)(iii); AC 20-62E 10.b
Name of the person who removed the part	Chain of custody has a documented starting point	AC 20-62E paragraph 10.b
Major alteration records, FAA Form 337	The module still conforms to approved type design	14 CFR 91.417(a)(2)(vi)

Advisory Circular 20-62E sets out the same list from the purchaser’s side. Paragraph 10.b tells a buyer of used parts to obtain AD status, life-limited parts status including time, time since overhaul, cycles and history, shelf-life data, the return to service date and the name of the person who removed the part. Paragraph 10.b(3) is explicit that life-limited parts status must be substantiated, and that for a serialised life-limited part both operational time and cycles must be indicated. Paragraph 10.j points back to 43.10. Note what the list does not say: it asks for history, not for back-to-birth records.

The three gaps that end a module deal

Packages fail in three recognisable ways, and only one of them is fatal.

The gap in the middle. The module has a birth record and a current disk sheet, but two or three operators in between are missing. This is the common case on aircraft that passed through leasing chains in the 1990s and 2000s. It is survivable if the surviving records bracket the gap and the accumulated figures reconcile against airframe hours. It is precisely the situation the 2009 Chief Counsel letter was written about.

The unsupported number. The seller quotes cycles remaining but cannot produce the document the number came from. This one ends deals, because there is nothing to reconcile and nothing for a receiving shop to sign against. A figure in an offer email is not a record under 43.10.

The wrong release. The paperwork is complete, but the release document is not one your authority accepts. That is a jurisdiction problem rather than a records problem, and it is solved before purchase rather than after — we covered the mechanics for Southeast Asian registries in our note on foreign authorised release certificates in Vietnam and Thailand.

What to do when the trace is broken

A broken trace is a pricing input, not automatically a refusal. The sequence that works:

First, reconcile what you have against an independent figure. Airframe hours, the last three shop visit reports and the removing operator’s utilisation records will usually bracket an LLP figure to within a tolerance a shop can accept. Second, ask the seller to identify the removing party by name and certificate number, because 20-62E expects that name to exist and a seller who cannot supply it is telling you something. Third, involve the receiving shop before purchase, not after: the organisation that will install the module is the one whose acceptance decides whether the file is sufficient, and that conversation costs nothing.

Fourth, price the residual. A module with an interrupted trace is worth materially less on resale than one with complete back-to-birth records, and that discount is the honest measure of the gap. Our comparison of exchange versus outright purchase for ageing fleets covers when it makes more sense to avoid owning the records problem at all.

A buyer checklist without an in-house CAMO

Operators without their own continuing airworthiness organisation carry this review themselves, and it is narrower than it looks. Confirm that a life-status record physically accompanies the module, as 43.10(d) requires. Confirm the LLP sheet is a document and not a claim. Confirm the AD list carries method of compliance and revision dates rather than a bare list of numbers. Confirm the release document is one your authority recognises. Decide separately, and in writing, whether the deal is priced as a file with back-to-birth records or without. Everything else is negotiation.

Two earlier notes go deeper on the adjacent questions: what a certificated source actually means when the part is used, in USM traceability and the certificated source, and the document review sequence itself, in release document checks for an operator without a CAMO.

When you are ready to source the module rather than read about it, the verified-seller aviation parts catalogue on Aviatrading lists engine material with the supporting paperwork stated up front, and an open RFQ puts your requirement in front of sellers who hold the records. Every transaction is protected by escrow, so payment releases after the documentation survives your inspection rather than before it. New listings and live requests also run through the Aviatrading Telegram channel.