AD/AT 800/2 Amdt 4 - Airframe Life Limits

The AD is structured around a small set of concepts that determine obligations and allowable options for operators.

Applicability. The AD applies to "All models AT-802 and AT-802A aeroplanes." That single applicability line identifies the affected fleet. The AD replaces prior amendment content for the applicable aircraft by revoking AD/AT 800/2 Amdt 3 and issuing Amdt 4.

Retirement Schedule. The core technical concept is the Retirement Schedule. It maps components (by description and part number) and, in some cases, by aircraft serial number, to maximum authorised time in service. Time in service is expressed as flight hours, as landings, or as either hours or landings whichever occurs first. The Schedule is the AD's normative list and contains the specific numeric limits that trigger mandatory retirement. For example, Plate Assembly , Fin Front Spar Attach (part 30511-1) has two distinct retirement lives depending on aircraft serial number: 4000 hours for S/N 0001-0041 and 20000 hours for S/N 0042 and up.

Recordkeeping rule for landings. The AD contains an evidentiary rule relevant to enforcement and compliance: "Where the total number of landings during a period of service has not been recorded, three landings per one hour time in service must be assumed." That rule converts flight hours (which may be recorded) to a notional number of landings for purposes of applying the retirement lives that are stated in landings.

Conditional life extension. The Retirement Schedule is not absolute for two items. Notes provide a pathway to extend splice block lives to 10000 hours (via Snow SL #185 revised issue dated 9/3/99) and to extend fin spar and attach plate lives to 20000 hours (via Snow SL #187). These life extensions are conditioned explicitly on incorporation of the named Snow service letters and their precise issue dates. The AD thus creates a link between regulatory retirement limits and the incorporation of manufacturer service documentation.

Interaction with other ADs and documentation. The AD makes two cross-references. It removes certain limits from this Retirement Schedule because they are now contained in AD/AT 800/3, and it corrects a documentation reference by noting that the lives are listed in the Owners Manual rather than the Maintenance Manual. The AD therefore functions partly by reallocation of life-limit content across multiple ADs and by directing operators to the Owners Manual and specific Snow SLs for authoritative life data or extensions.

Regulatory basis and effect. The AD is issued under subregulation 39.1(1) of CAR 1998, and the delegate's signature is dated 21 June 2001 with the AD becoming effective on 27 June 2001. The Background states the AD's purpose as ensuring compliance with manufacturer-determined airworthiness limitations and to correct an unsafe condition following further information from the manufacturer. The AD revokes the immediately preceding amendment and replaces the retirement schedule and applicability clarifications.

Operational mechanics. Practically the AD imposes three duties: identify the listed components and their part numbers and serial-number applicability; calculate accumulated time in service and landings using recorded data or the 3 landings per hour assumption; and retire the listed parts before they exceed the stated life. It neither prescribes what constitutes an acceptable replacement nor states explicitly the life-reset behaviour of replacement parts. The AD also establishes that some lives may be extended but only after incorporation of specified, dated manufacturer service letters.

The AD names the aircraft models to which it applies, and from that follows a defined set of stakeholders who bear duties, costs and decisions.

Primary affected parties. The AD applies to "All models AT-802 and AT-802A aeroplanes." Therefore registered owners and operators of those models must comply. Those parties are the direct duty-holders because the Requirement states that the "airframe components listed in the Retirement Schedule" must be "retire[d] from service" and the Compliance section requires retirement "prior to exceeding the applicable time in service listed in the Retirement Schedule." The AD was notified in the Commonwealth of Australia Gazette on 27 June 2001, rendering it an enforceable administrative instrument from that date.

Maintenance organisations and technicians. Maintenance providers, certified maintenance organisations and persons performing maintenance on AT-802/AT-802A aeroplanes are operationally affected because they must enact the retirements, verify part numbers and serial numbers against the Retirement Schedule and incorporate any Snow service letters where an extension is to be applied. The AD also points out that the area where lives are documented is the Owners Manual (Note 3), not the Maintenance Manual as stated in the Type Certificate Data Sheet. That affects where maintenance organisations look for baseline life limits.

Auditors, inspectors and CASA. CASA inspectors and delegated staff enforce compliance with ADs issued under CAR 1998. The AD is issued under subregulation 39.1(1) of CAR 1998 and bears the signature of a CASA delegate. While the AD text itself does not list penalties, enforcement rests on the broader CAR 1998 framework referenced. CASA as the regulator decides on the AD content and enforces compliance; the delegate made specific amendments and revoked the prior amendment.

Parts suppliers and aircraft parts managers. The Retirement Schedule is part number specific. Operators and parts suppliers will need to track inventories of parts with affected part numbers (for example 20602-1, 20602-2, 30511-1, 30505-1, 40091-2, 40091-3, 40092-5 and 40092-6). Suppliers holding second-hand or overhauled parts must be able to establish remaining life or ensure parts are not installed beyond the retirement life.

Operators seeking life extensions. Operators who intend to rely on the permitted life extensions must procure, incorporate and record the specified Snow service letters. Note 1 ties extensions for splice blocks to "Snow SL #185 revised issue dated 9/3/99" and Note 2 ties fin spar and attach plate lives to "Snow SL #187." Incorporation is the specified mechanism; the AD conditions the extension on incorporation of those specific documents.

Recordkeeping custodians. The AD imposes an evidentiary conversion rule for missed landing records: where landings are unrecorded, three landings per one hour must be assumed. That converts maintenance log and flight log recordkeeping into a compliance-relevant obligation. Parties responsible for flight logs, maintenance logs and component life tracking are consequentially affected.

Indirectly affected parties. Operators of aircraft that interact with AT-802/AT-802A operations may be secondarily affected through availability of spare parts and scheduling constraints created by mandated retirements. The AD also cross-references AD/AT 800/3 for wing spar cap lives; parties tracking compliance obligations across multiple ADs must align their maintenance programmes.

Who decides and who pays. The AD is decided by the CASA delegate (signature dated 21 June 2001) under CAR 1998 subregulation 39.1(1). The costs of compliance , retiring components, obtaining replacements, possible downtime and incorporation of service letters , fall on the aircraft owners/operators and their maintenance organisations because the AD's operative requirement is to retire parts before exceeding the listed life.

The AD sets out a short list of operative duties, limited permissions for life extension, and some informational corrections. The instrument does not enumerate rights in a statutory sense beyond the procedural elements it contains.

Duties

• Retire specified components. The Requirement instructs operators to "Retire from service the airframe components listed in the Retirement Schedule below." The Compliance clause requires retirement "prior to exceeding the applicable time in service listed in the Retirement Schedule." This creates a hard stop on the use of each listed part at the stated hours or landings.

• Apply the assumed landings rule if records are incomplete. The AD stipulates an evidential rule: "Where the total number of landings during a period of service has not been recorded, three landings per one hour time in service must be assumed." That rule obliges the record-keeper or operator to convert hours to an assumed landing count when landing records are missing.

• Observe serial-number dependent lives. Some retirement lives depend on aircraft serial number. For the Plate Assembly - Fin Front Spar Attach (30511-1) and Spar Assembly - Fin Rear (30505-1), retirement lives differ for S/N 0001-0041 (4000 hours) and S/N 0042 and up (20000 hours). Operators must check aircraft serial numbers to determine the applicable limit.

• Incorporate Snow SLs to obtain extensions. Where operators wish to rely on the life extensions noted, they must incorporate the exact Snow service letters named in the Notes. Note 1 states splice block lives "may be extended to 10000 hours on incorporation of Snow SL #185 revised issue dated 9/3/99." Note 2 states fin spar and attach plate lives "may be extended to 20000 hours on incorporation of Snow SL #187." The AD ties the availability of extended lives to incorporation of those specific documents.

• Consider cross-referenced ADs. Amendment 4 "is issued to delete the wing spar cap retirement lives from the retirement schedule; as the retirement lives are now contained in AD/AT 800/3." Operators must therefore consult AD/AT 800/3 for wing spar cap retirement lives and ensure compliance with both ADs where relevant.

Rights and procedural points in the AD

• No affirmative authorisation for alternate means of compliance (AMOC) is included in the AD text. The AD does not specify a process for approval of alternative compliance strategies within its own text. The AD also does not specify whether operators may exceed stated lives after life-extension work other than incorporation of the specified Snow SLs. The only permitted extensions are those expressly stated in Notes 1 and 2.

• The AD corrects documentation misstatements. Note 3 is informational: "The Type Certificate Data Sheet states that the lives are listed in the Maintenance Manual; however they are in fact listed in the Owners Manual." That correction affects where operators should look for the manufacturer's Airworthiness Limitations.

• Effective date and retroactivity. The AD becomes effective on 27 June 2001. The Compliance sentence requires retirement "prior to exceeding" the listed times. The AD does not explicitly create a phase-in or grace period for parts already beyond prescribed lives; the operative command is to retire prior to exceeding the limits, and the AD revokes the prior amendment. The Background history shows earlier amendments and effective dates, which may influence prior compliance obligations.

Unspecified or absent elements operators should note

• The AD does not specify how the life of a replacement part is to be recorded or whether the installation of a new or overhauled component resets the life to zero. The AD is silent on reworked parts or on allowances for repair actions that might restore a part to serviceable condition but not explicitly reset retirement life.

• The AD does not include a separate enforcement or penalty schedule. It is issued under CAR 1998 subregulation 39.1(1), but the AD text itself contains no penalty amounts or enforcement procedures beyond the statement of regulatory authority and the Gazette notification.

• The AD does not prescribe an approval process for incorporating Snow SLs within the text; it only states that life extensions are available on incorporation of the named service letters.

The AD is issued under the regulatory authority of CAR 1998 and is administered by CASA. The AD itself does not set out civil or criminal penalty amounts or an enforcement process within its text. The document does, however, make clear the following points that are relevant to enforcement and regulatory status.

Regulatory basis. The AD is issued by a CASA delegate "under subregulation 39.1 (1) of CAR 1998." The opening paragraph states the legal basis for the delegate's action and explains that the AD "requires that the action set out in the requirement section ... be taken in relation to the aircraft or aeronautical product mentioned in the applicability section" in specified circumstances and in accordance with the stated instructions and timing. The AD therefore is an administrative order made under CAR 1998.

Absence of penalty detail in the AD. The AD does not list infringement notices, monetary penalties, or specific enforcement steps for noncompliance. It states compliance obligations and effective dates, but any penalties or enforcement mechanisms must be sought in the broader CAR 1998 framework or other relevant enforcement instruments. The AD text alone provides no schedule of fines or criminal sanctions. Practitioners should not assume the AD defines penalties; instead the AD is an enforceable requirement by regulatory fiat under the cited subregulation.

Notified in the Gazette. The AD is notified in the Commonwealth of Australia Gazette on 27 June 2001. Publication in the Gazette is the formal public notification mechanism described in the AD. Gazette notification typically signals that the instrument is public and officially promulgated. The AD also includes the delegate's signature dated 21 June 2001 and an explicit effective date of 27 June 2001.

Enforcement actors. The delegate of CASA issued the AD; CASA and authorised inspectors are the likely enforcement bodies. The AD text, however, does not delineate the specific enforcement actions that CASA may take for contravention. Since the AD was issued under CAR 1998 subregulation 39.1(1), enforcement would be governed by the enforcement powers and processes provided under CAR 1998 and related aviation safety legislation, but these are not reproduced in the AD.

Evidential rules relevant to enforcement. The AD creates a clear compliance metric: retire parts prior to exceeding listed lives. It also provides an evidential conversion rule where landing totals are unrecorded, requiring an assumption of three landings per one hour of time in service. That evidentiary rule simplifies compliance verification where landing counts are missing by giving inspectors a specified conversion rate to apply.

Practical enforcement implications implicitly created by the AD

• Inspectors have a concrete list of parts, part numbers and in some cases serial number ranges against which to check logbooks and maintenance records. The AD provides the Retirement Schedule as the enforcement checklist.

• Life-extension clauses are conditional on incorporation of specific Snow service letters. Enforcement will therefore turn on whether the specified service documentation was incorporated and recorded.

• The AD's revocation of Amdt 3 and reallocation of certain retirement lives to AD/AT 800/3 means inspectors must check compliance across both ADs for the full set of airframe life limits.

What the AD does not say about enforcement

• It does not specify inspection intervals, audit powers or administrative penalties. It does not explain procedural rights for operators to seek relief or to apply for alternative means of compliance within this document. Those procedural and penalty mechanisms, if available, are likely to be found in CAR 1998 or CASA administrative procedures, neither of which is reproduced in the AD text.

For legal or regulatory challenges practitioners should note that the AD provides its legal footing by reference to CAR 1998 and that the AD itself focuses on the operative retirement requirements and documentary prerequisites for life extensions rather than an enforcement regime. Any challenge to enforcement actions taken under this AD will need to engage the wider CAR 1998 provisions and administrative law processes, which are outside the scope of the AD text.

The AD references and cross-links to regulatory instruments and manufacturer documentation. The AD text itself supplies a limited set of interaction points.

Connection to CAR 1998. The AD explicitly states that it is issued "under subregulation 39.1 (1) of CAR 1998." That identifies the parent regulatory instrument authorising the CASA delegate to issue airworthiness directives. The AD therefore operates within the legal framework of CAR 1998. The AD does not reproduce CAR 1998's provisions; it only cites the subregulation as the enabling source.

Interaction with other ADs. The AD revokes AD/AT 800/2 Amdt 3 and states that wing spar cap retirement lives have been deleted from this Retirement Schedule "as the retirement lives are now contained in AD/AT 800/3." Practically that means compliance with airframe life limits for an operator requires examining AD/AT 800/2 Amdt 4 alongside AD/AT 800/3 to obtain the full set of retirement lives for the aircraft. The AD therefore redistributes content across multiple AD instruments rather than being a self-contained life-limits compendium.

Manufacturer documentation and service letters. The AD ties life limits and extensions to manufacturer materials. The Background notes that the manufacturer published airframe component life limitations "in the Airworthiness Limitations section of the Owners Manual." Note 3 corrects an erroneous reference in the Type Certificate Data Sheet that had pointed to the Maintenance Manual. Notes 1 and 2 permit life extensions "on incorporation of Snow SL #185 revised issue dated 9/3/99" and "Snow SL #187" respectively. Those Notes create an explicit regulatory interaction between CASA's AD and the manufacturer's service documentation. The AD therefore conditions regulatory compliance on the incorporation and documentation of specified manufacturer service letters.

Gazettal and public law publication. The AD is "notified in the Commonwealth of Australia Gazette on 27 June 2001." Gazettal is the public notification mechanism and interacts with public law principles of notice and publication. The AD thereby becomes a public administrative instrument with an effective date communicated via the Gazette.

Type Certificate Data Sheet. The AD corrects a documentation inconsistency in the Type Certificate Data Sheet by stating that "the lives are listed in the Owners Manual," thereby interacting with type certification documentation and the maintenance/owners documentation regime. This correction affects where the formal airworthiness limitations may be located and therefore influences compliance with the aircraft’s type-certification-maintenance interface.

What the AD does not interact with explicitly

• The AD does not itself quote or reproduce the specific enforcement provisions or penalty regimes of CAR 1998, nor does it reference other civil aviation statutes or criminal law. It also does not specify interaction with international aviation standards or foreign regulatory ADs.

• The AD is silent on how life limits operate with respect to supply chain laws, parts resale or export/import controls on retired parts. Those issues would be governed by other statutes or customs rules, which the AD does not address.

For practitioners, the key interaction points to track are CAR 1998 (enabling regulation), AD/AT 800/3 (complementary AD containing wing spar cap lives), the Owners Manual (where the manufacturer lists airworthiness limitations) and the specific Snow service letters (SL #185 revised issue dated 9/3/99 and SL #187) that condition life extension. The AD situates itself as the regulatory implement that requires operators to follow the manufacturer’s life limits, with limited conditional extensions tied to specific manufacturer service documents.

The AD text includes a concise amendment history and records of earlier effective dates. The chronological changes recorded in the AD are the operative amendment history for AD/AT 800/2.

Original issue. The AD states that the original issue of this Directive "became applicable on 15 August 1996." That marks the initial issuance of AD/AT 800/2 in its first form.

Amendment 1. The Background reports that "Amendment 1 included new and revised lives for some landing gear components." The AD does not provide a date for Amendment 1 in this text. The content change is thus recorded as a revision to landing gear component retirement lives.

Amendment 2. Amendment 2 "implemented extended lives for wing and fin spar components and expressed tail gear spring lives in landings as well as hours, as for the MLG spring leg lives." Amendment 2 "became effective on 13 July 2000." This amendment therefore changed several life limits to longer values and changed the units or expression of limits for some tail gear springs to include landings as well as hours.

Amendment 3. Amendment 3 "became effective on 10 August 2000." The AD does not restate the content of Amdt 3 in full, but the present instrument, Amdt 4, revokes Amdt 3. Amdt 3's effective date is thus recorded.

Amendment 4. The current instrument, "AD/AT 800/2 Amdt 4," is effective 27 June 2001 and is issued to revoke AD/AT 800/2 Amdt 3. The AD explains that Amendment 4 follows "further information received from the manufacturer, and clarifies aircraft serial number applicability for the fin component lives. A part number error has also been corrected." Amendment 4 specifically deletes wing spar cap retirement lives from this Retirement Schedule because they are now contained in AD/AT 800/3. The AD bears the delegate’s signature dated 21 June 2001.

Notes and their amendment relevance. The AD’s Notes interact with the amendments. Note 1 and Note 2 provide manufacturer-based life-extension pathways that appear to have been added or clarified across amendments, particularly in the changes described for Amendment 2 and later clarifications in Amdt 4. Note 3 records a correction to where the lives are listed, which is a documentation correction rather than a change in numeric limits.

Effect of revocation. Amdt 4 expressly "revokes Airworthiness Directive (AD) AD/AT 800/2 Amdt 3." Practically that means Amdt 3 is no longer the operative AD text for retirement lives covered by Amdt 4. The AD directs operators to consult AD/AT 800/3 for wing spar cap lives that have been moved.

Timing of publications. The AD text records the effective dates of Amendments 2, 3 and the original issue, and sets the effective date for Amdt 4. It also shows the same effective date used for Gazette publication. The AD’s amendment history is self-contained insofar as it records prior effective dates and the reasons for the subsequent amendment actions.

For compliance and auditing, operators must be attentive to the amendment timeline because: (a) life limits may have been different under earlier amendments; (b) parts retired under earlier limits may have been replaced pursuant to those earlier amendments; and (c) Amdt 4 moves some limits to a different AD (AD/AT 800/3). The AD gives specific dates for Amendments 2 and 3 and the original issue, and dates for Amdt 4’s signature and effective date, which are necessary for establishing which retirement limits applied at a given past time.

The AD text contains no references to litigation, disputes, judicial review, appeals, or case law. It does not mention any legal challenges to its content or enforcement. The document records only administrative actions: issuance of the original AD and subsequent amendments, culminating in Amdt 4 effective on 27 June 2001 and notified that day in the Commonwealth of Australia Gazette.

Implications of silence on litigation. Because the AD does not mention any litigation, the instrument itself does not create a public record of court proceedings or administrative appeals concerning these specific retirement limits. Practitioners searching for litigation history should note that the AD text contains no statement of judicial proceedings and therefore any litigation or dispute would need to be sought in external judicial or administrative records. The AD provides no summary of disputes between the manufacturer, operators or CASA, nor does it cite precedent decisions.

Administrative process indications. The AD shows the administrative steps taken , original issuance, three amendments, signature by a CASA delegate and Gazette notification. That process is typical for airworthiness directives, but the AD does not include material indicating whether any part of the amendment process was contested in judicial or tribunal proceedings. Where contestation is relevant to a client, the AD does not itself provide evidence of challenge, so counsel should search court and tribunal records, as well as CASA correspondence, for any contested matters outside this text.

Practical note for litigators and counsel. If enforcement action is taken under this AD, the AD text will provide the substantive regulatory requirements that enforcement agencies will rely on. Any legal challenge to enforcement would need to engage the enabling statute (CAR 1998) and administrative law principles; because the AD does not record any prior litigation, counsel should plan fact-specific discovery on whether the AD was properly promulgated, whether the operator received fair notice, and whether the state provided any procedural mechanisms for alternative compliance or appeal. None of those procedural or judicial aspects are addressed in the AD text itself.

This AD contains several practical traps for operators and maintenance organisations that, if overlooked, can create inadvertent noncompliance. The AD text itself points to a number of specific areas requiring attention.

Assumed landings conversion can increase apparent wear. The AD requires assuming three landings per one hour if landings were not recorded. That conversion is unfavourable to operators with incomplete landing records because the conversion can materially accelerate the number of credited landings for parts whose retirement lives are stated in landings. For example, a component whose life is limited in landings but where only flight hours are recorded will have accelerated counting under the AD’s conversion rule. Operators should not treat this as a discretionary conversion; the AD mandates the assumption.

Serial-number dependent lives. Several components have retirement lives that depend on aircraft serial number ranges (e.g., plate assembly 30511-1 and spar assembly 30505-1 , S/N 0001-0041 have 4000 hours, S/N 0042 and up have 20000 hours). Failure to confirm the aircraft serial number and match it to the Retirement Schedule will lead to application of the wrong retirement life. Serial number applicability is a common compliance error when parts are swapped across airframes or when logbooks are incomplete.

Life-extension conditions must be strictly met. The AD permits extensions only on incorporation of specified Snow service letters: SL #185 revised issue dated 9/3/99 for splice blocks and SL #187 for fin spar and attach plate lives. Operators relying on extended lives must incorporate the exact documents named. The AD ties the life extension to incorporation; it does not authorise equivalent documentation or later revisions unless those are specifically stated. Operators should record incorporation in maintenance records; otherwise inspectors will not accept an unsubstantiated extension.

Relocation of wing spar cap lives. Amdt 4 deletes wing spar cap retirement lives from this AD because they are contained in AD/AT 800/3. A common gotcha is assuming that all airframe lives for the model are in AD/AT 800/2; operators must consult AD/AT 800/3 to obtain the full set of retirement lives for wing spar caps. Failure to consult the cross-referenced AD creates an incomplete compliance regime.

Documentation discrepancies. Note 3 highlights a documentation inconsistency between the Type Certificate Data Sheet and the actual location of the lives. The AD states that the lives are listed in the Owners Manual, not the Maintenance Manual as the Type Certificate Data Sheet claims. Operators that rely solely on the Type Certificate Data Sheet risk missing the correct source of airworthiness limitations.

No guidance on replacement part life resets or repaired parts. The AD requires retirement of listed components prior to exceeding the stated life, but it does not say whether the installation of a new or overhauled part resets the life or how repaired parts are to be treated. The absence of this guidance is a procedural risk: maintenance records must still document any replacement or overhaul, but the AD does not specify whether a repaired component can be returned to service with restored life, or whether its remaining life is prorated. Operators should note the silence and, if necessary, clarify with CASA or follow established maintenance programmes.

No explicit alternative compliance procedure in the AD text. The AD does not specify an AMOC process or provide a contact for seeking alternatives. Practitioners should not assume that informal remedies are permissible; the AD contains no authority for an alternative approach within its text.

Part number corrections and human error. The Background notes that "a part number error has also been corrected." Part number errors in earlier amendments could have caused incorrect retirements. Operators should verify current part-number listings against the AD text, and ensure that maintenance records reference the corrected part numbers.

Immediate compliance and past exposures. The AD became effective on 27 June 2001. Retirement is required "prior to exceeding" the applicable time in service. Where components have already exceeded limits under prior versions of the AD, the instrument provides no retrospective grace; operators must review historical compliance to ensure no parts are already beyond the permitted life. Because the AD revokes Amdt 3, determining whether a component was installed legally at a past date may require careful review of prior amendments' limits and records.

Interaction with AD/AT 800/3. Because wing spar cap lives are moved to AD/AT 800/3, failure to track both ADs can lead to incomplete maintenance planning. Practitioners should treat the Retirement Schedule in Amdt 4 as partial and confirm the operator’s full set of applicable retirement limits by reviewing AD/AT 800/3 as well.

The AD sets out clear operative requirements; compliance involves a sequence of documentary, inspection and maintenance actions. Below are concrete steps and control points that follow logically from the AD’s text.

1. Confirm applicability. Identify whether the aircraft is an AT-802 or AT-802A. The AD applies to "All models AT-802 and AT-802A aeroplanes." If the fleet includes these models, they are subject to the Retirement Schedule.

2. Inventory and map parts to the Retirement Schedule. Using component part numbers and, where specified, aircraft serial numbers, map installed components to the Retirement Schedule entries. Relevant part numbers in the AD include, without limitation, 20602-1, 20602-2, 30511-1, 30505-1, 40091-2, 40091-3, 40092-5 and 40092-6. For parts that show serial-number dependent lives (30511-1 and 30505-1), confirm the aircraft S/N (for S/N 0001-0041 apply 4000 hours; for S/N 0042 and up apply 20000 hours).

3. Audit flight hours and landing records. For each component, calculate accumulated time in service in accordance with your maintenance records. If the total number of landings during a period of service has not been recorded, apply the AD’s mandated conversion: assume three landings per one hour time in service. Use that conversion to compute an effective landing count for components whose lives are expressed in landings.

4. Schedule retirements before exceeding limits. The Compliance paragraph requires retirement "prior to exceeding the applicable time in service listed in the Retirement Schedule." Create a maintenance plan to remove and replace parts before they reach the listed hours or landings. For parts with dual metrics (hours or landings), the AD requires retirement at whichever limit occurs first.

5. Incorporate Snow SLs if seeking extensions. If you intend to rely on the life extensions noted in the AD, incorporate the specific Snow service letters. Note 1: ingestion of "Snow SL #185 revised issue dated 9/3/99" permits splice block lives to be extended to 10000 hours. Note 2: incorporation of "Snow SL #187" permits fin spar and attach plate lives to be extended to 20000 hours. Document the incorporation in maintenance records and ensure the version and issue date match the AD’s wording.

6. Consult AD/AT 800/3 for wing spar cap lives. The AD deletes wing spar cap retirement lives from this Retirement Schedule and states they are now in AD/AT 800/3. To ensure full compliance against all airframe life limits, obtain and comply with AD/AT 800/3 as well.

7. Update maintenance and recordkeeping procedures. Because the AD imposes a conversion formula for unrecorded landings and relies on the Owners Manual for airworthiness limitations (Note 3), update maintenance control documentation to:

   • Record both flight hours and landings where possible.
   • Capture incorporation of Snow SLs with signature, date and reference number.
   • Record part removals, replacements and remaining life status.
   • Note serial numbers of parts and the aircraft serial number to determine correct retirement lives.

8. Replace retired parts with serviceable components and document replacements. The AD requires retirement of specified components prior to exceeding limits. When replacing parts, document installation dates and the installed part’s identity. The AD does not address whether replacement parts’ lives reset; until clarified, treat replacements and new parts as starting fresh unless another AD or manufacturer guidance states otherwise. Record any overhauled or second-hand parts with their history.

9. Plan for logistics and downtime. Retirement of structural parts, landing-gear springs and spar attach plates will require parts procurement and maintenance hangar time. The AD’s retirement lives for some items (for example 6500 hours for certain wing attach blocks, and 20000 hours for some fin spars under Note 2) will influence stocking and overhaul scheduling. Budget for replacements, and ensure certified parts are sourced.

10. Maintain evidence for inspections. Because the AD will be the enforcement instrument referenced by CASA inspectors, maintain clear, contemporaneous records showing:

• Dates and hours/landings at removal.
• Records showing any assumptions used for landings where records were missing.
• Evidence of incorporation of Snow SLs when extensions are claimed.
• Cross-references to the Owners Manual and the relevant AD texts.

11. Verify documentation sources. Note 3 corrects where the manufacturer’s lives are recorded. Ensure that maintenance staff consult the Owners Manual for the Airworthiness Limitations section. Do not rely solely on the Type Certificate Data Sheet for life listings.

12. If in doubt, contact CASA. The AD does not set out an AMOC process within its text. If an operator seeks an alternative compliance approach, or if there is uncertainty about life-resetting for repaired or overhauled parts, seek written clarification from CASA via the usual regulatory contacts. Because the AD was issued under CAR 1998 subregulation 39.1(1), any formal relief or variation will likely need to proceed through CASA.

13. Audit historical compliance against amendment timeline. For components installed before Amdt 4’s effective date, verify whether prior amendments imposed different limits and whether retirements were performed accordingly. The AD records prior effective dates: original 15 August 1996; Amendment 2 effective 13 July 2000; Amendment 3 effective 10 August 2000; Amdt 4 effective 27 June 2001.

14. Cross-check part numbers. The Background notes that a part number error was corrected. Confirm the current, correct part numbers in your records and adjust any historical records that might reference superseded or erroneous part numbers.

Following these steps will align maintenance practices with the operative requirements set out in AD/AT 800/2 Amdt 4. Operators should treat the Retirement Schedule as the compliance driver and maintain documentary evidence for the application of any allowed extensions or assumptions.