AD/LEARJET/36 Amdt 1 - Tip Tank Flapper Valves

The AD operates through a handful of interlocking technical and administrative concepts drawn from the aircraft maintenance regime that the instrument directly references. These are: model/serial applicability, inspection criteria and methods, corrective action thresholds, part-number identification, manufacturer service-bulletin normative references, discrete compliance timing, and an installation prohibition.

• Applicability: The Directive is explicitly limited to Learjet Model 24 and 25 within specified serial-number ranges. Owners and operators must verify serial numbers against the Applicability block to determine whether the directive applies.

• Inspection scope and standard: Requirement 1 mandates inspections to "detect deterioration (such as cracks, cuts, breaks, splits, or warpage) of both flappers of the tip tank in each wing," in accordance with Learjet SB 23/24/25-28-2 dated 6 October 1995. The instrument therefore delegates the technical inspection procedures and the definition of acceptable condition to the Learjet service bulletin, which the AD makes normative.

• Corrective-action thresholds: The Directive distinguishes between two paths: if no deterioration is detected, a set of checks on positioning, retaining screws, seating, and free movement must be performed and any discrepancies corrected per the Learjet SB; if deterioration is detected, immediate replacement of the flapper valve per the Learjet SB is required. Thus the AD embeds decision points based on inspection findings.

• Replacement and termination of repetitive inspections: The AD requires replacement of both flappers in each wing in certain circumstances (Requirements 2 and 3). Requirement 5 introduces a part-number control concept: identification of specific improved part numbers (flappers P/N 2323006-802 and assemblies P/N 2323006-801) allows cessation of the prior repetitive inspections; conversely, discovery of particular older part numbers (flapper P/N 2323006-5 or assembly P/N 2323006-6) requires replacement under Bombardier SB 23/24/25-28-7 Rev 2 dated 9 May 2001, and that replacement also ends repetitive inspections.

• Use of maintenance records as an alternative to physical inspection: Requirement 5 expressly permits a maintenance-records review in lieu of physical inspection for part-number determination, but only if the P/N can be "conclusively determined from that review." The AD therefore provides a records-based compliance pathway, with the caveat of conclusive identification.

• Prohibition on installation: Requirement 6 establishes a forward-looking installation ban: "Do not install a flapper having P/N 2323006-5 or a flapper assembly having P/N 2323006-6, on any aeroplane" from the effective date.

• Compliance timing: The Compliance section repeats and retains multiple original-time requirements (e.g. "Within 50 hours time-in-service after 29 February 1996, or prior to the accumulation of 600 hours time-in-service since installation of the flapper valve, whichever occurs later" and later intervals, and "before further flight" triggers) and also prescribes intervals for repetitive inspections (generally 600 hours time-in-service where applicable) and specific timing for the P/N identification inspection (within 600 hours time-in-service since last replacement, or within 90 days after the effective date, whichever is later).

These concepts together create a compliance regime where operators must identify the parts they have fitted, inspect and, where necessary, replace to either remove an unsafe condition or to install the improved assembly that ends recurring inspection obligations. The AD references specific manufacturer documents which determine the fine detail of how each inspection and repair is to be performed and thus makes those documents part of the mandatory compliance chain.

The AD identifies directly affected aeroplanes by model and serial number (Applicability). That maps to a clearly defined set of aircraft owners and operators who are subject to the Directive: owners and operators of Learjet Model 24 S/N 24-100 through 24-357 inclusive, and Learjet Model 25 S/N 25-002 through 25-373 inclusive. The obligation to perform inspections and replacements falls on those responsible for the airworthiness of the aeroplane, which in practice will be the registered owner, the operator, or the maintenance organisation contracted to perform continuing airworthiness tasks, because they must ensure the required actions are accomplished in accordance with the AD and the referenced service bulletins.

Maintenance organisations, engineers and parts suppliers are also implicated. The AD makes specific manufacturer service bulletins normative: Learjet SB 23/24/25-28-2 (6 October 1995) and Bombardier SB 23/24/25-28-7 Revision 2 (9 May 2001). Those documents set the technical methods for inspection, removal, and installation. Therefore aircraft maintenance providers and parts suppliers must be capable of identifying flapper and flapper-assembly part numbers, supply the approved replacement P/Ns, and perform the work to the service-bulletin instructions. Where parts are replaced to terminate inspections, the parts suppliers must source P/N 2323006-802 flappers and P/N 2323006-801 assemblies, or provide the Bombardier replacement/modified assemblies reidentified per the Bombardier SB.

Regulators and authorised persons within the Civil Aviation Safety Authority (CASA) are referenced indirectly: the AD is issued by a CASA delegate (James Coyne) and becomes effective on a stated date, but the AD text itself does not spell out enforcement mechanisms or penalties. The Note references FAA AD 2005-16-09, which means that any party operating in jurisdictions connected to the FAA decision might need to be aware of corresponding FAA requirements.

Who pays. The Directive does not include any cost or funding provisions. The text requires inspections and part replacements; as a practical legal observation grounded in the AD, the owner/operator must arrange and pay for the inspections, any follow-on corrective actions, and parts and labour required to comply, because the AD places the obligation to "accomplish" actions on the operator and links them to the aircraft serial numbers and installed parts. Service-bulletin compliance will typically incur parts procurement and maintenance labour costs, and possibly AOG or scheduling impacts when "before further flight" actions are mandated.

Operationally affected flights. The AD includes "before further flight" triggers for certain corrective actions (Compliance: parts of Requirement 1 and Requirement 2 are "Before further flight" per the compliance table). Any operator with flappers found deteriorated or other immediate discrepancies will have to carry out rectification before flying that aeroplane. This creates an operational decision point for operators: either schedule inspections and replacements proactively or accept potential service disruption if a "before further flight" condition is discovered during routine checks.

In sum, affected parties are: owners and operators of the specified Learjet 24/25 serial numbers, the maintenance organisations and engineers who perform the required work, parts suppliers capable of supplying the approved P/Ns, and CASA as the issuing regulator. The AD places technical obligations on operators to inspect and, where necessary, replace parts and to follow particular manufacturer service bulletins.

The AD sets out a discrete set of duties, and within the text it also creates procedural options that operate as rights or alternatives.

Key duties

• Conduct inspections to detect deterioration of both tip-tank flappers in each wing in accordance with Learjet SB 23/24/25-28-2 dated 6 October 1995 (Requirement 1). The inspection must check for cracks, cuts, breaks, splits, warpage and then perform specified checks on fit and movement if no deterioration is found. Any corrective actions must be accomplished in accordance with the Learjet SB.
• If any flapper valve is found to be deteriorated, replace it with a new flapper valve in accordance with the Learjet SB (Requirement 1(b)).
• Replace both flappers of the tip tank in each wing with new flappers in accordance with the Learjet SB when required by the AD (Requirement 2).
• For aeroplanes on which the age and time-in-service of the flapper valve cannot be determined, replace both flappers in accordance with the Learjet SB (Requirement 3).
• Perform the follow-on repetitive inspections at the intervals prescribed in the Compliance section (for example, generally at intervals not to exceed 600 hours time-in-service where specified) (Compliance).
• Identify the part numbers of flappers and flapper assemblies either by physical inspection (raised letters/numbers "S-461" on the convex side identify certain parts) or by a conclusive maintenance records review (Requirement 5).
• Where older part numbers (flapper P/N 2323006-5 or assembly P/N 2323006-6) are found, replace the flapper valve or assembly with new or modified and reidentified assemblies as applicable, in accordance with Bombardier SB 23/24/25-28-7 Revision 2 dated 9 May 2001 (Requirement 5(b)).
• Do not install a flapper having P/N 2323006-5 or a flapper assembly having P/N 2323006-6, on any aeroplane from the effective date (Requirement 6).

Rights and alternatives provided by the AD

• Maintenance-records review alternative: Requirement 5 provides an explicit alternative to physical inspection for part-number identification. The records-review method is permitted "instead of inspecting the flappers and flapper assemblies" only if the P/N can be "conclusively determined" from the records. That is a conditional right: it reduces physical inspection burden provided documentary evidence is sufficient.
• Termination of repetitive inspections: The AD grants two ways to terminate the repetitive inspections previously mandated by the original AD. If an operator can demonstrate that four flappers with P/N 2323006-802 and four flapper assemblies with P/N 2323006-801 are installed, no further action is required and the repetitive inspections required by Requirements 1 and 4 can be stopped (Requirement 5(a)). Alternatively, accomplishment of replacements under Bombardier SB 23/24/25-28-7 Rev 2 also ends the repetitive inspections (Requirement 5(b)). This creates an incentive for operators to either confirm the presence of the improved P/Ns or to perform the specified replacements to avoid ongoing inspections.

Procedural duty: compliance with service bulletins. The AD makes Learjet and Bombardier service bulletins normative by reference; duties include strictly following the Accomplishment Instructions of the specified SBs for inspection and replacement work.

Temporal duties: The Compliance section sets deadlines and intervals. Several duties are explicit "before further flight" and others are stated as specific hours/time-in-service windows (e.g., "Within 50 hours time-in-service after 29 February 1996, or prior to the accumulation of 600 hours time-in-service since installation...").

Recordkeeping and traceability: Although the AD does not state recordkeeping obligations explicitly, Requirement 5's acceptance of maintenance-records review highlights the operational significance of accurate records. The right to avoid physical inspections depends on conclusively demonstrating installed part numbers via records.

Prohibition duty: From the effective date, there is an absolute prohibition on installing specified older P/Ns (Requirement 6).

In short, the AD imposes specific physical inspection and replacement duties, prescribes the exact technical references for how to perform them, creates conditional alternatives via records review, and provides mechanisms to terminate recurring obligations via fitting specified approved parts or completing the Bombardier replacement.

The AD text itself does not set out civil penalties, criminal sanctions, or the enforcement procedure. It is a directive issued by a CASA delegate (James Coyne) dated 15 September 2005 and states the effective date (27 October 2005), but the instrument does not include provisions that describe administrative penalties, the process for showing compliance to the regulator, or enforcement steps such as grounding or rectification notices. The only enforcement-relevant language inside the AD text is the mandatory nature of the technical requirements (Requirements 1 through 6) together with compliance timing instructions (Compliance).

Consequently, any statement about the specific legal penalties for non-compliance or the enforcement mechanisms used by CASA is beyond the scope of the AD text itself and is not specified in the instrument. The AD does, however, include operationally significant compliance triggers that have immediate practical consequences: several corrective actions must be carried out "Before further flight" when certain defects or conditions are identified (Compliance entries for Requirement 1(a) and Requirement 1(b) and Requirement 2 as indicated). That language imposes an operational constraint: the aircraft must not be further flown until the identified corrective action is completed. The AD therefore creates a regulatory precondition to flight for specified defect conditions.

The AD notes FAA AD 2005-16-09 Amdt 39-14214 (Note). This cross-reference signals that corresponding action may be required or recognised by another aviation authority, but the AD itself does not set out bilateral recognition, reciprocal oversight, or inter-authority enforcement procedures.

For practitioners concerned about enforcement and compliance exposure, the AD text provides the mandatory technical requirements and explicit timing instructions; demonstrating compliance requires following the AD and its referenced service bulletins. The absence of penalty language in the AD document means any civil or administrative enforcement action would be governed by the broader statutory and regulatory framework under which CASA operates, not by this AD text itself. The AD nonetheless functions as a binding technical instrument to which operators must adhere, and its "before further flight" conditions will materially affect operational decisions until the actions are performed.

Within the text, the AD expressly references and relies on several external instruments and documents, which creates a layered interaction between the AD and manufacturer documentation and between CASA and the FAA. The AD references Learjet Service Bulletin SB 23/24/25-28-2 dated 6 October 1995 and Bombardier Service Bulletin SB 23/24/25-28-7 Revision 2 dated 9 May 2001 as the source of procedural instructions and replacement specifications (Requirements 1 and 5(b)). By mandating compliance "in accordance with" those service bulletins, the AD folds those manufacturer documents into the regulatory compliance chain. This interaction means that the precise inspection procedures, torque values, part fitting, reidentification processes, and acceptance criteria specified in the SBs become normative for the purposes of complying with the AD.

The AD also contains a Note that refers to FAA AD 2005-16-09 Amdt 39-14214. That cross-reference indicates consistency or alignment with an FAA airworthiness directive addressing the same technical problem. The AD does not set out the content of the FAA AD but the note signals a relationship between CASA's action and the FAA's action. For operators that operate internationally or register aircraft across jurisdictions, the existence of a corresponding FAA AD may have administrative implications for continued airworthiness records and international acceptance of maintenance actions.

The AD modifies an earlier CASA AD (the original issue of this Directive effective 29 February 1996). The Background states that the original issue required repetitive inspections and replacement with new flappers, and that this amendment adds the inspection or maintenance-records review to determine part numbers and, where appropriate, replacement that ends the repetitive inspections. That historical interaction indicates that this instrument functions as a regulatory amendment to an existing airworthiness requirement.

While the AD does not state explicit interactions with civil aviation safety regulations, air operator certificate conditions, or other statutes, the AD’s mandatory language and effective-dating mechanism mean it will intersect operationally with obligations imposed by an operator’s continuing airworthiness management and with maintenance regulation. For example, the AD's "before further flight" triggers will interact with any obligations placed on operators to ensure the airworthiness of their aircraft before flight. The AD also conditions the right to cease repetitive inspections on demonstrable installation of particular P/Ns or completion of Bombardier replacement procedures. That creates a contractual and operational interaction between an operator's maintenance records framework, parts procurement, and ongoing regulatory compliance.

Practically, therefore, the AD interacts with:

• Manufacturer service bulletins by incorporating them as mandatory methods of compliance.
• Prior CASA ADs by amending the earlier directive (the Background identifies the original 29 February 1996 issue).
• The FAA regulatory framework indirectly through the Note referencing FAA AD 2005-16-09, which suggests parallel regulatory action in another jurisdiction.

Because the AD does not detail enforcement procedures nor broader statutory references, any questions about enforcement consequences, certificate action, or cross-border recognition of maintenance actions require examination of CASA’s governing statutes and regulations external to this AD document.

The AD text itself contains the historical milestones necessary to trace this amendment back to the original directive. The original issue of the Directive became effective on 29 February 1996 (Background). That original AD required repetitive inspections to detect deterioration of both flappers of the tip tank in each wing, and various follow-on actions including replacement and repetitive follow-on inspections. Over time, "numerous continual inspections and the approval of a new, improved flapper and flapper assembly" led to this amendment (Background).

This instrument is recorded as AD/LEARJET/36 Amdt 1, dated 11/2005, with the amendment effective date set out as 27 October 2005 (Compliance). The AD is signed by James Coyne as a Delegate of the Civil Aviation Safety Authority on 15 September 2005. The amendment's substantive change is to introduce an inspection of the flappers and flapper assemblies (or review of maintenance records) to determine part numbers and to require replacement of certain older flappers or flapper assemblies where necessary, which, once accomplished, ends the previously mandated repetitive inspections (Background; Requirement 5). The amendment therefore creates a path for terminating continual inspections by fitting improved parts or modified and reidentified assemblies.

The AD also records the normative service-bulletin references with their dates and revision status:

• Learjet Service Bulletin SB 23/24/25-28-2 dated 6 October 1995 is the principal document referenced for inspection protocols and immediate corrective actions (Requirement 1).
• Bombardier Service Bulletin SB 23/24/25-28-7 Revision 2 dated 9 May 2001 is referenced as the method for replacing older flappers or assemblies so as to end the repetitive inspections (Requirement 5(b)).

The AD retains many of the original compliance timeframes from the 1996 issue (Compliance) and states explicitly that certain requirements "Remain unchanged as detailed in the original issue of this Directive" while adding the P/N-identification requirement and the installation prohibition. The textual history provided indicates an iterative approach: initial repetitive inspections and replacement obligations were set in 1996; subsequent operational experience plus the availability of improved parts led CASA to permit termination of repeated inspections contingent on installation of improved parts or completion of Bombardier replacement procedures in 2005.

The AD also includes a Note that cross-references FAA AD 2005-16-09 Amdt 39-14214, which is part of the broader regulatory environment and suggests parallel regulatory action by the FAA.

No other amendments or prior revisions are included in the text provided. The amendment history as recorded in the AD therefore consists of:

• Original AD effective 29 February 1996.
• Amendment AD/LEARJET/36 Amdt 1 dated 11/2005, effective 27 October 2005, introducing P/N identification, replacement options that terminate repetitive inspections, and an installation prohibition.

The AD text does not mention any litigation, court decisions, appeals, or administrative disputes relating to the Directive. There are no cases, enforcement proceedings, or judicial reviews cited in the instrument. The Background explains the technical and operational reasons for the amendment,numerous continual inspections and the approval of an improved flapper and assembly,but does not reference any legal challenges or contested proceedings.

Because the AD does not include a litigation history, practitioners seeking records of disputes, enforcement actions, or interpretations would need to consult CASA records, tribunal or court databases, or industry notices external to this instrument. The AD itself simply sets out the technical requirements and effective dates without documenting any legal proceedings for or against the directive.

Therefore, based solely on the text provided, there is no litigation history to report. Any further inquiry into litigation, compliance audits, or enforcement cases would require searching beyond the AD document for regulatory enforcement records or judicial decisions that are not contained within this instrument.

The AD contains several operational and compliance details that can trap the unwary operator, and these are evident in its precise language.

• Historic compliance dates embedded in the AD: Several compliance timings reference past calendar dates such as "Within 50 hours time-in-service after 29 February 1996" (Compliance). The AD was amended in 2005 and became effective on 27 October 2005. Operators who still possess aircraft in the applicability serial-number range need to recognise that existing compliance windows pre-date the amendment and that the original obligations were time-critical years earlier. The presence of these historic dates creates a potential compliance-check confusion: the AD retains original timing language but the operator must still ensure that any outstanding actions required by the original directive have been accomplished.

• "Before further flight" obligations: Certain corrective actions are explicitly required "Before further flight" (Compliance). That phrase carries immediate operational consequence: if an inspection finds deterioration or defective conditions, the aircraft cannot be flown again until the specified corrective action is completed according to the Learjet SB. An operator who misunderstands the scope of "before further flight" or delays corrective action risks operating an aircraft in contravention of the AD.

• Records-review alternative contingent on conclusiveness: Requirement 5 allows an inspection substitution with a maintenance-records review only if "the P/N of the flappers and flapper assemblies can be conclusively determined from that review." The conditionality is strict. If records are incomplete, ambiguous, or not specific enough, the operator must proceed to physical inspection or replacement. Maintenance histories that use non-standard notations or incomplete part references can therefore force additional inspections or replacement work.

• Part-number identification detail: The AD provides a physical identifier for the improved parts: the raised letters and numbers "S-461" on the convex side of the flappers. If a maintenance person looks only for P/N stamping and misses the "S-461" marking, they could misidentify parts and either over-replace (cost) or fail to replace required parts (safety). Careful training and reference to the SB identification instructions are necessary.

• Replacement quantity rules: Requirement 2 and Requirement 3 specify replacement of "both flappers of the tip tank in each wing" in many instances. Replacing a single flapper may not meet the AD requirement where the AD mandates replacement of both. Misreading the AD and performing partial replacement could leave the operator non-compliant.

• Termination of repetitive inspections depends on exact P/N matches or Bombardier replacement: Requirement 5(a) permits cessation of repetitive inspections only if four flappers P/N 2323006-802 and four flapper assemblies P/N 2323006-801 are installed. A single non-conforming P/N will keep the aircraft subject to repetitive inspections. Similarly, Requirement 5(b) requires replacement in accordance with Bombardier SB 23/24/25-28-7 Rev 2; failure to follow that SB exactly may not achieve the intended termination of inspections.

• Installation prohibition is absolute from effective date: Requirement 6 forbids installing certain older P/Ns on any aeroplane from the effective date. Parts inventory and procurement systems must be adjusted to ensure older stock is not reinstalled; failure to segregate or mark stock could lead to inadvertent non-compliant installations.

• Dependency on manufacturer SBs: The AD delegates the technical specifics to manufacturer service bulletins. If a maintenance organisation does not have access to the exact SB revision cited (Learjet SB dated 6 October 1995 or Bombardier SB Rev 2 dated 9 May 2001) or misunderstands which revision is normative, compliance may be questioned. The AD requires compliance "in accordance with" those SBs, so the exact revision and date matter.

• Cross-reference to FAA AD: The Note referring to FAA AD 2005-16-09 Amdt 39-14214 may create confusion for owners/operators who operate internationally. They must reconcile CASA AD requirements and FAA AD requirements where both jurisdictions are relevant.

• No enforcement particulars in the AD: The AD does not describe enforcement steps, penalty levels, or how to document compliance for regulator audit. Operators must ensure rigorous recordkeeping and be prepared to demonstrate compliance under separate regulatory frameworks.

These "gotchas" are present in the AD’s precise language and the interplay with referenced SBs and records. Operators should plan for thorough part-number identification, precise adherence to SB instructions, timely replacement where required, documentation sufficient to satisfy records-review contingencies, and active inventory control to prevent prohibited installations.

The AD contains a clear set of practical steps and specified references to accomplish compliance. Below is an operational roadmap that follows the AD’s numbered Requirements and Compliance timeframes, drawing only on the AD text and the service-bulletin references it makes normative.

1. Determine applicability

   • Confirm the aeroplane model and serial number against the Applicability: Model 24 S/N 24-100 through 24-357 inclusive; Model 25 S/N 25-002 through 25-373 inclusive. If the serial number falls outside these ranges, the AD does not apply as written.

2. Obtain the referenced manufacturer service bulletins

   • Acquire Learjet Service Bulletin SB 23/24/25-28-2 dated 6 October 1995 for inspection procedures and corrective-action methodology (Requirement 1).
   • If replacement required under Requirement 5(b), obtain Bombardier Service Bulletin SB 23/24/25-28-7 Revision 2 dated 9 May 2001 and follow its Accomplishment Instructions.

3. Perform the initial inspection required by Requirement 1

   • Inspect both flappers in each wing to detect deterioration (cracks, cuts, breaks, splits, warpage) in accordance with Learjet SB 23/24/25-28-2.
   • If no deterioration is detected, perform the follow-up checks specified in the Learjet SB: verify proper positioning of each flapper valve; inspect the condition of the screws retaining the flapper valve to the plate assembly to ensure secure attachment; inspect that the flapper valve completely covers and is seated against the tube opening; verify that the flapper valve moves freely.
   • If any discrepancy is found during these checks, perform the corrective actions in accordance with Learjet SB 23/24/25-28-2.

4. If deterioration is detected

   • Replace the deteriorated flapper valve with a new flapper valve in accordance with Learjet SB 23/24/25-28-2 before further flight (Requirement 1(b) and Compliance).

5. If the AD requires replacement regardless of inspection (Requirements 2 and 3)

   • Requirement 2: Replace both flappers of the tip tank in each wing with new flappers as specified in Learjet SB 23/24/25-28-2. The Compliance table notes this action as "Before further flight" where indicated.
   • Requirement 3: If the age and time-in-service of the flapper valve cannot be determined, replace both flappers of the tip tank in each wing per Learjet SB 23/24/25-28-2 within the timing specified (Compliance).

6. Establish repetitive inspection schedule where required

   • If replacement is not yet accomplished that ends the repetitive inspections, continue with repetitive inspections as required: initial inspection within 50 hours TIS after 29 Feb 1996 or prior to accumulation of 600 hours since installation, and thereafter at intervals not to exceed 600 hours TIS (Compliance). Where replacements have occurred, inspections are to be repeated at intervals "not to exceed 600 hours time-in-service" after replacement (Requirement 4 and Compliance).

7. Identify installed part numbers (Requirement 5)

   • Either physically inspect the flappers and flapper assemblies to determine P/Ns, or conclusively determine the P/Ns via a maintenance-records review. The AD provides the physical identification cue: the raised letters/numbers "S-461" on the convex side of the flappers can indicate certain parts.
   • If the records review is used, ensure that the documentation is conclusive; if there is any ambiguity, perform the physical inspection.

8. Follow the part-number outcomes

   • If four flappers P/N 2323006-802 and four flapper assemblies P/N 2323006-801 are present, no further action under Requirement 5 is required and the repetitive inspections required by Requirements 1 and 4 can be stopped (Requirement 5(a)).
   • If any flapper P/N 2323006-5 or any flapper assembly P/N 2323006-6 is found installed, replace the flapper valve with a new flapper valve or replace the flapper assembly with new or modified and reidentified assemblies as applicable in accordance with Bombardier SB 23/24/25-28-7 Revision 2 dated 9 May 2001. Completion of that replacement ends the repetitive inspections required by Requirements 1 and 4 (Requirement 5(b)).

9. Do not install prohibited parts

   • From the effective date of the Directive, do not install a flapper having P/N 2323006-5 or a flapper assembly having P/N 2323006-6 on any aeroplane (Requirement 6). Implement parts-inventory controls to prevent reinstallation of prohibited P/Ns.

10. Observe the AD effective date and timing windows

• The AD amendment is effective on 27 October 2005 (Compliance). The AD preserves many original timing windows (including specific references to 1996 dates) and sets intervals for repetitive inspection (e.g. 600 hours). When planning compliance, ensure work is documented with the inspection date, method (inspection vs records review), P/N numbers determined, and SB reference used.

11. Record compliance actions

• While the AD does not itself specify recordkeeping steps, Requirement 5’s records-review alternative makes it essential to have robust maintenance records. Document the inspection findings, P/N identifications, SBs used, replacement work performed, and dates and hours time-in-service at which work was done, such that the operator can demonstrate to a regulator or auditor that the AD requirements have been met.

12. Coordinate with relevant authorities and maintenance organisations

• Since the AD references particular service-bulletin revisions and cross-references an FAA AD, coordinate with maintenance organisations and, if appropriate, CASA or the aircraft's continuing airworthiness management organisation to confirm that the chosen SB revisions and replacement parts meet the AD’s normative references.

By following these steps precisely, and by ensuring the work is done "in accordance with" the specified Learjet and Bombardier service bulletins and within the stated compliance windows, an operator will have complied with the obligations set out in this AD as written. Note that the AD does not specify enforcement procedures or penalty clauses within its text; operators should maintain complete documentation to evidence compliance under the applicable regulatory regime.