AD/750XL/12 - Wing Rear Spar

The directive organizes around a small set of technical and procedural concepts that determine scope, action and timing. Applicability is explicitly serial-number limited. The directive applies to PAC 750XL aircraft serial numbers 101, 102, and 104 through 128, except aircraft with modification PAC/XL/0273 incorporated. That exception means aircraft with PAC/XL/0273 are outside the AD’s mandatory scope (Applicability). The main remedial concepts are inspection, repair, replacement, and permanent modification.

Inspection: Requirement 1 specifies the inspection zone and items to be inspected. Inspectors must check the inboard end of both rear spars for security of blind rivets attaching the fuselage attach fitting to the rear spar and inboard rib, check the radii of the rear spar upper and lower flanges for cracking, inspect outboard to 8 inches (200 mm) from the attachment fitting, and inspect the aft flange of the inboard rib for cracking (Requirement 1). The instrument treats “signs of working” of rivets as a basis for remedial steps.

Repair and replacement: If the aft flange of the inboard rib is cracked or rivets show signs of working, repair must be carried out in accordance with modification PAC/XL/0270 (Requirement 1; Note 1). If the rear spar is cracked, the spar must be replaced before further flight. That creates a mandatory stop-flight condition where spar cracking is found.

Modification as normative remedy: Requirement 2 prescribes removal of NAS1738E-6-6 blind rivets and replacement with bolts or rivets as detailed in drawing No.11-20035 and PACSB/XL/022. The AD explicitly allows modification PAC/XL/0217 as an alternative means of compliance for Requirement 2, and identifies PAC/XL/0270 as a repair scheme that may be used as an alternative to spar replacement (Notes 1 and 2).

Timing (compliance intervals): The instrument layers short-term inspection cadence and a deadline for permanent modification. Initial inspection must be within 50 hours time in service after the effective date, unless done within the last 50 hours, and then every 150 hours until the permanent fix is installed. The permanent replacement of rivets with bolts or rivets must be done within 300 hours time in service or 12 months (Compliance). After the permanent modification, continued inspection intervals default to the aircraft maintenance manual, not exceeding 300 hours or 12 months.

Parts and documentation references: The AD references specific part numbers and technical drawings: blind rivet NAS1738E-6-6, rear spar part number 11-20031/32-1, drawing No.11-20035, PACSB/XL/022, modification numbers PAC/XL/0270, PAC/XL/0273 and PAC/XL/0217, and NZ CAA AD DCA/750XL/9 (Requirement, Notes, Applicability, Background). Those references are the prescriptive technical standards for compliance.

Regulatory instrument form: The document is presented as an Airworthiness Directive, signed by a delegate of the Civil Aviation Safety Authority, dated 1 May 2007, and stating that the AD becomes effective on 3 May 2007 (signature block; Compliance). The Background section states the safety objective: prevent damage to the rear spar due to working and failing rivets between the wing rear spar and inboard rib.

The directive targets a narrow population of aircraft and the persons who operate and maintain them. Primary affected parties are owners and operators of PAC 750XL model aircraft with serial numbers 101, 102, and 104-128, except those which have modification PAC/XL/0273 incorporated (Applicability). Those owners and operators carry the legal and operational obligation to ensure inspections and any required repairs or modifications are carried out within the mandated timeframes (Compliance; Requirement).

Secondary affected parties include maintenance organisations and certificated maintenance personnel who perform structural inspections, repairs and modifications on the identified aircraft. The AD prescribes inspection tasks, judgement calls about rivet security and cracking, and prescriptive modification work that relies on technical documents such as drawing No.11-20035 and PACSB/XL/022 (Requirement 1; Requirement 2). Maintenance providers must be able to interpret whether rivets "show signs of working" and must apply repairs in accordance with modification PAC/XL/0270 where required.

Supply-chain participants are implicated. The AD names specific fasteners and spar part numbers: blind rivet NAS1738E-6-6 and rear spar part 11-20031/32-1 (Requirement 2). Compliance may require locating approved bolts or rivets that conform to drawing No.11-20035 and PACSB/XL/022, or sourcing replacement spars if cracking is found. Where the AD allows alternative means of compliance in modification PAC/XL/0217 or PAC/XL/0270, the availability and provenance of those modifications become relevant to operators and maintainers (Notes 1 and 2).

Regulator and delegate: The AD is issued by the Civil Aviation Safety Authority, signed by David Villiers as a delegate (signature block). The instrument’s compliance periods and the directive’s effective date mean the regulator expects action timelines to be observed (Compliance; effective date). The Background identifies NZ CAA involvement by reference to NZ CAA AD DCA/750XL/9, indicating cross-reference to other aviation authority directives that may apply to similar aircraft or components (Note 3).

Excluded parties: Aircraft with modification PAC/XL/0273 incorporated are excluded from the AD’s applicability, meaning that owners/operators of such aircraft are not required by this AD to perform the specified inspections and modifications (Applicability). That exception creates administrative work for operators and maintenance organisations to verify modification status in records before undertaking AD compliance.

Financial burden: The AD allocates inspection, repair, replacement and modification costs to aircraft owners and operators. It prescribes physical work and parts rather than offering a funding mechanism. The AD does not specify who pays; that cost obligation falls to the parties responsible for aircraft airworthiness under the applicable regulatory framework (the instrument itself contains no funding provisions).

The directive creates specific duties for those in control of affected aircraft and for maintenance personnel. Duties are primarily procedural and time-bound.

Inspection duties: Within 50 hours time in service after 3 May 2007, unless already done within the last 50 hours, operators must inspect the inboard end of both left and right rear spars for security of the blind rivets that attach the fuselage attach fitting to the rear spar and inboard rib, inspect the radii of the rear spar upper and lower flanges for cracking, inspect from the attachment fitting outboard 8 inches (200 mm), and inspect the aft flange of the inboard rib for cracking (Requirement 1). Thereafter, inspections must be repeated at intervals not to exceed 150 hours time in service until Requirement 2 is accomplished (Compliance).

Repair and replacement duties: If the aft flange of the inboard rib is cracked or rivets show signs of working, the duty is to repair in accordance with modification PAC/XL/0270 (Requirement 1; Note 1). If the rear spar itself is cracked, the duty is to replace the rear spar before further flight. That replacement is an absolute pre-flight condition; no further flight is permitted until the spar is replaced (Requirement 1).

Permanent modification duty: On both left and right sides, operators must remove blind rivets NAS1738E-6-6 that join rear spar part number 11-20031/32-1 and the aft end of the inboard rib, and replace them with bolts or rivets as detailed in drawing No.11-20035 and PACSB/XL/022 (Requirement 2). Requirement 2 must be accomplished within 300 hours time in service or 12 months after 3 May 2007, whichever is earlier (Compliance).

Post-modification inspection duty: After Requirement 2 is completed, the directive requires continued inspection of the left and right wing aft attachment area in accordance with the aircraft maintenance manual, at intervals not exceeding 300 hours time in service or 12 months (Compliance).

Alternative compliance options: The AD recognises alternative means of compliance. Modification PAC/XL/0270 is an identified repair scheme that may be used as an alternative to spar replacement required where certain damage is found. Modification PAC/XL/0217, which installs a packer and uses bolts instead of rivets, is cited as an alternative means of compliance to Requirement 2 (Notes 1 and 2). Those alternatives create rights to comply by more than one approved technical route, provided the alternative is installed and documented.

Rights implicit in the text: The instrument does not articulate express rights such as appeal rights or compensation. It does, however, provide specific technical alternatives and a defined compliance timetable that afford affected parties the ability to plan and choose between technical options that the AD accepts (Notes 1 and 2).

Decision-making responsibilities: The AD places technical judgements on those conducting the inspection and repair. Determination of whether rivets "show signs of working" or whether cracking exists rests with the inspecting maintenance personnel, who must then apply the prescribed repair or replacement actions. The AD prescribes that spar replacement must occur before further flight if the rear spar is cracked, which is a mandatory operational decision triggered by a finding in inspection (Requirement 1).

Record-keeping and proof: While the AD does not spell out record-keeping requirements, compliance will depend on demonstrable inspection and modification records, including dates, hours in service at inspection, and the particulars of repairs or modifications carried out in accordance with the referenced drawings and modification numbers.

The directive text itself does not specify penalties, sanctioning mechanisms or enforcement procedures. The document records the AD’s effective date, the compliance deadlines and the specific technical duties, but it contains no express enforcement clause or prescribed penalties for non-compliance (Compliance; signature block). The instrument is framed as an Airworthiness Directive and states that it becomes effective on 3 May 2007 (Compliance). It is standard administrative practice for airworthiness directives to be mandatory within the issuing authority’s jurisdiction, and compliance is necessary to maintain legal airworthiness status, however those normative effects are not set out in this AD’s text.

Because the text does not include wording that creates or describes direct penalties, this AD leaves enforcement mechanisms and penalty regimes outside the instrument itself. The AD does not describe monitoring protocols, inspection audit powers, or civil or criminal penalties. It similarly does not set out processes for approval of alternative methods of compliance outside the notes that identify certain modifications as alternatives (Notes 1 and 2).

Practical enforcement implications drawn from the instrument’s form: The AD prescribes clear compliance windows and mandatory remedial steps. An operator who does not perform inspections, repairs, or the permanent modification within the prescribed intervals will, by definition, be non-compliant with the technical requirements of the AD. The AD’s lack of explicit penalty text means the operator must look to the applicable aviation regulatory framework outside this document for enforcement measures, which are not contained in the AD text.

Availability of alternatives and compliance proof: The AD identifies specific alternatives such as PAC/XL/0270 and PAC/XL/0217, and references technical drawings No.11-20035 and PACSB/XL/022. Compliance disputes or enforcement action, if any, would turn on demonstrable proof that inspections were carried out in the specified intervals, that detected defects were addressed in the specified manner, and that the permanent modification or its accepted alternative was installed within the 300-hour or 12-month deadline. The AD itself does not set out who verifies compliance or how verification is to be evidenced.

Signature and issuing authority: The directive is issued and signed by a delegate of the Civil Aviation Safety Authority, David Villiers, dated 1 May 2007. That signature identifies the administrative origin of the AD but does not itself set out enforcement processes (signature block).

The AD text cross-references other airworthiness modifications and an NZ CAA AD, which shows interaction with existing technical and regulatory instruments, but it contains no express provisions about its relationship to other statutes, regulations or enforcement regimes beyond those references.

Inter-modification relationships: The AD expressly excludes aircraft that have modification PAC/XL/0273 incorporated from its applicability. That means the presence of PAC/XL/0273 modifies the applicability of this AD in a way that current aircraft records must reflect (Applicability). The AD also treats certain other modifications as alternatives to mandated actions. Modification PAC/XL/0270 is identified as a repair scheme that may be used as an alternative means of compliance to spar replacement (Requirement 1; Note 1). Modification PAC/XL/0217 is identified as an alternative means of compliance to Requirement 2, addressing the installation of a packer and use of bolts instead of rivets (Requirement 2; Note 2). Those cross-references create dependency on the documentation and approval status of those modifications in whatever regulatory framework governs such modifications.

Cross-border or foreign authority interaction: The AD references a New Zealand Civil Aviation Authority Airworthiness Directive, NZ CAA AD DCA/750XL/9, by way of Note 3. That reference points to parallel or related regulatory action by another authority, but the AD does not itself state how this instrument interoperates with NZ regulatory requirements. The practical effect is that operators and maintainers who operate under jurisdictions affected by multiple authorities must account for the referenced NZ CAA directive as potentially relevant technical guidance, though the AD text is silent on legal priority or reciprocal enforcement.

Interaction with maintenance documentation: After accomplishment of Requirement 2, inspections are to continue in accordance with the aircraft maintenance manual at intervals not exceeding 300 hours time in service or 12 months (Compliance). That instruction binds the AD to the aircraft’s maintenance manual procedures and intervals, thereby creating a direct operational tie between the AD and the maintenance documentation that governs ongoing inspection practice.

Parts and engineering documentation: The AD references component part numbers, drawing No.11-20035 and PACSB/XL/022. Compliance therefore requires conformity to those technical specifications. That creates an interaction with supply-chain and engineering approval processes: authorised parts and documented installation instructions must be used to meet the AD’s requirements.

Operational law and airworthiness regime: The directive is framed as an Airworthiness Directive and therefore functions within the broader airworthiness regulatory system. The AD sets technical obligations relevant to airworthiness status, but it does not itself contain administrative enforcement language or specify how it interacts with statutory enforcement measures under broader aviation law. The issuing signature identifies the Civil Aviation Safety Authority as the administrative source, which implies the AD operates within that regulator’s legal remit, although the AD text itself does not articulate the statutory enforcement mechanisms.

The AD text supplied contains limited explicit amendment history. The instrument carries the identifier AD/750XL/12, dated and signed 1 May 2007 by a delegate of the Civil Aviation Safety Authority, and states that the Airworthiness Directive becomes effective on 3 May 2007 (signature block; Compliance). The header contains coding showing "7/2007 DM" adjacent to the AD identifier and subject matter (AD/750XL/12, Wing Rear Spar, 7/2007 DM). No prior versions of AD/750XL/12 are included in the supplied text.

The instrument also records cross-references to other modifications and directives which indicate an embedded technical amendment context. The AD refers to modification PAC/XL/0270 and PAC/XL/0217 as repair schemes or alternative means of compliance (Requirement; Notes 1 and 2). It also states that NZ CAA AD DCA/750XL/9 refers (Note 3). Those cross-references indicate a technical lineage of engineering changes and prior directives, but the AD does not provide a chronological listing of prior amendments to itself.

No subsequent amendments, revisions, supersessions, cancellations, revocations or replacement AD references are present in the supplied text. The AD is presented in final form with an effective date and no footnote or schedule indicating later changes. Therefore, based only on the supplied document, the amendment history consists of issuance on or around 1-3 May 2007, under the internal code 7/2007 DM, with cross-references to existing modifications and a related NZ CAA AD. If a reader needs the full legislative or regulatory amendment trail beyond this single instrument, they must consult the issuing authority’s AD database or the referenced modification documentation, which are not included in the supplied text.

The supplied AD text contains no information about litigation history. It does not mention any judicial or administrative proceedings, disputes, challenges, or determinations in relation to this specific directive. The AD does not quote or cite judicial authority, nor does it report any appeals, enforcement actions, or litigation outcomes. The only external reference is to NZ CAA AD DCA/750XL/9 (Note 3), but that is a technical regulatory reference and not litigation.

Because the AD text is silent on litigation, there is no record within this instrument of any court cases, procedural challenges, or dispute resolution concerning compliance obligations, the technical requirements, or the administrative issuance of the AD. Any litigation history that may exist would not be evidenced in the supplied material and would require independent inquiry outside the AD text, such as searches of administrative or judicial records. The AD itself provides no record of such activity.

For parties relying on this instrument, absence of litigation history in the AD means the directive should be treated, based solely on the text provided, as a technical regulatory prescription without accompanying commentary about legal disputes. The AD does not provide guidance on dispute resolution mechanisms or appeal channels in the text.

The AD contains several technical and administrative points that can easily be misread or overlooked. This section lists concrete issues that could cause non-compliance or operational disruption if not anticipated.

Narrow applicability carve-out: The AD applies only to PAC 750XL aircraft serial numbers 101, 102, 104-128, but expressly excepts aircraft with modification PAC/XL/0273 incorporated (Applicability). Operators must verify modification status in records before assuming the AD applies. Misreading the serial-number range or neglecting to check for PAC/XL/0273 could lead to unnecessary work or missed compliance.

Two-stage compliance regime with different inspection cadences: Requirement 1 imposes an immediate inspection duty within 50 hours time in service and interim inspections at 150-hour intervals until Requirement 2 is completed (Requirement 1; Compliance). Requirement 2 requires permanent removal and replacement of certain blind rivets within 300 hours time in service or 12 months. If operators only read the deadline for Requirement 2 and miss the interim inspection cadence, they risk overlooking progressive rivet deterioration that the interim inspections are designed to catch.

"Signs of working" is a judgement call: Requirement 1 triggers repair under PAC/XL/0270 if rivets "show signs of working." The AD leaves the assessment of "working" to the inspector’s judgement, creating potential variability in application. Operators should ensure that inspecting personnel are trained and that inspection criteria are documented to support consistent decisions.

Stop-flight trigger for spar cracking: If the rear spar is cracked, the AD mandates replacement of the rear spar before further flight (Requirement 1). That is an immediate operational impact and can ground the aircraft until a replacement spar is obtained and installed. Operators should plan for possible grounding time and parts availability.

Specific part numbers and drawings: Requirement 2 names blind rivet NAS1738E-6-6, rear spar part 11-20031/32-1, drawing No.11-20035 and PACSB/XL/022. Sourcing correct replacement bolts or rivets and ensuring conformity to the specified drawing is necessary for compliance. Using incorrect fasteners or undocumented installation methods risks non-compliance.

Alternative modifications as conditional relief: The AD recognises PAC/XL/0270 and PAC/XL/0217 as alternative means of compliance. But those alternatives must be properly documented and installed to be valid. Note that PAC/XL/0270 is described as a repair scheme and may be used as an alternative to spar replacement, while PAC/XL/0217 is described as an alternative means of compliance to Requirement 2. Operators should not assume that any aftermarket fix will suffice; the AD identifies only specific modifications as acceptable alternatives.

Continued inspection intervals change after modification: After Requirement 2 is accomplished, inspection intervals revert to the aircraft maintenance manual, but still not exceeding 300 hours or 12 months (Compliance). Operators must update maintenance schedules and logbooks to reflect the revised inspection regime once the permanent modification is installed.

No enforcement mechanics in the text: The AD contains no expressed penalties or enforcement procedures. That means operators must look to the broader regulatory framework for enforcement consequences and should not assume the AD text itself prescribes sanctions or monitoring mechanisms. The practical implication is that compliance should be maintained regardless of the absence of penalty wording.

Cross-reference to NZ CAA AD: Note 3 references NZ CAA AD DCA/750XL/9. Depending on registration and operational jurisdiction, operators may need to consider the NZ CAA instrument in parallel, but the AD text does not explain the legal interplay. This could cause uncertainty for operators with multi-jurisdictional operations.

Timing and effective date: The AD becomes effective on 3 May 2007, while the signature is dated 1 May 2007 (Compliance; signature block). Operators must ensure they calculate time-in-service deadlines relative to the effective date in the manner required by their airworthiness authority and logbook practice.

The AD sets out concrete steps and deadlines. Below is a practicable compliance checklist built strictly from the instrument’s text.

1. Verify applicability

   • Check the aircraft serial number. The AD applies only to PAC 750XL serial numbers 101, 102, and 104-128 (Applicability).
   • Check modification status. If modification PAC/XL/0273 has been incorporated, the AD does not apply to that aircraft (Applicability).

2. Schedule initial inspection

   • If applicable, carry out the inspection required by Requirement 1 within 50 hours time in service after 3 May 2007, unless already accomplished within the last 50 hours time in service (Compliance).
   • If inspection has already been performed within the preceding 50 hours, ensure records confirm that and note the date and hours.

3. Perform Requirement 1 inspections

   • Inspect the inboard end of left and right rear spars for security of the blind rivets that attach the fuselage attach fitting to the rear spar and inboard rib (Requirement 1).
   • Inspect the radii of the rear spar upper and lower flanges for cracking (Requirement 1).
   • Inspect from the attachment fitting to a point 8 inches (200 mm) outboard (Requirement 1).
   • Inspect the aft flange of the inboard rib for cracking (Requirement 1).
   • Document findings in the aircraft maintenance log, with hours time in service at inspection.

4. Respond to findings from Requirement 1

   • If the aft flange of the inboard rib is cracked or the rivets show signs of working, carry out repair in accordance with modification PAC/XL/0270 (Requirement 1; Note 1).
   • If the rear spar is cracked, replace the rear spar before further flight. Ensure the replacement spar conforms to the applicable part number and installation documentation (Requirement 1).

5. Interim inspection cadence

   • Until Requirement 2 is accomplished, repeat Requirement 1 inspections at intervals not to exceed 150 hours time in service (Compliance). Record each inspection.

6. Complete Requirement 2 permanent modification

   • Within 300 hours time in service or 12 months after 3 May 2007, whichever occurs first, remove blind rivet part number NAS1738E-6-6 from left and right sides where it joins rear spar part number 11-20031/32-1 and the aft end of the inboard rib (Requirement 2).
   • Replace these rivets with bolts or rivets pursuant to drawing No.11-20035 and PACSB/XL/022 (Requirement 2). Use only the specified bolts or rivets and conform strictly to drawing No.11-20035 and PACSB/XL/022.
   • Alternatively, if installed, modification PAC/XL/0217 that installs a packer and uses bolts may be used as an alternative means of compliance to Requirement 2; ensure that PAC/XL/0217 is properly documented in the aircraft records (Requirement 2; Note 2).

7. Post-modification inspection regime

   • After Requirement 2 is accomplished, continue to inspect the left and right wing aft attachment area in accordance with the aircraft maintenance manual, at intervals not exceeding 300 hours time in service or 12 months, whichever occurs first (Compliance). Update the maintenance schedule to reflect the new interval.

8. Documentation and records

   • For all inspections, repairs and modifications, document the work, the hours time in service at which the work was done, the parts used (including part numbers), drawings or modification references (PAC/XL/0270, PAC/XL/0217, drawing No.11-20035, PACSB/XL/022), and the name and certification of the individual or organisation performing the work.
   • If alternative modifications are used, retain documentation that demonstrates the alternative conforms to the AD’s Note 1 or Note 2 description and is properly installed.

9. Operational considerations

   • If a rear spar is found cracked, do not permit further flight until replacement is complete (Requirement 1). Plan for aircraft grounding time and parts acquisition.
   • Ensure maintenance personnel are competent to identify rivets that "show signs of working" and to apply PAC/XL/0270 repairs where required.

10. Technical references and queries

• Use drawing No.11-20035 and PACSB/XL/022 as the installation standard for Requirement 2. Use modification PAC/XL/0270 for specified repairs. Confirm the applicability of PAC/XL/0217 as an alternative if that modification is already installed or can be installed as the chosen compliance method (Requirement 2; Notes 1 and 2).
• Note the AD was issued and signed by a delegate of the Civil Aviation Safety Authority, David Villiers, dated 1 May 2007, and became effective on 3 May 2007 (signature block; Compliance). Use those dates when calculating compliance windows.

This checklist follows the AD text strictly and assumes that the operator will consult the referenced drawings and modification documents for the exact technical procedures. Where the AD allows alternative means of compliance, confirm that the particular alternative modification installed matches the wording describing an acceptable alternative in the notes.