AD/PA-31/118 Amdt 2 - Aileron Spar

The directive rests on a small set of tightly specified operational and technical concepts. First, the locus of concern is structural fatigue cracking in the aileron assembly: the aileron spar, spar doubler (front spar element), and rib flanges. The Background explicitly ties reported defects to “fatigue cracking” and “high out-of-plane stresses,” and notes consequences for hinge attachment strength and aileron flutter characteristics. The textual focus is on inspection for cracks rather than prescriptive modification or replacement.

Second, the inspection methodology is specified: an “approved dye penetrant inspection procedure” is mandated for the critical inspection tasks. Note 1 makes a process-level identification by naming “colour contrast dye penetrant used in accordance with Appendix II to CAO 108.10” as an approved inspection procedure. The instrument therefore links substantive compliance to a named, external inspection standard (Appendix II to CAO 108.10).

Third, the directive creates two pathways for compliance: the prescriptive removal-and-inspect pathway in paragraph 1(a), and an alternative, Authority-approved scheme under paragraph 1(b). That establishes delegation of some procedural discretion to the Civil Aviation Safety Authority, permitting alternative inspection schemes so long as they are approved.

Fourth, where defects are found, the instrument mandates further dismantling and dye-penetrant inspection (paragraph 2(a)), and it confines repair authority to instructions approved by either the holder of the USA type certificate, the Authority, or an appropriate CAR 35 authorised person (paragraph 2(b)). That distributes technical decision-making and approval authority among three named entities.

Finally, temporal concepts are central. The Compliance paragraph prescribes an initial threshold (before 5,000 hours aileron time in service) and a repeat interval (not exceeding 500 hours aileron time in service). Amendment history modifies prior inspection policies (Amendment 1) by replacing repeated dismantling with more frequent dye-penetrant inspections and inclusion of additional areas. The effective date of Amendment 2 is explicit: 12 February 2009.

The directive directly applies to “All PA-31 Series” aeroplanes, as the Applicability line states. The primary economic actors required to act are the operators and maintainers of those PA-31 aircraft: owners, operators, maintenance organisations and personnel who perform aileron maintenance and inspections. The requirement to remove LH and RH ailerons and associated brackets (Requirement 1(a)) imposes a maintenance task on the entity responsible for aircraft continuing airworthiness.

Those who perform repairs are constrained by the approval pathway in paragraph 2(b): repairs must be carried out “in accordance with instructions approved by the holder of the USA type certificate, the Authority or an appropriate CAR 35 authorised person.” That means technical repair instructions must come from one of those three authorities; maintenance organisations must either follow holder-authorised instructions or obtain approval from the Authority or a CAR 35 authorised person to perform and document repairs.

The Civil Aviation Safety Authority (the Authority) is also a direct actor: it has the power to approve alternative inspection schemes under paragraph 1(b), to approve repair instructions under paragraph 2(b), and to represent a locus for dispute or technical approval. The document is signed by a delegate of the Civil Aviation Safety Authority, showing it originates from that regulator.

Third parties who supply inspection services or materials are implicated: dye penetrant materials and the practitioners trained to perform dye-penetrant inspection in accordance with Appendix II to CAO 108.10 are required by Note 1. The directive therefore affects suppliers of inspection consumables and certified NDT (non-destructive testing) practitioners.

Finally, maintenance scheduling and operational planners are affected by the compliance timings: the initial inspection before 5,000 hours aileron time and repetitive inspections every 500 hours aileron time thereafter. These intervals impose operational planning constraints on utilisation, maintenance windows and aircraft availability for operators of PA-31 series aeroplanes.

Duties

• Conduct the initial inspection before 5,000 hours aileron time in service, and thereafter at intervals not exceeding 500 hours aileron time in service (Compliance paragraph). This is the core temporal duty; it prescribes when inspection must occur.

• Under Requirement 1(a), physically remove both left-hand and right-hand ailerons, remove the inboard and outboard hinge brackets and control horn brackets, strip and clean areas around bracket attachments including spar flanges, and inspect the visible surfaces of the front spar element (doubler) for cracks using an approved dye penetrant procedure. This is a hands-on dismantling and NDT duty.

• Alternatively, under Requirement 1(b), perform inspection “in accordance with an alternative scheme approved by the Authority.” That creates a duty to obtain prior approval from the Authority if the operator wishes to deviate procedurally from the removal-and-inspect method.

• If cracking or damage is identified, paragraph 2(a) requires dismantling sufficient aileron structure to remove the spar doubler and gain good access to the main spar element and the aft rib forward flange in the area of the defect, and inspection of all surfaces using an approved dye penetrant procedure.

• If cracking or damage exists, paragraph 2(b) imposes the duty to repair “in accordance with instructions approved by the holder of the USA type certificate, the Authority or an appropriate CAR 35 authorised person.” Repair work therefore must follow an approved repair instruction set.

Rights and procedural options

• The operator has a right to an alternative inspection regime, but only if that scheme is “approved by the Authority” (Requirement 1(b)). That is a discretionary procedural right conditioned on Authority approval.

• The operator has a choice of approved repair instruction sources: holder of the USA type certificate, the Authority or an appropriate CAR 35 authorised person (paragraph 2(b)). That distributes options for who may approve repair instructions.

• Note 1 effectively defines an approved inspection procedure by reference to an external standard: colour contrast dye penetrant used in accordance with Appendix II to CAO 108.10 is an “approved inspection procedure.” Operators may therefore elect to follow that specified technique as an established compliance route.

Information duty implied but not stated

• The directive prescribes specific operational steps and approval pathways but does not itself specify paperwork or record-keeping obligations in the text. The directive’s own prescriptions for inspection, dismantling, and approved repair instructions imply maintenance records will be required under broader airworthiness regulation, but such record obligations are not stated in this instrument.

The instrument as supplied contains no explicit penalty provisions or enforcement procedures. The text sets out mandatory inspection and repair requirements, compliance intervals and approval pathways, but it does not specify fines, suspension powers, directions or enforcement mechanisms within its own wording.

Because the directive is issued by the Civil Aviation Safety Authority and signed by a delegate, the practical enforcement consequences are linked to the regulator’s general powers under the Civil Aviation safety framework rather than to this instrument’s text. However, the directive itself does not detail those enforcement powers, nor does it specify administrative or criminal penalties for non-compliance.

The instrument does allocate certain decision-making authorities that will shape enforcement-relevant interactions: the Authority can approve alternative inspection schemes under Requirement 1(b) and can approve repair instructions under paragraph 2(b). Those approval processes will be the locus where compliance is assessed in respect of alternative schemes and repair instructions. Additionally, repairs are permissible if approved by the holder of the USA type certificate or an appropriate CAR 35 authorised person; that creates parallel compliance routes that may affect how the Authority evaluates conformity.

Because this directive does not list enforcement steps, regulated parties should assume that compliance will be checked in the course of normal regulatory oversight and continuing airworthiness monitoring. The absence of explicit penalties or enforcement actions in the text is a material point: the instrument imposes duties and prescribes processes and approvals, but it leaves enforcement and sanctioning mechanisms to the broader regulatory context rather than specifying them here.

The directive references and therefore interacts with other named regulatory instruments and authorities. The interactions recorded in the text are:

• CAO 108.10 (Appendix II): Note 1 states that “Colour contrast dye penetrant used in accordance with Appendix II to CAO 108.10 is an approved inspection procedure.” That means compliance with the directive requires adherence to the dye-penetrant practice described in Appendix II to CAO 108.10 where operators choose that approved procedure. The directive thus imports a technical inspection standard from CAO 108.10 by reference.

• CAR 35 authorised person: Paragraph 2(b) permits repair instructions approved by “an appropriate CAR 35 authorised person.” By naming CAR 35 authorised persons as authorised approvers, the directive situates repair approvals within the Authorisations regime established elsewhere in civil aviation regulation. The text assumes the existence and competence of CAR 35 authorised persons to approve repair instructions.

• Holder of the USA type certificate: Paragraph 2(b) lists the holder of the USA type certificate as an authorised approver for repairs. That references the international type-certification framework and assigns a role to the US type certificate holder in the repair-approval chain for PA-31 aircraft.

• The directive is issued by the Civil Aviation Safety Authority and is signed by a delegate. That places it within the Authority’s powers and procedural apparatus, though the directive itself does not recite statutory provisions granting the Authority the power to issue airworthiness directives. The text therefore functions operationally within the Authority’s enforcement and approval machinery.

Other interactions are implicit. The directive prescribes methods and approval channels but does not set out record-keeping obligations or enforcement mechanisms; those matters would be handled under broader civil aviation instruments and administrative law. Because the directive requires compliance with an Authority-approved alternative scheme or instructions approved by CAR 35 authorised persons or the US type certificate holder, it creates intersection points with approval processes and cross-border technical data supplied by the type certificate holder.

The instrument is presented as AD/PA-31/118 Amendment 2, and the text contains an internal amendment history. The document states that Amendment 1 was raised “to alleviate the requirement to repetitively dismantle structure which shows no sign of defect.” The Background also records that “As a result of service experience, visual inspection requirements have been upgraded to a recognised dye penetrant inspection procedure, at shorter intervals, and additional areas have been included.” That describes the functional changes introduced by Amendment 1: replacement of repetitive dismantling with more targeted NDT at shorter intervals and with additional inspection areas.

Amendment 2 is specifically described in the Background as being “raised to add paragraph 2(b) and to update the Compliance paragraph.” Paragraph 2(b) is the new text that requires repairs to be made “in accordance with instructions approved by the holder of the USA type certificate, the Authority or an appropriate CAR 35 authorised person.” The Compliance paragraph in the instrument reflects the updated inspection timing: initial inspection before 5,000 hours aileron time in service, followed by inspections at intervals not exceeding 500 hours aileron time in service. The document explicitly states that “Compliance with Amendment 1 of this airworthiness directive constitutes compliance with this Amendment,” which preserves continuity for operators who complied with the earlier amendment.

The instrument shows the effective date for this amendment as 12 February 2009 and is signed and dated 23 December 2008 by the delegate of the Civil Aviation Safety Authority, indicating the administrative finalisation timeline. The Background references “numerous reports” as the operational prompt for the original directive and for the subsequent amendments; Amendment 1 altered inspection modality (visual to dye penetrant, shorter intervals) and Amendment 2 added an explicit repair-approval clause and updated the compliance timeframe.

No further amendments beyond Amendment 2 are listed in the supplied text. The instrument therefore documents a three-step policy evolution: initial directive responding to service reports, Amendment 1 to reduce unnecessary dismantling and increase inspection sensitivity, and Amendment 2 to add repair approval clarity and update compliance timing.

The supplied text contains no references to litigation, judicial review, or tribunal decisions concerning AD/PA-31/118 or its amendments. There are no cited cases, appeals, or determinations recorded in the instrument. The document is a regulatory airworthiness directive and includes only administrative amendment history and the technical requirements and notes; it does not report any litigation or contested proceedings.

Given the absence of litigation references in the text, the instrument does not describe disputes about the content, validity, or application of the directive. It does, however, identify procedural decision points that could be the locus of future disagreement,approval of alternative inspection schemes (Requirement 1(b)), the content and sufficiency of repair instructions approved by the holder of the USA type certificate or an Authority or CAR 35 authorised person (paragraph 2(b)), and the interpretation of “aileron time in service” for the purpose of compliance scheduling. While such issues could give rise to administrative or judicial challenges in practice, the directive itself does not recount or reference any legal proceedings.

Because the text supplies no litigation history, practitioners seeking precedent or judicial interpretation tied to this AD will need to consult external sources; those are not contained in this instrument. The AD’s text confines itself to technical requirements, amendment notes, compliance intervals and approval pathways without offering or citing any litigation outcomes.

Several practical traps and interpretative points arise from the directive’s wording and structure, as set out in the text.

1. Definition and measurement of “aileron time in service.” Compliance intervals are expressed in “hours aileron time in service” (initial before 5,000 hours and thereafter at intervals not exceeding 500 hours). The directive uses that term but does not define it. Operators must ensure their maintenance records or timekeeping practices can identify aileron time separately from airframe hours, or must seek clarification from the Authority, because the compliance trigger is tied precisely to that metric.

2. Alternative inspection scheme requires Authority approval. Requirement 1(b) permits an “alternative scheme approved by the Authority.” That is an approval-conditioned right, not an automatic substitution. Operators who wish to avoid the removal-and-inspect route under 1(a) must obtain approval, and the text provides no detail on what the Authority will require to grant approval.

3. Removal and reinstallation workload. Paragraph 1(a) requires removal of LH and RH ailerons, hinge brackets and control horn brackets, stripping and cleaning of bracket attachment areas and dye-penetrant inspection. That is a substantive dismantling task with mechanical and access work, and the directive’s Note 1 and Description indicate the inspection technique required. The instrument does not prescribe time allowances, tooling, or reassembly checks; implementers must plan for the complete removal, NDT, and reinstallation.

4. Repair approval sources. Paragraph 2(b) restricts repair instructions to those approved by the holder of the USA type certificate, the Authority or an appropriate CAR 35 authorised person. Repairs carried out without such approved instructions would not meet the directive’s stated repair pathway. Operators must establish contact lines with the type certificate holder, the Authority, or CAR 35 authorised persons to obtain approved repair instructions if defects are found.

5. Note 2 identifies exacerbating factors. The directive notes that “Cracking in these areas may be exacerbated by degradation of the control system stiffness (eg due to pivot bearing wear) and by aileron deflection during ground handling and pre-flight inspection.” That suggests inspection should be attentive to control system components and to operational handling practices that might increase stress. The directive does not mandate corrective action for non-spar control-system wear except insofar as such wear is relevant to the presence of cracking; operators may need to consider parallel maintenance measures to address pivot bearing wear to reduce recurrence risk.

6. Interaction with CAO 108.10. Note 1 identifies a specific approved method: “Colour contrast dye penetrant used in accordance with Appendix II to CAO 108.10 is an approved inspection procedure.” Operators must ensure the dye-penetrant method they plan to use complies with that Appendix. Using another dye-penetrant method or a different NDT technique without Authority approval could be non-conforming.

7. Continuity for Amendment 1 compliance. The instrument states that “Compliance with Amendment 1 of this airworthiness directive constitutes compliance with this Amendment.” Parties who complied with Amendment 1 will not be required to repeat those tasks under Amendment 2, but they must ensure their records demonstrate Amendment 1 compliance.

8. No penalties specified. The directive does not list enforcement or penalty provisions. That absence does not equate to permissiveness; rather, practitioners must be aware that sanctions if any will arise under the broader regulatory regime, not from explicit clauses within this text.

9. Ambiguity around “visible surfaces” and “good access.” Paragraph 1(a) requires inspection of “the visible surfaces of the front spar element (doubler)” and paragraph 2(a) requires gaining “good access” to the main spar element and aft rib forward flange. These phrases leave room for interpretation about how much dismantling or removal is necessary to obtain a compliant inspection outcome. Operators should seek specific guidance from the Authority if in doubt.

10. Timing and operational impact. The compliance cadence (initial before 5,000 hours and repeat every 500 hours aileron time) will impose recurring maintenance slots for all PA-31 operators. Planning must account for downtime, parts, qualified NDT personnel, and potential repairs if defects are found.

Follow these steps, grounded in the directive text, to satisfy AD/PA-31/118 Amdt 2.

1. Establish “aileron time in service” accounting. Because the Compliance paragraph uses “aileron time in service” as the timing metric (initial inspection before 5,000 hours, then every 500 hours), ensure maintenance records or a time-tracking method capture aileron time separately or as required by your operator procedures. If the term is unclear internally, seek clarification from the Authority before the next inspection window.

2. Choose inspection pathway. Decide whether to follow Requirement 1(a) or pursue an alternative scheme under Requirement 1(b):

   • If following 1(a), plan to remove both LH and RH ailerons, remove the inboard and outboard hinge brackets and control horn brackets, strip and clean the areas around bracket attachments including spar flanges, and perform dye-penetrant inspection of visible surfaces of the front spar element (doubler).
   • If preferring an alternative inspection method, prepare a proposed scheme and submit it to the Civil Aviation Safety Authority for approval in advance of implementation, since 1(b) requires Authority approval.

3. Use an approved dye-penetrant procedure. Note 1 specifies that “Colour contrast dye penetrant used in accordance with Appendix II to CAO 108.10 is an approved inspection procedure.” Ensure NDT providers and technicians use the Appendix II method or obtain formal Authority approval for any alternative NDT method. Maintain evidence (procedures used, operator qualifications, NDT reports) demonstrating the inspection complied with the Appendix II standard if that route is used.

4. Inspect the correct areas and note exacerbating factors. The directive singles out the doubler, spar, hinge bracket attachment and horn bracket attachment areas, and the aft rib forward flange where defects are found. Where removal is necessary under paragraph 2(a), dismantle sufficient aileron structure to remove the spar doubler and gain good access to the main spar element and aft rib forward flange, then inspect all surfaces with dye penetrant. Also consider inspection of pivot bearings and control-system stiffness, since Note 2 identifies pivot bearing wear and ground handling deflections as factors that may exacerbate cracking.

5. If cracking or damage is found, inspect and prepare for repair. After detecting cracking:

   • Follow paragraph 2(a): dismantle sufficiently to remove the spar doubler and inspect the main spar element and adjacent rib flange areas using an approved dye-penetrant procedure.
   • Obtain repair instructions approved by one of the three permitted authorities under paragraph 2(b): the holder of the USA type certificate, the Authority, or an appropriate CAR 35 authorised person. Do not proceed with repairs using other instruction sets unless they have been approved through one of those routes.

6. Liaise with repair approvers early. If defects are found, contact the US type certificate holder, the Authority, or an appropriate CAR 35 authorised person promptly to obtain approved repair instructions. Repairs must be carried out in accordance with those instructions to meet the directive’s requirements.

7. Schedule recurring inspections. After the initial inspection (before 5,000 hours aileron time in service), establish a maintenance plan for inspections at intervals not exceeding 500 hours aileron time in service. Track compliance windows and plan NDT resource allocations accordingly.

8. Document compliance. Although the directive does not specify record-keeping in its own text, retain inspection reports, NDT certificates, repair instructions and approval documentation from the Authority or the type certificate holder. Because compliance is conditional on approved procedures and instructions (for alternative schemes and repairs), retain approvals and correspondence to evidence conformity.

9. Address contributing wear issues. Note 2 identifies pivot bearing wear and ground handling deflections as exacerbating factors. Implement measures within existing maintenance practices to monitor and, where necessary, remediate pivot bearings and related control-system components to reduce the risk of crack initiation or propagation.

10. Consider continuity for Amendment 1 compliance. If the aircraft has previously complied with Amendment 1, the instrument explicitly states that such compliance “constitutes compliance with this Amendment.” Maintain documentation of Amendment 1 compliance to demonstrate continuity.

11. Seek Authority guidance on ambiguities. For interpretative gaps,such as what constitutes “visible surfaces,” “good access,” or how to measure “aileron time in service”,seek formal guidance or approval from the Civil Aviation Safety Authority to ensure chosen procedures will be accepted as compliant.

12. Plan for downtime and resource needs. The removal, stripping, cleaning and dye-penetrant inspection steps require qualified technicians, appropriate tooling and NDT materials. Build those requirements into operational maintenance schedules to ensure inspections and any subsequent repairs can be carried out within the prescribed intervals.