AD/PA-24/32 Amdt 2 - Stabilator Attachment Bolts - Inspection

The central technical concept in this AD is the risk of corrosion of stabilator attachment bolts and the two compliance paths to manage that risk: periodic inspection of steel alloy bolts, or replacement with corrosion‑resistant bolts that remove the need for repeated inspection. The AD treats the four stabilator attachment bolts as a single locus of continued airworthiness attention; the Requirement states that the four bolts be removed and inspected for corrosion in accordance with Piper SL No. 667A, and if corrosion is found the affected hardware (bolt, nut and washer) must be replaced with unused parts of the same part numbers or equivalent before further flight (Requirement).

A second concept is material equivalence and specific part identification. The AD permits replacement with "equivalent corrosion‑resistant AN bolts" as an alternative to replacement with the same part numbers; it also names two part numbers (502329 and 502342) as corrosion‑resistant bolt options (Requirement, Note 1). The AD therefore creates a binary material regime: steel alloy bolts subject to inspection per Piper SL No. 667A, or corrosion‑resistant bolts that are treated as the mitigation that obviates the inspection cycle.

A temporal compliance regime is a third main concept. The Compliance section distinguishes aircraft that have not been inspected previously under the enumerated authorities (this AD, Piper SL No. 667A, or FAA AD 74-13-03) from those that have. For the former, inspection must be completed before further flight after 31 October 2008; for the latter, inspections must recur at intervals not exceeding three years or five hundred hours time in service, whichever occurs first. Thus the AD combines an initial catch‑up obligation for previously uninspected aircraft with a recurring time‑or‑hours‑based interval for continuing compliance (Compliance).

An administrative alignment concept appears in the Background: the AD’s amendment is explicitly intended to align inspection intervals with FAA AD 74-13-03 and to nominate Piper SL No. 667A as the inspection instructions for steel alloy bolts (Background). The Background also documents the historical change from an original replacement mandate in 1974 to inspection alternatives in light of supply difficulties and Piper service letter authorisations, explaining the current hybrid approach of inspection or replacement (Background).

Finally, applicability is a technical‑administrative concept: the AD specifies exact serial‑number ranges for affected models and adds PA‑24‑400 serial numbers at Amendment 2, but with the material caveat about corrosion‑resistant bolts in those aircraft (Applicability). This means compliance starts with an identification exercise: operators must confirm model, serial number and bolt material before deciding which compliance path they must follow.

The AD affects several clearly identifiable groups directly referenced in the text. First and primarily, it affects registered owners and operators of Piper PA‑24 (Comanche) series aircraft that fall within the listed serial number ranges: PA‑24, PA‑24‑250 and PA‑24‑260 with serial numbers 24‑1 to 24‑5047; and PA‑24‑400 with serial numbers 26‑2 to 26‑148 where the stabilator attachment bolts are not corrosion‑resistant (Applicability). Those owners or operators carry the operational obligation to ensure the inspection or replacement requirement is met before further flight (Compliance).

Second, the AD affects maintenance organisations and engineers authorised to perform removals and inspections. The Requirement specifies removal of the four stabilator attachment bolts and inspection "in accordance with Piper SL No. 667A". That service letter will provide the technical procedure details for those performing the work, so licensed maintenance providers and certifying staff are the agents who must apply those instructions and certify the aircraft airworthy following the inspection or replacement.

Third, parts suppliers and manufacturers are affected in two ways. One, the AD identifies corrosion‑resistant parts (502329 and 502342) and allows equivalent corrosion‑resistant AN bolts as alternatives. Suppliers of corrosion‑resistant AN bolts, and those who can supply the specific part numbers, therefore become the source of the alternative compliance route. Two, the Background notes historical supply difficulties that informed earlier amendments; although not a current instruction, that history signals the potential supply‑chain relevance to operators considering replacement versus recurrent inspection.

Fourth, regulators and delegated CASA staff are affected in that the AD is an instrument issued by CASA and signed by a CASA delegate, David Villiers. The document thus defines a regulatory duty that CASA will expect to see complied with, and CASA will be the deciding authority for the airworthiness directive (signature and effective date).

Finally, the AD potentially affects pilots who operate the affected aeroplanes by conditioning aircraft availability: the Compliance language requires inspection "before further flight" in certain circumstances and recurring inspections at defined intervals; therefore flight operations must be scheduled around the maintenance events. The source does not quantify downtime, but the requirement to remove the bolts for inspection means the aircraft must be taken out of service for at least the time required to perform the removal and inspection and, where necessary, replacement.

The AD creates specific, measurable duties for owners/operators and maintenance providers, and it sets some limited options that can be characterised as rights to choose an alternative compliance path.

Duties

• Identification obligation: Owners/operators must first determine whether their aeroplane falls within the specified applicability ranges and whether the stabilator attachment bolts are corrosion‑resistant, because the Applicability clause limits the AD to certain serial numbers and, in the case of PA‑24‑400, to aircraft with bolts that are not corrosion‑resistant (Applicability).
• Initial inspection duty: If the four stabilator attachment bolts have not previously been inspected in accordance with this AD, Piper SL No. 667A, or FAA AD 74‑13‑03, the owner/operator must have the bolts removed and inspected before further flight after 31 October 2008 (Compliance).
• Recurring inspection duty: If the bolts have previously been inspected under the enumerated instructions, the owner/operator must ensure inspections recur at intervals not exceeding three years or five hundred hours time in service, whichever occurs first (Compliance).
• Remedial duty: If corrosion is found on inspection, the owner/operator must replace the bolt, nut and washer with unused parts of the same part numbers or equivalent before further flight (Requirement).

Rights (permitted options)

• Alternative replacement right: Instead of repeated inspection, the owner/operator may replace the bolts with equivalent corrosion‑resistant AN bolts, which is expressly permitted by the Requirement as an alternative to replacing with the same part numbers or recurring inspections.
• Specific part recognition: The AD identifies parts 502329 and 502342 as corrosion‑resistant, providing owners/operators and maintenance providers with named part numbers that are acceptable for the corrosion‑resistant replacement route (Requirement, Note 1).

Instructional duty

• Use of Piper SL No. 667A: Where inspection of steel alloy bolts is undertaken, the AD directs removal and inspection "in accordance with Piper SL No. 667A" (Requirement). That nominates a specific technical source of instructions, which becomes a duty to follow those procedures for the inspection path.

Administrative duty

• Effective and transitional rules: The Amendment becomes effective on 23 October 2008 and contains a transitional rule that compliance with Amendment 1 constitutes compliance with this amendment, so operators who complied previously have their compliance carried forward (Compliance).

The AD does not set out penalties or enforcement procedures in the text supplied. It also does not specify record‑keeping, certification language, or who formally signs off release to service after maintenance; the Requirement does, however, prescribe precise technical actions and timing that constitute the core duties.

The AD text supplied does not set out specific penalties, fines or an enforcement mechanism in express terms. It is an airworthiness directive issued by the Civil Aviation Safety Authority, signed by a CASA delegate (David Villiers), and contains mandatory technical requirements for affected aircraft (signature block; Requirement; Compliance). The document therefore functions as a regulatory instrument that imposes duties on owners/operators and maintenance providers, but the AD itself does not state in‑instrument enforcement sanctions, inspection regimes, or civil or criminal penalty amounts.

What the text does establish for enforcement context is the mandatory nature of the requirements: removal and inspection, replacement when corrosion is found, inspection intervals, and the alternative of corrosion‑resistant replacement are all stated in mandatory language (Requirement; Compliance). The AD also identifies the technical standards to be applied , Piper SL No. 667A and FAA AD 74‑13‑03 are referenced , which provides CASA with objective benchmarks against which to assess compliance (Requirement; Background).

Because the AD is a CASA instrument, enforcement in practice would proceed under CASA’s regulatory powers and established enforcement processes outside the text of this AD; however, those enforcement powers and procedures are not recited in the AD as supplied. The AD does include transitional and conformity clauses such as "Compliance with this AD at amendment 1 constitutes compliance with this amendment" (Compliance), which affect how CASA would determine whether an operator is up to date.

In operational terms, the AD’s timing rules create obligations that, if not met, would leave an aircraft non‑compliant with the airworthiness directive and consequently not meeting the AD’s airworthiness requirement. The AD’s language that an inspection must be done "before further flight" where not previously done (Compliance) is functionally an immediate grounding for any aircraft that has not complied and intends to fly without the inspection or approved replacement. The AD itself, however, stops short of listing enforcement steps or penalty amounts; those items are matters of broader regulatory enforcement policy and are not in the supplied text.

The AD explicitly cross‑references and aligns with other technical instruments rather than general statutes. Two cross‑references are central.

First, the AD refers to and aligns with FAA AD 74‑13‑03. The Requirement states "FAA AD 74‑13‑03 refers" and the Background recounts that the FAA AD specified inspection at intervals not to exceed three years or five hundred hours, and that Amendment 2 aligns the inspection interval with FAA AD 74‑13‑03 (Requirement; Background). This creates a direct technical interaction: CASA’s AD adopts inspection intervals consistent with the FAA AD for the same issue, and nominates the FAA AD as an underlying reference point.

Second, the AD nominates Piper Service Letter No. 667A as the authority for inspection procedures on steel alloy bolts. The Requirement instructs removal and inspection "in accordance with Piper SL No. 667A" and the Background notes that Piper SL No. 667A authorises the inspection regime for new steel alloy bolts (Requirement; Background). By doing so, the AD imports the procedural content of a manufacturer service letter into the regulatorily enforceable requirement.

There is also an internal interaction between amendments of the same AD: the Compliance section states that "Compliance with this AD at amendment 1 constitutes compliance with this amendment" (Compliance). That provides an explicit transition rule within the instrument’s amendment history and resolves possible conflict between older compliance actions and the current amendment.

The AD does not reference other Acts, regulations, or statutory provisions in the text provided. It likewise does not specify how compliance with the AD interacts with certificate‑of‑airworthiness revalidation, continuing airworthiness management obligations, or maintenance release sign‑offs; those interactions are not stated in the AD text supplied. Any such interactions would derive from broader aviation regulatory architecture and not from this AD’s text, which confines itself to technical and temporal obligations, cross‑referencing manufacturer and FAA documents as the operational standards.

The supplied text contains an explicit internal amendment history spanning from the original 1974 AD through Amendment 2 (2008). The chronology and the mechanical changes made at each stage are set out in the Background and Compliance clauses.

• January 1974 (original issue): The original AD specified replacement of stabilator attachment bolts within 100 hours after 31 January 1974, based on Piper Service Letter No. 667 (Background). That was a mandatory replacement remedy directed at an immediate mitigation of corrosion risk.

• March 1974 (Amendment 1): Amendment 1 altered the approach by specifying inspection at 3 monthly intervals as an alternative to replacement. The Background explains this change was driven by difficulties with supply of suitable corrosion‑resistant bolts (Background). Also in March 1974, Piper issued Service Letter No. 667A authorising, as an alternative to corrosion‑resistant bolts, new steel alloy bolts with repetitive inspections at intervals not to exceed 500 hours in service (Background). Thus Amendment 1 reflected a shift from mandatory replacement to an inspection‑based alternative and the supplier/technical response by the manufacturer.

• June 1974 (FAA action): The FAA issued AD 74‑13‑03 (amdt 39‑1872) specifying inspection at intervals not to exceed three years or five hundred hours, whichever occurred first, as an alternative to replacement. FAA AD 74‑13‑03 nominated Piper SL No. 667A as the inspection instruction (Background). This indicates a later alignment between the US regulator and manufacturer service instructions.

• October 2008 (Amendment 2): Amendment 2 (the subject of the supplied instrument) was raised to add the applicable serial number range for Piper PA‑24‑400 aircraft; to align the inspection interval with FAA AD 74‑13‑03; to identify the FAA AD on which AD/PA‑24/32 is now based; and to add Piper SL No. 667A as the instructions for inspecting steel alloy bolts (Background). The Compliance clause makes clear that Amendment 2 is effective on 23 October 2008 and contains the transitional clause that compliance with Amendment 1 constitutes compliance with Amendment 2 (Compliance).

The amendment history therefore shows a progression from an initial replacement mandate to inspection alternatives due to supply‑chain constraints, manufacturer guidance for inspection of specific alloy bolts, FAA alignment on inspection intervals, and finally an administrative expansion of applicability to include particular PA‑24‑400 serial numbers with a material caveat. The Background explicitly records these technical and administrative changes, making clear what was altered and why: serial number inclusion, interval alignment, identification of the FAA AD, and inclusion of Piper SL No. 667A as the accepted inspection instruction.

The supplied instrument does not contain any litigation history, references to court decisions, or records of judicial review concerning AD/PA‑24/32 or its amendments. The Background records administrative and regulatory steps (initial AD, Amendment 1, Piper service letters, and FAA AD 74‑13‑03) but does not mention legal challenges or court proceedings (Background).

Because the AD is an administrative regulatory instrument that references technical instructions and an FAA AD, the document’s textual record is limited to regulatory history and technical clarifications. There are no named cases, court judgments, or other judicial materials in the text provided that would indicate disputes, enforcement litigation, or precedent decisions arising from compliance or non‑compliance with this AD.

Where a reader needs litigation context, the absence of any litigation references in the AD means that any inquiry into enforcement actions, disputes over interpretation, or judicial review would require searching external judicial and regulatory enforcement records outside this instrument. The AD itself confines its record to administrative amendments, manufacturer service letters, and FAA cross‑references (Background; Requirement; Compliance) and does not document or assert any litigation outcomes.

The AD contains several drafting and practical details that commonly trip up operators or maintenance providers if they are not read closely. These are concrete points drawn from the exact wording.

• Applicability is model and serial‑number specific and material‑conditional. The PA‑24‑400 inclusion is conditional: only PA‑24‑400 aircraft with serial numbers 26‑2 to 26‑148 are included, and only "if the four stabilator attachment bolts are not made of corrosion‑resistant steel" (Applicability). An operator must therefore determine both serial number and the material of the existing bolts before deciding applicability.

• Two effective dates appear that require attention. The Amendment becomes effective on 23 October 2008 (Compliance), but the Compliance clause requires inspection "before further flight after 31 October 2008" for aircraft that have not previously been inspected under the enumerated instructions. Operators must reconcile those dates: the AD is effective 23 October 2008, but the cut‑off language for "before further flight" is 31 October 2008, creating a narrow transitional window for aircraft that have not yet been inspected (Compliance).

• The AD creates alternative compliance paths; failing to understand the alternative can be functionally costly. The operator can either commit to periodic inspections at intervals not exceeding three years or 500 hours, or replace the bolts with corrosion‑resistant AN bolts to avoid the inspection regime. Choosing the replacement route requires sourcing equivalent corrosion‑resistant AN bolts or the named part numbers (502329 and 502342) (Requirement, Note 1). The AD does not prescribe a mandatory choice, but the economic and operational trade‑offs between recurring inspections and one‑time replacement are operator decisions that have maintenance, parts‑supply and downtime consequences.

• The inspection must be done "in accordance with Piper SL No. 667A" for steel alloy bolts (Requirement). That means the technical details and acceptance criteria are within the service letter. Operators who do not possess or follow SL No. 667A will not have followed the AD’s mandated inspection procedure.

• The AD allows replacement "with unused parts of the same part numbers or equivalent" when corrosion is found (Requirement). The term "equivalent" requires a judgement about material and specification equivalence; the AD does not define the equivalence threshold beyond the alternative of "equivalent corrosion‑resistant AN bolts" being acceptable. Maintenance providers need to ensure that any "equivalent" part meets the technical requirements referenced by the AD and by Piper SL No. 667A.

• Historical supply issues are part of the record. The Background records supply difficulties with corrosion‑resistant bolts that led to inspection alternatives in 1974 (Background). That history is a reminder that parts supply may influence the chosen compliance path; the AD itself does not resolve current supply availability.

• Transitional clause: "Compliance with this AD at amendment 1 constitutes compliance with this amendment" (Compliance). Operators that complied under the earlier amendment should ensure their records demonstrate that they complied under the terms recognised by Amendment 1 so they can rely on that transitional clause if needed.

• The AD nominates FAA AD 74‑13‑03 and Piper SL No. 667A as standards. Operators must ensure they consult those documents where required because the AD imports their technical content by reference (Requirement; Background).

The AD sets out a compact, task‑oriented compliance roadmap. Follow these concrete steps based on the Requirement and Compliance text.

1. Establish applicability

   • Confirm the aeroplane model and serial number: PA‑24, PA‑24‑250, PA‑24‑260 serial numbers 24‑1 to 24‑5047 are included; PA‑24‑400 serial numbers 26‑2 to 26‑148 are included only if the four stabilator attachment bolts are not corrosion‑resistant steel (Applicability).
   • If your model and serial number fall within the ranges, determine the current bolt material: are the four stabilator attachment bolts corrosion‑resistant or not? The applicability hinge requires this material check.

2. Determine whether an initial inspection is required immediately

   • If the four stabilator bolts have not previously been inspected in accordance with this AD, Piper SL No. 667A, or FAA AD 74‑13‑03, arrange for removal and inspection "before further flight after 31 October 2008" (Compliance). Practically, this means no flight following the effective date unless the inspection has been completed.

3. If previously inspected, schedule recurring inspections

   • If the bolts have already been inspected under the enumerated authorities, set up a recurring inspection interval not exceeding three years or five hundred hours time in service, whichever occurs first (Compliance). Track both calendar and hours criteria, because compliance is triggered by the first of the two.

4. Perform the inspection procedure

   • Have an appropriately authorised maintenance organisation or engineer remove the four stabilator attachment bolts and inspect them for corrosion in accordance with Piper SL No. 667A (Requirement). That service letter contains the specific inspection steps and acceptance criteria that the AD requires be followed.

5. If corrosion is found

   • Before further flight, replace the bolt, nut and washer with unused parts of the same part numbers or equivalent (Requirement). Operators must ensure the replacement parts meet the appropriate specifications. Alternatively, the AD allows replacement of the bolts with equivalent corrosion‑resistant AN bolts (Requirement).

6. Consider the alternative compliance route

   • If you prefer to avoid recurring inspections, procure equivalent corrosion‑resistant AN bolts and replace the existing bolts with them. The AD identifies parts numbered 502329 and 502342 as corrosion‑resistant and acceptable options (Requirement, Note 1). Replacement with corrosion‑resistant AN bolts is an explicit alternative to the inspection cycle (Requirement).

7. Records and proof of compliance

   • While the AD text does not specify record‑keeping, compliance with the AD will typically require maintenance release documentation demonstrating that the inspection or replacement was performed in accordance with Piper SL No. 667A or that corrosion‑resistant bolts were fitted. Given the Compliance clause that prior compliance under Amendment 1 carries forward, maintain documentation that shows the inspection history and dates to evidence compliance intervals.

8. Transitional compliance recognition

   • If the aeroplane complied with Amendment 1, that compliance is recognised as compliance with Amendment 2 (Compliance). Ensure your records clearly reflect compliance under the earlier amendment if relying on that transitional clause.

9. Coordinate parts procurement

   • If choosing the replacement route, confirm availability of either the specific corrosion‑resistant part numbers (502329, 502342) or acceptable equivalent corrosion‑resistant AN bolts. The Background notices past supply difficulties; factor potential lead times into the compliance plan.

10. Rely on nominated technical documents

• Use Piper SL No. 667A for the inspection instructions for steel alloy bolts and consult FAA AD 74‑13‑03 where relevant, because the AD aligns its intervals with that FAA AD and nominates it as a point of reference (Requirement; Background).

These steps track the AD’s instrument text: determine applicability (Applicability), execute removal and inspection per Piper SL No. 667A (Requirement), replace corroded hardware before further flight or fit corrosion‑resistant bolts as an alternative (Requirement), and observe the prescribed intervals or transitional provisions (Compliance).