AD/PA-30/23 Amdt 3 - Stabilator Attachment Bolts - Inspection

The AD rests on a small set of operational and technical concepts that define applicability and compliance pathways.

• Applicability by serial number and bolt material. The AD expressly limits its coverage to specific serial-number ranges for the two models and only where the stabilator attachment bolts are not corrosion-resistant (Applicability). This means the first gate for compliance assessment is: confirm aircraft model and serial number fall within the stated ranges, then confirm whether the existing stabilator bolts are corrosion-resistant; the AD does not apply if the bolts are corrosion-resistant by manufacture or prior retrofit.

• Inspection versus replacement as alternative remedies. The AD establishes two alternative methods to address the corrosion issue. One is a repetitive inspection regime (remove the four bolts and inspect for corrosion at prescribed intervals). The other is replacement of the bolts with corrosion-resistant AN bolts, or replacement with unused parts of the same part numbers or equivalent if corrosion is found (Requirement; Compliance; Notes 1-2). The alternatives create a trade-off between recurring inspection cost and one-off retrofit cost.

• Prescriptive inspection instructions. The AD does not invent inspection technique; it delegates the structural inspection method to Piper Service Letters SL No. 667A for PA-30 and SL No. 772 for PA-39 (Requirement). The instrument thus embeds third-party procedural material as the operative inspection standard. Operators must work to the specifics of those service letters when performing the bolt removal and corrosion inspection.

• Time/usage-based compliance interval. The AD mandates inspections at whichever occurs first: three years or 500 hours time in service (Compliance). This dual trigger ties compliance both to calendar time and operational use, imposing obligations on both low-utilisation and high-utilisation aeroplanes.

• Identified acceptable parts. The AD identifies particular part numbers (502329 and 502342) as corrosion-resistant bolts (Requirement, Note 1). It also permits "equivalent" parts or corrosion-resistant AN bolts, but places an explicit option to use the identified parts, thereby narrowing the technically acceptable bolt types by example.

• Regulatory alignment and continuity. The AD states it aligns with FAA AD 74-13-03 (Background) and records that complying with Amendment 2 constituted compliance with this amendment (Compliance, Note 3). The AD therefore situates itself in reciprocal regulatory practice, adopting inspection intervals consistent with earlier FAA material and referencing the FAA AD as foundational.

These concepts create a compliance architecture where an operator must: determine applicability, follow Piper SL inspection steps if inspection regime is followed, measure time-in-service and calendar time to meet the interval requirement, and use specified or "equivalent" parts for any replacements. The AD’s structure embeds a substitution effect: operators can avoid recurrent inspections by fitting corrosion-resistant AN bolts, or they can accept recurring inspections where suitable corrosion-resistant parts are not available or not chosen.

The AD explicitly affects owners and operators of Piper PA-30 and PA-39 Twin Comanche aeroplanes that fall within the serial-number ranges specified and that currently have four stabilator attachment bolts which are not corrosion-resistant. The Applicability paragraph sets the universe: all model Piper PA-30 with serial numbers from 30-1 to 30-2000, and all model Piper PA-39 with serial numbers from 39-1 to 39-155, if the four stabilator attachment bolts are not made of corrosion-resistant steel (Applicability). The instrument therefore does not apply to aircraft outside those serial number ranges or to those within the ranges that already have corrosion-resistant bolts fitted.

Who pays. The text places removal, inspection and any required replacement responsibility on the aircraft concerned. The Requirement stipulates removal and inspection, and replacement "before further flight" where corrosion is found; that supplies and part acquisition costs, removal/installation labour, and any aircraft downtime are the practical burdens falling on the operator or owner. The AD mentions alternatives that affect cost distribution: replacing with corrosion-resistant AN bolts is an operator choice that replaces a recurrent inspection cost stream with a one-time parts-and-installation cost.

Who decides. The instrument is issued by the Civil Aviation Safety Authority (CASA), signed by a delegate (David Punshon). The AD references Piper Service Letters for inspection instructions and the FAA AD for interval alignment, so technical decisions about how to perform the inspection are determined by the Piper service letters (Requirement). The regulator decides applicability and mandatory obligations by issuing the AD; the operator decides which compliance path to adopt within the alternatives provided (inspection on schedule or replacement with corrosion-resistant bolts).

Who services the aeroplane. The AD requires removal and inspection of the stabilator attachment bolts "in accordance with" the relevant Piper service letters. Where maintenance and replacement actions require certification or maintenance release under regulatory maintenance regimes, the operator will need suitably authorised maintenance providers to perform these tasks, because the AD prescribes physical work (removal, inspection, replacement) on primary flight-control attachments. The AD itself does not list authorised maintenance providers, but by its nature the tasks are ones that an owner/operator must arrange with maintenance personnel capable of complying with the referenced service letters.

Other affected parties. Manufacturers and parts suppliers are implicated: the AD explicitly identifies two corrosion-resistant part numbers and allows equivalent parts or AN bolts as alternatives. Parts availability is central; the Background notes historic supply constraints with corrosion-resistant bolts, a factor that previously influenced the allowance of repetitive inspections instead of mandatory replacements. The AD therefore affects supply chains for the specified bolts and for equivalent corrosion-resistant AN bolts.

Duties

• Applicability check. The operator must first determine whether the AD applies: verify aircraft model and serial number against the stated ranges and verify whether the stabilator attachment bolts are corrosion-resistant (Applicability). If the bolts are corrosion-resistant, the AD’s inspection requirement does not apply per the applicability language.

• Removal and inspection. For affected aircraft, the AD requires removal of the four stabilator attachment bolts and inspection for corrosion in accordance with the designated Piper Service Letters: SL No. 667A for PA-30 and SL No. 772 for PA-39 (Requirement). The AD makes the service letters the operative means for how the inspection is to be carried out.

• Action on corrosion findings. If corrosion is found on any of the removed bolts, the AD requires that before further flight the bolt, nut and washer be replaced with unused parts of the same part numbers or equivalent, or by equivalent corrosion-resistant AN bolts (Requirement). That replacement is a pre-flight condition where corrosion is present.

• Recurrence of inspection. If the operator chooses the inspection route rather than replacement, the AD prescribes inspection intervals not exceeding three years or 500 hours time in service, whichever occurs first (Compliance).

• Alternative one-off retrofit. The AD offers an alternative: the bolts can be replaced by equivalent corrosion-resistant AN bolts (Requirement). Fitting such bolts is presented as an alternative compliance path and is effectively a right to remove the recurring inspection obligation by undertaking a one-off retrofit.

Rights and allowances

• Use of equivalent parts. The AD permits replacement with "unused parts of the same part numbers or equivalent" and allows "equivalent corrosion-resistant AN bolts" as alternatives to the specified part numbers (Requirement). The presence of the word "equivalent" gives operators a degree of technical flexibility, though equivalence will be operationally judged against applicable maintenance and airworthiness standards and the service-letter instructions.

• Identified acceptable part numbers. The AD names two part numbers (502329 and 502342) explicitly as corrosion-resistant bolts (Requirement, Note 1). That identification functions as a positive list of acceptable corrosion-resistant parts, simplifying conformity assessment for operators able to obtain those items.

• Continuity credit. The AD states that compliance with Amendment 2 constitutes compliance with this amendment (Compliance, Note 3). Operators who complied with the earlier amendment do not need to take additional action solely to meet Amendment 3, which protects prior compliance investments.

Operational constraints implicit in duties

• "Before further flight" language. Where corrosion is found, replacement of the affected parts is required before the aeroplane is flown again (Requirement). That imposes immediate grounding until the corrective action is completed.

• Time in service or calendar trigger. The inspection frequency is governed by whichever occurs first of three years or 500 hours time in service (Compliance). This imposes obligations both on high-utilisation aircraft (triggered by hours) and low-utilisation aircraft (triggered by calendar time).

Delegated technical instructions

• Use of Piper service letters. The AD delegates the technical content of the inspection procedure to Piper SL No. 667A and SL No. 772 (Requirement). The operator’s duty is to follow those documents when performing the removal and inspection.

The AD does not state rights or processes for seeking exemptions, nor does it set out appeals, penalties or enforcement steps in the instrument text provided. The AD does, however, provide for alternative compliance via the corrosion-resistant retrofit and records prior amendment compliance credit (Notes 1-3; Compliance).

The AD text as supplied does not include express penalty provisions, enforcement mechanisms or administrative sanctions within its body. It sets out mandatory requirements (inspection intervals, replacement before further flight if corrosion is found, alternative retrofit option), an effective date and the issuing authority (Delegate of the Civil Aviation Safety Authority, David Punshon). The instrument does not itself specify fines, licence suspensions, or other enforcement measures in the text provided.

Where the AD prescribes that replacement must occur "before further flight" if corrosion is found (Requirement), the practical effect is that an operator cannot lawfully or safely put the aeroplane back into service without carrying out the corrective action described. The AD designates Piper Service Letters as the inspection instructions, which means the inspector must follow those procedures. The AD also identifies that compliance with Amendment 2 constitutes compliance with this amendment (Compliance, Note 3), an administrative continuity point that affects enforcement of compliance across amendment versions.

Because the AD is issued by the Civil Aviation Safety Authority (as shown by the signature block), it operates as a regulatory instrument from the national aviation regulator. The AD records its effective date as 12 February 2009. The AD references the FAA AD 74-13-03 (Background) and aligns the inspection interval with that AD. The instrument does not, however, itself list the mechanisms by which CASA will detect non-compliance, the evidentiary standards to establish non-compliance, nor the specific civil or criminal penalties that would attach to non-compliance. These enforcement details may be set out elsewhere in broader regulatory frameworks governing civil aviation operations and operator obligations, but they are not present in the AD text provided.

Readers should note the textual distinction between mandatory requirements in the AD (inspection, replacement before further flight if corrosion is found, inspection frequency) and the absence of enforcement procedures or penalty schedules within the AD itself. The AD’s practical enforceability will therefore rest on its status within the regulator’s suite of enforceable instruments and the broader aviation regulatory regime, elements that are not described in the supplied text.

This AD explicitly cross-references and aligns with other regulatory and technical instruments. The AD identifies FAA AD 74-13-03 as a foundational document and states that Amendment 3 aligns the inspection interval with FAA AD 74-13-03 (Background). The AD notes FAA AD 74-13-03 was previously re-issued at amendment 39-2588 to extend applicability to include Piper PA-39 (Background). The AD therefore operates in technical and regulatory dialogue with an FAA airworthiness directive, adopting the FAA’s inspection interval as its own.

The AD also expressly incorporates manufacturer-issued technical material by reference. The Requirement directs that the removal and inspection be performed "in accordance with" Piper SL No. 667A for PA-30 aircraft and Piper SL No. 772 for PA-39 aircraft. Those service letters are invoked as the operative technical standards for how the removal and inspection are to be done (Requirement). The AD’s effect is to bind operators to follow those Piper service letters when complying with the inspection obligation.

Amendment continuity. The AD records that compliance with Amendment 2 constitutes compliance with this amendment (Compliance, Note 3). That expresses a legal continuity: operators who met the obligations of the prior amendment need not re-do procedures simply because of the new amendment. This kind of continuity avoids duplication of burden and clarifies that earlier-completed inspections count towards regulatory compliance under the updated AD.

Part-number and standard references. The AD names specific part numbers (502329 and 502342) as corrosion-resistant bolts (Requirement, Note 1) and allows the use of "equivalent corrosion-resistant AN bolts". By identifying part numbers and an industry-standard bolt class (AN bolts), the AD interacts with standards and supply chains for maintenance parts. Decisions by parts manufacturers and suppliers to supply those part numbers or approved equivalents will therefore affect operators’ ability to comply with the AD.

Absence of express references to broader law in the text. The AD itself does not mention other national statutes, regulations outside the AD, or broader maintenance licensing rules; it does not, in the supplied text, set out how compliance with the AD integrates into continuing airworthiness record-keeping, Maintenance Release processes, or operator approvals. Those interactions may be governed elsewhere in the regulatory framework overseen by the same regulator, but they are not detailed in the AD text provided. The AD’s cross-references are therefore limited to FAA AD 74-13-03 and the Piper Service Letters SL No. 667A and SL No. 772.

Historic interaction with supply conditions. The Background notes that Amendment 1 in March 1974 specified inspection at three-monthly intervals as an alternative to replacement, "due to difficulties with supply of suitable corrosion-resistant bolts." That historical note records a previous regulatory accommodation to supply constraints and shows that the AD’s current form is shaped by prior interactions between technical requirements and parts-market realities.

In short, the AD interacts with: (1) FAA AD 74-13-03 for interval alignment and applicability; (2) Piper Service Letters SL No. 667A and SL No. 772 for inspection procedure; and (3) parts specifications identified by part numbers or by reference to corrosion-resistant AN bolts. The AD does not itself state how it is to be integrated with other elements of national aviation regulation beyond those cross-references.

The AD includes a detailed background that records the evolution of the requirement across several amendments and associated service-letter developments. The timeline in the supplied text is as follows.

• Original AD , January 1974. The original issue of the AD in January 1974 applied to Piper PA-30 only. It specified replacement of stabilator attachment bolts within 100 hours after 31 January 1974 and was based on Piper SL No. 667 (Background). The original action was a direct replacement mandate.

• Amendment 1 , March 1974. Amendment 1 in March 1974 changed the compliance approach by specifying inspection at three-month intervals as an alternative to replacement. The change was prompted by "difficulties with supply of suitable corrosion-resistant bolts" (Background). Piper issued SL No. 667A in March 1974 to authorise, as an alternative to corrosion-resistant bolts, new steel alloy bolts with repetitive inspections at intervals not to exceed 500 hours in service (Background).

• FAA action , June 1974. In June 1974 the FAA issued AD 74-13-03 (amendment 39-1872) specifying inspection at intervals not to exceed three years or 500 hours, whichever occurs first, as an alternative to replacement. Amendment 39-1872 nominated Piper SL No. 667A (Background). This shows a concurrent change in the FAA’s approach to interval standardisation.

• Amendment 2 , January 1975. Amendment 2 in January 1975 extended applicability to include Piper PA-39, based on defects reported in Australia (Background). This broadened the AD’s reach to include the PA-39 model after new information on defects was received.

• Piper Service Letter for PA-39 , February 1976. In February 1976 Piper issued SL No. 772 applicable to Piper PA-39 (Background). This provided the manufacturer’s inspection instructions for the PA-39 model akin to SL No. 667A for PA-30.

• FAA re-issuance , April 1976. In April 1976 the FAA re-issued AD 74-13-03 at amendment 39-2588 to extend applicability to include Piper PA-39 (Background). This harmonised FAA guidance with the expanded applicability.

• Amendment 3 , 12 February 2009. Amendment 3 (the subject of the supplied AD) was raised to align the inspection interval with FAA AD 74-13-03; to define serial number applicability; to identify the FAA AD on which AD/PA-30/23 is now based; and to add Piper SL No. 667A and SL No. 772 as the instructions for inspecting steel alloy bolts. The AD became effective on 12 February 2009 (Background; Compliance).

Administrative note. The AD explicitly states that compliance with the AD at Amendment 2 constitutes compliance with Amendment 3 (Compliance, Note 3). This means operators who complied under the prior amendment are not required to perform additional actions purely to satisfy the Amendment 3 instrument.

The amendment history documents a regulatory evolution from an initial short-term replacement order to a longer-term inspection regime and the addition of a model and service-letter-specific instructions. Supply difficulties for corrosion-resistant bolts affected the regulatory choices made in the 1970s. Amendment 3 formalised serial-number applicability and aligned inspection intervals with the FAA’s AD, while incorporating manufacturer service letters as the inspection standard.

The supplied AD text contains no litigation history, case names, court decisions, judicial interpretations or references to litigation challenging the AD. The document lists administrative background, FAA AD cross-references, Piper Service Letters, and amendment history, but it does not record any disputes, appeals, judicial reviews or litigation outcomes.

Because the AD text makes no mention of litigation, there are no source-grounded judicial holdings or case law for the reader to consult within the document provided. Any assertion about subsequent litigation, enforcement proceedings, or administrative disputes would require materials or sources beyond the AD text that is supplied here.

In practice, airworthiness directives can be subject to correspondence, petitions for exemption, or other administrative processes, but none of those processes or any specific actions are mentioned in the AD as supplied. Therefore, within the bounds of the supplied source, the litigation history is silent.

This AD contains a number of technical and administrative traps for operators that are explicit in the text or follow directly from the instrument’s structure. These should be checked to avoid unintended non-compliance.

• Applicability conditional on bolt composition. The AD applies only "if the four stabilator attachment bolts are not made of corrosion-resistant steel" (Applicability). Operators must positively confirm the material/part number of the existing bolts before assuming the AD does not apply. A mistaken belief that the bolts are corrosion-resistant when they are not would leave the operator non-compliant with both the AD and the AD’s “before further flight” requirement in the event corrosion is discovered.

• Serial-number limits. The AD limits applicability to PA-30 serial numbers 30-1 to 30-2000 and PA-39 serial numbers 39-1 to 39-155 (Applicability). Operators must verify accurate serial-number records; erroneously determining that an aircraft falls outside these ranges can lead to incorrect compliance assumptions. The AD is framed to cover those ranges only.

• "Before further flight" immediate grounding risk. The AD requires replacement of bolt, nut and washer "before further flight" if corrosion is found (Requirement). A discovery of corrosion during a scheduled inspection therefore immediately grounds the aeroplane until replacement parts and maintenance resources are available. Operators should plan for potential downtime and parts availability contingencies.

• Dual trigger for inspection interval. The inspection interval is the shorter of three years or 500 hours time in service (Compliance). Operators who track only hours,or only calendar intervals,may unintentionally miss inspections. Record-keeping must account for both triggers.

• Supply-chain history is relevant. The Background explicitly notes earlier "difficulties with supply of suitable corrosion-resistant bolts" which previously influenced the choice of inspection over replacement (Background). That historical note signals that parts availability has been an issue in the past and may still be a practical consideration. Operators relying on replacement as a one-off solution should confirm availability of the specified corrosion-resistant parts or acceptable equivalents.

• "Unused parts of the same part numbers or equivalent". The AD requires replacement with unused parts of the same part numbers or equivalent when corrosion is found (Requirement). The requirement for "unused" parts suggests that reconditioned parts will not satisfy the replacement criterion; operators intending to re-use previously removed parts should verify that those parts are not acceptable unless re-supply of unused parts matching part numbers is possible.

• Equivalence assessments. The AD permits replacement with "equivalent" parts or "equivalent corrosion-resistant AN bolts" (Requirement). Determining equivalence is a technical judgment that may require reference to Piper SLs or maintenance authority guidance. Operators should not assume generic AN bolts are acceptable without confirming equivalence to the specified part numbers or service-letter guidance.

• Reliance on Piper Service Letters for procedure. The AD mandates inspection "in accordance with" Piper SL No. 667A and SL No. 772 (Requirement). Failure to follow the precise steps and acceptance criteria set out in those service letters could render an inspection non-compliant, even if an inspection was performed. Operators must obtain and apply the latest applicable service letters in performing the required work.

• Prior amendment compliance credit. The AD states that compliance with Amendment 2 constitutes compliance with this amendment (Compliance, Note 3). Operators should keep documentary proof of prior compliance under Amendment 2 to avoid redundant work or to demonstrate compliance history if questioned.

• Reference to FAA AD. The AD aligns intervals with FAA AD 74‑13‑03 and identifies the FAA AD as the basis (Background). Operators should be cautious: alignment does not mean identical wording or obligations in every respect, and the AD’s own text and referenced Piper SLs govern compliance for the aircraft covered under this specific AD.

• Parts specifically identified. The AD names parts 502329 and 502342 as corrosion-resistant bolts (Requirement, Note 1). Operators should ensure that replacement bolts are the exact parts or can be proven equivalent; purchasing the wrong part number will not meet the AD’s explicit positive list.

These "gotchas" are all textually supported by the AD and its Background. They translate into operational tasks for an operator: verify applicability carefully, confirm bolt composition/part numbers, plan for parts and maintenance availability, follow the Piper service-letter procedures exactly, and maintain documentary evidence of compliance and of any prior compliance that the AD credits.

The AD itself prescribes the compliance steps and alternatives. To translate those requirements into an actionable checklist, operators should proceed as follows, strictly following the AD text and the referenced Piper Service Letters:

1. Confirm applicability.

   • Verify aircraft model and serial number fall within the AD’s stated ranges: PA-30 serial numbers 30-1 to 30-2000; PA-39 serial numbers 39-1 to 39-155 (Applicability).
   • Determine whether the four stabilator attachment bolts are corrosion-resistant steel. The AD applies only "if the four stabilator attachment bolts are not made of corrosion-resistant steel" (Applicability). If the bolts are already corrosion-resistant, the AD’s inspection requirement does not apply.

2. Obtain the referenced technical instructions.

   • Secure Piper Service Letter SL No. 667A for PA-30 inspections and Piper Service Letter SL No. 772 for PA-39 inspections. The AD requires removal and inspection "in accordance with" these service letters (Requirement). Do not proceed based on a summary; use the full service-letter procedure.

3. Plan timing for inspection.

   • Schedule the inspection at an interval not exceeding three years or 500 hours time in service, whichever occurs first (Compliance). Track both calendar time and hours to ensure timely compliance.

4. Perform the removal and inspection.

   • Remove the four stabilator attachment bolts and inspect for corrosion following the steps and acceptance criteria set out in the applicable Piper Service Letter (Requirement). Ensure maintenance personnel performing the work are authorised and competent to execute the procedures described by Piper and to interpret accept/reject criteria for bolt condition.

5. If corrosion is found.

   • Replace the corroded bolt, nut and washer with unused parts of the same part numbers or equivalent, or replace the bolts with equivalent corrosion-resistant AN bolts, before further flight (Requirement). The AD identifies parts 502329 and 502342 as corrosion-resistant bolts (Requirement, Note 1), which provides a direct sourcing option where those parts are available.

6. Alternative compliance , retrofit option.

   • Where operators prefer to avoid recurring inspections, replace the four stabilator attachment bolts with equivalent corrosion-resistant AN bolts. Once corrosion-resistant AN bolts are fitted, the need for the repetitive inspection under this AD is obviated as the AD offers the replacement as an alternative compliance path (Requirement; Compliance). Confirm that the installed AN bolts meet the mechanical and airworthiness standards required to be considered "equivalent."

7. Record-keeping.

   • Maintain documentation of inspection, findings, any replacements performed, and part numbers used. The AD provides that prior compliance with Amendment 2 constitutes compliance with Amendment 3 (Compliance, Note 3); keep documentary proof of any earlier compliance so it can be presented if needed.

8. Contingency planning for parts and downtime.

   • Given the historical note about supply difficulties with suitable corrosion-resistant bolts and the grounding risk when corrosion is found (Background; Requirement), plan for lead times to obtain parts and for maintenance availability. If corrosion is found, replacement is required before further flight, which carries operational downtime.

9. Confirm that the work meets the AD.

   • Ensure that any replacement parts are unused and match the same part numbers or are demonstrably equivalent. Where "equivalent" parts are used, confirm technical equivalence in writing according to the accepted maintenance and airworthiness processes.

10. Note effective date and amendment continuity.

• The AD became effective on 12 February 2009 (Compliance). If the operator complied with the AD as required under Amendment 2 prior to this Amendment 3, that prior compliance constitutes compliance with this amendment (Compliance, Note 3); retain records accordingly.

This checklist follows directly from the AD’s Requirement, Compliance and Applicability paragraphs and the Background notes identifying parts and service-letter instructions. Operators should not deviate from the Piper Service Letter procedures in performing inspections. Where questions of part equivalence or maintenance authority interpretation arise, operators should consult their maintenance authority or regulator, but those consultative steps are ancillary to the AD’s core steps as set out above.