AD/AC-112/16 - Aileron Hinges and Elevator Trim Tab Hinges

The AD is organised around a small set of technical and administrative concepts; each is stated in concise terms in the source.

• Applicability: The AD applies only to "Model 112, with serial numbers 3 to 120 inclusive" (Applicability). That numerical serial-range delimitation is the primary determinant of coverage. No other models or serial numbers are mentioned.

• Inspection scope and vantage: The required inspection is of "all hinge halves of both ailerons and both elevator trim tabs" and must be conducted "from the underside of the aircraft" (Requirement). The AD therefore defines physical scope (specific control surfaces), component units (hinge halves), and inspection viewpoint (underside). The instruction to inspect "all hinge halves" indicates a complete check of the named surfaces, not a sample.

• Binary hinge classification rule: The AD sets an objective classification rule for hinge construction. Hinges are to be identified as either "formed type, made by rolling the edge of a 1.016 mm (0.040 inches) thick flat sheet," or "the extruded type, 1.524 mm (0.060 inches) thick" (Requirement). The presence of measurable thickness values ties the classification to a quantifiable attribute.

• Conditional corrective action: The required corrective step follows the inspection outcome. If the hinges are extruded in all locations, "no further action is required" (Requirement). If a formed hinge piece is found at any inspected location, the AD requires replacement of "that complete hinge" with a specified replacement part number appropriate to the control surface in question (Requirement). The AD therefore uses a localized trigger: detection at a specific hinge drives replacement of that hinge only.

• Specified parts and method: Replacement hinges are prescribed exactly: Rockwell Commander Part No. 42251-1 for aileron hinges and Rockwell Commander Part No. 44020-5 for elevator trim tab hinges (Requirement). The handling of the inspection and any replacement must be "in accordance with Rockwell International Service Bulletin (SB) No. SB-112-6" (Requirement). Thus the AD binds compliance to a manufacturer service bulletin and to named OEM part numbers.

• Compliance timing and legal form: The AD sets a fixed compliance window ("within 30 days from the effective date"), declares an effective date (28 August 2008), and is issued under CASA authority with a Delegate signature dated 18 July 2008 (Compliance; signature block). It also records that the AD came after a review that disclosed Australia had not previously issued an AD in response to an FAA AD (Background).

These concepts are the operational mechanics: who and what is covered, how to inspect, how to decide what to do, what parts to use, what method to follow, and the compliance deadline. The AD therefore functions as a short, technical compliance instrument converting manufacturer and FAA guidance into a time-limited Australian regulatory requirement for a defined fleet.

The AD affects owners and operators of Gulfstream (Rockwell) Model 112 aeroplanes having serial numbers 3 through 120 inclusive. The "Applicability" section explicitly limits coverage to that serial-number range; no other aircraft models or serial numbers are named (Applicability). The instruction to "inspect all hinge halves of both ailerons and both elevator trim tabs" (Requirement) makes the operational duty specific to persons with custody or control of the affected aircraft (that will ordinarily be the registered owner or operator).

Operationally, those responsible for maintenance decisions and execution,maintenance organisations, aircraft maintainers, or licensed engineers acting under the operator's authority,are the practical actors required to perform the inspection and any required replacements "in accordance with Rockwell International Service Bulletin ... SB-112-6" (Requirement). The AD does not itself name a person or class of persons who must perform the task, but by mandating an inspection and replacement within a fixed time period it places an obligation on the party responsible for the aircraft's continuing airworthiness to ensure the work is done.

Suppliers and manufacturers are affected in narrower ways. The AD prescribes specific replacement parts: Rockwell Commander Part No. 42251-1 and Part No. 44020-5 (Requirement). Entities that supply those Rockwell Commander parts, or that hold stock or can source them, become relevant to operators seeking to comply. The AD also ties work to "Rockwell International Service Bulletin ... SB-112-6" (Requirement), so the originator of that bulletin becomes the reference technical authority for how inspections and replacements should be carried out.

Regulatory actors are engaged too. The document is an Australian AD issued by CASA and signed by a delegate, David Villiers, on 18 July 2008 (signature block). CASA, as the issuing authority, is the entity that promulgates the rule and will be the administrative owner of compliance records and any enforcement action, although the AD itself does not set out enforcement steps or penalties.

Third parties such as lessors and insurers may be indirectly affected: an AD that requires inspection and replacement within 30 days and that prescribes OEM parts may have consequences for aircraft availability, maintenance scheduling, and statements in lease or insurance agreements. The AD text does not address these contractual arrangements; however, the AD applies to the aircraft irrespective of ownership or leasing arrangements, so any party with contractual responsibility for maintenance must ensure compliance (Applicability; Requirement; Compliance). Finally, the AD references FAA AD 73-24-01 Amdt 39-1743, indicating there is international regulatory linkage; any party accustomed to complying with FAA directives likely already has a record of that FAA AD, and the Australian AD brings that requirement into CASA's domestic regulatory landscape (Requirement; Background).

The AD prescribes a small set of duties to be carried out by the persons responsible for the affected aircraft; it does not enumerate rights such as appeals or extensions in the text provided.

Duties:

• Inspect all hinge halves of both ailerons and both elevator trim tabs from the underside of the aircraft. The AD clearly states this as the initial mandatory action and provides the inspection vantage: "from the underside of the aircraft" (Requirement). The duty is not framed as discretionary or advisory; it is phrased as a command to "carry out the following" in accordance with the manufacturer service bulletin.

• Make a classification determination based on construction and thickness. The inspecting person must identify hinges as either "formed type, made by rolling the edge of a 1.016 mm (0.040 inches) thick flat sheet," or "extruded type, 1.524 mm (0.060 inches) thick" (Requirement). This creates an objective test the inspector must apply.

• Take corrective action where required. The AD mandates replacement when the formed type is present: "If a formed hinge piece is found, that complete hinge must be replaced with Rockwell Commander Part No. 42251-1 for the aileron hinges or Rockwell Commander Part No. 44020-5 for the elevator trim tab hinges" (Requirement). The unit of replacement is "that complete hinge," which indicates the replacement is targeted to the specific hinge found to be formed.

• Follow the manufacturer service bulletin. The AD requires that the inspection and any subsequent replacement be done "in accordance with Rockwell International Service Bulletin (SB) No. SB-112-6" (Requirement). This imports the content and procedural detail of that SB into the compulsory method of compliance.

• Comply within the mandated time window. The compliance section requires completion "within 30 days from the effective date of this AD" (Compliance). The AD's effective date is stated as 28 August 2008 (Compliance), so the duty is time-bound and must be satisfied within that short timeframe.

Rights and procedural absence:

• The AD text provided does not specify express procedural rights such as the right to apply for an extension, to seek an alternative means of compliance, or to appeal the directive. It likewise does not specify any administrative review mechanism within the AD itself. The AD does, however, reference the Rockwell service bulletin as the compliance method, which indicates an accepted, specified method exists for the actions required (Requirement). The absence of explicit procedural rights in the AD text means that any such options would need to be sought through CASA's general administrative procedures or existing regulatory mechanisms, which are not included in the text provided.

• The AD does not specify who pays for inspections or replacement parts; it does not set out reimbursement, indemnity, or cost-sharing rules. Practically, operators or owners who must ensure continuing airworthiness will bear direct costs for inspection labour, parts (the specified Rockwell Commander parts), and installation if replacement is required. The AD itself is silent on financial arrangements (Applicability; Requirement; Compliance).

• The AD does not specify enforcement procedures or penalties in the text provided. The document identifies CASA as the issuer and includes the delegate's signature, but it does not detail sanctions for non-compliance or how CASA proposes to verify compliance (signature block; Compliance).

In sum, the AD creates clear operational duties: inspect defined hinge components from a defined vantage, classify by construction and thickness, and replace any identified formed hinge with specified OEM parts, all within 30 days of the effective date and in accordance with the Rockwell SB. The AD does not articulate rights, appeals, or penalties within its text.

The AD text supplied does not contain explicit penalty provisions or a detailed enforcement mechanism. The instrument identifies itself as an Australian Airworthiness Directive (AD/AC-112/16) issued by the Civil Aviation Safety Authority and signed by its delegate (David Villiers), which establishes the issuing authority and the directive's regulatory character (signature block). It sets an effective date (28 August 2008) and a compliance timeframe ("within 30 days from the effective date of this AD") (Compliance). Beyond those elements, the AD document as provided does not set out sanctions, civil penalties, administrative processes, or criminal liability for non-compliance.

Because the AD does not specify enforcement text, practitioners should note the following from what the document does state and omit:

• The directive is a compulsory instrument from CASA and therefore operates within CASA's statutory remit to ensure airworthiness and aviation safety in Australia. The presence of an AD normally means that continued operation of an aircraft without complying with the directive would be inconsistent with maintaining an aircraft in an airworthy condition. The AD text, however, does not itself say what administrative steps CASA will take if compliance is not achieved within the stated period.

• The AD requires actions "in accordance with Rockwell International Service Bulletin (SB) No. SB-112-6" and prescribes specific replacement part numbers (Requirement). In practice, compliance records, maintenance logs, and approved release documentation are the sorts of materials CASA would expect to see, but the AD does not enumerate documentary evidence requirements or inspection/verification processes.

• There is no express statement in the AD about grounding, grounding notices, or prohibition of flight of non-compliant aircraft. The AD also does not identify a compliance reporting requirement back to CASA, nor does it point to a process for obtaining an alternative method of compliance. These omissions mean that the AD's enforcement mechanics are not self-contained in the text supplied.

• The AD refers to an FAA AD (FAA AD 73-24-01 Amdt 39-1743) and to a manufacturer service bulletin (SB-112-6), but it does not set out any cross-border enforcement arrangements or reciprocal enforcement language; it simply records those references (Requirement; Background).

Given those textual facts, the AD creates a regulatory obligation without specifying penalties in the text provided. Practitioners responsible for affected aircraft should therefore assume that CASA may rely on its general regulatory powers and inspection processes to enforce compliance, and should consult CASA guidance, aeronautical notices, or CASA administrative procedures for the specifics of enforcement, reporting, or requests for alternative compliance. Those administrative and enforcement procedures are not part of the AD text as presented.

The AD explicitly references external instruments and implicitly interfaces with the general regulatory framework for continuing airworthiness, but the text provided contains limited detail on statutory cross-interactions.

Direct references in the AD:

• Rockwell International Service Bulletin No. SB-112-6: The AD requires that the inspection and any required replacement be carried out "in accordance with Rockwell International Service Bulletin (SB) No. SB-112-6" (Requirement). This makes the manufacturer's service bulletin the mandatory method of compliance for fulfilling the AD's technical duties. The AD therefore constitutes a legal overlay on the manufacturer's guidance, converting that SB from advisory manufacturer material into a compulsory regulatory method.

• FAA Airworthiness Directive: The AD specifically notes "FAA AD 73-24-01 Amdt 39-1743 refers" (Requirement). The background explains that the Australian AD follows a review which indicated Australia had not issued an AD in response to that FAA AD (Background). This shows the AD interoperates with international regulatory practice: CASA is addressing an FAA-prescribed safety issue in its domestic regulatory context. The text, however, does not reproduce the FAA AD's full content, nor does it state whether the Australian AD is identical in content, broader, or narrower in scope,the AD simply records the FAA AD as a reference.

Interaction with CASA's regulatory powers and continuing airworthiness obligations:

• While the AD does not recite the statutory sections of the Civil Aviation Act or associated instruments, an Australian AD is a regulatory instrument utilised by CASA to ensure aircraft meet continuing airworthiness requirements. The AD functions as a mandatory maintenance directive that must be implemented by those responsible for aircraft continuing airworthiness. The AD text itself does not set out which statutory provisions it is made under, nor does it disclose enforcement or administrative appeal routes; these would be set out in CASA's governing legislation and administrative processes, which are not reproduced in this AD text.

Effects on contractual arrangements and private-law obligations:

• The AD will interact with existing contracts governing maintenance, leases, and insurance. The AD prescribes actions and parts, so maintenance providers and parts suppliers named in contracts may have duties or liabilities in practice to fulfil the AD. The AD itself does not address contractual allocation of costs or responsibilities; it simply imposes the requirement on the operator/owner of the affected aircraft by applicability and duty language.

Manufacturers and OEM parts:

• By specifying Rockwell Commander Part No. 42251-1 and Part No. 44020-5 for replacements, the AD creates a direct reliance on OEM parts for compliance (Requirement). That specification makes the manufacturer's part numbers and associated supply chain part of the compliance universe. The AD's instruction to follow SB-112-6 likewise ties the method of compliance to manufacturer-authored technical material.

International regulatory reciprocity:

• The AD's explicit reference to the FAA AD links Australian action to an identified U.S. AD. The AD does not, however, describe whether CASA will recognise compliance with the FAA AD or other foreign authority as satisfying the Australian AD; the text simply indicates the FAA AD "refers" and that Australia had earlier not issued a corresponding AD (Background). The practical effect is that CASA has now issued its own directive; operators must meet the Australian AD's requirements within the Australian timeframe and in the Australian format set by this directive.

In short, the AD binds manufacturers' service material and specified OEM parts into CASA's domestic regulatory framework for the named aircraft, and it references an FAA AD as the foreign counterpart that prompted action. The AD text does not detail statutory cross-references, enforcement powers, or administrative remedies; those are left to the broader regulatory framework outside the AD text.

The AD text provided contains only a single issuance record and a brief background explaining why it was issued. There is no multi-stage amendment trail in the supplied document.

What the document records:

• Identification and dating: The AD is designated "AD/AC-112/16" and dated "9/2008" in the header (title block). The compliance statement records that "This Airworthiness Directive becomes effective on 28 August 2008" and the signature block is dated "18 July 2008" with the signature of David Villiers, Delegate of the Civil Aviation Safety Authority (Compliance; signature block). The table at the top also lists the AD number, subject ("Aileron Hinges and Elevator Trim Tab Hinges"), and date "9/2008" consistent with the header.

• Background remark on prior non-issuance: The AD includes a one-paragraph "Background" note stating that the AD "follows a review of Australian Airworthiness Directives (AD) which indicated that, for reasons unknown, an Australian AD was not issued in response to FAA AD 73-24-01 Amdt 39-1743." This explains the immediate administrative trigger for the AD but does not indicate earlier versions or amendments of the Australian AD itself; rather, it explains Australia had previously not issued an AD in respect of that FAA AD (Background).

• Cross-reference to FAA AD: The Requirement text expressly notes "FAA AD 73-24-01 Amdt 39-1743 refers." That is a cross-reference to a U.S. issuance that appears to pre-date the Australian AD and that functioned as the reason for the Australian AD's issuance. The AD text does not reproduce the FAA AD or state whether the contents are identical.

What is absent:

• The supplied document does not list previous versions, superseded AD numbers, amendment dates, or corrigenda for AD/AC-112/16 itself. There is no text indicating that this AD amends an earlier Australian AD, or that it will be superseded by a further AD. The AD appears to be a single, standalone issuance.

• The AD does not record a later amendment history, re-issuances, or revocations. If such events occurred after the effective date, they are not included in the supplied text.

For historical accounting, the AD therefore records a single issuance. It sets an effective date of 28 August 2008, carries the date 9/2008 in the header, and is signed 18 July 2008 by a CASA delegate. The "Background" provides a reason for issuance,Australia's earlier omission to adopt an FAA AD,but no sequential amendment history is shown in the text provided.

The supplied AD text contains no information about litigation, court challenges, or administrative appeals relevant to AD/AC-112/16. The document records the directive, its technical content, applicability, compliance window, effective date, and a brief background, but it does not reference any court proceedings, disputes, legal challenges, or precedent.

Because the text is silent on litigation, two points follow directly from the AD's content:

• There is no litigation history recorded in the AD itself. The AD does not report any previous or ongoing court cases or formal legal challenges to its content or to the subject matter addressed.

• The AD does not specify administrative appeal mechanisms or dispute resolution steps within its text. Any legal or administrative recourse available to an operator disputing the AD's requirements would therefore be found in CASA's broader regulatory procedures or in the general administrative law fora in Australia, none of which are discussed in the AD as provided.

Practitioners requiring information about any subsequent litigation or challenges to this AD should seek authoritative external records,court databases, CASA administrative records, or official amendment notices,because the AD text does not provide that material. Within the AD itself, there is no litigation history to report.

The AD contains several precise technical, timing, and procedural points that can catch practitioners who do not read the instrument carefully. These are literal takeaways from the AD text and therefore require no external assumption.

• Narrow applicability by serial number: The AD applies only to "Model 112, with serial numbers 3 to 120 inclusive" (Applicability). Aircraft outside that serial-number range are not covered. Failure to check the aircraft serial number could result in unnecessary work or missing coverage for an affected aircraft. The term "inclusive" means both end numbers are included in the applicability range.

• Inspection vantage and scope are specific: The AD requires inspectors to "inspect all hinge halves of both ailerons and both elevator trim tabs from the underside of the aircraft" (Requirement). Inspecting from the wrong vantage or omitting any hinge halves is inconsistent with the AD's precise direction. The AD mandates inspection of all hinge halves of the specified surfaces, not a sample inspection.

• Measurable thickness thresholds: The AD gives explicit thickness values and construction descriptions connecting to the classification test: "formed type, made by rolling the edge of a 1.016 mm (0.040 inches) thick flat sheet" versus "extruded type, 1.524 mm (0.060 inches) thick" (Requirement). The use of both metric and imperial dimensions is explicit; inspectors should use measuring methods that correspond reliably to those values. Mis-reading the dimensional thresholds or applying the wrong measurement tolerance could lead to misclassification.

• Localised trigger and unit of replacement: The AD says "If a formed hinge piece is found, that complete hinge must be replaced" (Requirement). The unit of replacement is "that complete hinge" and the trigger is the detection of any formed hinge piece at an inspected location. Practitioners must note that replacement is not required across the whole aircraft when formed hinges are absent in all locations, but neither is it limited to swapping an individual half,"that complete hinge" suggests replacement of the hinge assembly at the affected location.

• OEM part-number specificity: The AD prescribes exact OEM parts: Rockwell Commander Part No. 42251-1 (ailerons) and Part No. 44020-5 (elevator trim tabs) for replacements (Requirement). Using non-specified parts or substitution without authorisation would not follow the AD's text, which requires replacement with the specified Rockwell Commander part numbers and adherence to the Rockwell service bulletin.

• Method of compliance mandated: The AD requires work "in accordance with Rockwell International Service Bulletin (SB) No. SB-112-6" (Requirement). That means the SB is the prescribed method and should be consulted. Failing to follow the SB's method may leave the AD incompletely complied with.

• Short compliance window: The AD requires compliance "within 30 days from the effective date of this AD" (Compliance). The effective date is 28 August 2008, so the work had to be completed within a tight, one-month window. Practically, this can create scheduling pressure for maintenance providers, parts procurement, and aircraft availability.

• Background context that may affect interpretation: The AD notes it was issued because "for reasons unknown, an Australian AD was not issued in response to FAA AD 73-24-01 Amdt 39-1743" (Background). That background explains the AD's existence but does not provide technical context such as service life, prior incidents, or risk quantification. There is no explicit statement in the AD about the consequences of non-compliance on the aircraft's legal airworthiness status; operators must treat the AD as a compulsory maintenance directive despite the absence of detailed legal consequences in the text.

• No enforcement detail or appeal process included: The AD does not articulate penalties, reporting requirements, or an alternative means of compliance in the text provided (Penalties and enforcement). Practitioners should not assume such mechanisms are absent from CASA's wider regulatory framework; however, they are not described here and so should be separately checked with CASA if needed.

• Potential supply-chain implication implicit in parts specification: The requirement to use specific Rockwell Commander part numbers binds compliance to those OEM parts (Requirement). Operators should ensure they can source the specified part numbers and that replacement following SB-112-6 does not require alternative approvals. The AD does not address part availability or substitutability.

These "gotchas" are procedural, technical, and timing traps that follow directly from reading the AD. They reflect the AD's precise technical language and mandatory structure; compliance requires attention to the serial-number applicability, inspection method and viewpoint, measurable criteria, OEM part numbers, adherence to the Rockwell SB, and the short 30-day compliance period.

The AD sets out a compact set of steps and a strict timeframe. The following is a faithful, step-by-step reading of the AD's compliance route, drawing only on the AD text.

1. Confirm applicability:

   • Verify the aircraft model and serial number. The AD applies only to "Model 112, with serial numbers 3 to 120 inclusive" (Applicability). If the aircraft's serial number falls outside this range, the AD does not apply.

2. Read the prescribed method:

   • Obtain and review Rockwell International Service Bulletin SB-112-6. The AD requires that inspection and any replacement be performed "in accordance with Rockwell International Service Bulletin (SB) No. SB-112-6" (Requirement). The SB is therefore the mandated technical procedure for carrying out the AD.

3. Perform the mandated inspection within the compliance window:

   • The AD requires action "within 30 days from the effective date of this AD" (Compliance). The AD becomes effective on 28 August 2008 (Compliance), so the inspection and any required replacement must be completed within the 30-day window starting on that effective date.
   • Inspect from the underside of the aircraft "all hinge halves of both ailerons and both elevator trim tabs" (Requirement). Ensure the inspection covers every hinge half on the specified surfaces, using the vantage of the underside as required by the AD.

4. Classify hinge halves according to the AD's objective test:

   • For each hinge half inspected, determine whether it is the formed type or the extruded type by applying the AD's definitions: the formed type is "made by rolling the edge of a 1.016 mm (0.040 inches) thick flat sheet," the extruded type is "1.524 mm (0.060 inches) thick" (Requirement). Use appropriate measuring tools and techniques capable of distinguishing those constructions and thicknesses in a maintenance environment. Record findings in maintenance logs or the aircraft's continuing airworthiness records.

5. Decide on corrective action according to inspection results:

   • If all hinge halves inspected on the both ailerons and both elevator trim tabs are the extruded type, "no further action is required" under the AD (Requirement). Document the inspection and its result in the required maintenance records.
   • If a formed hinge piece is found at any location, the AD mandates that "that complete hinge must be replaced with Rockwell Commander Part No. 42251-1 for the aileron hinges or Rockwell Commander Part No. 44020-5 for the elevator trim tab hinges" (Requirement). Replace the entire hinge assembly at the affected location with the specified Rockwell Commander part number, following the procedures and any installation instructions in SB-112-6.

6. Use the specified parts and maintain records:

   • The AD prescribes exact replacement part numbers (42251-1 and 44020-5). Use those parts for replacement unless an authorised alternative has been obtained through appropriate CASA-sanctioned means,which are not described in the AD itself (Requirement). Maintain traceability for parts installed (part numbers, batch/serial where applicable), and document the work in accordance with normal continuing airworthiness record-keeping practices.

7. Complete within the AD's timeframe and retain evidence:

   • Finish the inspection and any required replacements within 30 days from the effective date of the AD (Compliance). Retain maintenance documentation showing the inspection results, parts installed (if any), and confirmation of compliance with SB-112-6. The AD text does not specify a reporting route, but maintenance records will be the primary evidentiary basis for demonstrating compliance to CASA.

8. Consider related obligations:

   • The AD records that it follows an FAA AD (FAA AD 73-24-01 Amdt 39-1743). Operators who already complied with the FAA AD and maintained records of that compliance should cross-check their documentation against the Australian AD requirements (Requirement; Background). If the FAA compliance steps match the Rockwell SB and the Australian AD's thresholds, that documentation may assist in demonstrating compliance under the Australian AD, but the AD requires the Australian steps be followed and puts SB-112-6 as the method of compliance.

9. If uncertainty arises, consult CASA or authorised maintenance organisations:

   • The AD does not specify appeal, extension, or alternative compliance routes in the text provided. Where operators require clarification on procedural or evidentiary matters (for example, substitute parts or alternative inspection methods), they should consult CASA or make use of any formal mechanisms CASA provides outside the AD text to request an alternative method of compliance. The AD itself mandates the method and parts; any deviation would need appropriate CASA authorisation.

Summary checklist:

• Verify serial number falls within 3-120 inclusive.
• Obtain and follow Rockwell SB-112-6.
• Inspect all hinge halves of both ailerons and both elevator trim tabs from underside.
• Classify each hinge by construction/thickness threshold given.
• If all hinges are extruded type, document inspection and no further action.
• If any formed hinge is found, replace that complete hinge with the specified Rockwell Commander part number, following SB-112-6.
• Complete all actions within 30 days of the effective date (effective date 28 August 2008), and retain maintenance records proving compliance.

This sequence adheres strictly to the AD's own language: the inspection requirement and vantage, the classification rule with numeric thicknesses, the conditional replacement with specified part numbers, the mandate to follow the Rockwell service bulletin, and the fixed 30-day compliance period.