AD/AC-112/17 - Aileron Hinges and Elevator Trim Tab Hinges

The Directive uses a small set of tightly defined concepts that determine applicability and obligations. Applicability is narrowly defined by aircraft type and serial number range: Model 112, serial numbers 3 through 120 (Applicability). The AD distinguishes two discrete hinge-halves types by manufacturing form and measured thickness: formed hinges described as “made by rolling the edge of a 0.040 inch thick flat sheet,” and extruded hinges described as “0.060 inch thick” (Requirement (a)). The operative compliance test is a visual/physical identification from the underside of the aircraft; the inspection must determine the hinge type in both ailerons and both elevator trim tabs (Requirement (a)). The Directive sets out a binary outcome rule: if all hinge halves at the inspected locations are of the extruded type, there is no further action required (Requirement (b)); if any formed hinge piece is found in any inspected location, the complete hinge must be replaced with an explicitly named part number before further flight (Requirement (c)). The AD also introduces a conditional operational permission that allows limited movement: an aircraft with formed hinges but with no visually evident cracking may be flown to a base where replacement can be performed (Requirement (c), final sentence). The AD anchors its technical basis to two external documents by reference: an FAA Airworthiness Directive (FAA AD 73-24-01 Amdt 39-1743) and Rockwell International Service Bulletin SB-112-6, original issue or later FAA-approved revision (Note). The temporal constraint is explicit: compliance must be achieved “before 30 September 2008,” unless previously accomplished; the AD is effective from 25 September 2008 (Compliance; effective date). Finally, the Background statement frames the safety objective for the regulator: the Directive is “issued to ensure compliance of future imported aircraft,” which signals the regulator’s forward-looking aim in relation to aircraft entering Australian registry or operation (Background). These concepts determine who must act, what physical feature is the compliance focus, what parts must be used for corrective work, what limited operational flexibility exists, and the temporal window for compliance.

The Directive targets owners and operators of Gulfstream (Rockwell) Model 112 aeroplanes whose serial numbers fall between 3 and 120 inclusive (Applicability). The wording and operative requirements make the owner/operator the practical duty-bearer for inspection and replacement because the AD mandates inspection and part replacement “before further flight” in specified circumstances (Requirement (a)-(c); Compliance). Maintenance organisations, licensed aircraft maintenance engineers and persons authorised to perform inspections and part replacements under applicable maintenance regulations will be operationally engaged because the work requires inspection from the underside of the aircraft and the removal and replacement of complete hinge assemblies with specified Rockwell Commander part numbers (Requirement (a), (c)). The supply chain for Rockwell Commander Part Nos 42251-1 and 44020-5 is directly implicated: the AD mandates those exact part numbers for replacement of aileron and elevator trim tab hinges respectively (Requirement (c)). Inspectors, ramp maintenance personnel and base maintenance facilities are affected by the ferry permission: where formed hinges are found but show no visible cracking, the aircraft may be flown to a base for replacement, so flight operations and maintenance planning are implicated (Requirement (c), final sentence). The Civil Aviation Safety Authority (CASA) is the issuing authority and the delegate who signed the AD is David Villiers; CASA’s aircraft safety oversight and enforcement apparatus will be the entity to register compliance or enforce the Directive (signature and date). The Background statement indicates a particular regulatory interest in “future imported aircraft,” so importers, brokers and registrars who handle the entry of Gulfstream Model 112 aircraft into Australian operation may face procedural or pre-entry obligations to ensure these inspections and replacements have been completed, or will be completed, to meet domestic compliance expectations (Background). The AD’s reference to FAA and Rockwell documents also affects technicians and engineers who will consult those documents for technical detail; the AD itself references those documents for further technical guidance (Note).

The AD imposes discrete duties and a limited operational permission. The primary duty is to inspect all hinge halves of both ailerons and both elevator trim tabs from the underside of the aircraft to identify whether each hinge half is the formed type (0.040 inch rolled sheet) or the extruded type (0.060 inch thick) (Requirement (a)). This inspection duty is mandatory for all aircraft within the applicability range unless the work has “already been accomplished” (Compliance). Where all hinge halves at the inspected locations are extruded, the AD creates an immediate legal right for the owner/operator not to undertake further work under this Directive, because “no further action is required” (Requirement (b)). Conversely, where any formed hinge piece is found, the owner/operator has the duty to replace that complete hinge with the specified Rockwell Commander part number for the relevant surface before the aircraft undertakes any further flight (Requirement (c)). The AD prescribes the exact replacement parts: Part No. 42251-1 for aileron hinges and Part No. 44020-5 for elevator trim tab hinges (Requirement (c)). The AD affords one limited operational right: if formed hinges are present but “no cracks are visually evident in any formed hinges,” the owner/operator may ferry the aircraft to a base where the replacement can be performed; this is a constrained permission tied to the absence of visible cracking (Requirement (c), final sentence). The instrument does not itself set out exemptions, alternative parts, or procedures for approval of deviation; nor does it describe inspection documentation or record-keeping obligations in the text provided. The AD refers operators to FAA AD 73-24-01 and Rockwell SB-112-6 for further technical detail, which implies the technical normative content may be found in those documents rather than being fully replicated in the AD (Note). The compliance timeline is mandatory: unless already accomplished, the duties must be satisfied before 30 September 2008, with the AD effective from 25 September 2008 (Compliance; effective date). The Directive is prescriptive and self-contained in terms of the immediate obligations it creates: inspect, identify hinge type, replace with specified parts where formed hinges are present, and comply within the stated time window unless already done.

The AD text itself does not set out specific penalties or enforcement mechanisms beyond the requirement language and the compliance timeline. The Directive is issued by the Civil Aviation Safety Authority and is signed by the delegate, indicating it is an enforceable regulatory instrument within CASA’s administrative framework (signature and date). The compliance clause obliges affected aircraft to comply “unless already accomplished, before 30 September 2008,” and the AD states it “becomes effective on 25 September 2008” (Compliance; effective date). Those temporal statements operate as the statutory compliance window. The AD’s prescriptive commands,inspect, identify, and replace with specified parts before further flight where formed hinges are present,establish mandatory safety actions to be completed within the timeframe; failure to comply after the effective date and within the compliance window would leave an aircraft operating contrary to the requirements of the Directive as issued. The AD’s Note refers operators to FAA AD 73-24-01 and Rockwell International Service Bulletin SB-112-6 for technical reference, which may be used by CASA or its inspectors to verify that work has been performed in accordance with the relevant technical standards (Note). The document does not itself describe the process by which CASA will audit compliance, issue notices to produce maintenance records, ground non-compliant aircraft, or impose civil or administrative sanctions. Similarly, the AD does not list criminal offences, monetary penalties, or infringement regimes within its text. The authority and enforceability of the AD derive from its issuance by CASA and the issuance process that produced an effective date and compliance requirement; the specific enforcement actions that CASA may take for non-compliance are not detailed in this text and would rely on the broader legal framework and CASA’s enforcement policies, which are not included in the source. The AD does, however, create incontrovertible operational constraints for affected aircraft: formed hinges must be replaced with specified parts before further flight, unless replaced or compliant before the compliance deadline.

The Directive expressly incorporates and cross-references two external documents: FAA AD 73-24-01 Amdt 39-1743 and Rockwell International Service Bulletin No. SB-112-6 (original issue, or later FAA approved revision) (Note). That reference means the AD does not operate in isolation; it delegates some technical normative content to those referenced materials. Operators are directed to consult those documents for further technical detail, and the AD’s compliance assessment can reasonably be informed by those references. The Background clause frames the AD as a measure “to ensure compliance of future imported aircraft,” which places the Directive in the regulatory space that concerns imported aircraft meeting domestic airworthiness expectations (Background). The AD does not itself quote or reproduce the FAA AD or Rockwell Service Bulletin; it simply points to them, so the legal effect is that CASA’s Directive requires compliance with the actions as expressed in this instrument, with technical cross-reference to those foreign or manufacturer documents. The AD does not specify how it interacts with operator manuals, maintenance regulations, airworthiness certificates, or continuing airworthiness obligations beyond the immediate inspection and replacement tasks. The document does not set transitional arrangements for previously certificated aircraft beyond the general phrase “unless already accomplished” in the Compliance clause, so compliance history is relevant: if the mandated inspection/replacement had already been completed prior to the Directive’s issuance, the AD’s requirements are considered satisfied. The AD’s requirement that replacement parts be specific Rockwell Commander part numbers creates a direct normative link to manufacturer-specified components; the AD does not provide for alternative or equivalent parts, or for acceptance of parts approved under other regulatory authorities, within the text. Any wider interaction with Australian maintenance regulations, import-entry protocols, or enforcement statutes is not described in this AD; practitioners must read the Directive as a targeted instrument that imposes a mandatory inspection and, in certain circumstances, replacement with defined parts, while relying on broader aviation law and CASA policies for enforcement and administrative detail.

The AD text provides a single dated instrument and does not record subsequent amendments, consolidations or revocations within the text supplied. The document is dated 11 August 2008 and indicates that the Airworthiness Directive becomes effective on 25 September 2008 and requires compliance “before 30 September 2008” unless already accomplished (Compliance; effective date). The only amendment-like language in the Directive is the Note that permits reliance on “Rockwell International Service Bulletin No. SB-112-6 original issue, or later FAA approved revision” (Note). That language explicitly contemplates later FAA-approved revisions of the cited Rockwell service bulletin as being acceptable reference points for technical detail. The AD also cites an FAA AD (FAA AD 73-24-01 Amdt 39-1743) by reference; the presence of that FAA AD in the Note could be read as an acknowledgment that the CASA AD aligns with or references existing foreign regulatory action, but the supplied text contains no record of an amendment to the CASA AD itself. There is no statement in the document indicating prior versions of this CASA AD or that the AD supersedes any earlier CASA instrument. The signature line shows the authorising delegate and date but does not list amending dates or a history of revisions. Practitioners should note that the AD allows for later FAA-approved revisions of the Rockwell Service Bulletin to be referenced; however, the AD does not itself include a mechanism for its own amendment, such as a schedule of future reviews or an explicit sunset beyond the one compliance deadline. The text as supplied should therefore be treated as a single regulatory action with a specified effective date and compliance deadline, and any later CASA amendments, revocations or re-issuances would need to be located in subsequent CASA instruments or notices, none of which are present in the supplied source.

The supplied document contains no reference to litigation, appeals, administrative review, or judicial proceedings challenging the Airworthiness Directive. The text is a statement of regulatory obligation and includes only administrative details: applicability, requirement, compliance deadline and effective date, note references, background, and the delegate’s signature and date. There is no mention of disputes notified to CASA, decisions subject to appeal, or judicial intervention. The AD does not include an administrative review route within its text, nor does it cite any case law or judicial decisions. Given the absence of litigation references in the source, there is no recorded litigation history available in this document to summarise. Practitioners seeking information on any subsequent legal challenges, appeals, or enforcement proceedings would need to consult external records, tribunal decisions or court files outside of this AD; none of those are contained in the supplied text. For the purposes of reliance on the AD itself, the absence of litigation material in the instrument means the document should be treated as an unqualified regulatory directive issued by CASA with an effective date and compliance timeframe; any litigation that may have arisen would not be recorded in this source.

Several specific features of the AD may be overlooked if the text is not read carefully. First, applicability is restricted both by model and by serial number: Model 112 aircraft, serial numbers 3 through 120. Aircraft outside that serial number range are not included in the AD as written (Applicability). Second, the inspection location and method are specified: inspections must be performed from the underside of the aircraft and must cover all hinge halves of both ailerons and both elevator trim tabs; an incomplete inspection that fails to look at all those locations would not satisfy the AD’s expressed requirements (Requirement (a)). Third, the AD distinguishes hinge halves by manufacturing form and thickness: the formed type is described as being made by rolling the edge of a 0.040 inch thick flat sheet, while the extruded type is 0.060 inch thick; correct identification requires attention to both morphology and material thickness as described in the Directive (Requirement (a)). Fourth, the AD prescribes exact replacement part numbers if any formed hinge is found: Rockwell Commander Part No. 42251-1 for aileron hinges and Part No. 44020-5 for elevator trim tab hinges; the AD does not state any allowance for alternative parts or equivalent replacements within its text (Requirement (c)). Fifth, the AD allows the aircraft to be flown to a base for replacement only where no cracks are visually evident in any formed hinge; formed hinges with visible cracks are not eligible for ferry flight under the terms of the AD and must be replaced before further flight (Requirement (c), final sentence). Sixth, compliance is time-limited: unless already accomplished, the required work must be done before 30 September 2008, and the AD becomes effective on 25 September 2008, which provides a narrow window between effective date and compliance deadline (Compliance; effective date). Seventh, technical detail and possibly installation procedures are cross-referenced to FAA AD 73-24-01 and Rockwell SB-112-6, but those documents are not reproduced; reliance on them requires obtaining and reading the referenced documents to obtain complete technical instructions (Note). Eighth, the AD does not itself set out record-keeping, approval for alternative methods of compliance, or explicit enforcement mechanisms in its text; operators should not assume those administrative processes are contained in this document (Compliance; no other clauses). Finally, the Background language indicates the Directive’s purpose in relation to imported aircraft; practitioners handling imports should be vigilant about pre-entry compliance and documentation for aircraft that may be imported into Australia (Background).

Follow the Directive’s sequence exactly and consult the referenced technical documents for further detail. Step 1 , Confirm applicability: verify the aircraft model is Gulfstream (Rockwell) Model 112 and the airframe serial number is within the range 3 through 120 inclusive. The AD applies only to aircraft meeting those criteria (Applicability). Step 2 , Perform the inspection: inspect all hinge halves of both ailerons and both elevator trim tabs from the underside of the aircraft to determine whether each hinge half is the formed type (made by rolling the edge of a 0.040 inch thick flat sheet) or the extruded type (0.060 inch thick). Ensure all specified locations are inspected; incomplete inspection would not satisfy the AD’s requirement (Requirement (a)). Step 3 , Compare inspection findings to the Directive’s outcome rules: if extruded hinge halves are found in all inspected locations, the AD requires no further action and compliance is achieved (Requirement (b)). Step 4 , If a formed hinge is found: replace the complete hinge (not just the hinge half) with the exact Rockwell Commander part number prescribed in the AD: Part No. 42251-1 for aileron hinges and Part No. 44020-5 for elevator trim tab hinges. Replacement must be carried out before any further flight of the aircraft (Requirement (c)). Step 5 , Ferry permission condition: if formed hinges are present but no cracks are visually evident in any formed hinge, the aircraft may be flown to a base where the replacement can be performed; confirm the absence of visible cracking before any such ferry flight (Requirement (c), final sentence). Step 6 , Time compliance: complete the above work and any applicable ferry flight within the compliance window: unless already accomplished, the requirements must be satisfied before 30 September 2008, and the AD is effective from 25 September 2008 (Compliance; effective date). Step 7 , Technical reference: obtain and consult FAA AD 73-24-01 Amdt 39-1743 and Rockwell International Service Bulletin No. SB-112-6 (original issue or later FAA-approved revision) for further technical guidance on inspection and replacement procedures as the AD explicitly directs operators to those documents (Note). Step 8 , Engage qualified personnel: ensure inspections and replacements are performed by appropriately authorised maintenance personnel or maintenance organisations capable of identifying hinge types, performing the required replacements to the manufacturer’s standards, and certifying that maintenance has been completed consistent with the AD’s requirements. Step 9 , Documentation and proof of compliance: while the AD text does not prescribe record-keeping steps, best practice to demonstrate compliance is to record the inspection results, the serials or identifiers of replaced parts, the part numbers used (42251-1 and 44020-5 where applicable), and the maintenance release or certification by the authorised maintenance provider. Step 10 , If in doubt, consult CASA: because the AD references external FAA and manufacturer materials and does not itself contain procedural administration for alternative compliance, operators with uncertainty about equivalent parts, repair methods, or ferry permissions should seek CASA guidance or an approved alternative method of compliance under CASA procedures; the AD text does not itself describe an approval pathway.