AD/G1159/35 Amdt 1 - Takeoff Warning System

The core regulatory concept in this instrument is the airworthiness directive as a mandatory, prescriptive maintenance and modification requirement for a discrete fleet subset. The AD links model/serial‑numbered applicability to model‑specific compliance tasks and specific technical service documents. The directive is structured around three main operational obligations.

First, model‑specific operational checks. The AD mandates that operators perform operational checks of the takeoff warning system, but the technical method is not specified within the directive itself. Instead, the directive delegates the technical detail to identified manufacturer service documents: Gulfstream CB Number 388 Amendment 1 for G‑II/G‑IIB, CB Number 106 for G‑III, and ASC Number 122 for G‑IV (Requirement 1a-c). This approach separates the regulatory command (do the check) from the technical procedural content (follow the manufacturer CB or ASC).

Second, fault remediation tied to the checks. Any takeoff warning system found to be non‑functioning during the operational checks must be repaired in accordance with the same CB/ASC documents (Requirement 2). The AD therefore creates a two‑step compliance sequence: check, then repair where necessary.

Third, a discrete modification requirement for certain G‑IV aeroplanes. Requirement 3 requires modification of the takeoff warning range indication system for applicable G‑IV aeroplanes if that modification has not already been accomplished. The AD prescribes ASC Number 122 as the modification method and sets a 25‑hour TIS deadline after the effective date for operators who have not already done the modification.

Other concepts embedded in the AD:

• Differentiated deadlines and intervals. The AD distinguishes between aircraft already subject to repetitive checks under the AD or FAA AD 90‑02‑05 and aircraft that were not. If repetitive checks are already in place, the operator must continue checks at intervals not exceeding 150 hours TIS. If not, an initial check must be performed within 25 hours TIS followed by checks at intervals not exceeding 150 hours TIS (Compliance).
• Cross‑jurisdictional AMOC recognition. The directive explicitly accepts later revisions of the manufacturer CB(s) or ASC where those revisions have FAA approval as Alternate Methods of Compliance to FAA AD 90‑02‑05 Amdt 39‑6472 (see the "Later revision(s) ..." paragraph). The AD therefore sets up a path for reliance on FAA‑approved updates to the technical documents.
• Applicability constrained by model and serial number. For G‑IV series aeroplanes the AD only applies to serial numbers 1000 through 1092 (Applicability). That narrows the universe of affected aircraft within the G‑IV family.

The background material explains the technical risk the AD addresses: operator reports involving discrepancies in the rudder actuator attachment area (elongated bolt holes, cracks and loose fasteners) and notes that the original directive focused on G‑II and G‑IIB aircraft while the amendment extends coverage to G‑III and some G‑IV aircraft and adds the G‑IV modification requirement (Background).

Taken together, the instrument operates as a targeted safety‑management intervention: it prescribes inspection cadence, immediate repair obligations for discovered faults, and a retrofit modification for a subgroup of aircraft, while deferring procedural detail to manufacturer technical documents and recognising FAA‑approved updates as compliant alternatives.

The AD names the affected aircraft explicitly and therefore its direct economic and operational targets are the registered operators and owners of those aircraft and the maintenance organisations that service them. The AD’s "Applicability" paragraph states it applies to:

• All Model G‑II (G‑1159) and G‑IIB (G‑1159B) series aeroplanes;
• All Model G‑III (G‑1159A) series aeroplanes; and
• G‑IV series aeroplanes serial numbers 1000 through 1092.

Operators of these aircraft are required to implement and finance the operational checks, any necessary repairs, and, for affected G‑IV serial numbers, the takeoff warning range indication system modification. The AD does not distinguish between private, corporate, or commercial operators; the applicability language is model‑ and serial‑number based and so covers all registered operators of those aircraft.

Maintenance organisations and certificated maintenance personnel who will carry out the operational checks, repairs and modifications are direct implementers. The AD prescribes technical work to be performed "in accordance with" specified Gulfstream service documents (Requirement 1-3). Those service documents will determine the labour, parts, tooling and potential downtime required. The AD also recognises later revisions of those manufacturer documents approved by the FAA as acceptable (AMOC), which will affect maintenance planning and parts procurement where operators opt to follow a revised CB/ASC.

Regulators and certificating authorities sit on the decision side. CASA issued the AD and its delegate executed it (signature by William David on 11 December 2009). The AD also references FAA AD 90‑02‑05 Amdt 39‑6472 and recognises FAA‑approved alternate methods of compliance, so international regulatory coordination is implicated and may affect operators with cross‑registry considerations.

Third parties with economic exposure include charter customers and lessors. Aircraft unavailable for service while checks, repairs or modifications are performed represent opportunity costs borne by operators and, where aircraft are on lease or charter, by lessees and charter customers through schedule disruption and potential replacement costs. Owners, insurers and financiers are indirectly affected because the AD imposes work which may incur parts cost, labour cost, and downtime.

Finally, the safety rationale identifies a specific technical area , the rudder actuator attachment area , where operator reports recorded elongated bolt holes, cracks and loose fasteners (Background). That indicates a fleet‑level maintenance and structural concern relevant to ongoing airworthiness monitoring by operators and their technical providers.

Duties imposed by the AD are specific and procedural. The primary duties are set out in the "Requirement" and "Compliance" text:

• Duty to perform operational checks of the takeoff warning system (Requirement 1). Operators must perform the applicable operational check depending on the model:

  • For G‑II and G‑IIB follow Gulfstream CB No. 388, Amendment 1, dated 15 August 1989;
  • For G‑III follow Gulfstream CB No. 106, dated 1 May 1989;
  • For G‑IV perform the operational check in accordance with Gulfstream ASC No. 122 dated 31 May 1989.

• Duty to repair non‑functioning systems found during the Requirement 1 operational check (Requirement 2). Repair work must follow the CB or ASC as applicable.

• Duty to modify the takeoff warning range indication system for applicable G‑IV aeroplanes if the modification has not already been accomplished, in accordance with ASC No. 122 (Requirement 3). The Compliance text requires this to occur within 25 hours TIS after the effective date unless the modification has already been completed.

Timing duties:

• Operators who are already carrying out repetitive checks under AD/G1159/35 or FAA AD 90‑02‑05 must continue those checks at intervals not to exceed 150 hours TIS (Compliance).
• Operators not already performing such repetitive checks must perform an initial check within 25 hours TIS after the effective date and then continue at intervals not to exceed 150 hours TIS (Compliance).
• Repair duties are sequenced to occur "after the Requirement 1 operational check" (Compliance).
• The G‑IV modification must be done within 25 hours TIS after the effective date if it has not been previously accomplished (Compliance).

Rights and discretion under the AD:

• The AD provides a narrow avenue for technical alternative compliance: later revisions of the specified CB(s) or ASC are acceptable if they have been approved by the FAA as an Alternate Method of Compliance to FAA AD 90‑02‑05 Amdt 39‑6472. Therefore operators may elect to comply using such FAA‑approved revisions rather than strictly the dated documents listed in the AD. The AD states this explicitly: "Later revision(s) of the above CB(s) or ASC approved by the United States Federal Aviation Administration (FAA) as an Alternate Method of Compliance (AMOC) to FAA AD 90‑02‑05 is/are considered acceptable for compliance with the equivalent Requirements of this Amendment."

• The AD does not on its face provide for other AMOC routes such as CASA approval of an alternative method. The only alternate method referenced in the text is FAA‑approved AMOC to the FAA AD. Any other alternative compliance pathway is not set out in the text of this AD.

Who decides:

• CASA issued the directive; it is signed by a CASA delegate (William David). The FAA is recognised as the approving authority for AMOC revisions to the specified manufacturer documents. For operators, the choice is whether to rely on existing checks under previous ADs, perform initial checks within the 25‑hour window, or proceed to the G‑IV modification within 25 hours. Maintenance providers decide the specific implementation steps but must follow the CB or ASC referenced.

Allocation of costs:

• The AD places direct compliance costs , time for operational checks, repairs, the G‑IV modification, parts and labour, and aircraft downtime , on the aircraft operator or owner. The AD itself does not contain compensation, subsidies or cost‑sharing provisions.

Sequencing and recordkeeping:

• The AD mandates sequencing (check then repair; modification if not already done) and sets intervals for the repetitive checks. The AD does not specify recordkeeping protocols in the supplied text, although normal regulatory practice will require maintenance records reflecting compliance; the AD text itself does not elaborate recordkeeping or certification entries.

The AD text provided does not set out monetary fines, criminal penalties, or explicit enforcement procedures within its body. The instrument is a directive from the Civil Aviation Safety Authority (signed by a CASA delegate on 11 December 2009) and therefore operates as a mandatory airworthiness directive within CASA’s regulatory framework. The AD sets compliance obligations and effective dates which, if not met, would place the operator in breach of the AD; the supplied text does not specify the remedial enforcement mechanisms or sanctions that CASA may deploy for non‑compliance.

Operationally, the AD’s enforcement mechanism is implicit in the nature of airworthiness directives. The AD prescribes specific actions with explicit timing: initial checks within 25 hours TIS for operators not already performing repetitive checks, repetitive checks no less frequently than every 150 hours TIS, repairs following an operational check (Requirement 2), and a G‑IV modification within 25 hours TIS for applicable aircraft (Requirement 3, Compliance). An operator that fails to perform these mandated operational checks, repairs or modifications is out of compliance with the AD’s text. The AD does not identify a process for disputing the directive, nor does it include an administrative appeal clause within the provided text.

The AD recognises alternate compliance through FAA‑approved revisions to the manufacturer’s CB(s) or ASC, stating that later revisions so approved are acceptable as Alternate Methods of Compliance (AMOC) to the FAA AD and therefore acceptable equivalents for this CASA amendment. That recognition functions procedurally as an allowed compliance route and reduces enforcement ambiguity where the FAA has approved a revised CB/ASC as an AMOC.

Because the AD itself does not specify sanctions, readers must be cautious: statutory enforcement powers and administrative sanctions would arise from the broader aviation regulatory framework under which CASA operates and from other statutory provisions or regulations not included in the supplied instrument. The AD text does not reproduce those enforcement provisions. The AD does, however, specify precise mandatory actions and deadlines which constitute clear operating obligations for affected aircraft and which, if unmet, would be a matter for CASA compliance enforcement under its general statutory authority rather than under terms set out in this AD.

The AD explicitly cross‑references and coordinates with prior regulatory action from the United States Federal Aviation Administration. It refers to FAA AD 90‑02‑05 Amdt 39‑6472 and states that later revisions of the Gulfstream CB(s) or ASC that are approved by the FAA as an Alternate Method of Compliance to FAA AD 90‑02‑05 are acceptable to satisfy the equivalent Requirements of this CASA amendment. That creates a direct interaction between this CASA AD and the FAA’s AD regime. The relevant sentence is: "Later revision(s) of the above CB(s) or ASC approved by the United States Federal Aviation Administration (FAA) as an Alternate Method of Compliance (AMOC) to FAA AD 90‑02‑05 is/are considered acceptable for compliance with the equivalent Requirements of this Amendment."

This cross‑recognition implies a deference to FAA‑approved AMOCs for the technical manufacturer documents listed in the AD. For operators that operate internationally or that are used to complying with FAA ADs, this provision allows FAA‑approved manufacturer updates to be used as an alternate compliance method without needing a separate CASA‑specific AMOC for the identical technical revision. The AD nevertheless remains a CASA instrument and its effective date and compliance timings are binding in the Australian jurisdiction.

The AD also references the original national instrument: it is an amendment to AD/G1159/35 and continues requirements that had been in place since the original issue, which became effective on 17 May 1990. The amendment extends the original directive’s applicability and adds the G‑IV modification requirement. That historical linkage indicates that the AD interacts with earlier CASA directives as part of a continuing regulatory sequence.

The AD does not articulate interactions with statutory maintenance obligations, certification rules, or operator licensing requirements in its text. It prescribes actions (checks, repairs, modification) which, in practice, will need to be performed in accordance with applicable maintenance regulations and performed by certificated maintenance organisations and personnel. The AD itself does not restate those broader maintenance or certification obligations.

There is no mention in the supplied text of interaction with commercial law, lease agreements, insurance terms, or air operator certificates. Such interactions will arise in practice because performance of the required work has cost and downtime implications, but the AD’s text is silent on contractual or insurance consequences. Operators will need to consider their contractual obligations and insurance coverage outside the AD to manage the practical effects of downtime and repair costs.

Finally, the AD’s narrow recognition of FAA‑approved AMOCs is an explicit inter‑jurisdictional interaction: the CASA instrument will accept FAA‑approved AMOCs for the specified manufacturer documents. CASA’s choice to accept FAA AMOCs for the specified documents reduces duplication for operators subject to both regulatory regimes but does not otherwise delegate CASA’s authority. The supplied AD text does not provide for other bilateral recognition mechanisms or the converse (that FAA would accept CASA approvals), and it does not authorise CASA to accept other foreign approvals beyond the FAA AMOC route described.

The supplied AD is titled AD/G1159/35 Amdt 1 and is an amendment to an original Directive. Key dates and textual history contained in the instrument are:

• The original issue of this Directive became effective on 17 May 1990, according to the Background paragraph. The original directive applied to G‑II and G‑IIB series aeroplanes and required initial and repetitive operational checks of the takeoff warning system.

• This instrument is Amendment 1 (AD/G1159/35 Amdt 1). The amendment was signed by a CASA delegate, William David, on 11 December 2009, and the instrument states that "This Amendment becomes effective on 22 December 2009."

• The amendment continues the repetitive operational checks mandated by the original AD and extends the applicability of the directive to include G‑III aeroplanes and certain G‑IV aeroplanes (G‑IV serial numbers 1000 through 1092). The Background text makes this explicit: "This amendment continues the repetitive operational checks and extends the applicability of the Directive to include G‑III aeroplanes and certain G‑IV aeroplanes; it also requires a modification of the takeoff warning range indication system for G‑IV aeroplanes."

• The amendment adds a specific modification requirement for G‑IV series aeroplanes: "For Model G‑IV series aeroplanes, if not previously accomplished, modify the takeoff warning range indication system in accordance Gulfstream ASC Number 122." That is set out under Requirement 3.

• The amendment updates and consolidates the model‑specific operational check references, continuing to rely on dated Gulfstream CB or ASC documents as the technical method for the checks and repairs. For G‑II and G‑IIB the AD identifies CB No. 388 Amendment 1 dated 15 August 1989; for G‑III CB No. 106 dated 1 May 1989; for G‑IV ASC No. 122 dated 31 May 1989 (Requirement 1a-c).

• The amendment also recognises that later revisions of those CB(s) or ASC, where approved by the FAA as an AMOC to FAA AD 90‑02‑05, are acceptable for compliance with the equivalent Requirements of this Amendment. That provides a limited forward‑looking flexibility for operators that adopt FAA‑approved revisions.

No other amendments or serial changes are recorded in the supplied text. The AD itself is labelled with calendar reference "25/2009" in its heading block and is identified repeatedly as AD/G1159/35 Amdt 1 in the header lines. The supplied text does not include a record of other amendment numbers, revocations, supersessions, or later amendments to AD/G1159/35 beyond Amendment 1.

The supplied instrument contains no litigation history. The AD references FAA AD 90‑02‑05 Amdt 39‑6472 and Gulfstream service documents; it does not mention any proceedings, judicial review, appeal, or litigation that arose from either the original directive or this amendment. The background recounts operator reports of structural discrepancies but does not state any contested regulatory challenges to the directive.

Because the AD text does not record any legal challenges, there is no case law, judicial decision, or tribunal finding contained within the instrument to cite. The absence of litigation history in the AD cannot be taken as proof that no litigation occurred after issuance, but within the boundaries of the supplied document there are no named cases, no references to decisions, and no procedural contestation recorded. Readers seeking litigation outcomes, judicial interpretations, or administrative appeals related to this AD would need to consult external judicial and administrative records, as the AD itself does not address that material.

The only inter‑regulatory reference of potential procedural significance is the AD’s treatment of FAA‑approved AMOCs to FAA AD 90‑02‑05. That recognition may have implications where operators rely on FAA approvals rather than a CASA‑specific AMOC, but such procedural points are a matter of regulatory coordination described in the AD and not adjudicative history contained in this instrument.

The text contains several precise implementation details and limitations that can create pitfalls for operators and maintenance planners if overlooked.

1. Narrow serial‑number applicability for G‑IV series. The AD applies to "G‑IV series aeroplanes serial numbers 1000 through 1092" (Applicability). G‑IV airframes outside that serial‑number range are not covered by this AD. Misidentifying an airframe’s serial number or assuming all G‑IVs are included would lead to unnecessary work or missed compliance. Operators must verify serial numbers carefully before applying the AD.

2. Different documents for different models. The operational checks are model‑specific and each model’s check points to a different Gulfstream service document:

   • G‑II and G‑IIB use Gulfstream CB No. 388 Amendment 1 dated 15 August 1989;
   • G‑III uses Gulfstream CB No. 106 dated 1 May 1989;
   • G‑IV uses Gulfstream ASC No. 122 dated 31 May 1989. Failure to use the correct CB/ASC for the specific model would breach the AD’s expressed requirements (Requirement 1a-c).

3. Timing traps. There are multiple timing rules:

   • If repetitive checks are already being done under AD/G1159/35 or FAA AD 90‑02‑05, continue them at intervals not exceeding 150 hours TIS.
   • If not already being done, perform an initial check within 25 hours TIS after the effective date and then at intervals not exceeding 150 hours TIS.
   • The G‑IV modification (Requirement 3) must be completed "within 25 hours TIS after the effective date of this Directive" if not previously accomplished. Operators who assume a grace period beyond 25 hours TIS or who assume that prior ad hoc checks satisfy these precise deadlines risk non‑compliance.

4. Repair sequencing. The AD specifies that repair of non‑functioning systems is to be performed "in accordance with the CB or ASC as applicable" and that Requirement 2 applies "After the Requirement 1 operational check." That sequencing means that operators must inspect first, then repair to the manufacturer procedure. Immediate temporary fixes outside the CB/ASC procedure may not satisfy the AD unless they are consistent with those documents or an FAA‑approved AMOC.

5. Limited AMOC route referenced. The AD accepts later revisions of the listed CB(s) or ASC only when those later revisions are approved by the FAA as an AMOC to FAA AD 90‑02‑05. That is a narrow alternate route; the AD text does not state that CASA will accept other alternate methods or approvals. Operators cannot assume broader CASA acceptance of other foreign approvals unless expressly provided elsewhere.

6. Background risk specifics. The AD’s background refers to discrepancies in the rudder actuator attachment area , elongated bolt holes, cracks and loose fasteners , but the AD itself orders checks of the takeoff warning system and a G‑IV range indication modification. Operators may mistakenly treat this as only a structural repair AD. The operative duties are about the takeoff warning system checks, repairs per CB/ASC and G‑IV range indication modification. Structural repair obligations may follow from what an operational check finds, but the AD prescribes the takeoff warning checks as the mandated action.

7. No penalty language in this text. The AD does not set out enforcement sanctions or processes. Operators may therefore misinterpret the absence of penalty language to mean the AD is advisory. It is not. The AD is mandatory; however, the instrument itself does not specify enforcement steps or penalty amounts. Operators should not treat absence of sanction language as absence of enforceability.

8. Document dates are specified. The AD lists dated CB/ASC documents. Using an updated CB/ASC is only acceptable if that later revision has FAA AMOC approval to the FAA AD. Using an unapproved update or an internal procedure that differs from the listed CB/ASC could render compliance defective.

9. Repair standardisation. The AD requires repairs "in accordance with the CB or ASC as applicable" (Requirement 2). That ties the substantive standard for repair to manufacturer procedure. Operators must ensure maintenance providers have access to and follow the referenced documents and that parts used are compliant with the CB/ASC instructions.

10. Effective date and signature. The amendment was signed on 11 December 2009 and becomes effective on 22 December 2009. Operators must map their TIS windows to that effective date for the 25‑hour deadlines. Miscalculating the calendar or TIS timeframe relative to the effective date is a practical pitfall.

Operators, maintainers and owners should catalogue these specifics in their compliance checklists, verify serial numbers, cross‑check CB/ASC versions against FAA AMOC status, schedule immediate initial checks where necessary, and plan for the G‑IV modification workload within the 25‑hour TIS window if it has not already been done.

The AD prescribes a discrete set of steps and timing obligations. Below is a practical compliance checklist mapped to the AD text headings, suitable for an operator or maintenance organisation to follow.

1. Confirm applicability (Applicability).

   • Identify the aeroplane model and serial number.
   • The AD applies to all Model G‑II (G‑1159), Model G‑III (G‑1159A), Model G‑IIB (G‑1159B) series aeroplanes and G‑IV series aeroplanes serial numbers 1000 through 1092.
   • If the aircraft is outside these model/serial ranges, this AD does not apply as written.

2. Determine prior compliance status (Compliance).

   • Establish whether repetitive operational checks have already been or are being accomplished under either the original AD/G1159/35 or FAA AD 90‑02‑05 (as that status determines the timing regime).
   • If repetitive checks are already in place per the earlier ADs, schedule to continue those checks at intervals not to exceed 150 hours TIS.
   • If repetitive checks are not in place, you must perform an initial operational check within 25 hours TIS after the effective date (22 December 2009) and then continue checks at intervals not to exceed 150 hours TIS.

3. Identify and obtain the appropriate manufacturer document (Requirement 1).

   • For Model G‑II and G‑IIB: obtain Gulfstream CB No. 388, Amendment 1 dated 15 August 1989.
   • For Model G‑III: obtain Gulfstream CB No. 106 dated 1 May 1989.
   • For Model G‑IV: obtain Gulfstream ASC No. 122 dated 31 May 1989.
   • Alternatively, determine whether a later revision of the CB(s) or ASC exists that has FAA approval as an AMOC to FAA AD 90‑02‑05; if so, that FAA‑approved revision is acceptable for compliance with the equivalent Requirements of this Amendment.

4. Perform the operational check in accordance with the applicable CB/ASC (Requirement 1).

   • Engage certificated maintenance personnel to perform the operational check exactly as set out in the applicable CB/ASC.
   • Record the check results and ensure maintenance records reflect the AD reference and the CB/ASC used.

5. Repair any non‑functioning takeoff warning systems discovered during the operational check (Requirement 2).

   • Repairs must be carried out in accordance with the applicable CB/ASC.
   • Complete repairs before returning the aircraft to service for operations where the takeoff warning system is a required safety item.
   • Ensure parts and procedures used match the CB/ASC instructions and are documented in maintenance records.

6. For applicable G‑IV aeroplanes, perform the takeoff warning range indication system modification if not previously accomplished (Requirement 3).

   • If the G‑IV serial number is within 1000 through 1092 and the modification has not been done, carry it out in accordance with Gulfstream ASC No. 122 within 25 hours TIS after the effective date (22 December 2009).
   • Record the modification in the maintenance log, referencing the AD and ASC No. 122.

7. Schedule repetitive checks at intervals not to exceed 150 hours TIS.

   • Wherever the AD requires repetitive checks (either continued from prior adherence or initiated under this Amendment), set maintenance planning, aircraft utilisation and line schedules to ensure checks occur no less frequently than every 150 hours TIS.
   • Log each check to demonstrate ongoing compliance.

8. Consider AMOC pathway where appropriate.

   • If a later revision of the CB(s) or ASC is available and is FAA‑approved as an AMOC to FAA AD 90‑02‑05, that later revision is acceptable for compliance with this AD. Obtain confirmation of the FAA AMOC approval and retain that approval documentation alongside maintenance records.
   • If you intend to use any other alternative method of compliance, the AD text does not specify another CASA AMOC route; operators should seek formal CASA guidance or approval outside the AD text if they wish to pursue a CASA‑approved alternative.

9. Coordinate downtime, parts and labour.

   • Plan for potential downtime required to perform both the check and any consequent repairs, and for the G‑IV modification where applicable.
   • Source any parts required per the CB/ASC and verify availability. Ensure maintenance providers are familiar with the specific CB/ASC instructions and any FAA‑approved revisions you intend to rely upon.

10. Maintain documentation.

• Keep complete maintenance records showing aircraft identification, date and TIS at which checks and modifications were performed, the CB/ASC revision used, the nature of any faults found and repairs made, and references to this AD (AD/G1159/35 Amdt 1).
• Retain any FAA AMOC approvals relied upon as evidence that a later revision of a CB/ASC is acceptable.

11. Monitor for subsequent directives.

• The AD is an amendment and the Background references an original AD. Monitor for later amendments or additional ADs that may alter compliance intervals, require additional modifications, or expand applicability.

Following these steps will align day‑to‑day maintenance activity with the prescriptive duties in the AD: performing the right model‑specific checks, repairing any faults to manufacturer procedure, completing the G‑IV modification where applicable, and keeping checks at or below the 150 hours TIS interval while meeting the 25‑hour TIS initial and modification windows where they apply.