AD/RAD/82 - Prevent GPS Navigation unit from Providing Erroneous Cross-Deviation

Scope and applicability: The AD applies only to Apollo GX50, GX55, GX60 and GX65 models of Garmin AT GPS navigation units, certified to FAA TSO‑C129a and with software versions 3.0 through 3.4 inclusive. The AD lists specific part numbers and modification levels for each model in a table sourced from Service Bulletin 561‑4002‑001 (Note 1). The AD therefore targets a narrowly defined set of avionics hardware and software configurations.

Incorporation of remedial instructions: The AD does not itself contain technical steps for the software change; it requires compliance by reference to SB 561‑4002‑001, specifically paragraphs 3.B and 3.C for modification and testing and paragraph 3.D for reidentification. The SB is therefore the operative technical specification for the corrective action; the AD functions as the legal instrument mandating its execution.

Risk being addressed: The Background states that under certain conditions the GX series units with software versions 3.0-3.4 may provide erroneous cross‑deviation information, potentially causing brief course deviation and increasing flightcrew workload while other navigation data are monitored. The AD’s stated purpose is to prevent the GPS unit from providing erroneous information by mandating the software modification and testing.

Timing and sequencing: The AD prescribes a compliance schedule: the modification and testing must be completed within six months of the AD’s effective date; reidentification follows immediately after modification/testing. The AD is effective from 2 September 2004 and was notified in the Gazette on 11 August 2004; it is signed 20 July 2004.

Reference to other instruments: The AD explicitly references FAA AD 2004‑13‑20 (Amdt 39‑13702) and the UPS/GA Service Bulletin as the source for the applicability table. The AD therefore sits in a regulatory chain linking CASA action to FAA correspondence and manufacturer service instructions.

Legal basis: The AD is issued under subregulation 39.1 (1) of CASR 1998, which authorises a CASA delegate to require corrective action where an unsafe condition is identified. The AD text opens by stating that the delegate issues the AD under that subregulation and that the AD requires action “in relation to the aircraft or aeronautical product mentioned in the applicability section” and “in accordance with the instructions set out in the requirement section; and at the time mentioned in the compliance section.”

Aircraft owners and operators: Any Australian operator or owner of an aircraft fitted with one of the listed Apollo GX50/55/60/65 TSO‑C129a GPS units, with software versions 3.0 to 3.4 inclusive, is subject to this AD. The AD’s applicability table lists specific part numbers and modification levels; compliance is therefore limited to units matching those identifiers (see the Applicability table and Note 1).

Maintenance organisations and avionics shops: Entities performing avionics maintenance on affected units must implement the software modification and testing in accordance with SB 561‑4002‑001 paragraphs 3.B and 3.C. The AD makes the SB‑specified tasks mandatory; the organisation performing the work must be capable of performing the software change and the tests the SB requires.

Pilots and flightcrew: While the AD imposes no direct in‑flight operating limitation or procedure change in its text, it is issued because the Background identifies a flight‑safety risk , erroneous cross‑deviation indications and the resulting increased workload. Pilots flying aircraft with affected units are impacted indirectly because their aircraft must be modified by the operator within the compliance window, otherwise they may be operating with equipment CASA has identified as presenting a potential for misleading navigation information.

Regulators and their delegates: CASA or its delegates are the issuing authority; the AD references action under subregulation 39.1 (1) of CASR 1998 and identifies the delegate who signed the AD. The regulator is the decision maker for issuing, specifying the remedial action and the compliance schedule.

Third parties: The AD incorporates SB 561‑4002‑001 by reference; Garmin AT/UPS Aviation Technologies, as the manufacturer/issuer of the SB, is implicated as the source of the technical remedy. The FAA is also implicated as the source of the advisory action, via FAA AD 2004‑13‑20 referenced in Note 2. Any party relying on FAA guidance or the manufacturer’s SB must reconcile that guidance with CASA’s AD when operating in Australia.

Supply chain and logistics: The AD creates demand for whatever technical labour, tools, software images, test equipment and reidentification labels or records the SB requires. Where parts, software packages or qualified technicians are limited, operators may encounter scheduling or availability constraints. The AD itself sets a six‑month window for the modification and testing.

Duties imposed by the AD: The AD imposes two mandatory duties. Duty 1 is to modify and test the software for the affected Apollo GX50/55/60/65 TSO‑C129a GPS navigation units by accomplishing all actions specified in paragraphs 3.B and 3.C of SB 561‑4002‑001. Duty 2 is to reidentify the modified units according to paragraph 3.D of that SB. These duties are mandatory under the AD and must be undertaken within the times specified in the Compliance section.

Timing duty: The Compliance section imposes a temporal duty: Requirement 1, the modification and testing, must be completed within six months after the AD’s effective date (the AD is effective 2 September 2004). Requirement 2, the reidentification, must be done immediately after completing Requirement 1. The AD therefore requires sequencing: modification and testing first, then immediate reidentification.

Method and standard duty: The AD prescribes the method and standard by reference to particular paragraphs of the SB. Compliance must be “in accordance with the instructions set out in the requirement section,” which in practice means following the SB’s steps in paragraphs 3.B, 3.C and 3.D. The AD does not itself specify test criteria or reidentification format; those specifics reside in the SB.

Duty of identification and scope determination: Before performing the work, responsible persons must determine whether a unit falls within the applicability table , checking model, part number, modification level and software version 3.0-3.4 inclusive. The AD defines applicability narrowly in its table and Note 1.

Rights and procedural posture: The AD text does not enumerate rights of appeal, deferral or exemption within its content. It does note the statutory basis (subregulation 39.1 (1) of CASR 1998) for the delegate issuing the AD. Any right to seek relief, reprieve or alternative means of compliance is not recorded in the AD text; the AD simply prescribes the required action and schedule.

Information rights and access: The AD references SB 561‑4002‑001 and FAA AD 2004‑13‑20. Operators implicitly require access to those documents to comply. The AD’s note states the table was sourced from SB 561‑4002‑001 and referenced in FAA AD 2004‑13‑20; the AD does not reproduce the SB’s technical paragraphs, so duty holders must obtain and follow the SB to perform the mandated work.

Recordkeeping and evidence: The AD requires execution of the specified tasks. The AD does not specify documentary requirements, but the reidentification duty per paragraph 3.D of the SB is explicitly mandated; any documentation or physical marking required by paragraph 3.D becomes part of what the AD requires, once the SB is consulted.

Enforcement authority and legal basis: The AD is issued under subregulation 39.1 (1) of CASR 1998; the AD’s opening paragraph states that the CASA delegate issues the AD under that subregulation. The AD establishes that the actions in the requirement section are required in relation to the listed aircraft or aeronautical product, in the circumstances and timeframe stated. The AD’s legal force therefore derives from CASR 1998 as the empowering instrument.

Specified penalties: The AD text itself does not specify any civil or criminal penalties, infringement notices, or monetary fines for non‑compliance. The AD sets mandatory actions and compliance dates, but does not list enforcement measures or sanctions in its body. Any enforcement consequences for failing to comply will derive from the regulatory framework of CASR 1998 and related enforcement instruments, which the AD invokes by referencing subregulation 39.1 (1).

Operational enforcement: The AD requires modification and testing within six months of the effective date and reidentification immediately thereafter. In practice, enforcement may be operational , for example, an aircraft operating with an unmodified or unreidentified affected GPS unit after the compliance date is operating with an item identified by CASA as subject to mandatory corrective action. The AD text however does not define the operational consequences, such as grounding, conditional operations, or airworthiness approvals; those would be applied under the broader regulatory regime.

Compliance monitoring: The AD does not specify who will monitor or audit compliance, or the documentary proofs required. Because the AD mandates reidentification per SB paragraph 3.D, that paragraph likely contains a physical or documentary mark that will serve as evidence of compliance; the AD itself does not reproduce those requirements, it simply mandates them by reference.

Reference to other authorities: The AD references FAA AD 2004‑13‑20 and the manufacturer’s SB. Enforcement of the AD in Australia therefore operates alongside FAA and manufacturer actions, but the AD does not describe coordination mechanisms or reciprocal enforcement steps. The AD’s effectiveness date and Gazette notification establish its public promulgation; the AD is signed by a CASA delegate and notified in the Commonwealth Gazette, which gives regulatory notice to affected parties.

Statutory foundation: The AD is issued under subregulation 39.1 (1) of CASR 1998, and it explicitly cites that subregulation as the authority for the CASA delegate to require corrective action. The AD therefore operates as an instrument under the civil aviation regulatory framework established by CASR 1998.

Interaction with manufacturer instructions: The AD incorporates by reference specific paragraphs of Service Bulletin 561‑4002‑001 as the required remedial method. The AD effectively elevates those SB paragraphs from manufacturer guidance to mandatory action for Australian operators of the affected equipment. As a result, compliance with the SB’s specified steps becomes a legal requirement in Australia for affected units, rather than optional manufacturer guidance.

Interaction with FAA AD: The AD notes that FAA AD 2004‑13‑20 (Amdt 39‑13702) refers and that the applicability table was sourced from SB 561‑4002‑001 which the FAA AD referenced. The CASA AD aligns its remedial requirement with the FAA’s action by mandating the same SB paragraphs. The AD therefore sits in an international regulatory dialogue, referencing both FAA action and the manufacturer’s SB as the technical basis.

Airworthiness and operational rules: The AD requires modification and reidentification of an aeronautical product to address a safety deficiency. Execution of the AD will affect the continuing airworthiness status of the aircraft or product; once the AD actions are completed, the unit should be reidentified per the SB. The AD does not itself specify amendments to operations manuals, flight manuals or operating procedures, nor does it specify flight prohibition or conditional operations; any such operational interactions would be determined under CASR 1998 and the operator’s own continuing airworthiness obligations.

No civil‑law amendments: The AD does not purport to amend CASR text or create new statutory offences; it exercises the regulatory power to require corrective action under an existing subregulation. The AD text does not expand or limit other legal rights or private contractual obligations beyond imposing a regulatory requirement to perform the SB tasks.

Documentation and records: Because the AD requires performance “in accordance with the instructions set out in the requirement section,” and those instructions refer to SB paragraphs for reidentification, the obligations imposed by SB paragraph 3.D become part of the legal compliance framework. Any interaction with records or audit requirements under CASR 1998 is therefore mediated through the AD’s incorporation of the SB, but the AD text does not itself spell out record retention periods or audit rights.

Issuance and effective dates: The AD is signed by Bernard Malcolm Hole, Delegate of the Civil Aviation Safety Authority, on 20 July 2004. The AD states it becomes effective on 2 September 2004 and that it was notified in the Commonwealth of Australia Gazette on 11 August 2004. Those dates establish the administrative timeline: signature 20 July 2004, Gazette notification 11 August 2004, effective date 2 September 2004.

References to other instruments as amendments: The AD expressly refers to FAA AD 2004‑13‑20 Amdt 39‑13702 (Note 2) and states that the applicability table was sourced from UPS Aviation Technologies Service Bulletin 561‑4002‑001 dated 19 April 2002 (Note 1). The AD therefore aligns itself with prior manufacturer and FAA materials rather than presenting a textual amendment to technical requirements in the AD itself. The AD does not list any prior CASA ADs that it supersedes or amends.

No recorded revisions within the text: The AD as provided contains no internal amendment history, versioning or later modifications to AD/RAD/82. The AD establishes its requirements afresh for the affected units; it does not record any subsequent CASA amendments, revocations or supersessions in the provided text.

Implicit amendment of airworthiness status: By mandating modification and testing and prescribing reidentification, the AD functions as an amendment to the continuing airworthiness obligations applicable to aircraft or aeronautical products with the listed GPS units. That is, after the AD’s effective date, the actions it mandates are part of the unit’s required maintenance status for continued lawfulness of operation, but the AD does not provide a formal amendment log beyond its effective date and signature.

What is not present: The AD does not include an express clause amending other CASA instruments, nor does it provide a schedule of future reviews or a sunset clause. It does not state that it replaces an earlier CASA directive or that it will be reissued; the AD stands as the controlling CASA instrument for this issue as of the effective date stated.

No judicial or tribunal decisions recorded in the AD: The AD text contains no references to any litigation, court, tribunal, administrative appeal, or dispute regarding the AD’s issuance, scope, or compliance obligations. The AD does not cite any case law nor indicate that its enforceability has been the subject of judicial testing.

No recorded challenges or stays: The AD does not record any stays, suspensions or interim relief granted by a court or tribunal, nor does it indicate that any party sought judicial review of the AD in the materials provided. The AD stands as an administrative instrument issued by a CASA delegate, with the compliance obligations and timelines set out in the document.

Reliance on FAA AD and SB rather than litigation: The AD’s references are to technical and regulatory source documents (SB 561‑4002‑001 and FAA AD 2004‑13‑20), not to litigation or adjudicative determinations. The AD therefore appears to be a direct regulatory implementation of manufacturer and FAA technical findings, rather than the product of litigation or a settled legal challenge.

Implication for potential disputes: The AD’s language is prescriptive and incorporates the SB by reference. Because the AD does not set out dispute resolution or appeal mechanisms within the text, any legal challenges to the AD’s validity, scope, or enforcement would have to proceed under the general judicial review or administrative law processes applicable to CASA decisions. The AD text contains no record of such proceedings.

Scope limited to software versions 3.0-3.4: The AD applies only to units with software versions 3.0 through 3.4 inclusive. Units with earlier or later software versions are not listed in the AD’s applicability table. A potential compliance pitfall is failing to verify the unit’s exact software version before deciding whether the AD applies. The AD’s applicability table and the Note 1 sourcing must be checked against each unit’s identification details.

Complex applicability details: The AD’s applicability is presented as a table of model, part number, description and “modification level.” Some entries read “With any of the following mods: (H), (N), (P), (T) or (U); prior to (V)” or similar language for other models. That phrasing means certain modification states are included, and later modification levels (for example “prior to (V)” or “prior to (R)”) are relevant. Determining whether a specific hardware unit is “prior to” a later modification level may require inspection of internal modification level markings or maintenance records. Failure to properly interpret those modification‑level designations could lead to misclassification of whether a unit is subject to the AD.

AD does not reproduce SB technical detail: The AD mandates accomplishment of paragraphs 3.B, 3.C and 3.D of SB 561‑4002‑001 but does not reproduce those paragraphs. Operators must obtain the SB to know precisely what modification, tests and reidentification methods are required. Assuming what those paragraphs require, or attempting to substitute an alternate procedure without CASA agreement, risks non‑compliance.

Reidentification required immediately after modification: The AD requires reidentification (Requirement 2) “immediately following completion of Requirement 1.” The SB paragraph 3.D will specify the form of reidentification. Operators should not delay reidentification after completing the modification and test because the AD conditions the sequence , modification/testing first, then reidentification.

Timing constraints and operational scheduling: The six‑month compliance window for the modification and testing may create scheduling pressure, especially if affected units are numerous, technicians scarce, or SB parts/software images constrained. The AD sets a finite compliance window; it does not provide for staged compliance or partial relief in its text.

Interplay with FAA AD and manufacturer SB: The AD references FAA AD 2004‑13‑20 and the SB. If an operator has already complied with the FAA AD or followed a different manufacturer instruction, they must confirm that their action precisely meets paragraphs 3.B, 3.C and 3.D of SB 561‑4002‑001 as required by the CASA AD. Assumptions that FAA compliance automatically satisfies CASA requirements should be validated against the exact paragraphs cited.

No penalties stated in the AD text: The AD does not state enforcement penalties or consequences within its body. Operators may assume there is no enforcement, but the AD is issued under CASR 1998 powers and non‑compliance could have regulatory consequences under that regime.

Record evidence and proof of compliance not specified: The AD requires performance of the SB paragraphs but does not detail how compliance is to be evidenced for audit or inspection purposes. Because reidentification is mandated, that action may provide a visible marker, but operators should be aware that the AD itself does not spell out documentary proof requirements.

Step 1 , Identify affected units: Check each aircraft’s installed GPS navigation unit(s) against the AD’s Applicability table and Note 1. Confirm model (GX50, GX55, GX60, GX65), part number, modification level and software version. The AD applies to units with software versions 3.0 through 3.4 inclusive and to the specific part numbers and modification levels listed in the table that was sourced from SB 561‑4002‑001.

Step 2 , Obtain the Service Bulletin: Acquire UPS/Garmin AT Service Bulletin 561‑4002‑001 dated 19 April 2002. The AD mandates accomplishing all actions specified in paragraphs 3.B and 3.C for modification and testing, and paragraph 3.D for reidentification. The AD does not reproduce those paragraphs, so the SB is the required technical specification.

Step 3 , Plan work within the compliance window: Requirement 1 must be completed within six months after the AD effective date (AD effective date 2 September 2004). Arrange maintenance slots, qualified personnel and any necessary software images, tools or test equipment to meet that timeline.

Step 4 , Execute modification and testing: Follow all steps in SB paragraphs 3.B and 3.C to modify and test the software exactly as specified. The AD makes those SB paragraphs mandatory. Ensure that testing includes the criteria the SB specifies; the AD requires testing as part of Requirement 1.

Step 5 , Reidentify immediately after modification: After completing the modification and testing, perform the reidentification required by SB paragraph 3.D immediately, as required by Requirement 2 of the AD. The form of reidentification (data plate change, software ID, logbook entry, label, or other) will be specified in paragraph 3.D; comply exactly.

Step 6 , Maintain records and readiness for inspection: Although the AD does not set out documentary proof requirements, retain evidence of compliance , records of the SB procedures performed, test results, details of the reidentification action (including any serial numbers or new software version identifiers), the date of completion and the identity of the organisation or technician who performed the work. Such records will assist in demonstrating compliance to an inspector, regulator or auditor.

Step 7 , Coordinate with the manufacturer or authorised service centres where necessary: The AD requires work that may involve proprietary software images, approved test procedures, or tools that only the manufacturer or authorised service providers hold. If the SB requires manufacturer software or proprietary procedures, obtain those through the manufacturer’s channels or authorised agents.

Step 8 , Confirm airworthiness status before return to service: After completing the SB procedures and reidentification, ensure that the aircraft’s continuing airworthiness records reflect the AD compliance and that any required sign‑offs by certifying staff are made before placing the aircraft back into commercial or private operation.

Step 9 , Consider related FAA actions: The AD references FAA AD 2004‑13‑20 and the SB source. If operators have already performed actions under FAA direction or other regulatory mandates, verify that those actions conform precisely to SB paragraphs 3.B, 3.C and 3.D to ensure they satisfy the CASA AD requirements.

Step 10 , Where uncertainty exists, seek CASA guidance: The AD sets mandatory actions but does not specify procedures for alternative methods of compliance, extensions or deviations. If an operator cannot meet the requirements as written , for example due to parts availability or unique unit configuration , the operator should approach CASA for guidance or approval of alternatives under the regulatory framework enabling deviations or approvals, recognising that the AD itself does not provide those mechanisms inside its text.