AD/BEECH 400/27 - Generator Control Unit

The Directive revolves around a small set of interlocking technical concepts and compliance mechanisms. The primary hardware elements named are:

• Generator Control Unit (GCU): the component that controls the DC starter generator output. The Directive identifies specific GCU part numbers relevant to compatibility checks: P/N 45AS88801-19, P/N 45AS88801-25, and Shinko GCUs (manufacturer implied by the replacement instruction).
• Current sense transformers: two transformers on the lower inboard quadrant of each engine inlet, whose part number must be identified and, if necessary, replaced with P/N 45AS88801-21.
• Installation kits and starter-generator kit: kit P/Ns used to identify prior modifications include installation kit P/N 128-3001-1P and 128-3001-3P (GCU installation kits), and an earlier starter-generator kit P/N 128-3004-1P or 128-3004-3P (Lucas Aerospace/Goodrich DC starter generator) which is part of the applicability statement.

Key procedural concepts and documents:

• Raytheon Service Bulletin SB 24-3713, dated November 2005: the Directive instructs that the logbook review, inspections and replacement actions must be performed "in accordance with the Accomplishment instructions" of this Service Bulletin. The SB is therefore the procedural vehicle for inspection detail, part installation procedures, and any torque, wire-routing, testing or functional checks required to complete the AD’s Requirements.
• FAA AD 2006-15-16 and AMOC mechanism: the Directive explicitly references FAA AD 2006-15-16 (Amdt 39-14697) and states that later revisions of SB 24-3713 that the FAA has approved as an Alternate Method of Compliance will be acceptable to meet the equivalent Requirements of this Directive. Thus AMOC approval by the FAA is the cross‑jurisdictional acceptance mechanism for modified procedures.

Applicability and scope:

• Serial-numbered applicability is narrow and explicit: Model 400 series S/N RJ-1 through RJ-65 inclusive, and Model 400A series S/N RK-1 through RK-23 inclusive, but only those aeroplanes “on which kit P/N 128-3004-1P or 128-3004-3P has been incorporated.” The Directive therefore targets a defined subset of airframes modified with a particular starter-generator kit.

Time constraints and effect:

• The Directive imposes a finite compliance window: 200 hours time in service or six months after the effective date, whichever occurs first. The effective date is 28 September 2006.

Risk logic:

• The Directive’s stated risk logic is causal and component-level: reports of over-voltage conditions with the DC starter generator are attributed to incompatibility between certain GCUs and related components; incompatibility can lead to electrical system failures and damage. The remedy is component identification and replacement where mismatched or non‑specified part numbers are present.

Compliance device:

• The AD uses part-number verification and replacement as the enforcement instrument. Identification relies on logbook entries and subsequent physical inspection; replacement actions reference the service bulletin for execution.

The Directive affects a defined set of parties and aircraft. Explicitly named affected aircraft are:

• Raytheon (Beech) Model 400 series aeroplanes, serial numbers RJ-1 through RJ-65 inclusive, on which kit P/N 128-3004-1P or 128-3004-3P has been incorporated.
• Raytheon (Beech) Model 400A series aeroplanes, serial numbers RK-1 through RK-23 inclusive, on which kit P/N 128-3004-1P or 128-3004-3P has been incorporated.

Practical roles likely to be engaged by the Directive, as implied by the text, are:

• Operators/owners of the affected aeroplanes: they must ensure that Requirements 1-5 are completed within the specified compliance window. The Directive’s first procedural step is a logbook review, typically an operator responsibility.
• Maintenance organisations and engineers performing the inspections and replacements: the AD mandates performing physical inspections of GCUs and current sense transformers and replacement where required, "in accordance with SB 24-3713", so maintenance providers must follow that Service Bulletin’s Accomplishment instructions.
• Parts suppliers: the AD specifies exact replacement part numbers (e.g., GCUs P/N 45AS88801-19 or -25; current sense transformers P/N 45AS88801-21; installation kit P/N 128-3001-1P or -3P). Entities procuring and fitting parts must source the specified items.
• Civil Aviation Safety Authority (CASA) and delegated officials: CASA’s delegate issued the Directive and will be the enforcing authority responsible for recording the AD, its effective date, and any follow-on administrative measures. The Directive is signed by James Coyne, a CASA delegate, dated 14 August 2006.

Note on identification complexity: The Applicability paragraph ties aircraft inclusion to both serial-number range and the incorporation of a specific starter-generator kit (P/N 128-3004-1P or -3P). Therefore operators who have aircraft in the serial-number ranges but do not have that kit incorporated are not the target of this AD. The Directive recognises that the kit incorporation must be confirmed (hence the logbook review), and provides the replacement pathway where the kit P/N “cannot be conclusively determined” from records, thereby widening the group of aircraft that will be brought into compliance if records are unclear.

Timing burdens: The compliance window (200 hours time in service or six months after 28 September 2006) imposes a scheduling requirement on operators and maintenance providers. Aircraft with high utilisation may reach 200 hours quickly, requiring earlier action; low-utilisation aircraft may have up to six months.

Cross-jurisdictional actors: Because the AD accepts later SB revisions approved by the FAA as AMOCs, operators and maintenance organisations that rely on FAA approvals or FAA-authorised AMOCs will be able to apply those to satisfy this Directive, which affects entities accustomed to working to FAA ADs and SBs.

Duties mandated by the Directive

• Logbook review: Requirement 1 directs an immediate duty to "Review the aeroplane logbook, in accordance with the Accomplishment instructions of Raytheon Service Bulletin SB 24-3713, dated November 2005, to determine whether generator control unit (GCU) installation kit, P/N 128-3001-1P or 128-3001-3P, is installed." That is the starting obligation.
• Replacement where kit P/N absent or inconclusive: Requirement 2 imposes a duty to replace Shinko GCUs with new Lucas Aerospace/Goodrich GCUs (installation kit P/N 128-3001-1P or -3P) where the logbook does not show the GCU installation kit or where the kit P/N cannot be conclusively determined. The replacement must be "in accordance with SB 24-3713."
• Inspection when kit is present: Requirement 3 requires inspection to determine the P/N of both GCUs, following SB 24-3713, and then to apply Requirement 4 or 5 as relevant.
• Transformer inspection and replacement: Under Requirement 4, if both GCUs have P/N 45AS88801-19 or -25, the operator must inspect the P/N of both current sense transformers on the lower inboard quadrant of both engine inlets in accordance with SB 24-3713; if either transformer is not P/N 45AS88801-21, it must be replaced.
• GCU replacement when P/N differs: Under Requirement 5, where either GCU is not P/N 45AS88801-19 or -25, that GCU must be replaced with a new GCU (P/N 45AS88801-19 or -25), and then the two current sense transformers must be inspected and replaced where necessary.

Timing duty

• Comply within 200 hours time in service or six months after the effective date (28 September 2006), whichever occurs first. The Directive explicitly says, "For Requirements 1, 2, 3, 4 and 5 - Within 200 hours time in service or 6 months after the effective date of this Directive, whichever occurs first."

Documentary and procedural duty

• Follow SB 24-3713: Every procedural step is to be executed "in accordance with SB 24-3713." Thus a duty exists to use that Service Bulletin’s Accomplishment instructions for the actual inspection, replacement and testing tasks.

Rights and compliance flexibilities stated in the Directive

• Use of FAA-approved AMOC SB revisions: The Directive states that "Later revisions of the above SB, approved by the United States Federal Aviation Administration (FAA) as an Alternate Method of Compliance (AMOC) to FAA AD 2006-15-16, are considered acceptable for compliance with the equivalent Requirements of this Directive." This grants operators or maintenance organisations the right to rely on SB revisions that have FAA AMOC approval as satisfying the Directive’s Requirements, rather than being constrained strictly to the November 2005 version.
• Implicit reliance on logbooks: The Directive’s structure permits reliance on documented logbook entries to determine whether the GCU installation kit P/N is installed. If the logbook shows the required kit P/N, the operator follows the inspection path; if it does not or is inconclusive, the Directive requires replacement. This makes logbook records a determinative factual input to which the Directive defers.

Procedural limitation

• The Directive ties the performance standard to the Service Bulletin. There is no separate technical specification in the AD beyond part numbers and locations; the SB supplies the detailed work instructions. Consequently, compliance requires access to and adherence to SB 24-3713, or an FAA-approved later revision.

Delegated authority

• The AD is issued by CASA via a delegate ("James Coyne, Delegate of the Civil Aviation Safety Authority") indicating CASA’s administrative authorship. The Directive does not on its face spell out enforcement mechanisms or how CASA will verify or record compliance; it establishes substantive obligations and timing.

The text of this Airworthiness Directive sets out mandatory technical requirements and a compliance timeframe, but it does not spell out penalties or a specific enforcement regime within its own text. The document contains the following enforcement‑adjacent features:

• Mandatory actions and timeframe: The AD explicitly requires completion of Requirements 1-5 "Within 200 hours time in service or 6 months after the effective date of this Directive, whichever occurs first." That placement of mandatory obligations and a deadline is an enforcement trigger in regulatory practice.
• Issuing authority: The Directive is issued by the Civil Aviation Safety Authority, indicated by the signature block "James Coyne, Delegate of the Civil Aviation Safety Authority." The identity of the issuing body indicates where enforcement responsibility would ordinarily sit, though the AD text does not itself prescribe particular sanctions.
• Lack of internal penalty text: The Directive contains no provision describing penalties, fines, suspension of certificates, or administrative sanctions. There is no text describing monitoring, audit, or reporting obligations (for example, submission of compliance reports), nor is there any description in the AD of how CASA will verify completion or record compliance.

Implications a reader should draw from the Directive’s text, strictly on its face:

• The AD imposes mandatory technical duties on operators of the applicable aeroplanes, together with a finite compliance window. The Directive establishes what must be done and by when, but does not in its wording set out the consequences of non‑compliance.
• Because enforcement and penalty mechanisms are not specified in the AD’s text, any enforcement procedure, penalties or follow-up compliance verification would be governed by the broader regulatory powers and administrative processes of the issuing authority (CASA) and relevant aviation safety legislation and instruments, none of which are reproduced in this Directive text. The Directive itself does not authorise, describe, or limit particular enforcement actions.

Practical consequence for operators and maintainers:

• Operators should treat the Directive as mandatory for the affected aircraft and plan to perform the required inspections and replacements within the stated timeframe. Absent an FAA‑approved AMOC SB revision, the route to compliance is to follow SB 24-3713.
• Because the AD does not specify the enforcement mechanics, operators should consult CASA’s regulatory framework or contact CASA to confirm procedural steps for declaring compliance (logbook entries, maintenance release records, or formal notifications) and to understand any penalties or administrative consequences for non‑compliance. The Directive itself does not provide those administrative details.

The Directive, as published, explicitly references and integrates other regulatory and manufacturer documents; it does not purport to supersede or alter those documents, but it sets compliance pathways that rely on them. The interactions disclosed in the text are:

Reference to U.S. FAA AD and AMOC process

• FAA AD 2006-15-16 (Amdt 39-14697) is cited as a related instrument in the Directive’s Note. The Directive states that "Later revisions of the above SB, approved by the United States Federal Aviation Administration (FAA) as an Alternate Method of Compliance (AMOC) to FAA AD 2006-15-16, are considered acceptable for compliance with the equivalent Requirements of this Directive." This creates an express cross-acceptance link: where the FAA has approved an alternate method via the AMOC process for its AD, CASA will accept that same SB revision as complying with the equivalent Requirements of this Australian Directive.
• Mechanism: The interaction is functional rather than normative; an FAA-approved AMOC revision of SB 24-3713 is treated as acceptable compliance with the Australian Directive’s equivalent Requirements. That ties CASA’s acceptance of alternative procedures to FAA administrative determinations.

Dependence on manufacturer service documentation

• The Directive repeatedly directs operators to perform actions "in accordance with the Accomplishment instructions of Raytheon Service Bulletin SB 24-3713, dated November 2005." The Australian AD therefore depends on the manufacturer’s Service Bulletin for procedural detail. The relationship is typical: the AD provides mandatory obligations and references the SB for technical execution.
• Effect: The SB supplies the step-by-step technical instructions, torque values, installation details and checks that the AD references; later SB revisions that receive FAA AMOC approval can be used to satisfy the AD.

No mention of other domestic statutes, regulations or civil remedies

• The Directive contains no textual cross-reference to Australian aviation statutes, Civil Aviation Safety Regulations, general administrative law, or penalty provisions. It does not specify how CASA will record completion, whether completion must be notified, nor any particular enforcement process such as suspension of operations or certificate action for non‑compliance.
• Practical effect: While the AD imposes obligations, it leaves the enforcement mechanics and interaction with broader Australian safety regulation unstated; parties must look outside the AD to CASA’s regulatory framework for enforcement procedures and penalties (not reproduced here).

No modification of aircraft registration or airworthiness certificate text

• The Directive does not purport to amend certificates, nor does it provide an exemption mechanism other than acceptance of FAA‑approved AMOCs for SB revisions. It requires physical works and inspections which, once performed, would typically be recorded in maintenance logs consistent with airworthiness management, but the AD does not itself prescribe the records format or filing.

Cross-jurisdictional compliance alignment

• Because the AD accepts FAA AMOCs for later SB revisions, an operator who has already complied with FAA AD 2006-15-16 via an FAA‑approved method may be able to demonstrate compliance with this Directive by relying on the same FAA approval. This interaction reduces duplication where the same technical issues are managed under both FAA and CASA frameworks, at least to the extent described in the Directive.

The Directive text includes limited material on its own issuance timeline and does not list a sequence of formal amendments within the document. The only amendment‑relevant items present in the text are:

• Date of signature and issuer: The AD is signed by "James Coyne, Delegate of the Civil Aviation Safety Authority" and dated 14 August 2006. That indicates the administrative origin and date of issue.
• Effective date: The AD states, "This Airworthiness Directive becomes effective on 28 September 2006." That sets the legal commencement of the compliance window.
• AD identifier and date tag: The AD is labelled "AD/BEECH 400/27" and "10/2006" in multiple places in the header, establishing the AD docket identifier and the year/month context.
• Service Bulletin reference and AMOC note: The Directive refers to Raytheon Service Bulletin SB 24-3713 dated November 2005 and states that "Later revisions of the above SB, approved by the United States Federal Aviation Administration (FAA) as an Alternate Method of Compliance (AMOC) to FAA AD 2006-15-16, are considered acceptable for compliance with the equivalent Requirements of this Directive." This is not an amendment to the AD itself but does authorise the use of later SB revisions if those later revisions carry FAA AMOC approval.

What the Directive does not contain about amendments

• There is no trace in the text of subsequent amendments to AD/BEECH 400/27. No later AD numbers, superseding ADs, or internal amendment entries are shown in the provided text.
• The AD does not provide a process within its own text for amending or revoking the Directive, nor does it provide a history chain showing prior versions of the AD; it simply records the AD number, the issue tag "10/2006", the issuance date and the effective date.

Practical consequence for readers

• If a practitioner needs to know whether AD/BEECH 400/27 has been amended after the date of this document, or whether CASA later issued a superseding AD, they must consult CASA’s AD registry or subsequent publications. The Directive itself, as provided, contains no amendment log beyond its original issue data and the stated acceptance of FAA‑approved later SB revisions as AMOCs.
• The Directive does not record any post-issuance corrections, errata or retractions in the supplied text.

The provided Directive text contains no litigation history. The document does not reference any court decisions, administrative appeals, disputes, or proceedings by or against CASA, Raytheon, operators, manufacturers or other parties in relation to AD/BEECH 400/27. Specific points to note from the text:

• No cases named: The Directive does not name any judicial or tribunal decisions, nor does it include references to litigation or adjudicated challenges to the Directive’s content or to the underlying FAA AD.
• No appeals information: The AD does not set out an appeals process, nor does it record whether any affected party has sought review or stayed the Directive.
• No compliance disputes recorded: The AD’s Background section mentions FAA reports of over-voltage conditions and frames the safety rationale, but it does not recount any contested factual findings or legal disputes.

Implication for researchers and practitioners

• Because the Directive contains no litigation history, practitioners seeking to know whether the AD was the subject of legal challenge or whether its requirements have been interpreted in litigation must search external sources (for example, CASA records, administrative tribunal decisions, court files or operator correspondence). The AD itself provides no account of litigation, appeals or contested enforcement actions.

The Directive contains multiple precise technical and procedural points where mistakes or misunderstandings can cause non‑compliance or unnecessary work. The following are concrete "gotchas" directly implied by the text:

1. Applicability is dual‑gated: serial number range plus kit incorporation

   • The applicability requires both a serial number in the stated ranges and that kit P/N 128-3004-1P or 128-3004-3P "has been incorporated." Mere presence of a serial number alone does not automatically make an aeroplane subject to the AD. Operators must confirm kit incorporation. If they rely on serial number alone they may wrongly apply or ignore the AD.
   • The Directive drives the logbook review as the primary confirmatory step, making accurate maintenance records central. The AD anticipates inconclusive records by specifying replacement where the kit P/N "cannot be conclusively determined," which expands practical reach when logbooks are incomplete.

2. Part numbers must be precisely identified

   • The Directive uses exact part numbers for GCUs (45AS88801-19 or -25), current sense transformers (45AS88801-21), and installation kits (128-3001-1P or -3P, and starter-generator kit P/Ns 128-3004-1P or -3P). Any typographical misreading or incorrect translation of a part number can lead to incorrect compliance decisions.
   • The physical location is specific: the current sense transformers on "the lower inboard quadrant of the left-hand and right-hand engine inlets." Inspectors must know exactly where to look.

3. Two branches of action depending on GCU P/Ns

   • Requirement 3 instructs an inspection of GCU P/Ns and then bifurcates into two distinct paths (Requirements 4 and 5). Mistaking which path applies could lead to unnecessary GCU replacement or failure to replace required parts.

4. If kit P/N cannot be determined, replacement is mandatory

   • Where the logbook does not show the GCU installation kit or the kit P/N "cannot be conclusively determined," Requirement 2 mandates replacement of Shinko GCUs with Lucas/Goodrich GCUs using kit P/N 128-3001-1P or -3P. That procedural default to replacement in the face of record uncertainty can impose parts and labour costs for aircraft that might in fact already be compliant but lack documentary proof.

5. Service Bulletin dependence

   • The AD requires actions "in accordance with SB 24-3713." If an operator does not have access to that Service Bulletin or misapplies its instructions, the physical work may not meet the AD’s intended standard. The AD gives no implementation detail itself; reliance on the SB is mandatory.

6. Timing window may be short for high‑utilisation aircraft

   • Compliance is required within 200 hours time in service or six months after the effective date, whichever occurs first. Aircraft with high utilisation could reach 200 hours well before six months, shortening the available window and requiring scheduling of maintenance during operational periods.

7. AMOC acceptance limited to FAA‑approved SB revisions

   • The AD accepts later SB revisions only if the FAA has approved them as AMOCs for FAA AD 2006-15-16. An SB revision without FAA AMOC approval is not accepted by this AD. Operators must check FAA AMOC status for later SB revisions before relying on them.

8. The AD does not specify reporting or recording processes

   • The Directive does not state whether operators must formally notify CASA upon compliance or what proof is required. Practitioners should not assume that logbook entries alone satisfy administrative obligations; they must clarify with CASA how compliance is to be recorded, because the AD text itself is silent on this administrative step.

9. Ambiguity around "Shinko" GCUs

   • The Directive directs replacing "Shinko GCUs" where the kit P/N is not found, but it does not define Shinko part numbers explicitly. Maintenance personnel must ensure correct identification of manufacturer and part numbers to avoid incorrect part swaps.

10. No penalties or enforcement steps stated in the text

    • Because the AD contains no enforcement details, operators may be uncertain of the consequences of non‑compliance. That absence is itself a compliance risk if operators delay on the assumption of leniency; conversely, it could leave operators unsure how to evidence compliance administratively.

In short, the main practical risks are misidentifying affected aircraft, misreading or misapplying part numbers, not following the correct branch of the Requirements, failing to use SB 24-3713 precisely, and depending on unverified SB revisions that lack FAA AMOC approval. Each of these risks flows from particular lines in the Directive and the AD’s reliance on external technical documents and record accuracy.

Compliance with this Directive requires a sequence of documentary checks, inspections and, where necessary, replacement work performed in accordance with Raytheon Service Bulletin SB 24-3713 (November 2005), taking into account the FAA AMOC acceptance pathway for later SB revisions. The Directive sets out discrete steps; follow them in order and observe the compliance deadline.

Step‑by‑step compliance path (as required by the AD)

1. Confirm applicability

   • Identify whether the aeroplane is within the serial number ranges specified: Model 400 series S/N RJ-1 through RJ-65 inclusive, or Model 400A series S/N RK-1 through RK-23 inclusive.
   • Confirm whether kit P/N 128-3004-1P or 128-3004-3P "has been incorporated." If records show kit incorporation, proceed to Step 2. If records do not show incorporation or are inconclusive, the AD still requires action (see Step 3).

2. Logbook review (Requirement 1)

   • Perform a documented logbook review "in accordance with the Accomplishment instructions of Raytheon Service Bulletin SB 24-3713, dated November 2005" to determine whether GCU installation kit P/N 128-3001-1P or 128-3001-3P is recorded as installed.
   • Record the results of the logbook review in maintenance records. The AD uses the logbook as the determinant of whether the installation kit is present; accurate recordkeeping is therefore essential.

3. If kit P/N absent or inconclusive (Requirement 2)

   • Where the logbook does not show the GCU installation kit or the kit P/N "cannot be conclusively determined," replace Shinko GCUs with new Lucas Aerospace/Goodrich GCUs using installation kit P/N 128-3001-1P or -3P, following the SB instructions.
   • After replacement, proceed to inspect current sense transformers as required by the SB and the AD (Requirement 4/5 logic will apply depending on the GCU P/Ns).

4. If kit P/N present (Requirement 3)

   • If the logbook shows the GCU installation kit P/N, inspect to determine the part number of both GCUs in accordance with SB 24-3713.
   • Based on the GCU part numbers, carry out Requirement 4 or 5 as applicable.

5. If both GCUs are P/N 45AS88801-19 or -25 (Requirement 4)

   • Inspect both current sense transformers located on the lower inboard quadrant of the left-hand and right-hand engine inlets as described in SB 24-3713 to determine their P/Ns.
   • If both transformers are P/N 45AS88801-21, no further action is required by the Directive.
   • If either transformer is not P/N 45AS88801-21, replace that transformer with P/N 45AS88801-21 in accordance with SB 24-3713.

6. If either GCU is not P/N 45AS88801-19 or -25 (Requirement 5)

   • Replace the GCU(s) that are not P/N 45AS88801-19 or -25 with new GCU(s) P/N 45AS88801-19 or -25 per SB 24-3713.
   • After replacement, inspect both current sense transformers as per Requirement 4; if either transformer is not P/N 45AS88801-21, replace it per SB 24-3713. If both transformers are P/N 45AS88801-21, no further action is required.

7. Observe the compliance window

   • Complete Requirements 1-5 within 200 hours time in service or six months after the effective date of the Directive (28 September 2006), whichever occurs first.

8. Use FAA‑approved SB revisions if applicable

   • If a later revision of SB 24-3713 exists, confirm whether the United States FAA has approved it as an AMOC to FAA AD 2006-15-16. If the FAA has approved the later SB revision as an AMOC, the AD states that that later revision is "considered acceptable for compliance with the equivalent Requirements of this Directive."
   • Do not rely on later SB revisions that lack FAA AMOC approval for compliance with this AD.

Practical compliance considerations

• Access to SB 24-3713: Acquire and review the Raytheon Service Bulletin SB 24-3713 (November 2005) before starting any work. The AD requires actions "in accordance with" that SB; the SB contains the detailed technical steps, torque settings, and specific inspection criteria the AD does not recite.
• Part procurement: Ensure availability of the specified replacement parts before scheduling maintenance: GCUs P/N 45AS88801-19 or -25; current sense transformers P/N 45AS88801-21; installation kit P/N 128-3001-1P or -3P if replacements are required.
• Qualified personnel: Perform inspections and replacements by appropriately qualified aircraft maintenance technicians and in accordance with the methods and checks specified in SB 24-3713.
• Recordkeeping: Document the logbook review, the inspection results (including part numbers found), the details of any replacements made (part numbers and installation kits used), and the date and aircraft time in service at which the work was completed. Although the AD does not specify administrative reporting to CASA within its text, maintain full records in the aircraft’s maintenance logbook as the AD relies on those records for applicability determinations.
• Cross-check AMOC status: If planning to rely on a later SB revision, verify FAA AMOC status before proceeding. The AD only accepts later SB revisions that are FAA‑approved AMOCs as satisfying the equivalent Requirements.
• Scheduling: Given the 200‑hour/6‑month compliance window, plan maintenance availability appropriately, especially for aircraft with high utilisation where 200 hours may be reached quickly.

By following the AD’s express Requirements and executing the detailed technical steps set out in SB 24-3713 (or an FAA‑approved later SB revision as AMOC), operators will satisfy the Directive’s stated objective of addressing the reported over‑voltage condition risk associated with incompatibility between certain GCUs and related components.