{"id":"F2006B06104","name":"AD/PC-12/41 - Generator Control Unit","slug":"ad-pc-12-41-generator-control-unit","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":46851,"registerId":"commonwealth-F2006B06104-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.001.png)  \n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\n![](image.001.png)  \n\nPilatus PC-12 Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/PC-12/41 Generator Control Unit 6/200","sectionType":"part","heading":"AD/PC-12/41 Generator Control Unit 6/2004","content":"# AD/PC-12/41 Generator Control Unit 6/2004\n\nApplicability: All PC-12 and PC-12/45 airplanes, Manufacturer Serial Numbers (MSN) 101 through 507 with the second battery factory option and which do not have Generator Control Unit (GCU) part number (P/N) 988.21.15.103 installed.\n\nRequirement: 1. Remove GCU P/N 988.21.15.102 and install GCU P/N 988.21.15.103 in accordance with the Accomplishment Instructions of Pilatus PC-12 Service Bulletin (SB) No. 24-022 dated 13 June 2003.\n\nNote 1: The following Service Bulletins should be accomplished before or at the same time as PC-12 SB No. 24-022, as applicable:\n\nPC-12 SB 24-010 Revision 1 dated 06 October 2003.\n\n    \\- When an Electrosystems generator P/N 978.87.24.121 is installed.\n\nPC-12 SB 24-019 Revision 1 dated 06 June 2003.\n\n    \\- When an Electrodelta voltage regulator P/N 988.21.15.101 is installed. (This SB changes the P/N of the GCU to 988.21.15.103.)\n\n2. GCUs with P/N 988.21.15.102 may not be installed as a replacement part on any aeroplane with the second battery factory option installed.\n\nNote 2: FOCA (Switzerland) AD HB-2004-101 refers.\n\nCompliance: For Requirement 1 \\- At the next 100 hour or annual inspection, but no later than 90 days after the effective date of this Directive.\n\nFor Requirement 2 - As of the effective date of this Directive. This Airworthiness Directive becomes effective on 10 June 2004.\n\nBackground: The Swiss Federal Office for Civil Aviation (FOCA) has received reports of incidents on PC-12 series aeroplanes with the second battery installation where the 2nd battery was discharged due to loss of the 2nd generator output, without any failure being indicated.","sortOrder":1}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope. It addresses a specific unsafe condition identified in a particular aircraft configuration (PC-12 with second battery option) and mandates a targeted hardware replacement. There is no evidence of scope creep; the directive remains focused on the original safety issue of silent generator failure."},"complexity_factors":["Single, specific technical requirement with clear part numbers and reference to external technical document (Pilatus Service Bulletin)","Narrow applicability criteria requiring three conditions to be met simultaneously (specific aircraft model, serial number range, second battery option, specific GCU part number)","Two separate compliance deadlines with different timing requirements","Cross-reference to foreign aviation authority directive (FOCA Switzerland AD HB-2004-101)","Conditional note requiring additional service bulletins to be completed in certain configurations (generator and voltage regulator variants)"],"plain_english_summary":"Owners/operators of Pilatus PC‑12/PC‑12‑45 (s/n 101–507) with the factory second battery and GCU P/N 988.21.15.102 must replace that Generator Control Unit with P/N 988.21.15.103 per Pilatus Service Bulletin 24‑022. The swap is required at the next 100‑hour or annual inspection or within 90 days of 10 June 2004, and the old GCU is banned from future use immediately. This mandatory AD prevents silent generator failures and potential total electrical loss in flight."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The Directive stays narrowly focused on correcting a specific unsafe hardware condition (loss of 2nd generator output leading to second battery discharge) by mandating replacement of a specific part and prohibiting re‑installation of the older part. It does not expand the regulatory scope beyond that purpose (no new operational limits, no broadened applicability beyond the stated MSNs and battery option)."},"complexity_factors":["Narrow, specific applicability: MSNs 101–507 with second battery option (one paragraph)","Small number of defined part numbers: two GCUs (P/N 988.21.15.102 and 988.21.15.103)","Single mandated action plus an immediate prohibition (two requirements only)","One clear compliance deadline with two timing options (next 100‑hour or next annual, but no later than 90 days)","Cross-references to three Pilatus Service Bulletins (SB 24‑022 mandatory; SB 24‑010 and SB 24‑019 as related actions)","Reference to an external foreign authority AD (FOCA) but no extensive regulatory cross-references","No layered exceptions or multi-part conditional logic"],"plain_english_summary":"**What this directive does (mechanical change):**\n\n- It requires owners/operators of certain Pilatus PC-12 series aeroplanes to remove the Generator Control Unit (GCU) with part number (P/N) 988.21.15.102 and fit GCU P/N 988.21.15.103.  (GCU = the electronic unit that controls generator output; P/N = manufacturer part number.)\n- It also bans installation of the older GCU P/N 988.21.15.102 as a replacement part on affected aeroplanes from the effective date.\n\n**Which aircraft are affected (who this applies to):**\n\n- All Pilatus PC-12 and PC-12/45 aeroplanes with Manufacturer Serial Numbers (MSN) 101 through 507 that have the factory option for a second battery, and which do not already have GCU P/N 988.21.15.103 installed.\n\n**When and how to comply (timing and method):**\n\n- The replacement must be done in accordance with the Accomplishment Instructions of Pilatus Service Bulletin (SB) No. 24-022 (dated 13 June 2003).\n- Comply at the next 100‑hour inspection or the next annual inspection, but no later than 90 days after the Directive’s effective date.\n- The prohibition on fitting the older GCU is effective immediately from the Directive’s effective date.\n- Two other Pilatus service bulletins (SB 24‑010 Rev 1 and SB 24‑019 Rev 1) are identified as related and should be done before or at the same time as SB 24‑022 where applicable (for specific generator or voltage regulator installations).\n\n**Why the rule was issued (stated safety rationale):**\n\n- The Swiss aviation authority (FOCA) reported incidents where aeroplanes with the second battery option experienced loss of the second generator’s output without any failure indication, causing the second battery to become discharged. The Directive’s stated purpose is to correct that unsafe condition by installing the revised GCU.\n\nAnalysis of effects, costs and trade-offs (practical, implementation-focused):\n\n- Who pays: aircraft owners/operators (costs for the replacement GCU part, labour, possible inspection downtime). The AD requires compliance during scheduled inspection windows to limit unscheduled downtime.\n- Who decides / enforces: CASA’s delegate issued the Directive under the Civil Aviation Safety Regulations; compliance is mandatory for Australian-registered aeroplanes meeting the applicability criteria.\n- Behaviour changes enforced: remove and replace a specific component (GCU), and stop using the earlier GCU part as a replacement. This narrows permissible equipment choices for affected aeroplanes until another change is made.\n- Compliance burden: arranging procurement of the specified GCU, booking maintenance at the next 100‑hr/annual inspection or earlier, and following Pilatus SB instructions (which sets the technical steps). Maintenance may be performed by approved independent maintenance organisations following the SB.\n- Implementation risks and trade-offs: if replacement GCUs are in short supply, operators could face scheduling delays or higher costs; the requirement to comply within 90 days creates a hard deadline that may compress supply/repair capacity. There is also minor opportunity cost from diverting inspection time and workshop capacity to perform the replacement.\n- Market/competition impact: the AD prescribes a specific manufacturer part; it does not create new regulatory barriers to independent maintenance providers who can carry out the Service Bulletin work, but it does restrict use of the older GCU part number (limits operators’ ability to accept cheaper/used replacements of the older P/N).\n- Concentration of benefits and costs: safety benefit accrues to pilots/operators and passengers of affected aircraft (concentrated beneficiaries); costs are concentrated on those same aircraft owners/operators who must buy parts and arrange work.\n- Source link to international action: the AD references a corresponding FOCA (Switzerland) AD, indicating the action follows foreign authority findings rather than broad domestic rulemaking beyond correcting the identified hardware issue.\n\nKey references inside the Directive: applicability (which MSNs and battery option), Requirement 1 (replace P/N 988.21.15.102 with P/N 988.21.15.103 per Pilatus SB 24‑022), Requirement 2 (ban on installing P/N 988.21.15.102), Compliance timings (next 100‑hr/annual but within 90 days), and Background (FOCA reports of unexplained loss of 2nd generator output)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pc-12-41-generator-control-unit","history":"/api/acts/ad-pc-12-41-generator-control-unit/history","analysis":"/api/acts/ad-pc-12-41-generator-control-unit/analysis","conflicts":"/api/acts/ad-pc-12-41-generator-control-unit/conflicts","importantCases":"/api/acts/ad-pc-12-41-generator-control-unit/important-cases","documents":"/api/acts/ad-pc-12-41-generator-control-unit/documents"}}