{"id":"F2007L03995","name":"AD/PC-12/51 - Main Landing Gear Special Bolts","slug":"ad-pc-12-51-main-landing-gear-special-bolts","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":160789,"registerId":"commonwealth-F2007L03995-current","compilationNumber":null,"startDate":"2026-04-04","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Pilatus PC-12 Series Aeroplanes","sectionType":"division","heading":"Pilatus PC-12 Series Aeroplanes","content":"### Pilatus PC-12 Series Aeroplanes\n\n| AD/PC-12/51 | Main Landing Gear Special Bolts | 11/2007 |\n| ----------- | ------------------------------- | ------- |\n\n| Applicability: | All Model PC-12, PC-12/45 and PC-12/47 aircraft, with Manufacturer Serial Number 101 through MSN 749; equipped with MLG assemblies and special bolts as listed below:MLG assemblies part number, 532.10.12.037, 532.10.12.038, 532.10.12.041, 532.10.12.042, 532.10.12.043, 532.10.12.044, 532.10.12.047, 532.10.12.048, 532.10.12.049. 532.10.12.050, 532.10.12.051 and 532.10.12.052 delivered before31 December 2006; and held as a spare.Special bolts part number 532.10.12.110, 532.10.12.205. 532.10.12.077 and 532.10.12.202 delivered before 31 December 2006; and held as a spare.Modification kit numbers 500.50.12.267, 500.50.12.286, and 500.50.12.299 delivered before 31 December 2006; and held as a spare.                                                                                                                                                                                |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Perform an inspection of the special bolts that attach the MLG retraction actuators and the special bolts that attach the shock absorbers to the MLG assemblies to identify the serial numbers that start with the letters AT or have a supplier code AT; in accordance with paragraph 3.A. of PILATUS PC-12 Service Bulletin (SB) No. 32-020.If affected bolts are identified during the above inspection, before further flight, replace the affected special bolts with new bolts with new part numbers; in accordance with paragraph 3.B. of SB No. 32-020.2. Perform an inspection of applicable MLG assemblies held as spares, special bolts held as spares, and modification kits incorporating special bolts held as spares in accordance with paragraph 4. of SB No. 32-020. If affected bolts are identified, replace the affected special bolts.Note: Switzerland FOCA AD HB-2007-382 refers. |\n| Compliance:    | For Requirement 1 and 2: Within 100 hours time in service or 3 months after25 October 2007, whichever occurs first.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |\n|                | This Airworthiness Directive becomes effective on 25 October 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |\n\n| Background: | The manufacturer has determined that certain main landing gear bolts may be affected by hydrogen embrittlement. Bolts in this condition that are installed in the main landing gear have a decreased fatigue life, and unless detected and corrected, could lead to main landing gear collapse during operation. |\n| ----------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n7 September 2007","sortOrder":0},{"sectionNumber":"AD/PC-12/51","sectionType":"part","heading":"AD/PC-12/51","content":"## AD/PC-12/51","sortOrder":1},{"sectionNumber":"Main Landing Gear Special Bolts","sectionType":"part","heading":"Main Landing Gear Special Bolts","content":"## Main Landing Gear Special Bolts","sortOrder":2},{"sectionNumber":"11/2007","sectionType":"part","heading":"11/2007","content":"## 11/2007","sortOrder":3}],"analysis":{"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":5,"scope_assessment":{"changed":false,"description":"The directive applies only to the specifically listed aircraft serial numbers, MLG assembly and special-bolt part numbers, and kits delivered before 31 December 2006. The text does not indicate any expansion or narrowing of that scope beyond the stated applicability."},"complexity_factors":["Narrow, technical applicability defined by aircraft MSNs and multiple part numbers (Applicability)","Identification task requires reading serial-number prefixes or supplier codes on small components (Requirement 1 and 2)","Immediate safety consequence forces replacement \"before further flight\" for affected bolts (Requirement 1.B)","Two-tier compliance window (100 flight hours or 3 months) creates scheduling pressure for operators (Compliance)","Obligation covers both installed items and spares/kits, increasing inspection scope (Requirement 2)","Procedures reference an external service bulletin (Pilatus SB No. 32‑020), adding dependency on manufacturer documentation (Requirement)","Potential logistics burden to source replacement parts with new part numbers and complete maintenance actions","Recordkeeping and maintenance-release actions required to show compliance before flight"],"plain_english_summary":"This directive requires operators/owners of Pilatus PC‑12 aircraft (MSN 101–749) with specified MLG assemblies, special bolts or modification kits delivered before 31 December 2006 to inspect bolts for serial numbers or supplier code starting “AT” and, if found, replace those bolts with new part numbers as described in Pilatus SB No. 32‑020. Compliance for installed items and spares is within 100 flight hours or three months after 25 October 2007. The action responds to a manufacturer finding of possible hydrogen embrittlement that can reduce bolt fatigue life and risk landing gear collapse."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a standard, targeted airworthiness directive addressing a specific safety defect. The scope remains tightly focused on the identified hydrogen embrittlement issue in specific bolt batches. The inclusion of spare parts is standard practice for ADs to prevent reintroduction of defective parts into service."},"complexity_factors":["Multiple nested applicability conditions (aircraft models, serial number ranges, specific part numbers, delivery dates, and spare parts status)","Cross-reference to external technical document (Pilatus Service Bulletin No. 32-020) for detailed inspection and replacement procedures","Specific identification criteria requiring interpretation of serial number prefixes and supplier codes","Dual compliance pathway (inspection followed by conditional replacement if affected parts found)","Separate but parallel requirements for installed aircraft components versus spare parts inventory"],"plain_english_summary":"This CASA Airworthiness Directive requires owners/operators of Pilatus PC‑12 (serials 101–749) to inspect and, if needed, replace certain main landing‑gear bolts (and spares) delivered before 31 Dec 2006 that may suffer hydrogen embrittlement. Affected bolts must be grounded and replaced before flight to prevent fatigue cracking that could cause MLG collapse. Actions are required within 100 flight hours or three months after 25 Oct 2007."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pc-12-51-main-landing-gear-special-bolts","history":"/api/acts/ad-pc-12-51-main-landing-gear-special-bolts/history","analysis":"/api/acts/ad-pc-12-51-main-landing-gear-special-bolts/analysis","conflicts":"/api/acts/ad-pc-12-51-main-landing-gear-special-bolts/conflicts","importantCases":"/api/acts/ad-pc-12-51-main-landing-gear-special-bolts/important-cases","documents":"/api/acts/ad-pc-12-51-main-landing-gear-special-bolts/documents"}}