{"id":"F2006B06357","name":"AD/PT6A/16 - Improved Strength P.T. Shaft Housing and Reduction Gearbox Condition Monitoring","slug":"ad-pt6a-16-improved-strength-p-t-shaft-housing-and-reduction-gearbox-condition-monitoring","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47585,"registerId":"commonwealth-F2006B06357-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PT6A/16 - Improved Strength P.T. Shaft Housing and Reduction Gearbox Condition Monitoring","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nPratt and Whitney Canada Turbine Engines \\- PT6A Series\n\nAD/PT6A/16 Improved Strength P.T. Shaft Housing and\n\nReduction Gearbox Condition Monitoring\n\n  \n10/85\n\nApplicability: All PT6A-6, \\-6A, \\-6B, \\-6/C20, \\-20, \\-20A, 20B, \\-21. PT6B-9, PT6A-27, \\-28, \\-34.\n\nRequirement: 1. Modify affected engine fitted with the P.N 3010548 welded power turbine shaft housing by incorporation of UACL SB No. 1138, Rev. 3.\n\nNote: Information regarding affected engine model S/Nos., etc. will be found in UACL SBs No. 1138, Rev. 3 and 1217, Rev. 4.\n\n    2. Modify all affected engines by installation of a magnetic chip detector in accordance with paragraphs 2.A.1. and 2.A.2 of UACL SB No. 1217, Rev. 4.\n\n    3. For engines modified in accordance with paragraph 2 above, check the magnetic chip detector pins for electrical continuity using any utility volt ohmmeter. If continuity is detected, remove the detector and inspect the magnetic pole pieces for contaminants and also perform the oil filter inspection described in paragraph 4 below. Determine subsequent action in accordance with the guidance provided in the paragraphs relating to oil filter element inspections in Part 3, Section 3 of the latest issue of the applicable engine Maintenance Manual.\n\n    4. For all engines, remove the main engine oil filter element and inspect visually for signs of metallic contamination. If no visible contamination is present, use a ten power magnifying glass and magnet (minimum lift 225 grammes (8 oz)) to further inspect the element for magnetic and non-magnetic particles. Determine subsequent action in accordance with the guidance provided in the paragraphs relating to oil filter element inspections in Part 3 Section 3 of the latest issue of the applicable engine maintenance manual.\n\nCompliance: For Para. 1 \\- during the next overhaul shop visit but not later than next engine reconditioning after 30 April 1975.\n\nFor Para. 2 \\- For engines requiring modification in accordance with Para. 1 \\- as soon as the necessary parts are available, but not later than 30 October 1975. For all other affected engines - not later than 31 January 1976.\n\nFor Para. 3 \\- At intervals not exceeding 25 hours time in service after 30 April 1975\\. For Para. 4 \\- At intervals not exceeding 50 hours time in service after 30 April 1975.\n\nNote 1: Notwithstanding the foregoing, when engines comply with the requirements of Australian AD/UAC-T/26 the oil filter and chip detector check and inspection intervals may revert to those called for in the normal aircraft maintenance procedures.\n\nNote 2: To comply with the certification requirements of Air Navigation Orders, certifications must include reference to the parts of this Directive complied with.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nor AD/UAC-T/23D.\n\nBackground: This Directive is raised in issue in order to allow oil filter and chip detector check to revert to normal aircraft maintenance inspection periods, when certain power turbine blade containment modifications are included in the engine build status (Ref.\n\nAD/UAC-T/26).","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This directive maintains its original narrow scope — safety modifications for specific PT6A engine models. The background note clarifies that the directive was reissued solely to incorporate a cross-reference to related blade containment modifications (AD/UAC-T/26), allowing inspection interval relief. This is a technical amendment rather than scope expansion."},"complexity_factors":["Multiple cross-references to external documents (UACL Service Bulletins 1138 Rev. 3 and 1217 Rev. 4, and engine Maintenance Manuals)","Four distinct compliance deadlines with different applicability conditions (overhaul visits vs. calendar dates vs. hours in service)","Conditional logic: Paragraph 3 inspections only apply to engines modified under Paragraph 2","Nested exception in Note 1 allowing reversion to normal procedures if AD/UAC-T/26 compliance is achieved","Technical aviation terminology requiring specialized knowledge (P/N, S/Nos., magnetic chip detectors, power turbine shaft housing)","Dual measurement systems (metric grammes and imperial ounces)"],"plain_english_summary":"This mandatory Airworthiness Directive requires operators of certain Pratt & Whitney Canada PT6A and PT6B-9 engines to fit a strengthened power turbine shaft housing, add magnetic chip detectors, and institute regular inspections of detectors and oil filters. It targets aircraft like King Airs, Cessna Caravans, and similar turboprops to prevent catastrophic turbine-shaft failures by enabling early detection of internal damage. Operators who install approved blade-containment modifications can revert to normal maintenance intervals."},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"This directive modifies earlier inspection requirements by allowing oil‑filter and chip‑detector check intervals to revert to normal maintenance periods when specified blade‑containment modifications (AD/UAC‑T/26) are incorporated. Previously the AD imposed more frequent checks from set dates; the current text makes those intervals conditional on additional modifications being present, shifting some ongoing inspection burden back to standard maintenance if the condition is met."},"complexity_factors":["Multiple engine models listed across PT6A and PT6B series, increasing applicability tracking","Cross‑references to two specific UACL Service Bulletins (No.1138 Rev.3 and No.1217 Rev.4) for the technical modifications","Prescribed inspection methods and a minimum magnetic lift (225 grammes) for oil filter checks","Different compliance timelines for retrofit and detector installation depending on overhaul status and parts availability","Conditional provision allowing reversion to normal maintenance intervals when another AD (AD/UAC‑T/26) is complied with","Requirement to follow maintenance manual guidance for subsequent action introduces reliance on up‑to‑date manuals"],"plain_english_summary":"Requires operators of the listed Pratt & Whitney Canada PT6A and PT6B engines to retrofit an improved power‑turbine shaft housing (per UACL SB No.1138 Rev.3), install a magnetic chip detector (per UACL SB No.1217 Rev.4), and carry out prescribed chip‑detector and oil‑filter inspections at set intervals and deadlines. The directive says this work lets oil‑filter and chip‑detector checks revert to normal maintenance intervals when certain power‑turbine blade‑containment modifications (AD/UAC‑T/26) are present. It creates parts, inspection and record‑keeping obligations for engine owners and maintenance organisations."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pt6a-16-improved-strength-p-t-shaft-housing-and-reduction-gearbox-condition-monitoring","history":"/api/acts/ad-pt6a-16-improved-strength-p-t-shaft-housing-and-reduction-gearbox-condition-monitoring/history","analysis":"/api/acts/ad-pt6a-16-improved-strength-p-t-shaft-housing-and-reduction-gearbox-condition-monitoring/analysis","conflicts":"/api/acts/ad-pt6a-16-improved-strength-p-t-shaft-housing-and-reduction-gearbox-condition-monitoring/conflicts","importantCases":"/api/acts/ad-pt6a-16-improved-strength-p-t-shaft-housing-and-reduction-gearbox-condition-monitoring/important-cases","documents":"/api/acts/ad-pt6a-16-improved-strength-p-t-shaft-housing-and-reduction-gearbox-condition-monitoring/documents"}}