{"id":"F2019L01376","name":"AD/UH-1/20 Amdt 2 Tail Boom and Fin - Fretting and Cracking","slug":"ad-uh-1-20-amdt-2-tail-boom-and-fin-fretting-and-cracking","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":100218,"registerId":"commonwealth-F2019L01376-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Bell Helicopter Textron UH-1 (All Varian","sectionType":"part","heading":"Bell Helicopter Textron UH-1 (All Variants) Series Helicopters","content":"# Bell Helicopter Textron UH-1 (All Variants) Series Helicopters\n\n| AD/UH-1/20 Amdt 2 | Tail Boom and Fin - Fretting and Cracking | 22/2019 |\n| ----------------- | ----------------------------------------- | ------- |\n\n| Applicability: | All models of Bell Helicopter Textron Inc UH-1 (All Variants) Series Helicopters. |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | 1. Visually inspect the tail boom skin joint at tail boom Station 194 for fretting or cracking (inspect 10 inches forward and 10 inches aft of Station 194 as per Figures 1. and 2 below) .2. Visually inspect the vertical fin front spar cap at its intersection with the tail rotor gear box support fitting for cracks as per Figure 1.3. Conduct a radiographic inspection using a CASA approved procedure, or approved alternative procedure, of the tail boom skin at Station 194 splice joint. (inspect 10 inches forward and 10 inches aft of Station 194 as per Figures 1. and 2 below).4. Replace any cracked skin panels found while performing Requirement 1 or Requirement 3 inspections, with serviceable panels.5. Replace any cracked fin spar caps found while performing Requirement 2 inspection, with serviceable parts. |\n| Compliance: | 1.and 2 a. Within 100 hours’ time in service after the commencement date of this AD.b. At intervals no greater than 100 hours’ time in service thereafter.3. a. Within 90 days of the commencement date of this AD.b. At intervals no greater than 500 hours’ time in service thereafter.4. and 5. Before further flight. |\n| | This AD commences on 25 October 2019. |\n| | Note 1: Federal Aviation Administration of the United States of America (FAA) Airworthiness Directive (AD) 83-03-03 Amdt 39-4556 (FAA AD) has been referenced as a source document for Figure 1.Note 2: National Transportation Safety Board of the United States of America (NTSB) Safety Recommendation(s) A-82-52 has been referenced as a source document for Figure 2. |\n\n| | Note 3: CASA may approve a radiographic inspection procedure designed by an NDT Level 3 from ASTM Standards and recommended by the National Aerospace Non-Destructive Testing Board for accomplishing Requirement 2 for this AD. CASA Airworthiness Bulletin (AWB) 02‑060 Issue 01 “NDT Data - The Use of During the Course of Maintenance” guidance material refers.Note 4: An alternate non-destructive inspection method, other than the radiographic inspection method detailed in the AD, can be used if approved by CASA in writing. |\n| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Background: | FAA AD 83-03-03 Amdt 39-4556 with an effective date of 14 March 1983 was issued to detect cracks and prevent possible failure of the tail boom and fin. The FAA had determined that tail boom skin cracks occurred in a model UH-1B which crashed. A metallurgical examination revealed cracks to be due to structural fatigue.Since this condition is likely to exist or develop on other helicopters of the same design, the FAA AD was issued. The AD requires visual and radiographic inspections for fretting and cracking, and repair or replacement, as necessary, of the tail boom skin and the fin spar cap on Bell Helicopter Textron Inc Model UH-1 series helicopters.CASA’s predecessor conducted a review of FAA AD 83-03-03 Amdt 39-4556 on 9 March 1983. At the time of the review no Bell Helicopter Textron Inc UH-1 (All Variants) series helicopters were on the Australian civil aircraft register.It has since come to CASA’s attention that Bell Helicopter Textron Inc UH-1 series helicopters have now been placed on the Australian civil aircraft register and will require inspections to be accomplished in accordance with FAA AD 83-03-03 Amdt 39-4556. Consequently, CASA issued AD/UH-1/20 to mandate the requirements of the FAA AD.Amendment 1 of this AD corrected a reference to FAA Advisory Circular 43-13B Change 1, which has been removed with the issue of Amendment 2.Amendment 2 of this AD clarifies the intent of the original FAA AD 83-03-03 to reflect contemporary circumstances. It inserts references to the associated FAA AD and NTSB Safety Recommendations as source documents for Figures 1 and 2 respectively. Amendment 2 of this AD also provides guidance for proposing and approving of a radiological or alternative inspection procedures. It also extends the previous compliance time from 14 days to 90 days to allow sufficient time for the development of appropriate CASA approved NDT procedures and industry capacity to conduct the inspection activities. |\n\n![](image.001.png)\n\nFigure 1.\n\n![](image.002.png)\n\nFigure 2.\n\n![A drawing of a face\nDescription automatically generated](image.003.jpeg)\n\nPieter van Dijk \nDelegate of the Civil Aviation Safety Authority\n\n25 October 2019","sortOrder":0},{"sectionNumber":"AD/UH-1/20 Amdt 2","sectionType":"part","heading":"AD/UH-1/20 Amdt 2","content":"## AD/UH-1/20 Amdt 2","sortOrder":1},{"sectionNumber":"Tail Boom and Fin - Fretting and Crackin","sectionType":"part","heading":"Tail Boom and Fin - Fretting and Cracking","content":"## Tail Boom and Fin - Fretting and Cracking","sortOrder":2},{"sectionNumber":"22/2019","sectionType":"part","heading":"22/2019","content":"## 22/2019","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":true,"description":"Amendment 2 refines and extends the original instrument: it clarifies the FAA and NTSB documents as source material for the inspection figures, provides a CASA approval pathway for radiographic or alternative NDT procedures (including allowance for procedures designed by an NDT Level 3 and referenced ASTM guidance), and extends the initial compliance window from 14 days to 90 days to allow time for CASA‑approved procedure development and industry capability. The AD also applies the FAA inspection requirements to UH‑1 helicopters now on the Australian register, which were not present at the time of the original 1983 FAA review."},"complexity_factors":["Two inspection methods required: visual inspections and radiographic (NDT) inspections with differing intervals (visual: 100 hours; radiographic: within 90 days then every 500 hours).","Radiographic procedures must be approved by CASA or an approved alternative, requiring operator submission and CASA discretion.","Mandatory replacement of cracked tail‑boom skin panels or fin spar caps before further flight (immediate grounding until rectified).","Applicability to all Bell UH‑1 variants on the Australian civil register increases the universe of affected operators.","References to external source documents (FAA AD and NTSB recommendations) and reliance on supplied figures for inspection locations.","Amendment 2 introduces procedural guidance for proposing/approving NDT methods and extends earlier short compliance time to allow industry capacity development."],"plain_english_summary":"**This AD** mandates periodic visual and CASA‑approved radiographic inspections of the UH‑1 tail boom and fin, and requires replacement of any cracked tail‑boom skin or fin spar cap before further flight. It applies to all Bell UH‑1 series helicopters on the Australian civil register to detect fretting and fatigue cracking and reduce the risk of structural failure.\n\nOperators pay for inspections and repairs, must comply with specified inspection intervals and obtain CASA approval for radiographic or alternative NDT procedures; CASA decides approvals in writing."},"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"},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This amendment remains tightly focused on its original purpose: ensuring structural integrity of UH-1 tail booms and fins. Amendment 2 makes procedural clarifications and extends compliance timeframes but does not expand the scope beyond the original safety intent established by the referenced FAA AD 83-03-03."},"complexity_factors":["Multiple inspection types with different intervals (visual every 100 hours vs radiographic every 500 hours)","Specific technical references to aircraft structural locations (Station 194, tail boom skin joint, vertical fin front spar cap)","Cross-references to external documents (FAA AD 83-03-03, NTSB Safety Recommendations, CASA Airworthiness Bulletin AWB 02-060)","Conditional compliance requirements (different deadlines for initial vs recurring inspections)","Approval requirements for alternative procedures (requires written CASA approval)","Amendment history tracking (references to Amendment 1 and original AD intent)"],"plain_english_summary":"This AD mandates recurring inspections of Australian-registered Bell UH-1 helicopters’ tail boom (Station 194) and vertical fin attachment for fretting and fatigue cracks — visual checks every 100 flight hours and radiographic inspections every 500 hours — and requires replacing any cracked parts before flight. It responds to a fatigue-related UH-1B crash and aligns with the FAA rule; Amendment 2 extends initial compliance to 90 days and clarifies approval for alternative inspection methods."}},"importantCases":[],"_links":{"self":"/api/acts/ad-uh-1-20-amdt-2-tail-boom-and-fin-fretting-and-cracking","history":"/api/acts/ad-uh-1-20-amdt-2-tail-boom-and-fin-fretting-and-cracking/history","analysis":"/api/acts/ad-uh-1-20-amdt-2-tail-boom-and-fin-fretting-and-cracking/analysis","conflicts":"/api/acts/ad-uh-1-20-amdt-2-tail-boom-and-fin-fretting-and-cracking/conflicts","importantCases":"/api/acts/ad-uh-1-20-amdt-2-tail-boom-and-fin-fretting-and-cracking/important-cases","documents":"/api/acts/ad-uh-1-20-amdt-2-tail-boom-and-fin-fretting-and-cracking/documents"}}