{"id":"F2006B10117","name":"AD/G21/3 - Horizontal Stabiliser Forward Attachment and Strut Upper Terminal - Inspection","slug":"ad-g21-3-horizontal-stabiliser-forward-attachment-and-strut-upper-terminal-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":55648,"registerId":"commonwealth-F2006B10117-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/G21/3 - Horizontal Stabiliser Forward Attachment and Strut Upper Terminal - Inspection","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nGrumman G21 (Goose) Series Aeroplanes\n\nAD/G21/3 Horizontal Stabiliser Forward Attachment\n\nand Strut Upper Terminal \\- Inspection\n\n  \n10/77\n\nApplicability: All models.\n\nRequirement: 1. Inspect visually the stabiliser forward attachment fittings P/Nos. 12548 and 12093 for cracks extending radially from the outside edge of the lugs to the inside of the hole into which the shoulder bushings are pressed.\n\n2. Inspect visually, the upper terminal P/N 12561-1 of stabiliser strut P/N 12560 for cracks extending radially from the outside edge of the lugs to the inside of the hole into which the shoulder bushings are pressed.\n\nNote: FAA AD 53-24-1 Amendment 39-1264 refers.\n\nCompliance: 1. Initially before issue of Certificate of Airworthiness and thereafter at intervals not exceeding 50 hours time in service.\n\n2. Initially before issue of Certificate of Airworthiness and thereafter at intervals not exceeding 100 hours time in service.\n\nFederal Register of Legislative Instruments F2006B10117","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive focused specifically on inspection requirements for two identified components of one aircraft type. It has not expanded beyond its original purpose of ensuring structural integrity of the horizontal stabiliser attachment points."},"complexity_factors":["Very short document (under 300 words)","Only 2 defined part numbers referenced (P/Nos. 12548, 12093, 12561-1, 12560)","Simple conditional structure: inspect X for Y, repeat every Z hours","No cross-references to other legislation beyond a single note about an FAA directive","Clear, unambiguous compliance deadlines","Single applicability clause ('All models') with no exceptions or exemptions"],"plain_english_summary":"This mandatory AD requires owners, operators and maintenance engineers of Grumman G21 “Goose” seaplanes to perform regular visual inspections of the horizontal stabiliser forward attachment fittings and the upper terminal of its supporting strut for cracks. Inspections are required before initial airworthiness and at repeating intervals (50 flight hours for the fittings, 100 hours for the strut terminal).  \n\nIt matters because detected cracking could lead to tail structural failure and loss of control; the directive prevents that by ensuring early detection."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"Scope is limited to inspection requirements for the listed stabiliser fittings on Grumman G21 series aircraft, with initial checks before Certificate of Airworthiness and recurring intervals (50 and 100 hours). The instrument text itself does not expand or narrow that scope beyond these specified parts and intervals."},"complexity_factors":["Narrow technical focus: inspects only two distinct component groups by part number (Requirement 1; Requirement 2).","Recurring, short intervals create operational impact and scheduling burden (Compliance: 50‑hour and 100‑hour intervals).","Inspection method is visual only, which is subjective and may require trained personnel to ensure consistency (Requirement 1; Requirement 2).","No detailed acceptance/repair criteria or non‑visual NDT mandated in the text, leaving follow‑up actions and judgement to operators/maintenance providers.","Cross-reference to FAA AD adds an external standard to consider (Note: FAA AD 53‑24‑1), potentially requiring consultation of another document.","Applicability stated as 'All models' focuses scope but may require fleet‑wide compliance even where utilisation differs."],"plain_english_summary":"**What it does:** This Airworthiness Directive requires operators of Grumman G21 (Goose) aeroplanes to carry out visual inspections for radial cracks on specified horizontal stabiliser forward attachment fittings (P/Ns 12548, 12093) and the stabiliser strut upper terminal (P/N 12561‑1).\n\n**When:** Inspections must be done initially before issue of a Certificate of Airworthiness and then every 50 hours (forward attachments) or 100 hours (upper terminal); the AD cites FAA AD 53‑24‑1."}},"importantCases":[],"_links":{"self":"/api/acts/ad-g21-3-horizontal-stabiliser-forward-attachment-and-strut-upper-terminal-inspection","history":"/api/acts/ad-g21-3-horizontal-stabiliser-forward-attachment-and-strut-upper-terminal-inspection/history","analysis":"/api/acts/ad-g21-3-horizontal-stabiliser-forward-attachment-and-strut-upper-terminal-inspection/analysis","conflicts":"/api/acts/ad-g21-3-horizontal-stabiliser-forward-attachment-and-strut-upper-terminal-inspection/conflicts","importantCases":"/api/acts/ad-g21-3-horizontal-stabiliser-forward-attachment-and-strut-upper-terminal-inspection/important-cases","documents":"/api/acts/ad-g21-3-horizontal-stabiliser-forward-attachment-and-strut-upper-terminal-inspection/documents"}}