{"id":"F2006B10118","name":"AD/G21/4 - Rudder Control Push-Rod Assembly P/N 12727-1 - Inspection","slug":"ad-g21-4-rudder-control-push-rod-assembly-p-n-12727-1-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":55651,"registerId":"commonwealth-F2006B10118-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/G21/4 - Rudder Control Push-Rod Assembly P/N 12727-1 - 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/G21/4 Rudder Control Push-Rod Assembly P/N 12727-1 - Inspection\n\n  \n10/77\n\nApplicability: All models.\n\nRequirement: 1. Remove rudder control push rod assembly P/N 12727-1.\n\n    2. Thoroughly clean both rod end fittings.\n\n    3. Inspect both fittings for cracks using a dye penetrant technique in conjunction with at least a 10X magnifying glass.\n\nNote 1. Push rod assembly P/N 12727-1 is connected to the LH rudder pedals and is located below the pilot’s compartment floor approximately 240 mm to the right of the aircraft centre line.\n\nNote 2. FAA AD 63-27-2 Amendment 655 refers.\n\nCompliance: Inspect initially before issue of Certificate of Airworthiness and thereafter at intervals not exceeding 100 hours time in service.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD applies to all models of the Grumman G21 and addresses inspection of a specific push‑rod assembly (P/N 12727-1). The instrument sets an initial and recurring inspection schedule and specifies the inspection technique. There is no text in the AD indicating a change in scope from an earlier or original intent; it implements a narrowly scoped inspection mandate consistent with ensuring airworthiness of that component (Requirement; Note 1; Compliance; Note 2)."},"complexity_factors":["Narrow technical scope — single part (P/N 12727-1) and specific fittings reduce breadth of obligations","Explicit, stepwise procedure (remove, clean, dye‑penetrant inspect with ≥10X magnification) reduces interpretive ambiguity","Recurring timing requirement (initial before Certificate of Airworthiness, then ≤100 hours TIS) creates operational scheduling complexity","Requires specific inspection technique and equipment (dye‑penetrant, ≥10X magnifier) — technical competence and tools necessary","Cross‑reference to FAA AD introduces an external document that may need to be consulted for background","AD mandates inspection only and does not specify corrective actions, leaving follow‑on decisions to maintenance/airworthiness authorities"],"plain_english_summary":"## What this directive does\n\nThis Airworthiness Directive (AD) requires a specific inspection of the rudder control push‑rod assembly with part number 12727-1 fitted to Grumman G21 (Goose) aeroplanes (applies to all models). Mechanically, it requires: 1) removal of the push‑rod assembly, 2) thorough cleaning of both rod end fittings, and 3) a crack inspection of both fittings using a dye‑penetrant technique together with at least a 10X magnifying glass. (Requirement)\n\nThe AD identifies the component location: it is connected to the left‑hand rudder pedals and located below the pilot’s compartment floor about 240 mm right of the aircraft centre line. (Note 1)\n\nIt cross‑refers an FAA directive (FAA AD 63‑27‑2 Amendment 655). (Note 2)\n\n## When it must be done\n\nThe inspection must be carried out before the issue of a Certificate of Airworthiness and then repeated at intervals not exceeding 100 hours time in service. (Compliance)\n\n## Who it affects and who pays\n\n- Who it affects: Owners/operators of Grumman G21 aeroplanes that have push‑rod assembly P/N 12727-1 fitted.\n- Who pays: Owners/operators must arrange and fund the removal, cleaning and the dye‑penetrant inspection (Requirement; Compliance).\n- Who decides/does the work: A maintenance organisation or authorised personnel must remove the assembly and carry out the specified inspection technique (Requirement).\n\n## Practical consequences and implementation mechanics\n\n- Compliance imposes a recurring maintenance task (initial check before Certificate of Airworthiness, then every 100 hours). That creates recurring direct costs (labour, materials, outage time) and scheduling needs for operators. (Compliance)\n- The inspection technique is specified: dye‑penetrant plus at least a 10X magnifier. Operators must have access to the technique and tools and apply them to both rod end fittings. (Requirement)\n- The AD specifies the inspection only; it does not state corrective actions or replacements to be taken if cracks are found. That implies follow‑on work (repairs or part replacement) would be governed by maintenance standards/airworthiness rules or other documents. (Requirement)\n- Initial compliance is a prerequisite to issuing a Certificate of Airworthiness, so non‑compliance blocks certification of the aircraft. (Compliance)\n\n## Trade‑offs, burdens and risks (mechanisms, not conclusions)\n\n- The principal burden is recurring maintenance time and cost for removal, cleaning and dye‑penetrant inspection every 100 hours and prior to first CoA. (Compliance; Requirement)\n- Inspection effectiveness depends on proper application of the dye‑penetrant technique and appropriate magnification; inspection quality therefore affects the AD’s practical ability to detect cracks. The AD sets the minimum method and magnification but not the detailed acceptance criteria. (Requirement)\n- The AD aligns with an FAA action by cross‑reference, which means operators and maintainers may need to consider related or underlying FAA material to understand context. (Note 2)\n\nSources cited in this summary: Requirement; Note 1; Note 2; Compliance."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive focused on one specific mechanical component. It has not expanded beyond its original purpose of ensuring the structural integrity of the rudder control push-rod assembly."},"complexity_factors":["Single, discrete maintenance task with only 3 procedural steps","No defined terms section or interpretation provisions","No cross-references to other legislation (only a reference to a related FAA directive in a non-binding note)","Simple conditional logic: initial inspection + recurring 100-hour intervals","Extremely short document (approximately 150 words of substantive content)","Clear applicability statement ('All models') with no exceptions or carve-outs"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by the Civil Aviation Safety Authority (CASA) that requires owners and operators of specific aircraft to perform specific maintenance checks.\n\n**Who it affects:** Owners and operators of **Grumman G21 (Goose) series aeroplanes** — a type of amphibious aircraft originally built in the 1930s-1940s.\n\n**What it requires:**\n- **Remove** a specific rudder control component (push-rod assembly part number 12727-1)\n- **Clean** both end fittings thoroughly\n- **Inspect** both fittings for cracks using dye penetrant (a chemical that seeps into cracks to make them visible) and at least 10x magnification\n\n**When to do it:**\n- **First time:** Before the aircraft can get its Certificate of Airworthiness (basically, before it's allowed to fly legally)\n- **Ongoing:** Every 100 hours of flight time\n\n**Why it matters:** This component connects to the left-hand rudder pedals and sits beneath the pilot's floor. If it cracks and fails, the pilot could lose rudder control — a serious safety risk. The directive references an earlier US Federal Aviation Administration (FAA) safety order (AD 63-27-2), showing this addresses a known defect pattern.\n\n**The bottom line:** If you own or operate a Grumman Goose, you legally must inspect this specific rod regularly for cracks, or the aircraft cannot fly."}},"importantCases":[],"_links":{"self":"/api/acts/ad-g21-4-rudder-control-push-rod-assembly-p-n-12727-1-inspection","history":"/api/acts/ad-g21-4-rudder-control-push-rod-assembly-p-n-12727-1-inspection/history","analysis":"/api/acts/ad-g21-4-rudder-control-push-rod-assembly-p-n-12727-1-inspection/analysis","conflicts":"/api/acts/ad-g21-4-rudder-control-push-rod-assembly-p-n-12727-1-inspection/conflicts","importantCases":"/api/acts/ad-g21-4-rudder-control-push-rod-assembly-p-n-12727-1-inspection/important-cases","documents":"/api/acts/ad-g21-4-rudder-control-push-rod-assembly-p-n-12727-1-inspection/documents"}}