{"id":"F2006B06322","name":"AD/PR/23 - Feathering Springs - Operational Inspection","slug":"ad-pr-23-feathering-springs-operational-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47469,"registerId":"commonwealth-F2006B06322-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PR/23 - Feathering Springs - Operational Inspection","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 107 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nPropellers \\- Variable Pitch \\- Dowty Rotol\n\nAD/PR/23 Feathering Springs \\- Operational Inspection 12/83\n\nApplicability: Propeller Aircraft R306/3-82-F/7 Gulfstream Aerospace Commander 690C, 690D, 695 and 695A R321/4-82-F/8 Fairchild Aircraft SA-227AC (Metro III) R321/4-82- F/9 Fairchild Aircraft SA-227AT (Merlin IVC) R324/4-82-F/9 Fairchild Aircraft SA- 227TT (Merlin IIIC) R333/4-82-F/12 Jetstream 31 R334/4-82-F/13 CASA 212.\n\nRequirement: Carry out a ground feathering check in accordance with Dowty Rotol Service bulletin 61-A995.\n\nCompliance: (i) On fitment to the Aircraft prior to its first flight.\n\n(ii) For those propellers already installed, no later than 14 January 1984.\n\nBackground: In order to check that no undetected assembly failure exists, the manufacturer has deemed it necessary to carry out a once only feathering check.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive with a narrow, specific purpose. It has not expanded beyond its original intent of addressing a specific assembly failure risk in specific propeller models."},"complexity_factors":["Single, specific technical requirement with clear reference to manufacturer service bulletin","Limited applicability — only 8 specific aircraft models affected","Simple two-part compliance deadline (new fitment vs. existing installation)","No defined terms section, no cross-references to other legislation beyond the enabling Civil Aviation Regulations","Background explanation is straightforward and non-technical","Total length is approximately 200 words"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). Think of it like a compulsory vehicle recall notice, but for aircraft.\n\n**What it does:** It requires owners and operators of specific aircraft to perform a one-time safety check on their propellers. The check involves testing the \"feathering\" function — that's when the blades of a propeller are turned edge-on to the wind to reduce drag if an engine fails in flight. This is a critical safety feature that can mean the difference between a controlled glide and a crash.\n\n**Who it affects:** This applies to specific models of aircraft using Dowty Rotol variable-pitch propellers:\n- Gulfstream Commander 690C, 690D, 695 and 695A\n- Fairchild Metro III, Merlin IVC, and Merlin IIIC\n- British Aerospace Jetstream 31\n- CASA 212\n\n**What must be done:** A ground-based feathering check must be performed following the manufacturer's service bulletin (technical instruction manual).\n\n**When:** \n- For new propellers being installed: before the aircraft's first flight\n- For propellers already on aircraft: by 14 January 1984\n\n**Why it matters:** The manufacturer discovered a risk of undetected assembly failures in the feathering spring mechanism. Without this check, a propeller might not feather properly during an engine failure, potentially causing loss of control of the aircraft."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The instrument's scope is consistent with its stated purpose: it mandates a once‑only feathering check for the listed aircraft/propeller combinations to detect potential assembly failures. The text does not indicate any expansion or narrowing of that scope beyond the listed applicability and the two compliance deadlines."},"complexity_factors":["Narrow, clearly defined applicability limited to specific aircraft models and propeller type (Applicability).","Single, one‑off required action rather than recurring obligations (Requirement; Background).","Prescriptive deadline structure: before first flight after fitment, or a fixed calendar date for existing installations (Compliance).","Technical procedure delegated to an external document (Dowty Rotol Service Bulletin 61‑A995), requiring access to that bulletin (Requirement).","No procedural detail in the directive about enforcement, cost allocation, recordkeeping, or who exactly must perform the check, creating practical implementation questions despite simple mandate (Requirement; Compliance)."],"plain_english_summary":"What this instrument does (mechanically):\n\n- The Civil Aviation Safety Authority requires a one‑off ground feathering inspection of Dowty Rotol variable‑pitch propellers fitted to a specified list of propeller aircraft. The inspection must follow the procedure set out in Dowty Rotol Service Bulletin 61‑A995. (Requirement)\n\nWho is affected:\n\n- The directive applies to the listed aircraft models with the specified propellers: Gulfstream Aerospace Commander 690C, 690D, 695 and 695A; Fairchild SA‑227AC (Metro III); Fairchild SA‑227AT (Merlin IVC); Fairchild SA‑227TT (Merlin IIIC); Jetstream 31; and CASA 212. (Applicability)\n\nWhen it must be done:\n\n- If the propeller is fitted to an aircraft, the check must be done prior to that aircraft's first flight after fitment. (Compliance (i))\n- For propellers already installed on the listed aircraft, the check must be completed no later than 14 January 1984. (Compliance (ii))\n\nWhy the check is required (stated purpose):\n\n- The manufacturer stated the need for a once‑only feathering check to determine whether any undetected assembly failure exists. (Background)\n\nOperational mechanics and immediate effects:\n\n- The directive prescribes a specific maintenance action (a ground feathering check) to be performed in accordance with the named service bulletin. (Requirement)\n- Compliance is time‑bound: mandatory before first flight after fitment or by the specified calendar date for existing installations. (Compliance)\n\nWho pays and who decides:\n\n- The instrument is issued by the Civil Aviation Safety Authority (header). It prescribes the action and deadlines but does not allocate costs or specify enforcement penalties in the text provided. The entity responsible for meeting the requirement (for example, the aircraft operator, owner or maintenance organisation) must arrange for the inspection to be performed to the service bulletin standard. (Applicability, Requirement, Compliance)\n\nCompliance burden and implementation considerations:\n\n- The directive requires a single, prescriptive inspection event rather than ongoing recurring checks. (Background; Requirement)\n- The procedure to be followed is external to the directive and is the manufacturer’s service bulletin (Dowty Rotol Service Bulletin 61‑A995). The directive therefore delegates technical detail to that bulletin. (Requirement)\n- The text does not specify who must carry out the inspection (e.g. licensed maintenance organisation vs. owner‑operator), nor does it specify penalties, recordkeeping requirements or who bears the cost of downtime or labour. (Requirement; Compliance)\n\nTrade‑offs, incentives and risks (as grounded in the instrument):\n\n- Stated benefit: the manufacturer’s stated objective is detection of undetected assembly failures via a once‑only check. (Background)\n- Concrete cost/incentive effects in the text: the requirement imposes a one‑time action and associated resource/time use for those operating the affected aircraft. The directive relies on the service bulletin for technical steps; compliance therefore requires access to and implementation of that bulletin. The instrument does not describe how compliance will be monitored or enforced. (Requirement; Compliance)\n\nNet practical effect:\n\n- Owners/operators of the listed aircraft with the specified propellers must ensure a one‑time ground feathering check is performed according to Dowty Rotol Service Bulletin 61‑A995 either before first flight after fitment or by 14 January 1984 for existing installations. The manufacturer frames this as necessary to detect possible assembly failures. (Applicability; Requirement; Compliance; Background)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-pr-23-feathering-springs-operational-inspection","history":"/api/acts/ad-pr-23-feathering-springs-operational-inspection/history","analysis":"/api/acts/ad-pr-23-feathering-springs-operational-inspection/analysis","conflicts":"/api/acts/ad-pr-23-feathering-springs-operational-inspection/conflicts","importantCases":"/api/acts/ad-pr-23-feathering-springs-operational-inspection/important-cases","documents":"/api/acts/ad-pr-23-feathering-springs-operational-inspection/documents"}}