{"id":"F2006B02813","name":"AD/B737/109 Amdt 2 - Flying Control Power Control Unit Cylinder Bore Replacement","slug":"ad-b737-109-amdt-2-flying-control-power-control-unit-cylinder-bore-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42155,"registerId":"commonwealth-F2006B02813-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# ![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/B737/109 Amdt 1 and issues the following AD under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\n![](image.001.png)  \n\nBoeing 737 Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/B737/109","sectionType":"part","heading":"AD/B737/109","content":"# AD/B737/109\n\nAmdt 2\n\n  \n\nFlying Control Power Control Unit Cylinder Bore Replacement\n\n  \n11/2002","sortOrder":1},{"sectionNumber":"TX","sectionType":"part","heading":"TX","content":"# AD/B737/109\n\nAmdt 2\n\n  \n\nFlying Control Power Control Unit Cylinder Bore Replacement\n\n  \n11/2002\n\n# TX","sortOrder":2}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This appears to be a routine amendment (Amendment 2) to an existing Airworthiness Directive. The scope remains tightly focused on the original safety issue: the Power Control Unit cylinder bore in Boeing 737 aircraft. Amendment 2 likely updates technical instructions or compliance timeframes without expanding the scope beyond the original safety concern."},"complexity_factors":["Short, single-purpose directive focused on one specific mechanical component","Minimal defined terms — relies on standard aviation terminology (PCU, cylinder bore) assumed known to intended audience","Simple structure: applicability (Boeing 737), requirement (replacement), compliance (timeframe)","No nested exceptions or conditional logic visible in this extract","Cross-references limited to: (a) the regulation it is issued under (CAR 1998 subreg 39.1(1)), and (b) the previous version it revokes (AD/B737/109 Amdt 1)","Technical complexity exists in the engineering task itself, but the legal instrument is straightforward"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by the Civil Aviation Safety Authority (CASA) that requires specific repairs or inspections on aircraft.\n\n**What it does:**\nThis directive orders owners and operators of **Boeing 737 series aeroplanes** to replace the cylinder bore in the **Power Control Unit (PCU)** — a critical component of the aircraft's flying control system. The PCU is essentially the hydraulic 'muscle' that moves the plane's control surfaces (like ailerons, elevators, or rudders).\n\n**Why it matters:**\nThe cylinder bore is part of what makes the hydraulic system work. If it fails, pilots could lose control of the aircraft. This AD revokes an earlier version (Amendment 1) and replaces it with updated requirements.\n\n**Who must comply:**\n- Operators of Boeing 737 series aircraft\n- Maintenance organisations servicing these aircraft\n\n**What must happen:**\nThe specific replacement work must be carried out according to the instructions in the directive, within the timeframe specified in the compliance section (not fully shown in this extract).\n\n**Legal basis:**\nIssued under the **Civil Aviation Regulations 1998** (specifically subregulation 39.1(1)), which gives CASA the power to issue mandatory safety directives when an unsafe condition is found in an aircraft or aircraft part."},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":true,"description":"The instrument explicitly revokes AD/B737/109 Amdt 1 and issues AD/B737/109 Amdt 2 under subregulation 39.1(1) of CAR 1998, so the legal obligation on affected Boeing 737 operators has been altered by replacement of the prior amendment (see: \"revokes ... Amdt 1 and issues the following AD\"). The supplied text does not include the full requirement, compliance timing, or background content, so the precise substantive differences in technical or timing scope between Amdt 1 and Amdt 2 cannot be determined from the material provided."},"complexity_factors":["Legal mechanics: revocation of a prior AD and issuance of a new AD under CAR 1998 subregulation 39.1(1) (requires understanding of regulatory amendment process).","Technical specificity implied: the AD concerns replacement of a flying control power control unit cylinder bore — a component-level maintenance action likely requiring technical instructions not included in the provided text.","Dependence on external sections: the AD mandates actions referenced to a requirement section, compliance section and background section that are not reproduced here, creating analysis friction.","Operational impact: compliance timing and operational downtime considerations affect airline scheduling and maintenance planning.","Administrative discretion: the CASA delegate’s authority and decision to revoke and reissue the AD create a controlled but centralised decision point."],"plain_english_summary":"This AD replaces AD/B737/109 Amdt 1 and mandates replacement of the flying control power control unit cylinder bore on Boeing 737 series aeroplanes. Issued by a CASA delegate under CAR 1998, it legally obliges aircraft owners/operators and their maintenance/parts suppliers to perform the specified corrective work within the AD’s instructions and compliance times. Compliance imposes direct costs, downtime and logistical demands on operators."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-109-amdt-2-flying-control-power-control-unit-cylinder-bore-replacement","history":"/api/acts/ad-b737-109-amdt-2-flying-control-power-control-unit-cylinder-bore-replacement/history","analysis":"/api/acts/ad-b737-109-amdt-2-flying-control-power-control-unit-cylinder-bore-replacement/analysis","conflicts":"/api/acts/ad-b737-109-amdt-2-flying-control-power-control-unit-cylinder-bore-replacement/conflicts","importantCases":"/api/acts/ad-b737-109-amdt-2-flying-control-power-control-unit-cylinder-bore-replacement/important-cases","documents":"/api/acts/ad-b737-109-amdt-2-flying-control-power-control-unit-cylinder-bore-replacement/documents"}}