{"id":"F2006B05390","name":"AD/PA-18/11 Amdt 1 - Lower Horizontal Stabiliser Brace Wire Fuselage Attachment Tab - Inspection and Modification","slug":"ad-pa-18-11-amdt-1-lower-horizontal-stabiliser-brace-wire-fuselage-attachment-tab-inspection-and-mod","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":46005,"registerId":"commonwealth-F2006B05390-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PA-18/11 Amdt 1 - Lower Horizontal Stabiliser Brace Wire Fuselage Attachment Tab - Inspection and Modification","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)  \nPiper PA-18 and 19 (Super Cub) Series Aeroplanes\n\nAD/PA-18/11\n\nAmdt 1\n\n  \n\nLower Horizontal Stabiliser Brace Wire Fuselage Attachment Tab - Inspection and Modification\n\n  \n12/81\n\nApplicability: All models PA-18-150 with S/Nos. 18-8602 to 18- 8109013.\n\nDocument: Piper Service Bulletin No. 706A. (FAA AD 81-06-80 Letter of 13-3-81 refers).\n\nNote: Aircraft modified to Piper SB No. 706 do not require further rework.\n\nCompliance: 1. Unless already accomplished, inspect within 100 hours time in service after 31 December 1981.\n\n2. Unless already accomplished, modify within 300 hours time in service after 31 December 1981.\n\nBackground: Revision “A” of Piper SB introduces a revised template shape for horizontal stabiliser brace wire additional support plate.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The amendment (Amdt 1) incorporates Piper Service Bulletin No. 706A (Revision A) as the required method and explicitly states that aircraft already modified under the earlier Piper SB No. 706 do not require further rework. Mechanically, the amendment therefore updates the prescribed modification to use the revised template shape (Background; Document) and clarifies which aircraft are exempt (Note), while maintaining the inspection and modification deadlines (Compliance 1–2)."},"complexity_factors":["Narrow aircraft applicability limited to a specific model and serial number range (Applicability).","Requirement references an external technical document (Piper Service Bulletin No. 706A) which contains the detailed method (Document).","Two-step compliance timetable with short-term inspection (100 hours) and later modification (300 hours) deadlines (Compliance 1–2).","Technical nature of modification (revised template for support plate) requires maintenance skill and possibly parts (Background).","Clear exemption for aircraft already modified under the earlier SB No. 706 reduces scope for some owners (Note)."],"plain_english_summary":"What this instrument requires\n\n- The Civil Aviation Safety Authority (under Part 39 of the Civil Aviation Regulations) requires owners/operators of certain Piper PA-18-150 aeroplanes to inspect and, if needed, modify the lower horizontal stabiliser brace wire fuselage attachment tab. (See header and \"Applicability\".)\n\nWho it affects\n\n- Applies to all Piper PA-18-150 aircraft with serial numbers 18-8602 through 18-8109013. (Applicability.)\n- Costs and work are borne by the aircraft owner/operator and by the maintenance provider they engage. The work is to be carried out in accordance with Piper Service Bulletin No. 706A. (Document.)\n\nWhat must be done and when\n\n- If the work has not already been done, the aircraft must be inspected within 100 hours time in service after 31 December 1981. (Compliance 1.)\n- If the work has not already been done, the modification must be completed within 300 hours time in service after 31 December 1981. (Compliance 2.)\n- Aircraft that have already been modified in accordance with Piper Service Bulletin No. 706 do not require further rework. (Note / Document.)\n\nWhat changed and why it matters mechanically\n\n- The amendment references Piper Service Bulletin No. 706A (Revision “A”) which introduces a revised template shape for the additional support plate used at the horizontal stabiliser brace wire fuselage attachment tab. That revised template is the basis for the required modification. (Background; Document.)\n\nOperational effects, incentives and trade-offs (mechanics, not judgment)\n\n- Who pays: the aircraft owner/operator pays for inspection and any modification work and for parts or shop labour required to implement the SB 706A modification. (Applicability; Document; Compliance.)\n- Who decides and enforces: the regulator (Civil Aviation Safety Authority) prescribes the mandatory action via this airworthiness directive under Part 39; compliance is achieved by following the referenced Piper service bulletin. (Header; Document.)\n- Compliance burden and timing: owners must schedule and complete an inspection within 100 hours and a modification within 300 hours of service since the specified date; those are concrete deadlines that require planning and use of maintenance resources. (Compliance 1–2.)\n- Implementation risk and required capability: the modification follows a specific manufacturer service bulletin (706A). Maintaining airworthiness will usually require a maintenance organisation or technician able to interpret and implement that bulletin. (Document; Background.)\n- Effects on private choice and market participants: independent maintenance providers and parts suppliers can perform the inspection and modification if they follow the service bulletin. Aircraft already modified under the earlier SB No. 706 are explicitly exempted from repeat work, so some owners avoid further expenditure. (Note; Document.)\n\nPractical trade-offs and opportunity cost\n\n- Operators must allocate maintenance hours and funds to meet the inspection and modification deadlines; that uses workshop capacity and may displace other maintenance work. (Compliance 1–2.)\n- The amendment ties the mandated fix to a manufacturer-prescribed template (SB 706A). That focuses corrective work on a specific engineering solution but requires access to the service bulletin and any parts or tooling it specifies. (Document; Background.)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a narrow, technical airworthiness directive focused on a specific aircraft part. It has not expanded beyond its original purpose of addressing a known safety defect in the Piper PA-18 stabiliser attachment."},"complexity_factors":["Single, clearly defined applicability (specific model and serial number range)","Only two compliance requirements with straightforward time-in-service deadlines","Single exemption clearly stated in a note","No defined terms section or complex cross-referencing","Background limited to one sentence explaining the technical change","Total length: approximately 150 words"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It applies to specific **Piper PA-18-150 Super Cub aircraft** (serial numbers 18-8602 through 18-8109013).\n\n**What it requires:**\n- **Inspection:** Owners must check a specific part — the lower horizontal stabiliser brace wire fuselage attachment tab — within 100 hours of flying time after 31 December 1981.\n- **Modification:** They must also install a revised support plate design within 300 hours of flying time after the same date.\n\n**Who it affects:**\n- Owners and operators of the affected Piper aircraft models.\n\n**Why it matters:**\n- This directive addresses a potential structural weakness in the aircraft's tail section. The brace wire attachment tab is critical for keeping the horizontal stabiliser (the small wings at the tail) properly secured. Failure of this component could lead to loss of control.\n\n**Key exemption:**\n- Aircraft already modified under an earlier Piper Service Bulletin (No. 706) don't need to do anything further — they're already compliant.\n\n**In short:** If you own one of these specific Super Cubs and haven't already fixed this issue, you were legally required to inspect and then modify a tail component by specific flight-hour deadlines back in 1981–1982."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pa-18-11-amdt-1-lower-horizontal-stabiliser-brace-wire-fuselage-attachment-tab-inspection-and-mod","history":"/api/acts/ad-pa-18-11-amdt-1-lower-horizontal-stabiliser-brace-wire-fuselage-attachment-tab-inspection-and-mod/history","analysis":"/api/acts/ad-pa-18-11-amdt-1-lower-horizontal-stabiliser-brace-wire-fuselage-attachment-tab-inspection-and-mod/analysis","conflicts":"/api/acts/ad-pa-18-11-amdt-1-lower-horizontal-stabiliser-brace-wire-fuselage-attachment-tab-inspection-and-mod/conflicts","importantCases":"/api/acts/ad-pa-18-11-amdt-1-lower-horizontal-stabiliser-brace-wire-fuselage-attachment-tab-inspection-and-mod/important-cases","documents":"/api/acts/ad-pa-18-11-amdt-1-lower-horizontal-stabiliser-brace-wire-fuselage-attachment-tab-inspection-and-mod/documents"}}