{"id":"F2006B05962","name":"AD/PA-38/23 - Upper Forward and Aft Vertical Fin Spar - Inspection and Reinforcement","slug":"ad-pa-38-23-upper-forward-and-aft-vertical-fin-spar-inspection-and-reinforcement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":136133,"registerId":"commonwealth-F2006B05962-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PA-38/23 - Upper Forward and Aft Vertical Fin Spar - Inspection and Reinforcement","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Piper PA-38 (Tomahawk) Series Aeroplanes\n\n \n\n# AD/PA-38/23 Upper Forward and Aft Vertical Fin\n\nSpar - Inspection and Reinforcement Applicability: All model PA-38-112 with S/Nos. 38-78A0001 to 38-82A0122. Document:               Piper Service Bulletin No. 763.\n\n# 9/83\n\nCompliance:   On vertical fins which have achieved 500 hours time in service, within 25 hours time in service and thereafter at intervals not exceeding 100 hours time in service until Kit 764-965 is installed.\n\n \n\nBackground:  Field reports indicate that cracks have occurred in the area where the horizontal stabiliser attachment brackets attach to the upper end of the vertical fin forward and aft spars.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The supplied directive does not indicate any change from an earlier scope or a modification of applicability. It sets a clear, specific scope (PA-38-112 with serial numbers 38-78A0001 to 38-82A0122) and a procedural compliance path (inspections tied to time-in-service until Kit 764-965 is installed). There is no information in the supplied text showing that the scope has been expanded or narrowed from a prior version."},"complexity_factors":["Narrow and explicit applicability limited to a specific model and serial-number range (reduces scope complexity). (Applicability)","Timing rules mix a threshold (500 hours TIS), a short follow-up window (within 25 hours TIS), and a recurring interval (≤100 hours TIS) which requires careful tracking of component time-in-service. (Compliance)","Requirement continues until a specified reinforcement kit (Kit 764-965) is installed; operators must decide between repeated inspections or one-off kit installation. (Compliance)","Technical details of how to inspect/reinforce are delegated to Piper Service Bulletin No. 763, so compliance depends on an external document for the procedures. (Document: Piper Service Bulletin No. 763)","Background identifies a specific cracking location, which narrows the inspection focus but implies potential repair complexity if cracking is found. (Background)"],"plain_english_summary":"### What this directive does\n\nThis airworthiness directive applies to a specific set of Piper PA-38-112 (Tomahawk) aeroplanes (serial numbers 38-78A0001 to 38-82A0122) and requires repeated inspections of the upper forward and aft vertical fin spars where the horizontal stabiliser attachment brackets attach. The inspections are intended to detect cracks in that area and must continue until a reinforcement kit (Kit 764-965) is fitted. (See: Applicability; Document: Piper Service Bulletin No. 763; Compliance; Background.)\n\n### Who it affects\n\n- Owners and operators of the listed PA-38-112 aeroplanes (those within the specified serial-number range). (Applicability)\n- The manufacturer or approved maintenance organisations that supply and install Kit 764-965, and that may perform the inspections specified in the service bulletin. (Document: Piper Service Bulletin No. 763)\n\n### How it works mechanically\n\n- Trigger for inspections: When a vertical fin has reached 500 hours time in service, an inspection must be carried out within 25 hours time in service. After that first inspection, inspections must be repeated at intervals not exceeding 100 hours time in service. These recurring inspections continue until Kit 764-965 is installed on that fin. (Compliance)\n- Reference procedure: The directive relies on Piper Service Bulletin No. 763 for the inspection/reinforcement work. (Document: Piper Service Bulletin No. 763)\n- Safety concern prompting the directive: Field reports of cracks at the locations where the horizontal stabiliser attachment brackets attach to the upper end of the vertical fin forward and aft spars. (Background)\n\n### Who pays, who decides, and what changes in behaviour\n\n- Who decides: The Civil Aviation Safety Authority issued the directive (it is presented as a Schedule of Airworthiness Directives). (header)\n- Who pays: Aircraft owners/operators must bear the costs of performing the mandated inspections and of purchasing and installing Kit 764-965 when they choose to fit it. Maintenance providers may charge for labour and parts. (Applicability; Document; Compliance)\n- Behaviour changes required: Operators must (a) monitor time in service for the affected fins, (b) carry out the initial inspection within the 25-hour window after 500 hours TIS and then at intervals not exceeding 100 hours TIS, and (c) install Kit 764-965 to remove the need for further recurring inspections on that fin. (Compliance)\n\n### Incentives, costs and trade-offs (mechanical, not political)\n\n- Incentive to install the kit: Installing Kit 764-965 ends the need for ongoing 100‑hour inspections for that fin, so operators trade a one‑off kit and installation cost for lower ongoing inspection burden and downtime. (Compliance)\n- Ongoing compliance cost: Until the kit is fitted, operators face recurring inspection labour and aircraft downtime every ≤100 hours time in service, plus recordkeeping and possibly repair costs if cracks are found. (Compliance; Background)\n- Implementation risk and discretion: The directive refers to a Piper service bulletin for technical steps, so the precise inspection method and reinforcement fitment depend on the procedures in that bulletin and on maintenance organisations' adherence to it. The directive sets the timing requirement but delegates the technical steps to the referenced service document. (Document: Piper Service Bulletin No. 763; Compliance)\n\n### Concentration of benefits and costs\n\n- Benefits (reduced risk of structural failure from undetected cracks) accrue to operators and their passengers; these benefits are concentrated on the owners of the affected serial-numbered aircraft. (Background)\n- Costs (inspection and kit/installation) are borne by those same owners/operators until they fit the kit. (Applicability; Compliance)\n\n### Practical note on reading the compliance timing\n\n- The compliance sentence ties inspections to the fin reaching 500 hours TIS, requires the first inspection within 25 hours thereafter, and then repeats at intervals not exceeding 100 hours until the reinforcement kit is installed. Operators must track fin time-in-service and ensure inspections occur within those windows. (Compliance)\n\n(References in parentheses refer to the labelled parts of the supplied directive: Applicability; Document: Piper Service Bulletin No. 763; Compliance; Background.)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, targeted airworthiness directive addressing a specific structural defect in a specific aircraft type. The scope remains precisely limited to the identified safety issue without expansion into unrelated operational or maintenance requirements."},"complexity_factors":["Single, clearly defined applicability (specific aircraft model and serial number range)","Straightforward compliance timeline (500 hours trigger, 25-hour window, 100-hour intervals)","Single exit condition (installation of specified kit)","No defined terms section or complex cross-referencing","Plain language background explanation included","Total length is approximately 150 words"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — a mandatory safety order issued by the Civil Aviation Safety Authority (CASA) for specific Piper Tomahawk aircraft.\n\n**Who it affects:** Owners and operators of Piper PA-38-112 Tomahawk aeroplanes with serial numbers between 38-78A0001 and 38-82A0122.\n\n**What it requires:**\n- **Inspection:** Once the aircraft's vertical fin has flown 500 hours, you must inspect it within the next 25 flying hours.\n- **Ongoing checks:** After that first inspection, you must repeat the inspection every 100 flying hours.\n- **Permanent fix:** These repeated inspections stop only when you install \"Kit 764-965\" (a reinforcement kit that permanently fixes the problem).\n\n**Why it matters:** Cracks have been found where the horizontal tail (stabiliser) attaches to the vertical tail (fin). This is a critical structural area — if the cracks worsen, the tail could fail in flight. The directive prevents accidents by catching cracks early or permanently reinforcing the structure.\n\n**In short:** Check your tail for cracks regularly until you install the official fix."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pa-38-23-upper-forward-and-aft-vertical-fin-spar-inspection-and-reinforcement","history":"/api/acts/ad-pa-38-23-upper-forward-and-aft-vertical-fin-spar-inspection-and-reinforcement/history","analysis":"/api/acts/ad-pa-38-23-upper-forward-and-aft-vertical-fin-spar-inspection-and-reinforcement/analysis","conflicts":"/api/acts/ad-pa-38-23-upper-forward-and-aft-vertical-fin-spar-inspection-and-reinforcement/conflicts","importantCases":"/api/acts/ad-pa-38-23-upper-forward-and-aft-vertical-fin-spar-inspection-and-reinforcement/important-cases","documents":"/api/acts/ad-pa-38-23-upper-forward-and-aft-vertical-fin-spar-inspection-and-reinforcement/documents"}}