{"id":"F2006B05506","name":"AD/PA-23/79 - Stabilator Assembly Lower Surface - Inspection","slug":"ad-pa-23-79-stabilator-assembly-lower-surface-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":46358,"registerId":"commonwealth-F2006B05506-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PA-23/79 - Stabilator Assembly Lower Surface - Inspection","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-23 (Apache and Aztec) Series Aeroplanes\n\n \n\nAD/PA-23/79 Stabilator Assembly Lower Surface - Inspection 10/79\n\nApplicability: All model PA-23-250 (six place) with S/Nos. 27-7654001 to 27-7954044, fitted with stabilator S/Nos. referenced in Piper SB No. 606.\n\n \n\nDocument: Piper SB No. 606.\n\n \n\nCompliance: Within 100 hours time in service after 31 October 1979 and there- after at intervals not exceeding 100 hours time in service until stabilator assembly is replaced or modified in accordance with SB No. 606.\n\n \n\nBackground:  The manufacturer has determined that the affected stabilator assemblies may not have proper bonding between the ribs and skins.\n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD confines its requirements to the specific PA-23-250 serial number range and to stabilator serial numbers listed in Piper SB No. 606, and imposes interim inspections until replacement or modification under SB No. 606 is completed. The text does not expand applicability or introduce requirements beyond that manufacturer's-identified concern; it enforces inspections and points to a single corrective path (SB No. 606). (See: Applicability; Compliance; Document; Background)"},"complexity_factors":["Narrow applicability by aircraft model and serial number range (Applicability)","Recurrent inspection timing tied to 'hours time in service' with a 100‑hour interval (Compliance)","Cross-reference to an external technical document (Piper SB No. 606) for the approved modification/replacement method (Document)","Dependence on the effectiveness of inspection techniques to detect bonding defects (Background)","Operational and logistical issues (parts, skilled labour, downtime) implicit in carrying out SB modifications or replacements (Document; Compliance)","Regulatory provenance is clear (CASA/Part 39 header) but the AD itself delegates the corrective method to the manufacturer's service bulletin (header; Document)"],"plain_english_summary":"Owners/operators of certain Piper PA‑23‑250 (serials 27‑7654001 to 27‑7954044) with specified stabilator serial numbers must begin recurring inspections of the stabilator lower surface within 100 hours TIS after 31 Oct 1979 and repeat every ≤100 hours until the stabilator is replaced or modified per Piper Service Bulletin No. 606. CASA issued this AD because of possible rib‑to‑skin bonding defects; operators bear inspection and modification costs."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive issued in 1979 addressing a specific manufacturing defect in specific aircraft. It has not expanded beyond its original purpose of ensuring stabilator structural integrity through inspection requirements."},"complexity_factors":["Very short document (approximately 150 words)","Only 4 defined elements: applicability (aircraft serial numbers), document reference, compliance timeframe, and background","No cross-references to other legislation or regulations beyond the parent Civil Aviation Regulations 1998","Simple conditional logic: single applicability test (specific serial numbers) leading to single compliance action","No nested exceptions or sub-conditions","Single-purpose directive with clear stop condition (replacement/modification per SB 606)"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). Think of it as a \"recall notice\" for aircraft, but legally enforceable.\n\n**What it requires:** Owners and operators of specific **Piper PA-23 Apache and Aztec aircraft** (six-seat models with serial numbers 27-7654001 to 27-7954044) must inspect the **stabilator** (the moveable horizontal tail surface that controls the aircraft's pitch — basically the \"elevator\" on this particular plane design).\n\n**The problem:** The manufacturer (Piper) discovered that some stabilators might have **poor bonding between the internal ribs and the outer skin**. This means the metal parts inside aren't properly glued/attached to the covering, which could cause structural failure in flight.\n\n**What must be done:**\n- **First inspection:** Within 100 hours of flying time after 31 October 1979\n- **Repeat inspections:** Every 100 hours of flying time thereafter\n- **Stop condition:** Continue until the stabilator is replaced or modified per Piper Service Bulletin No. 606\n\n**Who it affects:** Anyone operating the specific Piper PA-23-250 models listed, with the affected stabilator serial numbers referenced in Piper SB 606.\n\n**Why it matters:** This is a **flight safety critical issue**. A stabilator failure could cause loss of control and crash. The repetitive inspection requirement reflects that this is a \"watch and monitor\" situation until a permanent fix is applied."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pa-23-79-stabilator-assembly-lower-surface-inspection","history":"/api/acts/ad-pa-23-79-stabilator-assembly-lower-surface-inspection/history","analysis":"/api/acts/ad-pa-23-79-stabilator-assembly-lower-surface-inspection/analysis","conflicts":"/api/acts/ad-pa-23-79-stabilator-assembly-lower-surface-inspection/conflicts","importantCases":"/api/acts/ad-pa-23-79-stabilator-assembly-lower-surface-inspection/important-cases","documents":"/api/acts/ad-pa-23-79-stabilator-assembly-lower-surface-inspection/documents"}}