{"id":"F2006B10995","name":"AD/JT8D/5 - Sixth Stage Compressor Disc","slug":"ad-jt8d-5-sixth-stage-compressor-disc","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56586,"registerId":"commonwealth-F2006B10995-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/JT8D/5 - Sixth Stage Compressor Disc","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nPratt and Whitney Turbine Engines \\- JT8D Series\n\nAD/JT8D/5 Sixth Stage Compressor Disc 6/70\n\nApplicability: All JT8D series engines incorporating sixth stage compressor disc P/N 586906 (wide rim).\n\nRequirement: 1. Inspect and rework as necessary the sixth stage compressor disc P/N 586906 (wide rim) in accordance with the requirements of the JT8D Overhaul Manual, Inspection Section 72-33-2, Page 301, Paras. 1 to 5 as amplified by Pratt & Whitney Service Telegram SE : RWJ : 9-6-24-1 dated 24 June 1969. Alternatively replace the disc by a serviceable disc of the same or later part number.\n\nNote: For the purposes of this Airworthiness Directive a blade failure is defined as one in which any portion of the blade root is separated from the blade.\n\n2. AD/PW-T/28.\n\nCompliance: Before further flight following a sixth stage blade failure.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive focused on a specific mechanical failure mode in a specific engine component. It has not expanded beyond its original purpose of addressing sixth stage compressor disc integrity following blade failures."},"complexity_factors":["Very short document (under 200 words)","Only 1 defined term ('blade failure' explicitly defined in Note)","Single applicability criterion (specific part number)","Straightforward binary compliance path (inspect/repair OR replace)","No cross-references to legislation beyond a single reference to another AD","Clear, immediate compliance trigger ('before further flight') with no conditional timelines or exceptions"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft engines.\n\n**What it does:**\nThis directive applies to Pratt & Whitney JT8D series jet engines (commonly used in older Boeing 737s and similar aircraft). It requires immediate inspection and repair of a specific engine component — the \"sixth stage compressor disc\" (part number 586906 with wide rim) — if a blade in that section fails.\n\n**Who it affects:**\n- Airlines and operators flying aircraft with JT8D engines\n- Maintenance engineers and approved workshops servicing these engines\n- Any aircraft with the specific compressor disc part mentioned\n\n**What must happen:**\nIf a sixth stage compressor blade fails (defined as any separation of the blade root from the blade itself), the operator must **before the next flight**:\n- Either inspect and repair the disc following specific Pratt & Whitney technical instructions, OR\n- Replace the disc entirely with a serviceable one\n\n**Why it matters:**\nCompressor disc failures can cause catastrophic engine damage and potentially endanger the aircraft. This rule ensures that after any blade failure in this critical section, the disc itself is checked for damage that could lead to more serious failures. The \"before further flight\" requirement makes this an immediate grounding issue — no exceptions.\n\n**Note on AD/PW-T/28:** The directive references another airworthiness directive, suggesting this replaces or works alongside earlier safety requirements for Pratt & Whitney engines."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The text sets a narrowly targeted scope: all JT8D engines fitted with sixth stage compressor disc P/N 586906 (wide rim) and actions required after a blade root separation. The instrument itself contains no indication that its applicability or intended scope was altered from an original broader or narrower intent; it consistently defines applicability, required actions and the compliance trigger within the document (Applicability; Requirement; Note; Compliance)."},"complexity_factors":["Narrow technical scope: applies only to JT8D engines with sixth stage compressor disc P/N 586906 (wide rim) (Applicability).","Operational trigger tied to a specific event (blade root separation) and a clear timing requirement (before further flight) (Note; Compliance).","Dependence on external technical documents (JT8D Overhaul Manual Section 72-33-2 and Pratt & Whitney Service Telegram SE : RWJ : 9-6-24-1) for inspection/rework procedures (Requirement).","Alternative compliance route (inspect/rework per manual or replace with serviceable disc) reduces procedural complexity but requires parts availability (Requirement).","Reference to another airworthiness directive (AD/PW-T/28) adds a cross-reference obligation (Requirement)."],"plain_english_summary":"Applies to JT8D engines fitted with sixth-stage compressor disc P/N 586906 (wide rim): after any sixth-stage blade failure (root separation), the disc must be inspected and, if required, reworked per the JT8D Overhaul Manual and Pratt & Whitney Service Telegram—or replaced by a serviceable disc—before the engine is next flown. Operators, owners and maintenance organisations bear the cost and downtime; the AD also cross‑references AD/PW‑T/28 for related obligations."}},"importantCases":[],"_links":{"self":"/api/acts/ad-jt8d-5-sixth-stage-compressor-disc","history":"/api/acts/ad-jt8d-5-sixth-stage-compressor-disc/history","analysis":"/api/acts/ad-jt8d-5-sixth-stage-compressor-disc/analysis","conflicts":"/api/acts/ad-jt8d-5-sixth-stage-compressor-disc/conflicts","importantCases":"/api/acts/ad-jt8d-5-sixth-stage-compressor-disc/important-cases","documents":"/api/acts/ad-jt8d-5-sixth-stage-compressor-disc/documents"}}