{"id":"F2006B11008","name":"AD/JT9D/15 - High Pressure Turbine Airseal","slug":"ad-jt9d-15-high-pressure-turbine-airseal","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56607,"registerId":"commonwealth-F2006B11008-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/JT9D/15 - High Pressure Turbine Airseal","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 - 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Pratt and Whitney Turbine Engines - JT9D Series\n\n \n\nAD/JT9D/15 High Pressure Turbine Airseal 12/86\n\nTX\n\n \n\nApplicability: JT9D-7R4D, E models.\n\n \n\nRequirement: Carry out the requirements of Pratt and Whitney ASB JT9D-7R4-72-318, Paragraph 2 \"Accomplishment Instructions\".\n\n \n\nCompliance: According to a program agreed to by the Secretary. Effective:  1 December 1986.\n\nBackground:  This Directive has been issued to require compliance with the Accomplishment Instructions of P.W.A. A.S.B. JT9D-7R4-72-318. The A.S.B. details inspection and modification of the high pressure turbine to preclude cracking of the stage 1-2 airseal.\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":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue safety directive from 1986 addressing a specific mechanical defect in specific engine models. It has not expanded beyond its original narrow technical purpose."},"complexity_factors":["Very short document (under 200 words)","Only 2 defined applicability criteria (engine model numbers)","Single requirement referencing an external technical document (Pratt & Whitney service bulletin)","No nested conditions, exceptions, or cross-references to other legislation","Simple compliance structure: follow the manufacturer's instructions by an agreed date"],"plain_english_summary":"**What this is:** An Airworthiness Directive (AD) — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires aircraft owners or operators to inspect or fix a specific mechanical problem.\n\n**What it does:** This directive orders operators of certain Pratt & Whitney JT9D jet engines (specifically the -7R4D and -7R4E models) to follow the inspection and repair instructions in a Pratt & Whitney service bulletin. The bulletin deals with the \"high pressure turbine airseal\" — a critical seal in the engine's hot section that prevents air leaks between turbine stages.\n\n**Why it matters:** The airseal can develop cracks. If left unchecked, these cracks could cause engine damage, power loss, or potentially catastrophic engine failure. This AD mandates action to catch and fix the problem before it becomes dangerous.\n\n**Who must comply:** Anyone operating aircraft with these specific engine models in Australia. They must work with the Secretary (of the Department responsible for aviation) to establish a compliance program.\n\n**When it took effect:** 1 December 1986."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD's scope is congruent with its stated purpose: it requires operators of JT9D-7R4D and -7R4E engines to perform the inspections and modifications described in the specified Pratt & Whitney A.S.B. to prevent cracking of the stage 1-2 airseal. The text does not expand or narrow that applicability beyond the listed engine models and the referenced A.S.B.; compliance timing is to be agreed with the Secretary. (Applicability; Requirement; Compliance; Background)"},"complexity_factors":["Reference to an external manufacturer document (P.W.A. A.S.B. JT9D-7R4-72-318) for technical procedures rather than including procedures in the regulation (Requirement)","Need to coordinate a compliance program with the Secretary (regulator) rather than a single fixed compliance schedule (Compliance)","Technical nature of required actions (inspection and modification of HPT stage 1-2 airseal) requiring specialised maintenance capability (Background)","Narrow applicability to specific engine models, reducing scope but concentrating technical demands on affected operators (Applicability)","Regulatory brevity: the AD sets obligations but relies on external documents for details, increasing operational dependence on the content and availability of the A.S.B. (Requirement; Background)"],"plain_english_summary":"This AD requires owners/operators of Pratt & Whitney JT9D-7R4D and -7R4E engines to carry out the Accomplishment Instructions in P&W Service Bulletin JT9D-7R4-72-318 for inspection and modification of the stage 1–2 high‑pressure turbine airseal. Compliance, scheduled under a program agreed with the Secretary, is intended to prevent airseal cracking; implementation costs and downtime fall to the operators."}},"importantCases":[],"_links":{"self":"/api/acts/ad-jt9d-15-high-pressure-turbine-airseal","history":"/api/acts/ad-jt9d-15-high-pressure-turbine-airseal/history","analysis":"/api/acts/ad-jt9d-15-high-pressure-turbine-airseal/analysis","conflicts":"/api/acts/ad-jt9d-15-high-pressure-turbine-airseal/conflicts","importantCases":"/api/acts/ad-jt9d-15-high-pressure-turbine-airseal/important-cases","documents":"/api/acts/ad-jt9d-15-high-pressure-turbine-airseal/documents"}}