{"id":"F2006B11033","name":"AD/JT9D/4 - Incorporation of Main Gearbox Spray Nozzles","slug":"ad-jt9d-4-incorporation-of-main-gearbox-spray-nozzles","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56643,"registerId":"commonwealth-F2006B11033-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/JT9D/4 - Incorporation of Main Gearbox Spray Nozzles","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/4 Incorporation of Main Gearbox Spray Nozzles 6/74\n\nApplicability: JT9D-3A and JT9D-7 engines.\n\n \n\nDocument: 1. Pratt & Whitney TE SB 4043, Rev. 2; or 2. FAA AD 74-10-04; or\n\n3. AD/PW-T/31.\n\n \n\nCompliance: 1 February 1975.\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\n \n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The text specifies a focused, time-limited requirement: fit main gearbox spray nozzles to JT9D-3A and JT9D-7 engines by the stated date, using one of the listed technical documents. There is no text indicating an expansion or narrowing of that applicability or an amendment to the original requirement; the instrument as presented is consistent with a single-purpose AD requiring incorporation per the referenced procedures. (Applicability; Document; Compliance)."},"complexity_factors":["Very narrow applicability (only JT9D-3A and JT9D-7 engines). (Applicability)","Single technical requirement (incorporation of main gearbox spray nozzles). (Title/Applicability)","Compliance tied to a single fixed date, which simplifies scheduling but concentrates implementation before that date. (Compliance)","Relies on external technical documents for the detailed procedure (manufacturer SB, FAA AD, or alternate AD), requiring consultation of those documents. (Document)","Regulatory enforcement through a standard airworthiness-directive mechanism (Part 39), leaving little regulatory discretion but operational discretion on scheduling. (Schedule heading; Document; Compliance)"],"plain_english_summary":"This airworthiness directive mandates that owners/operators of aircraft with Pratt & Whitney JT9D-3A and JT9D-7 engines install main gearbox spray nozzles by 1 February 1975. Compliance is compulsory and must follow one of three specified technical documents (manufacturer’s service bulletin or the listed ADs). Operators bear the cost, scheduling and downtime; the regulator prescribes the requirement and the acceptable methods for meeting it."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive from 1974/1975 addressing a specific technical modification to specific engine models. It has not expanded beyond its original scope; it remains a narrow safety mandate for a defined hardware modification."},"complexity_factors":["Very short document (approximately 150 words of substantive content)","Only 2 applicability criteria (specific engine models)","Single compliance action required (incorporation of spray nozzles)","Only 3 reference documents listed","No defined terms section","No cross-references to other legislation beyond the enabling regulations","No conditional logic or exceptions","Straightforward deadline (single date)"],"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) under the Civil Aviation Regulations 1998.\n\n**What it does:** It requires owners and operators of specific Pratt & Whitney jet engines (the JT9D-3A and JT9D-7 models) to modify their engines by installing or incorporating \"Main Gearbox Spray Nozzles.\" These nozzles are part of the lubrication or cooling system for the engine's main gearbox — a critical component that transfers power from the engine to aircraft systems.\n\n**Who it affects:** Airlines, aircraft operators, and maintenance organisations in Australia that operate aircraft powered by these specific Pratt & Whitney JT9D engines (commonly used on early Boeing 747 aircraft).\n\n**Why it matters:** The directive addresses a safety issue that could affect the reliability of the main gearbox. Without this modification, there may be a risk of gearbox failure due to inadequate lubrication or cooling. Compliance was mandatory by **1 February 1975**.\n\n**How to comply:** Operators must follow one of three referenced technical documents:\n- Pratt & Whitney Service Bulletin 4043 (Revision 2), or\n- The equivalent US Federal Aviation Administration (FAA) directive AD 74-10-04, or\n- An earlier Australian directive AD/PW-T/31\n\n**Key point:** This is not optional. Airworthiness Directives are legally binding safety requirements. Non-compliance means the aircraft cannot legally fly."}},"importantCases":[],"_links":{"self":"/api/acts/ad-jt9d-4-incorporation-of-main-gearbox-spray-nozzles","history":"/api/acts/ad-jt9d-4-incorporation-of-main-gearbox-spray-nozzles/history","analysis":"/api/acts/ad-jt9d-4-incorporation-of-main-gearbox-spray-nozzles/analysis","conflicts":"/api/acts/ad-jt9d-4-incorporation-of-main-gearbox-spray-nozzles/conflicts","importantCases":"/api/acts/ad-jt9d-4-incorporation-of-main-gearbox-spray-nozzles/important-cases","documents":"/api/acts/ad-jt9d-4-incorporation-of-main-gearbox-spray-nozzles/documents"}}