{"id":"F2006B11014","name":"AD/JT9D/21 - Drain Tube Replacement","slug":"ad-jt9d-21-drain-tube-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56614,"registerId":"commonwealth-F2006B11014-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/JT9D/21 - Drain Tube Replacement","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/21 Drain Tube Replacement 5/90\n\nApplicability: JT9D-7R4 engines fitted to Boeing 767 aircraft.\n\n \n\nRequirement: Replace three existing drain tubes and a tee fitting as detailed in Boeing Service Bulletin 767-71A0057.\n\n \n\nCompliance: Prior to 31 December 1990.\n\n \n\nBackground:  This Directive requires replacement of certain drain lines and a tee fitting to prevent possible oil loss due to chafing of the number three oil pressure line against a drain tube tee fitting.\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 directive’s scope is confined to JT9D-7R4 engines fitted to Boeing 767 aircraft and requires a specific parts replacement to address chafing of the number three oil pressure line. The text does not indicate any expansion or narrowing of that scope from an earlier or different stated intent; it sets a targeted technical correction and a fixed deadline for compliance. (Applicability, Requirement, Compliance, Background)"},"complexity_factors":["Narrow applicability: single engine model (JT9D-7R4) on a single aircraft type (Boeing 767) (Applicability).","Single, discrete technical action required (replace three drain tubes and one tee fitting) rather than an ongoing programme (Requirement).","Fixed compliance deadline imposes scheduling pressure but simplifies enforcement (Compliance).","Dependence on an external technical document (Boeing Service Bulletin 767-71A0057) for implementation details increases operational dependency on the manufacturer (Requirement).","No alternative compliance methods, exemptions or phased approach stated in the text, reducing regulatory complexity but increasing operational inflexibility (Requirement).","Safety-critical context (risk of oil loss) implies stricter practical controls and potential for inspection/enforcement, though enforcement mechanisms are not detailed in the text (Background)."],"plain_english_summary":"What the instrument changes mechanically\n\n- This Airworthiness Directive requires the physical replacement of three drain tubes and one tee fitting on Pratt & Whitney JT9D-7R4 turbine engines when those engines are installed on Boeing 767 aircraft. The replacement must be done in accordance with Boeing Service Bulletin 767-71A0057. (Requirement)\n\nWho is affected and who decides\n\n- The rule applies only to JT9D-7R4 engines fitted to Boeing 767s. (Applicability)\n- The Civil Aviation Safety Authority issued the directive under the Commonwealth civil aviation framework. (header)\n\nWhy the change is required (official rationale)\n\n- The stated purpose is to prevent possible oil loss caused by chafing of the number three oil pressure line against a drain tube tee fitting. (Background)\n\nPractical effects, costs and incentives\n\n- Operators of affected Boeing 767s must schedule and carry out the specified part replacements before the compliance date. This creates direct costs for parts, labour and aircraft downtime; the instrument itself does not specify who pays, so those costs will fall on the aircraft owners/operators who must perform the work. (Requirement, Compliance)\n- The directive fixes a deadline (prior to 31 December 1990), which forces operators to prioritise this maintenance work within their existing maintenance programmes. A fixed deadline increases scheduling pressure and may raise short-term costs if work must be accelerated. (Compliance)\n- The technical method for compliance is delegated to Boeing's service bulletin: implementers must follow that external technical document to meet the directive. Relying on a manufacturer service bulletin concentrates technical authority with the manufacturer for the detailed steps while the regulator sets the mandatory outcome. (Requirement)\n\nTrade-offs, risks and implementation notes\n\n- The directive substitutes a one-time replacement action for the risk it identifies: it removes an installed configuration that can cause chafing and oil loss. The text does not state continuing inspection options or alternative methods of compliance; it mandates the specific replacement action as described in the Boeing bulletin. (Requirement)\n- Implementation risk is practical (sourcing parts, scheduling, completing work by the deadline). The directive does not set out exemptions, waivers or criteria for alternative means of compliance within the text provided; any such discretion would need to appear elsewhere in regulatory guidance. (Requirement)\n\nWhat changes in behaviour\n\n- Maintenance decision-makers must allocate resources to replace the specified drain lines and tee fitting before the deadline, following Boeing Service Bulletin 767-71A0057. Operators that do not make the change risk non-compliance with the directive. (Requirement, Compliance)\n\nSource references: Applicability, Requirement, Compliance, Background."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive focused on a specific mechanical defect. It has not expanded beyond its original purpose of mandating replacement of particular drain tubes and a tee fitting to prevent oil loss."},"complexity_factors":["Extremely short document — only 6 substantive lines of regulatory text","Single, unambiguous requirement with no conditional logic or exceptions","Only one defined applicability criterion (JT9D-7R4 engines on Boeing 767s)","No cross-references to other legislation or regulations beyond the parent Civil Aviation Regulations 1998","Single compliance date with no phased implementation or alternative methods of compliance","Background explanation is straightforward mechanical issue (chafing → oil loss) with no legal or technical ambiguities"],"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 like a recall notice for aircraft, but legally binding.\n\n**What it does:** It orders airlines and aircraft operators to replace three specific drain tubes and one tee fitting on **Pratt & Whitney JT9D-7R4 engines** that power **Boeing 767 aircraft**.\n\n**Why it matters:** The old parts could rub against each other (\"chafing\"), causing oil to leak from the number three oil pressure line. Oil loss in a jet engine can lead to engine failure — obviously bad news when you're flying.\n\n**Who must comply:** Anyone operating a Boeing 767 with these specific engines in Australia.\n\n**The fix:** Operators must follow **Boeing Service Bulletin 767-71A0057** — a technical instruction manual from the manufacturer — to swap out the parts.\n\n**Deadline:** The work had to be done before **31 December 1990**.\n\n**Bottom line:** This was a targeted safety fix to prevent mechanical wear from causing engine oil leaks. Simple, specific, and time-critical."}},"importantCases":[],"_links":{"self":"/api/acts/ad-jt9d-21-drain-tube-replacement","history":"/api/acts/ad-jt9d-21-drain-tube-replacement/history","analysis":"/api/acts/ad-jt9d-21-drain-tube-replacement/analysis","conflicts":"/api/acts/ad-jt9d-21-drain-tube-replacement/conflicts","importantCases":"/api/acts/ad-jt9d-21-drain-tube-replacement/important-cases","documents":"/api/acts/ad-jt9d-21-drain-tube-replacement/documents"}}