{"id":"F2006B02916","name":"AD/B737/22 Amdt 1 - APU Fuel Drains","slug":"ad-b737-22-amdt-1-apu-fuel-drains","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42258,"registerId":"commonwealth-F2006B02916-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B737/22 Amdt 1 - APU Fuel Drains","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)  Boeing 737 Series Aeroplanes\n\n \n\n# AD/B737/22\n\nAmdt 1\n\nApplicability: All model B737 series.\n\n# APU Fuel Drains 5/92\n\n \n\nRequirement: 1. Action in accordance with Boeing Service Letter 737-SL-47-14-A until requirement 2 incorporated.\n\n \n\n2. Action in accordance with Boeing Service Bulletin 737-49-1073.\n\n \n\nNote: FAA AD 92-03-07 AMDT 39-8162 refers.\n\n \n\nCompliance: 1. At intervals not exceeding 500 hours time in service.\n\n \n\n2. Prior to 31 March 1995\n\n \n\nBackground: An uncontained APU tail pipe fire, fuelled by undrained fuel from an unsuccessful APU start, caused severe damage to the empennage flight control surfaces. This amendment provides terminating action for this Directive.\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":true,"description":"The amendment adds a terminating action: operators must carry out the Boeing Service Bulletin 737-49-1073 (Requirement 2) by 31 March 1995, replacing ongoing reliance solely on the interim Service Letter procedure. The Directive therefore moves from a continuing recurring-drain requirement (every 500 hours) to a path that ends recurring work once the Service Bulletin modification is completed (Requirement 1 & 2; Compliance 1 & 2; Background)."},"complexity_factors":["Clear, limited scope: applies to all B737 models but addresses a single issue (APU fuel drains). (Applicability, Requirement)","Two-step compliance path: interim recurring procedure (Service Letter) then terminating modification (Service Bulletin). (Requirement 1 & 2)","Fixed, short-term deadlines: recurring interval (500 hours) and an absolute calendar deadline for terminating action (prior to 31 March 1995). (Compliance 1 & 2)","Dependence on external manufacturer documents (Service Letter and Service Bulletin) which operators must obtain and follow. (Requirement 1 & 2)","Cross-reference to a foreign regulator's AD (FAA AD noted), adding an external point of reference but not altering the Directive's prescribed actions. (Note)"],"plain_english_summary":"Applies to all Boeing 737s: operators must perform recurring APU fuel-drain actions per Boeing Service Letter (no more than every 500 flight hours) until the terminating modification in Boeing Service Bulletin 737-49-1073 is installed by 31 March 1995. The directive addresses risk of uncontained APU tailpipe fires from undrained fuel. Compliance and modification costs fall to operators and their maintenance providers; meeting the deadline removes the recurring maintenance burden."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is an amendment (Amdt 1) that adds terminating action to the original directive, but does not expand beyond the original safety purpose of addressing APU fuel drain hazards. The scope remains tightly focused on the specific technical issue identified in the background."},"complexity_factors":["Very short document (under 300 words)","Only 2 substantive requirements with clear compliance dates/intervals","Minimal defined terms (only standard aviation acronyms like APU)","No nested conditional logic or cross-references to other legislation","Simple structure: applicability, requirements, compliance, background","References only external technical documents (Boeing bulletins) rather than complex legislative cross-references"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order — for all Boeing 737 aircraft operating in Australia.\n\n**What it does:**\nIt requires airlines and aircraft operators to perform specific maintenance checks on the **Auxiliary Power Unit (APU)** fuel drains. The APU is a small engine at the back of the plane that provides power when the main engines are off.\n\n**Why it matters:**\nAfter an incident where fuel that wasn't properly drained caused a fire that severely damaged an aircraft's tail and flight controls, the safety regulator mandated regular checks to prevent this happening again.\n\n**What operators must do:**\n- **Requirement 1:** Follow Boeing's Service Letter 737-SL-47-14-A, checking the fuel drains every 500 flight hours.\n- **Requirement 2:** By 31 March 1995, complete a permanent fix by following Boeing Service Bulletin 737-49-1073 (this \"terminating action\" means once done, the repetitive 500-hour checks are no longer needed).\n\n**Who it affects:**\nAnyone operating Boeing 737 aircraft in Australia — airlines, charter operators, and maintenance organisations."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-22-amdt-1-apu-fuel-drains","history":"/api/acts/ad-b737-22-amdt-1-apu-fuel-drains/history","analysis":"/api/acts/ad-b737-22-amdt-1-apu-fuel-drains/analysis","conflicts":"/api/acts/ad-b737-22-amdt-1-apu-fuel-drains/conflicts","importantCases":"/api/acts/ad-b737-22-amdt-1-apu-fuel-drains/important-cases","documents":"/api/acts/ad-b737-22-amdt-1-apu-fuel-drains/documents"}}