{"id":"F2006B03103","name":"AD/B747/203 - Lavatory Drain System Leak Tests","slug":"ad-b747-203-lavatory-drain-system-leak-tests","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42475,"registerId":"commonwealth-F2006B03103-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B747/203 - Lavatory Drain System Leak Tests","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nBoeing 747 Series Aeroplanes\n\nAD/B747/203 Lavatory Drain System Leak Tests 6/99\n\nApplicability: Model 747-100, \\-200, \\-300, \\-SP and \\-400F series aeroplanes certificated in any category.\n\nRequirement: Inspection and maintenance requirements of US FAA AD 99-08-10 are to be performed.\n\nNote: FAA AD 99-08-10 amendment 39-11116 refers.\n\nCompliance: Initial action and subsequent repetitive actions as defined in US FAA AD 99-08-10 Amdt 39-11116, with a revised effective date of 17 June 1999.\n\nThis Airworthiness Directive becomes effective on 17 June 1999.\n\nBackground: Certain design features of the 747 toilet flush system have lead to an increase in the incidences of “blue ice” forming on the airframe and detaching in flight causing damage to the airframe and property on the ground. This directive introduces inspections and maintenance actions to improve the reliability of the system and reduce the possibility of leaks and, ultimately, the likelihood of “blue ice” forming and detaching in flight.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical issue (lavatory drain leaks) on specific aircraft models. It has not expanded beyond its original purpose; it remains a narrow technical maintenance requirement."},"complexity_factors":["Very short document (approximately 150 words)","Only 1 defined term implicitly referenced (the US FAA AD number)","No nested conditional logic or exceptions","Single cross-reference to external US FAA document (AD 99-08-10)","Straightforward applicability criteria (specific aircraft models by series number)","Clear, single compliance requirement with explicit effective date"],"plain_english_summary":"CASA's Airworthiness Directive mandates inspections and maintenance of toilet/lavatory drain systems on Australian‑registered Boeing 747-100, -200, -300, -SP and -400F aircraft, adopting FAA AD 99-08-10. It targets leaks that can freeze into \"blue ice\" and break off in flight or fall to the ground, risking damage or injury. Operators and maintenance crews must complete the initial check by 17 June 1999 and perform the required recurring inspections."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"Scope remains the same as the source: it adopts the inspection and maintenance requirements of FAA AD 99-08-10 for the listed 747 models to reduce lavatory drain leaks and blue-ice formation. Compliance timing and actions are those in the referenced FAA AD, with the directive effective 17 June 1999 (Applicability; Requirement; Compliance; Background)."},"complexity_factors":["Cross-reference to US FAA AD 99-08-10 (Amdt 39-11116) — requires Australian operators to follow a foreign AD rather than a standalone Australian procedure (Requirement).","Repetitive compliance schedule — initial and ongoing inspections and maintenance increase operational and record-keeping burden (Compliance).","Broad model applicability — applies to multiple 747 series variants, so varied fleet configurations may affect inspection methods and costs (Applicability).","Revised effective date specified — administrative coordination required to align local maintenance planning with the stated effective date of 17 June 1999 (Compliance/Effective date).","Safety risk tied to specific subsystem (lavatory drain/flush) — may require targeted maintenance access, parts and labour that vary by aircraft age and configuration (Background/Requirement)."],"plain_english_summary":"This Airworthiness Directive requires operators of Boeing 747-100/200/300/SP/400F aeroplanes to perform the lavatory drain-system inspections and maintenance set out in US FAA AD 99-08-10 (Amdt 39-11116). It copies the FAA compliance schedule (initial and repetitive actions) and becomes effective 17 June 1999. Operators pay for and carry out the inspections and repairs; the directive's purpose is to reduce leaks that can form and shed so-called “blue ice.”"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-203-lavatory-drain-system-leak-tests","history":"/api/acts/ad-b747-203-lavatory-drain-system-leak-tests/history","analysis":"/api/acts/ad-b747-203-lavatory-drain-system-leak-tests/analysis","conflicts":"/api/acts/ad-b747-203-lavatory-drain-system-leak-tests/conflicts","importantCases":"/api/acts/ad-b747-203-lavatory-drain-system-leak-tests/important-cases","documents":"/api/acts/ad-b747-203-lavatory-drain-system-leak-tests/documents"}}