{"id":"F2006L01326","name":"AD/B727/93 Amdt 4 - Forward Entry Door Frame","slug":"ad-b727-93-amdt-4-forward-entry-door-frame","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":58826,"registerId":"commonwealth-F2006L01326-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 727 Series Aeroplanes","sectionType":"division","heading":"Boeing 727 Series Aeroplanes","content":"### Boeing 727 Series Aeroplanes\n\n| AD/B727/93 Amdt 4 | Forward Entry Door Frame | 6/2006 |\n| ----------------- | ------------------------ | ------ |\n\n| Applicability: | Model 727, 727C, 727-100, 727-100C, 727-200, and 727-200F series aircraft; as identified in Boeing Alert Service Bulletin 727-53A0153 Revision 7, dated14 August 2003, or later FAA approved revision.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Action in accordance with the technical requirements of FAA AD 2006-07-10 Amdt 39-14537.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |\n| Compliance:    | As specified in the Requirement document, with a revised effective date of8 June 2006.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |\n|                | This Amendment becomes effective on 8 June 2006.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |\n| Background:    | Cracking of the forward entry door forward frame has been found in service. Undetected cracking of the frame at Body Station 303.9 could result in cracking of the fuselage skin and consequent rapid decompression of the aircraft.Amendment 2 reduced the inspection threshold from 25,000 to 15,000 landings; based on service experience.Amendment 3 required repetitive inspections of aircraft previously modified, in response to reports of cracking of frames previously modified.Amendment 4 is issued in response to a new FAA AD, which was prompted by new reports of cracking of the forward entry doorway frame of aircraft previously modified. This Directive requires adding new post-repair and post-modification inspections for previously repaired or modified aircraft, mandating the optional modification, and introducing additional aircraft to applicability. |\n\n![](image.001.png)  \nRichard Castles  \nDelegate of the Civil Aviation Safety Authority\n\n28 April 2006","sortOrder":0},{"sectionNumber":"AD/B727/93 Amdt 4","sectionType":"part","heading":"AD/B727/93 Amdt 4","content":"## AD/B727/93 Amdt 4","sortOrder":1},{"sectionNumber":"Forward Entry Door Frame","sectionType":"part","heading":"Forward Entry Door Frame","content":"## Forward Entry Door Frame","sortOrder":2},{"sectionNumber":"6/2006","sectionType":"part","heading":"6/2006","content":"## 6/2006","sortOrder":3}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"Yes. Compared with the original directive, Amendment 4 broadens the instrument in multiple ways: it adds additional aircraft to the applicability list, introduces mandatory post-repair and post-modification inspections (targeting aircraft that were previously thought addressed), and makes a previously optional structural modification mandatory. Earlier amendments had already reduced inspection thresholds and required repetitive inspections; Amendment 4 therefore represents a cumulative expansion of regulatory obligations beyond the narrow original inspection threshold and schedule (Background; Applicability; Requirement)."},"complexity_factors":["Short, single-subject airworthiness directive (limited length)","Cross-reference to FAA AD 2006-07-10 (external normative document)","Cross-reference to Boeing Alert Service Bulletin 727-53A0153 Revision 7 (external technical document)","Multiple aircraft models listed in the applicability clause","Amendment history: prior changes (Amendments 2 and 3) changed inspection thresholds and introduced repetitive inspections — this amendment adds post-repair/post-mod inspections and mandates a previously optional modification","Conditional requirements (post-repair and post-mod inspections apply only to aircraft previously repaired or modified)","Operational dependencies: compliance timing and technical details are determined in the referenced FAA/Boeing documents rather than fully set out in the AD text"],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- This is an airworthiness directive that applies to Boeing 727 series aeroplanes as identified in Boeing Alert Service Bulletin 727-53A0153 Revision 7 (see \"Applicability\").\n- It requires operators to carry out the inspections, repairs and other actions set out in FAA Airworthiness Directive 2006-07-10 (\"Requirement\").  The directive is effective 8 June 2006.\n- Amendment 4 specifically adds: new inspections to be done after a repair or after a previous modification, makes a previously optional structural modification mandatory, and extends the set of aircraft to which the directive applies (see \"Background\").\n\n**Who is affected**\n\n- Owners and operators of the listed Boeing 727 variants (727, 727C, 727-100, 727-100C, 727-200 and 727-200F) identified in the referenced Boeing service bulletin.  (Applicability)\n- Maintenance organisations and engineers who perform the inspections, repairs and modifications required by the FAA AD and the Boeing service bulletin.\n\n**Why it matters (official rationale and practical effects)**\n\n- Official rationale: cracking was found in the forward entry door forward frame at Body Station 303.9. Undetected cracking could lead to fuselage skin cracking and rapid decompression. Amendment 4 responds to new reports of cracking on aircraft previously repaired or modified and therefore adds post-repair/post-mod inspections and mandates the formerly optional modification. (Background)\n\n**Practical implications, costs and trade-offs**\n\n- Who pays: the financial cost (inspection labour, engineering time, parts, and any modification or repair) falls on aircraft owners/operators. The directive does not fund or subsidise those costs (Requirement; Applicability).\n- What operators must do: schedule and carry out the inspections and any corrective actions exactly as specified in FAA AD 2006-07-10 and the Boeing service bulletin; if the modification is mandated, arrange for and complete that modification. Non-compliance would breach the airworthiness requirement for the aircraft. (Requirement)\n- Operational effects: inspections and modifications may require aircraft down-time. That can reduce utilisation, increase direct maintenance costs and — for some operators — create incentives to retire, sell, or re-purpose affected aircraft rather than pay for repeated inspections or structural modification.\n- Effects on service providers and markets: demand rises for certified MRO (maintenance, repair and overhaul) providers able to perform the specific structural inspections and repairs; smaller or less-equipped providers may be disadvantaged if specialised capability or FAA/Boeing-approved parts/techniques are required.\n- Concentration of costs and diffuse benefits: costs are concentrated on the relatively small group of 727 operators; benefits (reduced risk of decompression events) are diffuse, affecting passengers and airworthiness safety broadly.\n- Compliance risk and implementation: the AD relies on external documents (FAA AD 2006-07-10 and Boeing Alert Service Bulletin 727-53A0153 Rev 7). This creates an implementation dependency: operators must obtain and follow those documents exactly. Changes or revisions to those external documents may affect obligations (Applicability; Requirement).\n\n**Mechanisms and behavioural effects**\n\n- Enforcement mechanism: CASA has adopted the FAA AD requirements as mandatory; compliance is enforced through the usual airworthiness oversight framework (Requirement).\n- Behavioural change required: operators must increase inspection frequency for the forward entry door frame where specified, add inspections after repairs or modifications, and perform the now-mandatory modification where required. These are discrete, procedurally-prescribed actions rather than discretionary policy choices.\n\n**Source claims vs costs and trade-offs**\n\n- The directive's stated purpose is to prevent dangerous structural failure by detecting and correcting frame cracking (Background). That objective implies increased inspection intensity and structural modification. The trade-offs are clear and mechanical: safer structures at the expense of inspection/modification costs and aircraft availability. Implementation risk centres on correct execution of the external technical instructions and timely scheduling by operators.\n\n(References in the instrument: Applicability; Requirement; Compliance; Background.)"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":true,"description":"The original directive (1993) applied to specific Boeing 727 models for initial inspection requirements. Amendment 4 significantly expanded scope by: (1) adding new post-repair inspection requirements for aircraft already modified under earlier amendments, (2) converting an optional modification into a mandatory requirement, and (3) explicitly expanding applicability to additional aircraft series. The directive has evolved from a simple inspection mandate into a comprehensive, multi-layered safety regime covering initial inspections, repetitive inspections, post-modification monitoring, and mandatory structural modifications."},"complexity_factors":["Short, single-purpose instrument (approximately 250 words of substantive content)","Only 6 defined aircraft models in applicability table","Single cross-reference to external technical document (FAA AD 2006-07-10)","No nested conditional logic or exceptions — compliance is straightforward: follow the FAA directive","Historical context provided in Background section but does not create additional legal obligations","No interpretation section with defined terms"],"plain_english_summary":"This airworthiness directive mandates inspection of the forward entry door frame on Boeing 727 series aircraft for cracking, and requires repair or modification when cracks are found. Amendment 4 adds extra inspections for previously repaired or modified planes, makes a formerly optional modification mandatory, and expands the affected models. It applies to owners, operators and maintenance organisations of 727-series aircraft and matters because unchecked cracks can spread to the fuselage and cause rapid decompression; it aligns Australian rules with FAA requirements."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-93-amdt-4-forward-entry-door-frame","history":"/api/acts/ad-b727-93-amdt-4-forward-entry-door-frame/history","analysis":"/api/acts/ad-b727-93-amdt-4-forward-entry-door-frame/analysis","conflicts":"/api/acts/ad-b727-93-amdt-4-forward-entry-door-frame/conflicts","importantCases":"/api/acts/ad-b727-93-amdt-4-forward-entry-door-frame/important-cases","documents":"/api/acts/ad-b727-93-amdt-4-forward-entry-door-frame/documents"}}