{"id":"F2006B02621","name":"AD/B717/8 - Upper Centre Fuselage Longerons","slug":"ad-b717-8-upper-centre-fuselage-longerons","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41937,"registerId":"commonwealth-F2006B02621-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.001.png)\n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\n![](image.001.png)  \n\nBoeing 717 Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/B717/8 Upper Centre Fuselage Longeron","sectionType":"part","heading":"AD/B717/8 Upper Centre Fuselage Longerons 8/2003","content":"# AD/B717/8 Upper Centre Fuselage Longerons 8/2003\n\nApplicability: Model 717-200 aircraft, manufacturer’s fuselage numbers 5001 through 5056.\n\nRequirement: Modify the longeron to frame installation of the upper centre fuselage between stations Y=655.000 and Y=813.000, at longerons L-5L to L-5R (includes fabrication of the angles and installation of support angles and doublers) in accordance with Boeing Service Bulletin 717-53-0001, dated 20 March 2001.\n\nNote: FAA AD 2003-10-08 Amdt 39-13153 refers.\n\nCompliance: Before the accumulation of 30,000 total flight cycles or within 10 years after 7 August 2003, whichever occurs first.\n\nThis Airworthiness Directive becomes effective on 7 August 2003.\n\nBackground: The FAA requires certain actions to prevent fatigue cracking of the longerons of the upper centre fuselage. Such cracking could result in reduced structural integrity of the fuselage.\n\n![Signature of David Punshon, Delegate of the Civil Aviation Safety Authority.](image.002.png)  \n\nDavid Punshon\n\nDelegate of the Civil Aviation Safety Authority 26 June 2003\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 16 July 2003.","sortOrder":1}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD is narrowly focused on correcting an identified structural fatigue risk in a defined set of Boeing 717-200 airframes. It does not broaden the regulator’s actions beyond that original safety remediation purpose: the directive simply mandates a specific modification set out in the manufacturer’s service bulletin and sets a clear compliance window. There is no evidence in the text that the AD expands scope beyond addressing the described unsafe condition."},"complexity_factors":["Single, narrow applicability (Model 717-200, fuselage numbers 5001–5056)","One mandatory technical instruction referenced (Boeing Service Bulletin 717-53-0001) rather than detailed technical steps in the AD","Single compliance condition with two triggers (before 30,000 total flight cycles or within 10 years after 7 Aug 2003, whichever is earlier)","Cross-reference to FAA AD (FAA AD 2003-10-08) and external service bulletin increases operational complexity despite simple legal text","No multiple nested exceptions or numerous defined terms in the AD text","Short document length and few separate operative provisions"],"plain_english_summary":"**What this instrument does (mechanically):**\n\n- Requires a physical modification to the upper centre fuselage longeron installation on certain Boeing 717-200 aeroplanes. The work includes fabricating angle pieces and installing support angles and doublers, carried out in accordance with Boeing Service Bulletin 717-53-0001 (20 March 2001). (Requirement)\n- Applies only to Boeing 717-200 aircraft with manufacturer fuselage numbers 5001 through 5056. (Applicability)\n- Must be done before the aeroplane reaches 30,000 total flight cycles or within 10 years after 7 August 2003, whichever happens first. (Compliance)\n- The Australian Civil Aviation Safety Authority (CASA) delegate issued the directive under CASA regulation powers; it adopts the technical instructions in the Boeing service bulletin and cross-references the FAA airworthiness directive. (Authority and references)\n\n**Who this affects:**\n\n- Aircraft operators and owners of the specific Boeing 717-200 airframes listed (fuselage numbers 5001–5056).\n- Maintenance organisations and engineers who must perform the modification to the aircraft structure according to the Boeing Service Bulletin.  \n- Potentially suppliers or workshops that fabricate the required angle pieces and doublers.\n\n**Why it matters (official purpose and mechanical effect):**\n\n- Officially, the AD is intended to prevent fatigue cracking of the longerons in the upper centre fuselage, which the regulator says could otherwise reduce structural integrity of the fuselage. (Background)\n\n**How it changes behaviour and who pays:**\n\n- Operators must schedule and pay for the structural modification (parts, labour, engineering time, and any aircraft downtime). Compliance is mandatory under the AD; failure to comply would leave the aircraft non-compliant with an airworthiness requirement. (Requirement & Compliance)\n- The CASA delegate decides that the modification is required; the detailed method of compliance is the Boeing Service Bulletin (the manufacturer’s instructions). The operator follows those instructions to satisfy the AD. (Requirement)\n\n**Costs, incentives and trade-offs (implementation risks and practical effects):**\n\n- Direct costs: fabrication of angle pieces, installation of support angles and doublers, labour, and aircraft out-of-service time. These are borne by the aircraft owner/operator. (Requirement)\n- Operational trade-offs: operators may need to reallocate maintenance slots or delay other work; they may also consider alternative responses such as increased inspections if available, early retirement of affected airframes, or sourcing parts and specialised labour. The AD itself mandates modification rather than optional inspection, so substitution options are limited by the directive. (Compliance & Requirement)\n- Implementation risk: availability of parts and skilled labour to execute the structural modification; the AD depends on the Boeing Service Bulletin for technical detail, so timely access to that SB and to any required parts is critical. (Requirement and references to Boeing SB)\n- Regulatory interaction: the AD references an FAA AD (FAA AD 2003-10-08). That means the action aligns with or mirrors the FAA’s findings; CASA enforces compliance in Australia. (Note / Background)\n\n**Scope and targeting:**\n\n- The scope is narrow and specific: only 56 particular 717-200 fuselages are listed. The requirement is time- and flight-cycle-limited (30,000 flight cycles or 10 years after 7 August 2003). (Applicability & Compliance)\n\n**Source claim vs. practical cost:**\n\n- The stated safety claim is that the modification prevents fatigue cracking and preserves structural integrity (Background). The practical cost is borne by operators in parts, labour and downtime. The AD removes operators’ contractual choice about whether to implement the structural modification: compliance is mandatory under the airworthiness regime. The AD therefore replaces a private cost-benefit choice with a regulator-imposed safety action, with predictable direct compliance costs and demand on maintenance capacity.\n\n(References: Applicability; Requirement; Compliance; Background; Note referencing FAA AD.)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, narrow airworthiness directive targeting a specific structural defect in a specific aircraft model. It has not expanded beyond its original purpose of mandating a safety modification to prevent fatigue cracking."},"complexity_factors":["Single, clearly defined applicability (specific aircraft model and fuselage number range)","One straightforward requirement referencing an external technical standard (Boeing Service Bulletin)","Simple compliance deadline with two alternative triggers (flight cycles or calendar time)","No defined terms section, no cross-references to other legislation beyond the enabling regulation (CASR 1998)","Minimal conditional logic (only the 'whichever occurs first' compliance timing)","Short document (approximately 250 words excluding headers and images)"],"plain_english_summary":"This is a safety order (called an \"Airworthiness Directive\") issued by Australia's aviation safety regulator (CASA) that applies to specific Boeing 717-200 aircraft. It requires airlines and aircraft owners to carry out a structural modification to prevent metal fatigue cracks from developing in the upper centre fuselage longerons (structural support beams running along the length of the aircraft body). The modification must follow Boeing's official repair instructions (Service Bulletin 717-53-0001). Aircraft operators must complete this work before the plane reaches 30,000 flight cycles or within 10 years from 7 August 2003, whichever comes first. This directive became mandatory on 7 August 2003 and affects aircraft with fuselage numbers 5001 through 5056."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b717-8-upper-centre-fuselage-longerons","history":"/api/acts/ad-b717-8-upper-centre-fuselage-longerons/history","analysis":"/api/acts/ad-b717-8-upper-centre-fuselage-longerons/analysis","conflicts":"/api/acts/ad-b717-8-upper-centre-fuselage-longerons/conflicts","importantCases":"/api/acts/ad-b717-8-upper-centre-fuselage-longerons/important-cases","documents":"/api/acts/ad-b717-8-upper-centre-fuselage-longerons/documents"}}