{"id":"F2006B03053","name":"AD/B747/151 - Wing Front Spar Web","slug":"ad-b747-151-wing-front-spar-web","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42412,"registerId":"commonwealth-F2006B03053-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B747/151 - Wing Front Spar Web","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/B747/151 Wing Front Spar Web 8/95\n\nApplicability: All B747-100 aircraft except SP versions.\n\nRequirement: Visually and ultrasonically inspect the wing front spar web, upper and lower chords, stiffeners, rib posts and fasteners between front spar stations 570 and 684 in accordance with Boeing Service Bulletin (SB) 747-57A2266, Revision 4.\n\nNote: FAA AD 95-02-15 refers.\n\nCompliance: Initially inspect before 13 000 flights.\n\nRe-inspect at intervals not to exceed 2000 flights.\n\nReplacement of fasteners in accordance with Boeing SB 747-57A2266, Revision 4 cancels the requirement of this Directive.\n\nBackground: An operator has reported a 460 mm crack in the web of the right hand wing front spar. The cracks, occurring above the number two and three engines, will eventually cause a fuel leak which could result in a fire.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive sets a defined inspection requirement, intervals, and a cancellation condition tied to a specific Boeing service bulletin. The text does not indicate an expansion or narrowing of scope from a prior version; it presents the inspection mandate, timing and the option to cancel recurring inspections by replacing fasteners, consistent with the directive’s stated purpose to detect and address cracking in the specified spar region."},"complexity_factors":["Narrow applicability (B747-100 series except SP) — limits scope but requires fleet-specific tracking.","Technical inspection methods required (visual plus ultrasonic) — needs specialist equipment and trained personnel.","Dependency on an external procedural document (Boeing Service Bulletin 747-57A2266, Revision 4) for inspection and replacement steps.","Defined compliance timing (initial before 13,000 flights; re-inspect every 2,000 flights) — requires operational flight-count monitoring.","A clear cancellation condition (replacement of fasteners per the SB) that creates a maintenance choice for operators.","Safety-critical detection uncertainty inherent in non-destructive inspection techniques (visual/ultrasonic).","Reference to an FAA AD (coordination with another regulator) which may affect interpretation and concurrent compliance.","Specific physical location (front spar stations 570–684) and multiple component types (web, chords, stiffeners, rib posts, fasteners) increase inspection detail."],"plain_english_summary":"What this directive does (mechanics)\n\n- It requires operators of Boeing 747-100 aeroplanes (except SP variants) to inspect specific parts of the wing front spar — the web, upper and lower chords, stiffeners, rib posts and fasteners — between front spar stations 570 and 684. (Applicability; Requirement)\n- Inspections must be both visual and ultrasonic and must follow the procedures in Boeing Service Bulletin 747-57A2266, Revision 4. (Requirement)\n- The first inspection must be done before the aeroplane reaches 13,000 flights, and thereafter at intervals not exceeding 2,000 flights. (Compliance)\n- If the operator replaces the fasteners in accordance with Boeing SB 747-57A2266, Revision 4, the requirement to perform the recurring inspections is cancelled. (Requirement)\n- The directive cross-references a related FAA airworthiness directive (FAA AD 95-02-15). (Note)\n\nWhy the rule exists (stated purpose and risk)\n\n- The directive is prompted by a reported 460 mm crack in the right-hand wing front spar web that occurred above the number two and three engines. The background statement says such cracks can lead to fuel leaks that could result in a fire. (Background)\n\nWho decides and who acts\n\n- The Civil Aviation Safety Authority (CASA) issues the directive; aircraft operators are responsible for carrying out the inspections and any repairs or fastener replacements. (Applicability; Requirement; Compliance)\n- Boeing’s service bulletin prescribes the inspection and replacement procedures to be used. (Requirement)\n\nWho pays and what it costs in behaviour terms\n\n- Operators bear the direct costs: arranging and performing visual and ultrasonic inspections, labour, possible removal/access work, and any repairs or fastener replacement. (Requirement; Compliance)\n- If operators choose to replace the fasteners per the Boeing service bulletin, they incur the up-front replacement cost but can eliminate the recurring inspection requirement. That creates a clear trade-off between repeated inspection costs and a one-time replacement cost. (Requirement)\n\nCompliance burden, implementation risk and practical trade-offs\n\n- Compliance requires scheduled downtime for inspections at the specified intervals and access to ultrasonic inspection equipment and suitably qualified personnel. (Requirement; Compliance)\n- Ultrasonic inspection capability and the effectiveness of visual checks are practical determinants of the directive’s ability to detect cracks before they grow. The directive does not specify detection limits; it relies on the service bulletin procedures. (Requirement)\n- The directive’s cancellation condition (replacement of fasteners) gives operators discretion: they can either accept recurring inspections or choose a hardware modification that removes the inspection obligation. That decision changes maintenance planning and cash flow for the operator. (Requirement)\n\nOther operational notes\n\n- The directive applies only to B747-100 aircraft excluding SP versions; it targets a defined structural zone (stations 570–684) above the number two and three engines. (Applicability; Requirement; Background)\n- The FAA AD reference indicates parallel or related regulatory action outside this directive. (Note)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete airworthiness directive addressing a specific structural defect in a specific aircraft type. It has not expanded beyond its original safety purpose."},"complexity_factors":["Single, specific applicability (one aircraft model, one exclusion)","Straightforward compliance timeline (initial + recurring interval)","Single technical reference document (Boeing SB 747-57A2266 Rev 4)","Clear termination condition (fastener replacement cancels requirement)","No defined terms section, no cross-references to other legislation beyond the FAA AD note","Minimal conditional logic — essentially 'do this, unless you do that'"],"plain_english_summary":"This is a **safety order for old Boeing 747 planes**. It tells airlines they must check a specific part of the wing — the front spar web (a structural beam that helps hold the wing together) — for cracks.\n\n**Who it affects:** Airlines operating Boeing 747-100 aircraft (but not the shorter SP models).\n\n**What they must do:**\n- **First check:** Inspect the wing structure before the plane has flown 13,000 times.\n- **Ongoing checks:** Re-inspect every 2,000 flights after that.\n- **How:** Use visual checks and ultrasound (a special scan that can see inside metal) on specific parts of the wing between two measurement points (stations 570 and 684).\n- **Follow this manual:** Boeing Service Bulletin 747-57A2266, Revision 4.\n\n**The escape clause:** If airlines replace the fasteners (bolts/screws) as described in that Boeing manual, they don't have to keep doing these inspections.\n\n**Why it matters:** A crack was found in this area on one plane — a 46-centimetre crack in the metal web. If these cracks aren't caught, fuel can leak out and potentially catch fire. This directive exists to stop planes from falling out of the sky due to structural failure."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-151-wing-front-spar-web","history":"/api/acts/ad-b747-151-wing-front-spar-web/history","analysis":"/api/acts/ad-b747-151-wing-front-spar-web/analysis","conflicts":"/api/acts/ad-b747-151-wing-front-spar-web/conflicts","importantCases":"/api/acts/ad-b747-151-wing-front-spar-web/important-cases","documents":"/api/acts/ad-b747-151-wing-front-spar-web/documents"}}