{"id":"F2006B01980","name":"AD/A320/90 Amdt 1 - Fuselage Frame 46 / Stringer 37 Intersection","slug":"ad-a320-90-amdt-1-fuselage-frame-46-stringer-37-intersection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41202,"registerId":"commonwealth-F2006B01980-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/A320/90 Amdt 1 - Fuselage Frame 46 / Stringer 37 Intersection","content":"![](image.001.png)\n\n![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/A320/90 and issues the following AD under subregulation 39.1 (1) of CAR 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\nAirbus Industrie A319, A320 and A321 Series Aeroplanes\n\nAD/A320/90\n\nAmdt 1\n\n  \nFuselage Frame 46 / Stringer 37 Intersection 7/2002\n\nApplicability: All Model A320-111, \\-211, 212, and 231 aircraft without Modification 21202 incorporated at production or Service Bulletin A320-53-1033 incorporated in-service.\n\nRequirement: 1. Perform an ultrasonic inspection of the bottom panel of the keel beam at the pressure bulkhead frame 46/stringer 37 intersection and repair if required, in accordance with Service Bulletin A320-53-1034 Revision 2.\n\n    2. Depending upon the inspection result, repeat the Requirement 1 inspection.\n\nNote 1: Repetitive inspections are not required on the area where a repair procedure is performed in accordance with the Requirement document.\n\nNote 2: DGAC AD 2002-260(B) refers.\n\nCompliance: 1. Unless already accomplished, at the latest of the following thresholds:\n\n    Before accumulating 24,200 flight cycles or 48,400 flight hours, whichever occurs first; or,\n    Within 3,500 flight cycles from 11 July 2002; without exceeding 30,000 total flight cycles.\n\n2. At the intervals specified in the Requirement document. This Amendment becomes effective on 11 July 2002.\n\nBackground: During full scale fatigue test, cracks were detected on the bottom panel of the keel beam at the bulkhead frame 46/stringer 37 intersection.\n\nAirbus Industrie A319, A320 and A321 Series Aeroplanes\n\nAD/A320/90 Amdt 1 (Continued)\n\nAmendment 1 is issued in response to a revision of the Requirement document and related DGAC AD which introduce revised inspection threshold and intervals, as a result of a review of A320 in-service aircraft fleet mission parameters and those originally considered.\n\nThe original issue of this Airworthiness Directive became effective on 29 January 1998\n\n![](image.002.jpeg)  \n\nDavid Alan Villiers\n\nDelegate of the Civil Aviation Safety Authority 27 May 2002\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 19 June 2002.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"This amendment refines inspection thresholds and repeat intervals (timing) based on revised fleet mission data but does not expand the population of affected aircraft or add new types of obligations beyond inspection, repair and repetition. In other words, it adjusts how and when the original safety measure must be carried out rather than growing the AD’s substantive scope or introducing new regulatory purposes."},"complexity_factors":["Single focused subject (frame 46 / stringer 37 intersection) limiting breadth","Short document length (one-page AD amendment)","Cross-reference to multiple external documents: Service Bulletin A320-53-1034 Rev 2, Service Bulletin A320-53-1033, Modification 21202, and DGAC AD 2002-260(B)","Two alternative initial compliance thresholds (cycles OR hours OR within 3,500 cycles from a specific date) plus an absolute cap (not to exceed 30,000 total flight cycles)","Repetitive-inspection regime whose intervals are defined in an external Service Bulletin (adds conditionality and reliance on another document)","Exemption where repair is performed according to the Requirement document (nested exception)","Applicability limited to specific model variants (A320-111, -211, -212, -231)","Dependence on technical inspection method (ultrasonic) which carries operator-dependent variability"],"plain_english_summary":"**What this instrument does (mechanics)**\n\n- Requires operators of certain Airbus A320-family aeroplanes to carry out an ultrasonic inspection of the bottom panel of the keel beam where pressure bulkhead frame 46 meets stringer 37 (Requirement).\n- If cracks are found, the aircraft must be repaired in accordance with Service Bulletin A320-53-1034 Revision 2 (Requirement).\n- Depending on the result of the inspection, the ultrasonic check must be repeated at the intervals specified in that Service Bulletin (Requirement and Compliance).\n- Aircraft that already have Modification 21202 fitted at production or Service Bulletin A320-53-1033 incorporated in-service are excluded from this AD (Applicability).\n- Repetitive inspections are not required on areas that have been repaired according to the Service Bulletin (Note 1).\n- Two alternative initial compliance thresholds are provided: complete the inspection before the aeroplane accumulates 24,200 flight cycles or 48,400 flight hours (whichever comes first), or within 3,500 flight cycles from 11 July 2002 — but in any case not later than when the aeroplane reaches 30,000 total flight cycles (Compliance).\n\n**Which aircraft are affected**\n\n- All Airbus A320 models listed: A320-111, -211, -212 and -231, unless they already have Mod 21202 or Service Bulletin A320-53-1033 incorporated (Applicability).\n\n**Why it was issued (stated purpose)**\n\n- The AD says cracks were found during full-scale fatigue testing at the keel-beam bottom panel where frame 46 intersects stringer 37 (Background).\n- The amendment revises the inspection thresholds and intervals after a review of in-service fleet mission parameters (Background).\n\n**What changes for operators and maintenance providers (practical effects)**\n\n- Who pays: aircraft operators bear the cost of inspections and any repairs, plus aircraft downtime while work is done (Requirement, Compliance).\n- Who decides: the CASA delegate enforces the AD; the specific inspection method, repair and repeat intervals are defined by Airbus Service Bulletin A320-53-1034 Revision 2 (Requirement).\n- Behaviour changes required: operators must schedule ultrasonic inspections, apply the Service Bulletin procedures if cracks are found, and either repeat inspections per the Service Bulletin or stop repeating on repaired areas.\n- Timing and enforcement: inspectors must meet the flight-cycle or flight-hour thresholds in the Compliance section; failure to comply would contravene the AD issued under subregulation 39.1(1) of the Civil Aviation Regulations 1998 (preamble).\n\n**Costs, incentives and trade-offs**\n\n- Direct costs: recurring nondestructive testing (ultrasonic), repair parts and labour, and potential aircraft out-of-service time.\n- Incentives: operators may choose to incorporate Mod 21202 or Service Bulletin A320-53-1033 (if available and approved) to avoid the AD’s inspection requirement for aircraft that already have those modifications (Applicability). Incorporating the approved modification or service bulletin in-service may remove the inspection burden for that area.\n- Trade-offs: the AD imposes maintenance costs and scheduling constraints in return for addressing an identified structural cracking risk. The Service Bulletin dictates repeat intervals, so frequency of inspections (and therefore ongoing cost) depends on the technical assessment Airbus supplied.\n- Concentrated benefits, diffuse costs: the immediate safety benefit accrues to operators and their passengers and crews; the financial burden falls on operators of the affected A320 variants.\n\n**Implementation and compliance risks**\n\n- Inspection quality risk: ultrasonic inspection accuracy depends on correct technique, equipment calibration and trained personnel; inconsistent inspections could produce false negatives or false positives.\n- Dependence on external documents: the AD requires compliance with a specific Service Bulletin (A320-53-1034 Rev 2), so any ambiguity or later revisions to that SB affect how the AD is implemented (Requirement).\n- Scheduling pressure: windows defined by flight cycles/hours and the alternative 3,500-cycle-from-date option create operational scheduling constraints; operators near the thresholds may need to ground aircraft temporarily to comply.\n\n**Source claim and testing it against costs and implementation**\n\n- The AD claims it is necessary because fatigue testing found cracks at the frame 46/stringer 37 intersection (Background). The corrective mechanism chosen is targeted ultrasonic inspection plus repair per a Service Bulletin.\n- The mechanism addresses detection and repair of cracks but requires recurring inspections unless repair is performed. This creates an ongoing maintenance burden proportional to fleet exposure and the repeat interval specified in the Service Bulletin.\n\n(References in the AD: Applicability; Requirement; Notes 1–2; Compliance; Background.)"},"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"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment remains tightly focused on its original purpose — addressing the specific structural cracking issue at frame 46/stringer 37. The amendment merely updates inspection thresholds and intervals based on new fleet data, without expanding to new aircraft types, new structural areas, or new regulatory mechanisms."},"complexity_factors":["Multiple applicability conditions (specific model variants AND exclusion criteria for modified aircraft)","Tiered compliance deadlines with three alternative thresholds (flight cycles, flight hours, and calendar/cycle hybrid)","Cross-reference to external technical documents (Service Bulletin A320-53-1034 Revision 2, DGAC AD 2002-260(B))","Conditional logic: inspection results trigger repeat requirements, and repairs exempt future inspections","Technical aviation terminology requiring domain knowledge (keel beam, pressure bulkhead, frame/stringer intersection, flight cycles)"],"plain_english_summary":"This AD requires ultrasonic inspection and necessary repair of the keel-beam bottom panel at the frame 46 / stringer 37 intersection on certain Airbus A320 family aircraft (A319/A320/A321 variants specified) that have not received Mod 21202 or SB A320-53-1033. Inspections must be repeated per Airbus instructions until a terminating repair is done.\n\nIssued after fatigue-test cracks were found, the rule protects against potential structural failure and applies to affected owners/operators within the specified timing limits."}},"importantCases":[],"_links":{"self":"/api/acts/ad-a320-90-amdt-1-fuselage-frame-46-stringer-37-intersection","history":"/api/acts/ad-a320-90-amdt-1-fuselage-frame-46-stringer-37-intersection/history","analysis":"/api/acts/ad-a320-90-amdt-1-fuselage-frame-46-stringer-37-intersection/analysis","conflicts":"/api/acts/ad-a320-90-amdt-1-fuselage-frame-46-stringer-37-intersection/conflicts","importantCases":"/api/acts/ad-a320-90-amdt-1-fuselage-frame-46-stringer-37-intersection/important-cases","documents":"/api/acts/ad-a320-90-amdt-1-fuselage-frame-46-stringer-37-intersection/documents"}}