{"id":"F2006L01297","name":"AD/CONVAIR/23 - Fuselage Stringer and Beltframe Attachment between Stations 140 and 889","slug":"ad-convair-23-fuselage-stringer-and-beltframe-attachment-between-stations-140-and-889","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":58763,"registerId":"commonwealth-F2006L01297-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Kelowna Flightcraft (General Dynamics/Co","sectionType":"division","heading":"Kelowna Flightcraft (General Dynamics/Convair) Series Aeroplanes","content":"### Kelowna Flightcraft (General Dynamics/Convair) Series Aeroplanes\n\n| AD/CONVAIR/23 | Fuselage Stringer and Beltframe Attachment between Stations 140 and 889 | 6/2006 |\n| ------------- | ----------------------------------------------------------------------- | ------ |\n\n| Applicability: | Model 340 and 440 series aircraft, including all such model aircraft converted to turbopropeller power.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. For aircraft with more than 52,000 hours time in service, perform an initial detailed visual, above floor level, inspection of the stringers and beltframes for evidence of cracks at all stringer to beltframe attach points between stations 140 and 889; and,a. Aircraft certificated at a maximum gross weight of 55,000 lbs or less, and without a main cargo door, perform a detailed visual inspection of all stringer to frame attachment, above and below floor level, for evidence of cracks between stations 140 and 889; and thereafter,(i) Perform a detailed visual inspection of all stringer to frame attachment for evidence of cracks below the floor between stations 681 and 889; and,(ii) Perform a detailed visual inspection of all stringer to frame attachment for evidence of cracks between stations140 and 889 above the floor and between stations 140 and 681 below the floor.b. Aircraft with a main deck cargo door and aircraft certificated at a maximum gross weight of more than 55,000 lbs, perform a detailed visual inspection of all stringer to frame attachment, above and below floor level, for evidence of cracks between stations 140 and 889.2. For aircraft with more than 42,000 hours time in service, up to and including 52,000 hours time in service, perform an initial detailed visual, above floor level, inspection of the stringers and beltframes for evidence of cracks at all stringer to beltframe attach points between stations 140 and 889. Repetitively inspect in accordance with Requirement 1.a. or 1.b. |\n\n|     | 3. For aircraft with more than 35,000 hours time in service, up to and including 42,000 hours time in service, perform an initial detailed visual, above floor level, inspection of the stringers and beltframes for evidence of cracks at all stringer to beltframes attach points between stations 140 and 889. Perform a repetitive detailed visual inspection of all stringer to frame attachment, above and below floor level, for evidence of cracks between stations 140 and 889. Refer to Requirement 6 for reduction in repetitive inspection interval.4. For aircraft with more than 25,000 hours time in service up to and including 35,000 hours time in service, perform an initial detailed visual, above the floor level, inspection of the stringers and beltframes for evidence of cracks at all stringer to beltframe attach points between stations 140 and 889. Perform a repetitive detailed visual inspection of all stringer to frame attachment, above and below floor level, for evidence of cracks between stations 140 and 889. Refer to Requirement 6 for reduction in repetitive inspection interval.5. For aircraft with less than 25,000 hours time in service, and have not previously been inspected for cracks, perform an initial detailed visual, above the floor level, inspection of the stringers and beltframes for evidence of cracks at all stringer to beltframe attach points between stations 140 and 889. Perform a repetitive detailed visual inspection of all stringer to frame attachment, above and below floor level, for evidence of cracks between stations 140 and 889. For those aircraft which have been previously been inspected in accordance with the above initial inspection, accomplish the above repetitive inspections at the intervals required by Requirements 1 through 4. The first above repetitive inspection must be accomplished before accumulating 28,000 hours time in service or 10,000 additional hours time in service from the above initial inspection, whichever occurs later.6. The second inspection, for aircraft affected by Requirements 3 and 4, will be within the 7,500 or 10,000 hours time in service as specified; however, for subsequent inspections, the interval will be based upon the aircraft time in service at the time of the last inspection rather than the total time in service which results in the aircraft reaching the next category. If the last inspection was accomplished when the aircraft had more than 42,000 hours time in service, all subsequent inspections must be at intervals not to exceed 5,000 hours additional time in service.If cracks are detected during any inspection, before further flight, repair in accordance with the applicable structural repair manual.Note: FAA AD 74-16-01 Amdt 39-1904 refers. |\n| --- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n| Compliance: | 1. Unless already accomplished, within 300 hours time in service after 8 June 2006, unless accomplished within the last 4,700 hours time in service.a. Within 5,000 hours time in service after the initial inspection.(i) Within 5,000 hours time in service after the Requirement 1.a. inspection, and thereafter at intervals not to exceed 5,000 hours time in service.(ii) Within 7,500 hours time in service after the Requirement 1.a. inspection, and thereafter at intervals not to exceed 7,500 hours time in service.b. Within 5,000 hours time in service after the initial inspection, and thereafter at intervals not to exceed 5,000 hours time in service.2. Unless already accomplished, within 1,500 hours time in service after 8 June 2006, unless accomplished within the last 3,500 hours time in service.3. Unless already accomplished, within 3,000 hours time in service after 8 June 2006, unless accomplished within the last 4,500 hours time in service. Repetitively inspect thereafter at intervals not to exceed 7,500 hours time in service.4. Unless already accomplished, within 3,000 hours time in service after 8 June 2006, unless accomplished within the last 7,000 hours time in service. Repetitively inspect thereafter at intervals not to exceed 10,000 hours time in service.5. Unless already accomplished, within 3,000 hours time in service after accumulating 25,000 hours time in service. Repetitive inspections must be performed at the intervals required by Requirements 1 through 4.6. As specified in Requirement 6. |\n| ----------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n|             | This Airworthiness Directive becomes effective on 8 June 2006.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |\n| Background: | The FAA requires certain actions to prevent loss of structural integrity of the aircraft, due to longitudinal cracks in the stringer or beltframe at the beltframe attach points.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n11 April 2006","sortOrder":0},{"sectionNumber":"AD/CONVAIR/23","sectionType":"part","heading":"AD/CONVAIR/23","content":"## AD/CONVAIR/23","sortOrder":1},{"sectionNumber":"Fuselage Stringer and Beltframe Attachme","sectionType":"part","heading":"Fuselage Stringer and Beltframe Attachment between Stations 140 and 889","content":"## Fuselage Stringer and Beltframe Attachment between Stations 140 and 889","sortOrder":2},{"sectionNumber":"6/2006","sectionType":"part","heading":"6/2006","content":"## 6/2006","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":7,"scope_assessment":{"changed":false,"description":"This AD addresses a narrowly defined safety issue: detection and repair of cracks at stringer-to-beltframe/frame attachment points for Convair 340/440 series aeroplanes between stations 140 and 889. The requirements are age/usage-tiered inspections and mandatory repairs. The instrument remains within that original safety-focused scope: it does not expand into unrelated regulatory domains, introduce novel obligations beyond inspection and repair, or add broader operational or economic controls. It aligns CASA action with an existing FAA AD and therefore does not represent a substantive expansion of scope beyond addressing the stated structural integrity risk."},"complexity_factors":["Multiple tiered service-hour bands for triggering and defining inspections (5 bands: >52,000; 42,000–52,000; 35,000–42,000; 25,000–35,000; <25,000) (Requirements 1–5).","Different inspection scopes depending on aircraft configuration (presence of main deck cargo door and certificated maximum gross weight > or ≤ 55,000 lbs) (Requirement 1.a & 1.b).","Separate above-floor and below-floor inspection requirements which vary by station ranges (e.g. stations 140–889, and specifically 681–889 below floor for some aircraft) (Requirement 1.a.i–ii).","Multiple repetitive inspection intervals (5,000; 7,500; 10,000 hours) and transition rules for moving between bands (Requirements and Compliance).","Complex timing/compliance credit rules tied to inspections already performed within specific prior-hour windows (e.g. \"unless accomplished within the last 4,700 hours\", \"within the last 3,500 hours\", etc.) (Compliance).","Requirement 6 changes interval calculation method after the second inspection, creating a non-linear rule: subsequent intervals are based on time-in-service at last inspection rather than band thresholds, with an overriding cap if last inspection was >42,000 hours (Requirement 6).","Cross-reference to external documents: the applicable structural repair manual for repairs and reference to FAA AD 74-16-01 (note and repair requirement).","Several conditional cross-references and nested requirements (e.g. Requirement 2 instructs to repetitively inspect in accordance with Requirement 1.a or 1.b), increasing interpretive steps.","Short-term compliance windows expressed as hours after the effective date with multiple differing grace periods (300, 1,500, 3,000 hours etc.) (Compliance)."],"plain_english_summary":"**What this instrument does**\n\n- This is an Airworthiness Directive (a mandatory safety order) that requires owners/operators of Convair Model 340 and 440 series aeroplanes to carry out repeated visual inspections of the fuselage stringer and beltframe attachment points between fuselage stations 140 and 889.  The inspections look for cracks where stringers attach to beltframes/frames. (See \"Requirement\".)\n\n**Which aircraft are affected**\n\n- All Convair Model 340 and 440 series aeroplanes, including those converted to turboprops. The scope of the inspection work differs by aircraft hours-in-service and by two configuration/weight distinctions: whether the aeroplane has a main deck cargo door and whether its certificated maximum gross weight is over 55,000 lbs. (See Requirements 1.a and 1.b and Requirements 2–5.)\n\n**Who must do the work and who pays**\n\n- The aircraft operator/owner must arrange and pay for the inspections and any repairs. Repairs required because cracks are found must be done before further flight and must follow the applicable structural repair manual. (See the last paragraph of the Requirement.)\n\n**How it works (mechanics)**\n\n- Inspections are triggered by the aircraft's hours time in service. There are five service-hour bands that determine the initial inspection required and the subsequent repetitive inspection intervals: (a) more than 52,000 hours; (b) 42,000–52,000 hours; (c) 35,000–42,000 hours; (d) 25,000–35,000 hours; and (e) less than 25,000 hours (see Requirements 1–5).\n\n- The scope of each inspection varies by band and by aircraft configuration:\n  - For some bands the initial inspection is \"above floor level\" only; for other bands it requires inspection both above and below the cabin floor. (Requirements 1–5.)\n  - For aircraft without a main cargo door and certificated at 55,000 lbs or less, the AD sets slightly different below-floor inspection areas (e.g. additional below-floor checks between stations 681 and 889). (Requirement 1.a.)\n\n- Inspection frequency varies by band and configuration. Examples:\n  - For the highest-risk category (aircraft >52,000 hours) inspections are initially required promptly (see Compliance times) and then at either 5,000- or 7,500-hour intervals depending on the aircraft type/weight (Requirement 1.a.i–ii and Compliance table).\n  - For mid-range bands (25,000–42,000 hours) the AD requires repetitive inspections at intervals up to either 7,500 or 10,000 hours depending on the band. (Requirements 3–4 and Compliance.)\n\n- Requirement 6 changes the way later inspection intervals are set: after the second inspection for certain bands, intervals are based on the aircraft's hours at the last inspection rather than the hours that move the aircraft into the next band. If the last inspection was done when the aircraft had >42,000 hours, all subsequent intervals must not exceed 5,000 hours. (Requirement 6.)\n\n- If any cracks are found, the AD requires repair before the airplane flies again, using the structural repair manual process that applies to the aircraft. (Requirement: \"If cracks are detected ... repair ...\")\n\n**Deadlines and short-term compliance timing**\n\n- The AD became effective 8 June 2006. It sets short-term deadlines for initial inspections expressed as hours-in-service after that effective date (for example: within 300 hours TS unless already done within the prior 4,700 hours; other bands have 1,500 or 3,000-hour windows). Those deadlines also take account of recent inspections done before the AD by allowing credit where an inspection was done within a specified number of prior hours. (See the Compliance table.)\n\n**Why it matters (stated purpose and practical trade-offs)**\n\n- The stated purpose is to prevent loss of structural integrity from longitudinal cracks at stringer-to-beltframe/frame attachment points. (Background.)\n\n- Who benefits and who pays: The safety benefit (reduced risk of structural failure) is concentrated on passengers, crew and owners operating the affected aircraft and on regulators/public safety; the inspection and repair costs (labour, parts, aircraft downtime) fall on the aircraft owners/operators because they must perform and fund the inspections and repairs. (Requirement; Compliance.)\n\n- Implementation and operational effects:\n  - Inspections that require access below the cabin floor can increase labour time, may require partial disassembly or interior access panels, and therefore increase maintenance man-hours and aircraft downtime.\n  - The AD applies progressive inspection intensity as aircraft age (hours-in-service thresholds). That creates a clear incentive for operators to track hours carefully and may alter operational decisions about how long to continue operating older airframes versus retiring or modifying them.\n  - Repairs mandated by the structural repair manual can be time-consuming and can require certified maintenance organisations and parts; operators must schedule work into their maintenance program to keep compliance and airworthiness records current.\n\n**Authority and linkage to other instruments**\n\n- The AD implements actions consistent with an FAA airworthiness directive (FAA AD 74-16-01 Amdt 39-1904 is referenced). This AD therefore aligns CASA’s mandatory inspection requirements for these models with prior FAA guidance. (Note following Requirement text.)\n\n**Bottom-line mechanics in one sentence**\n\n- Operators of Convair 340/440 series aeroplanes must perform regular, tiered visual inspections of fuselage stringer-to-beltframe/frame attachment points between stations 140 and 889 at specified hour-based intervals and repair any cracks found before further flight; the exact inspection scope and frequency depend on the aeroplane’s hours-in-service and configuration (main deck cargo door and certificated weight). (See Requirements 1–6 and Compliance.)"},"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":7,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive with focused scope. It addresses a specific structural fatigue issue in a defined aircraft type. The multiple requirements and flight-hour categories represent necessary granularity for safety regulation of aging aircraft, not scope creep. The original intent — mandating inspections to prevent structural failure — remains tightly aligned with the content."},"complexity_factors":["Six distinct applicability categories based on flight hours (25K, 25-35K, 35-42K, 42-52K, 52K+), each with different inspection requirements","Nested conditional logic: inspection scope varies by both flight hours AND aircraft configuration (cargo door presence, weight certification above/below 55,000 lbs)","Complex compliance timing: multiple overlapping deadlines referencing 'hours time in service after 8 June 2006' versus 'hours time in service after initial inspection'","Requirement 6 contains a recursive calculation method for subsequent inspection intervals based on 'time in service at the time of the last inspection' rather than total accumulated hours","Cross-references between requirements (e.g., 'Refer to Requirement 6', 'in accordance with Requirements 1 through 4') creating dependency chains","Technical aviation terminology requiring domain knowledge ('stations 140 and 889', 'stringers', 'beltframes', 'detailed visual inspection')","Dual reference system: CASA AD number (AD/CONVAIR/23) and FAA AD number (74-16-01 Amdt 39-1904) in the note"],"plain_english_summary":"This CASA Airworthiness Directive mandates mandatory fuselage inspections for owners/operators of Convair 340/440 series (including turboprop conversions) to detect longitudinal cracking in stringers and beltframes. Inspections and repeat intervals vary by airframe hours-in-service, with initial checks and deadlines measured in flight hours and most actions required within 300–3,000 hours from 8 June 2006.\n\nCracks must be repaired before further flight. The AD protects aging airframes from fatigue-related structural failure."}},"importantCases":[],"_links":{"self":"/api/acts/ad-convair-23-fuselage-stringer-and-beltframe-attachment-between-stations-140-and-889","history":"/api/acts/ad-convair-23-fuselage-stringer-and-beltframe-attachment-between-stations-140-and-889/history","analysis":"/api/acts/ad-convair-23-fuselage-stringer-and-beltframe-attachment-between-stations-140-and-889/analysis","conflicts":"/api/acts/ad-convair-23-fuselage-stringer-and-beltframe-attachment-between-stations-140-and-889/conflicts","importantCases":"/api/acts/ad-convair-23-fuselage-stringer-and-beltframe-attachment-between-stations-140-and-889/important-cases","documents":"/api/acts/ad-convair-23-fuselage-stringer-and-beltframe-attachment-between-stations-140-and-889/documents"}}