{"id":"F2006L01338","name":"AD/CONVAIR/22 - Wing Lower Skin Inboard of Station 8","slug":"ad-convair-22-wing-lower-skin-inboard-of-station-8","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":58850,"registerId":"commonwealth-F2006L01338-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/22 | Wing Lower Skin Inboard of Station 8 | 6/2006 |\n| ------------- | ------------------------------------ | ------ |\n\n| Applicability: | Model 340 and 440 aircraft, and all such model aircraft converted to turbopropeller power.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. For aircraft with 15,000 hours or less time in service:Clean the inside surface of the wing lower skin inboard of Station 8 in the vicinity of the second rivet from the outboard end of the short stringer in line with the wing access door in the wheel well, and conduct a detailed visual inspection of that area for any indication of wing skin cracks. If cracks are detected accomplish Requirements 4, 5, or 6.2. For aircraft with more than 15,000 hours time in service and less than 20,000 hours time in service:Clean the inside surface of the wing lower skin inboard of Station 8 in the vicinity of the second rivet from the outboard end of the short stringer in line with the wing access door in the wheel well, and conduct a detailed visual inspection of that area for any indication of wing skin cracks. If cracks are detected accomplish Requirements 4, 5, or 6.3. For aircraft with 20,000 hours time in service or more:Clean the inside surface of the wing lower skin inboard of Station 8 in the vicinity of the second rivet from the outboard end of the short stringer in line with the wing access door in the wheel well, and conduct a detailed visual inspection of that area for any indication of wing skin cracks. If cracks are detected accomplish Requirements 4, 5, or 6.For aircraft with no wing lower skin cracks detected in the specified inspection area, the inspection intervals may be increased to 1,000 hours time in service when the aircraft is modified as follows:Remove the 3/16-inch rivet located above where the cracks originate, enlarge the hole to 1/4-inch, and inspect the wing lower skin around the hole. If no wing skin crack is detected, install a close tolerance -8 rivet or 1/4-inch bolt. If cracks are detected, accomplish Requirements 4, 5, or 6, as applicable. |\n\n|     | 4. For aircraft with wing skin cracks less than 6-inches in length, unless already repaired in accordance with Requirements 6 or 7, modify and inspect as follows:a. For wing skin cracks less than 2-inches long, before further flight, stop drill each end of the crack with a 0.50-inch diameter drill. Repetitively inspect thereafter in accordance with Requirement 1, 2, or 3, as applicable. If during any inspection the crack is found to have progressed beyond a stop drill hole, but the total length remains less than 2-inches, the crack may be stop drilled and the 100-hour interval inspections continued. When a crack reaches the 2-inch limit, the provisions of Requirement 4.b. apply.b. For wing cracks between 2 and 3-inches in length, before further flight, stop drill each end of the crack with a 0.50-inch diameter drill and revise the airspeed limitations for the aircraft by reducing the never exceed speed (Vne) to 243 knots and the normal operating speed (Vno) to 217 knots and install a placard in the cockpit, in full view of the pilot stating the reduced speeds. An internal visual repetitive inspection of the stop drilled crack is to be accomplished in accordance with Requirements 1, 2, or 3, as applicable. If during any inspection the crack is found to have progressed beyond a stop drill hole, but the total length remains less than 3-inches, the crack may be stop drilled and the 100-hour interval inspections and speed restrictions continued. When a crack reaches the 3-inch limit, the provisions of Requirement 4.c. apply.c. For wing skin cracks between 3 and 6-inches in length, before further flight, repair the wing lower skin by installing internal reinforcement plates inboard of Station 8 in accordance with Convair Service Engineering Report No. 6820-340-47B/440-47B, dated 15 January 1963, and revise the airspeed limitations for the aircraft by reducing the never exceed speed (Vne) to 243 knots and the normal operating speed (Vno) to 217 knots and install a placard in the cockpit, in full view of the pilot stating the reduced speeds. An internal visual repetitive inspection is to be accomplished in accordance with Requirements 1, 2, or 3, as applicable. If during any inspection further cracking is detected, but in no case more than 1,000 hours time in service from above mentioned temporary repair, repair the aircraft in accordance with Requirement 6.5. An aircraft with wing skin cracks less than 2-inches in length, including stop drill holes, unless repaired in accordance with Requirement 6, may be permanently repaired by installing internal reinforcement plates inboard and outboard of Station 8 in accordance with Convair Service Engineering Report No. 6820-340-47B/440-47B.6. Aircraft with wing skin cracks greater than 6-inches in length must be repaired in accordance with Convair Service Engineering Report No. 6820-340-47B/440-47B. |\n| --- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n|             | 7. The requirements of this Directive do not apply to aircraft repaired in accordance with Requirement 5 or 6 before the effective date of this Directive or if, before any wing skin cracking in the area described in Requirements 1, 2, or 3, the aircraft has been modified between stringers 6 and 10, in accordance with Convair Service Engineering Report No. 15-4-340-18/440-22 dated 9 May 1958. Also, the repetitive inspections required by Requirements 1, 2, 3, and 4 may be discontinued, and the operating limitations and placard specified in Requirements 4.b. and 4.c. may be removed from the aircraft when it is repaired in the manner specified in Requirement 5 or 6; and if, before any wing skin cracking in the area described in Requirements 1, 2, or 3, the aircraft has been modified between stringers 6 and 10, in accordance with Convair Service Engineering Report No. 15-4-340-18/440-22.Note: FAA AD 63-10-03 Amdt 562 Part 507 refers.                                                                                                                                                                                                                                                                                                                                                                                                  |\n| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Compliance: | 1. Before the accumulation of 15,100 hours time in service, and thereafter at intervals not to exceed 1,000 hours time in service, until the accumulation of 20,000 hours time in service. After the accumulation of 20,000 hours time in service, and before the accumulation of 20,500 hours time in service, accomplish Requirement 1 at intervals not to exceed 500 hours time in service.2. Unless the initial inspection is already accomplished; within 100 hours time in service after 8 June 2006, unless accomplished within the last 900 hours time in service, and thereafter at intervals not to exceed 1,000 hours time in service. After the accumulation of 20,000 hours time in service, and before the accumulation of 20,500 hours time in service, accomplish Requirement 2 at intervals not to exceed 500 hours time in service.3. Unless the initial inspection is already accomplished; within 100 hours time in service after 8 June 2006, unless accomplished within the last 400 hours time in service, and thereafter at intervals not to exceed 500 hours time in service.4.a. At intervals not to exceed 100 hours time in service.4.b. At intervals not to exceed 100 hours time in service.4.c. At intervals not to exceed 500 hours time in service.5. As specified in Requirement 5.6. Before further flight.7. As specified in Requirement 7. |\n|             | This Airworthiness Directive becomes effective on 8 June 2006.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |\n\n| Background: | The FAA requires certain inspections and modifications to detect and correct wing lower skin fatigue cracking. |\n| ----------- | -------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n11 April 2006","sortOrder":0},{"sectionNumber":"AD/CONVAIR/22","sectionType":"part","heading":"AD/CONVAIR/22","content":"## AD/CONVAIR/22","sortOrder":1},{"sectionNumber":"Wing Lower Skin Inboard of Station 8","sectionType":"part","heading":"Wing Lower Skin Inboard of Station 8","content":"## Wing Lower Skin Inboard of Station 8","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"},"kimi_summary":{"content_quality":"ok","complexity_score":7,"scope_assessment":{"changed":false,"description":"This AD appears focused on its original safety purpose: addressing wing skin fatigue cracking in specific Convair aircraft models. The detailed crack-length thresholds and repair options represent technical precision rather than scope creep. The reference to FAA AD 63-10-03 suggests this aligns with original international safety coordination for this known airworthiness issue."},"complexity_factors":["Multiple overlapping compliance categories based on aircraft flight hours (15,000 hrs or less / 15,000–20,000 hrs / 20,000+ hrs)","Nested conditional requirements: crack detection triggers different repair paths (Requirements 4, 5, or 6)","Crack-length-based sub-categories within Requirement 4 (4.a: <2 inches, 4.b: 2–3 inches, 4.c: 3–6 inches), each with different speed restrictions, inspection intervals, and repair methods","Cross-references to external technical documents (Convair Service Engineering Reports No. 6820-340-47B/440-47B and No. 15-4-340-18/440-22)","Complex compliance timing with multiple 'unless already accomplished' clauses and varying intervals (100 hrs, 400 hrs, 500 hrs, 900 hrs, 1,000 hrs)","Exception to the exception in Requirement 7 (exemptions for pre-existing repairs and modifications)","Technical aviation terminology requiring specialised knowledge (Station 8, stringers, stop-drilling, Vne/Vno speeds, close tolerance rivets)"],"plain_english_summary":"This AD mandates recurring inspections of the lower wing skin on Convair 340/440 (including turboprop conversions), with inspection frequency increasing as airframe hours accumulate, and requires staged repairs, speed restrictions, or grounding if fatigue cracks are found.  \n\nIt affects owners, operators and maintenance organisations of these types — aiming to detect and repair wing-skin cracking early to prevent structural failure and catastrophic accidents."},"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":false,"description":"The directive is narrowly targeted at detecting and repairing fatigue cracks in a particular wing lower‑skin area of Convair Model 340/440 aircraft. Its requirements—inspections, stop‑drill temporary measures, speed restrictions, and repair by referenced Convair engineering reports—remain within that original safety-focused scope. There is no substantive expansion beyond addressing the specified structural fatigue risk; the AD primarily provides graded corrective options and exemptions for prior qualifying repairs or modifications."},"complexity_factors":["Multiple time‑in‑service tiers (<15,000; 15,000–20,000; ≥20,000 hours) that change inspection frequency and compliance windows","Different numbered Requirements (1–7) with nested subparts and conditionally different actions","Graduated corrective actions based on measured crack length with numeric thresholds (<2\", 2–3\", 3–6\", >6\")","Variable repetitive inspection intervals (100, 500, 1,000 hours) depending on condition and repair state","Mandatory operational constraints (reduced Vne/Vno and cockpit placard) tied to repair state","Cross‑references to external technical documents (Convair Service Engineering Report Nos. 6820-340-47B/440-47B and 15-4-340-18/440-22) for repair procedures and exemptions","Allowance for a specific modification (riveting/bolting alteration) that changes inspection intervals, introducing an optional compliance path","Exemptions for prior repairs or prior modifications introducing retroactive carve-outs","Multiple conditional stop‑drill and reinspection rules (including escalation when cracks grow past thresholds)","Compliance timing rules tied to a calendar effective date and hours-in-service windows (creating some administrative complexity)"],"plain_english_summary":"**What this instrument does (mechanically):**\n\n- Requires owners/operators of Convair Model 340 and 440 aeroplanes (including conversions to turboprop power) to clean and carry out a detailed internal visual inspection of a specific patch of the wing lower skin inboard of Station 8 (the area near the second rivet from the outboard end of the short stringer aligned with the wing access door in the wheel well). (Requirement 1–3)\n- Sets different initial inspection windows and ongoing inspection intervals depending on the aircraft's accumulated hours-in-service (time-in-service). (Compliance table)\n- If cracks are found, prescribes a graduated set of corrective actions depending on crack length:\n  - < 2 inches: stop-drill each crack end (0.50-inch diameter) and continue repetitive inspections. (Requirement 4.a)\n  - 2–3 inches: stop-drill, reduce maximum speeds (Vne to 243 kt, Vno to 217 kt), install a cockpit placard with the reduced speeds, and continue internal inspections. (Requirement 4.b)\n  - 3–6 inches: install internal reinforcement plates per Convair Service Engineering Report No. 6820-340-47B/440-47B, reduce speeds and placard as above, and continue inspections. (Requirement 4.c)\n  - > 6 inches: repair in accordance with Convair Service Engineering Report No. 6820-340-47B/440-47B (Requirement 6)\n- Allows one modification that, when performed and found free of cracks, permits inspection intervals to be increased to 1,000 hours: remove a 3/16-inch rivet above the crack origin, enlarge the hole to 1/4-inch, inspect, and install a close-tolerance -8 rivet or 1/4-inch bolt. (Requirement 1)\n- Exempts aircraft that were already repaired in the specified ways before the directive’s effective date, or aircraft previously modified between stringers 6 and 10 in accordance with Convair Service Engineering Report No. 15-4-340-18/440-22. After those repairs/modifications, the repetitive inspections and speed placards may be removed. (Requirement 7)\n\n**Who it affects:**\n\n- Direct effect on owners/operators of Convair Model 340 and 440 aeroplanes (and turboprop conversions of those models).\n- Maintenance organisations and engineers who perform inspections, stop-drilling, reinforcement-plate installation, and repairs per the referenced Convair engineering reports.\n\n**Why it matters (stated purpose and practical implications):**\n\n- The stated purpose (from the instrument) is to detect and correct wing lower-skin fatigue cracking before it propagates to a length likely to affect structural integrity. The mechanical measures enforce inspection, temporary repair (stop-drilling), operational limits (reduced Vne/Vno and cockpit placards), or permanent repair (reinforcement plates or full repair per Convair reports).\n\n**Who pays, who decides, and what behaviour changes:**\n\n- Owners/operators pay: labour, inspection time, parts (rivets/bolts, reinforcement plates), and aircraft downtime for repairs.\n- Decisions follow the AD’s prescriptions: maintenance personnel implement cleaning, inspection, stop-drilling, placarding, and repairs as required; the aircraft operator must comply with revised operating speeds when those are imposed.\n- Behaviour changes include more frequent structural inspections for the specified area, possible imposition of permanent speed limits until repair, and choices between recurring inspections or performing the qualifying modification/repair to reduce inspection frequency.\n\n**Costs, incentives and trade-offs (practical testing of the stated purpose):**\n\n- Direct costs: recurring inspection labour and access time, materials for temporary or permanent repairs, and downtime that reduces aircraft availability (opportunity cost to operators). (Requirements 1–6; Compliance table)\n- Incentives: because inspections are periodic and repairs are graded, operators face a trade-off between ongoing inspection costs and the one‑off cost of permanent repair/modification that can remove repetitive inspections and speed limitations. The instrument explicitly provides the modification/repair route to reduce future inspection burden (Requirement 1 and 7).\n- Operational trade-off: when temporary repairs are in place (stop-drilling or reinforcement plates), the AD imposes reduced airspeeds and a cockpit placard, limiting operational performance until a permanent repair or qualifying modification is made (Requirement 4.b/4.c).\n- Implementation risks and compliance burdens: accurate detection of small cracks requires good access and careful inspection; references to Convair Service Engineering Reports set prescriptive repair methods that may require specific skills, drawings or parts. Availability of parts or approved repair facilities could affect the time and cost to bring an aircraft back into unrestricted service. (Requirements 4–6; referenced service reports)\n- Effects on market choices: increased maintenance costs can lower utilisation or hasten retirement of older airframes; independent maintenance organisations can perform the work if they are qualified and have access to the referenced instructions, so competition among MROs is possible but dependent on capability to follow those engineering reports.\n\n**Trade-offs not explicitly addressed in the instrument:**\n\n- The AD does not quantify cost vs safety benefit; operators must weigh ongoing inspection costs versus the cost and downtime of permanent repair.\n- The directive references older Convair engineering reports for repairs; sourcing approved parts/technical data and ensuring conformity to those reports is an operational task that can vary by operator and MRO capability.\n\n**Relevant source text pointers:**\n\n- Inspection instructions and intervals: Requirements 1–3 and the Compliance table.\n- Graded corrective actions and speed restrictions: Requirement 4 (subparts a–c) and Requirement 6 for larger cracks.\n- Modification that permits longer intervals and exemptions: Requirement 1 (modification paragraph) and Requirement 7 (exemptions and removal of placard/inspections when repaired per Requirements 5 or 6).\n\n(An Airworthiness Directive (AD) is a mandatory safety instruction issued by the aviation regulator; this AD prescribes inspections and repairs for a specific structural location to maintain airworthiness.)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-convair-22-wing-lower-skin-inboard-of-station-8","history":"/api/acts/ad-convair-22-wing-lower-skin-inboard-of-station-8/history","analysis":"/api/acts/ad-convair-22-wing-lower-skin-inboard-of-station-8/analysis","conflicts":"/api/acts/ad-convair-22-wing-lower-skin-inboard-of-station-8/conflicts","importantCases":"/api/acts/ad-convair-22-wing-lower-skin-inboard-of-station-8/important-cases","documents":"/api/acts/ad-convair-22-wing-lower-skin-inboard-of-station-8/documents"}}