{"id":"F2005L02832","name":"AD/LEARJET/36 Amdt 1 - Tip Tank Flapper Valves","slug":"ad-learjet-36-amdt-1-tip-tank-flapper-valves","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":37797,"registerId":"commonwealth-F2005L02832-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Gates Learjet 24 & 25 Series Aeroplanes","sectionType":"division","heading":"Gates Learjet 24 & 25 Series Aeroplanes","content":"### Gates Learjet 24 & 25 Series Aeroplanes\n\n| AD/LEARJET/36 Amdt 1 | Tip Tank Flapper Valves | 11/2005 |\n| -------------------- | ----------------------- | ------- |\n\n| Applicability: | Model 24 aeroplanes S/N 24-100 through 24-357 inclusive.Model 25 aeroplanes S/N 25-002 through 25-373 inclusive. |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | 1. Perform an inspection to detect deterioration (such as cracks, cuts, breaks, splits, or warpage) of both flappers of the tip tank in each wing, in accordance with either Learjet Service Bulletin SB 23/24/25-28-2, dated 6 October 1995.(a) If no deterioration of the flapper valve is detected, inspect the flapper valve to ensure proper positioning, inspect the condition of the screws that retain the flapper valve to the plate assembly to ensure that the flapper valve is secure, inspect to ensure that the flapper valve completely covers the opening of the tube and is seated against the tube, and inspect the flapper valve to verify that it moves freely; and accomplish the follow-on corrective actions, if any discrepancy is found in accordance with Learjet Service Bulletin SB 23/24/25-28-2.(b) If any flapper valve is found to be deteriorated, replace it with a new flapper valve in accordance with Learjet Service Bulletin SB 23/24/25-28-2.2. Replace both flappers of the tip tank in each wing with new flappers in accordance with Learjet Service Bulletin SB 23/24/25-28-2.3. For aeroplanes on which the age and time-in-service of the flapper valve cannot be determined: replace both flappers of the tip tank in each wing in accordance with Learjet Service Bulletin SB 23/24/25-28-2.4. Accomplish the requirements of Requirement 1 of this Directive.5. Inspect the flappers and flapper assemblies of the tip tank in each wing to determine their part numbers (P/N). The raised letter and numbers \"S-461\" on the convex side of the flappers can identify these parts. Instead of inspecting the flappers and flapper assemblies, a review of aeroplane maintenance records is acceptable if the P/N of the flappers and flapper assemblies can be conclusively determined from that review.(a) If four flappers having P/N 2323006-802 and four flapper assemblies having P/N 2323006-801 are found installed, no further action is required by this Requirement, and the repetitive inspections required by Requirements 1 and 4 of this Directive can be stopped.(b) If any flapper having P/N 2323006-5 or any flapper assembly having P/N 2323006-6 is found installed, replace the flapper valve with a new flapper valve or replace the flapper assembly with new or modified and reidentified assembly, as applicable. The replacement must be done in accordance with the Accomplishment Instructions of Bombardier Service Bulletin SB 23/24/25-28-7 Revision 2 dated 9 May 2001. Accomplishment of the replacement ends the repetitive inspections required Requirements 1 and 4 of this Directive.6. Do not install a flapper having P/N 2323006-5 or a flapper assembly having P/N 2323006-6, on any aeroplane.Note: FAA AD 2005-16-09 Amdt 39-14214 refers. |\n| Compliance: | 1. Remains unchanged as detailed in the original issue of this Directive as: Within 50 hours time-in-service after 29 February 1996, or prior to the accumulation of 600 hours time-in-service since installation of the flapper valve, whichever occurs later, thereafter repeat at intervals not to exceed 600 hours time-in-service.(a) Before further flight.(b) Before further flight.2. Remains unchanged as detailed in the original issue of this Directive as: Except as provided in Requirement 3 of this Directive, at the later of the times specified below in (2)(a) and (2)(b) of this Directive:(a) Within 5 years since date of installation of the flapper valve, or prior to the accumulation of 2,400 total hours time-in-service on the flapper valve, whichever occurs earlier.(b) Within 50 hours time-in-service after 29 February 1996.3. Remains unchanged as detailed in the original issue of this Directive as within 50 hours time-in-service after 29 February 1996.4. Within 600 hours time-in-service following replacement of any flapper valve in accordance with the requirements of this Directive, and thereafter at intervals not to exceed 600 hours time-in-service.5. Within 600 hours time-in-service since last replacement of any flapper valve in accordance with the requirements of this Directive, or within 90 days after the effective date of this Directive, whichever occurs later.(b) Within 600 hours time-in- service since last replacement of any flapper valve in accordance with the requirements of this Directive.6. From the effective date of this Directive. |\n| | This Amendment becomes effective on 27 October 2005. |\n| Background: | The original issue of this Directive required repetitive inspections to detect deterioration of both flappers of the tip tank in each wing of the aeroplane, and various follow-on actions. This Directive also required replacing the flappers with new flappers, and repetitively performing certain other follow-on actions.This amendment requires an inspection of the flappers and flapper assemblies of the tip tank in each wing or a review of the aeroplane maintenance records to determine the part numbers, and replacement of certain flappers or flapper assemblies if necessary, which ends the existing repetitive inspections. This Directive results from numerous continual inspections and the approval of a new, improved flapper and flapper assembly.The actions detailed in this Directive are to prevent significant reduction in the lateral control of the aeroplane due to imbalance of the fuel loads in the wings of the aeroplane.The original issue of this Directive became effective 29 February 1996. |\n\n![](image.001.png) \nJames Coyne \nDelegate of the Civil Aviation Safety Authority\n\n15 September 2005","sortOrder":0},{"sectionNumber":"AD/LEARJET/36 Amdt 1","sectionType":"part","heading":"AD/LEARJET/36 Amdt 1","content":"## AD/LEARJET/36 Amdt 1","sortOrder":1},{"sectionNumber":"Tip Tank Flapper Valves","sectionType":"part","heading":"Tip Tank Flapper Valves","content":"## Tip Tank Flapper Valves","sortOrder":2},{"sectionNumber":"11/2005","sectionType":"part","heading":"11/2005","content":"## 11/2005","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":true,"description":"Yes. The amendment adds a requirement to identify flapper and assembly part numbers (by inspection or records) and mandates replacement of specified older parts. Where approved new parts are fitted, the amendment terminates the prior repetitive inspections. It also prohibits installation of the older part numbers from the effective date, shifting the compliance outcome from ongoing inspections to a one-time parts-replacement path for affected aircraft."},"complexity_factors":["Conditional requirements tied to specific part numbers (P/N 2323006-802 vs 2323006-5 and assemblies 2323006-801 vs 2323006-6).","Multiple, differing compliance timeframes (initial, repetitive and replacement intervals; some actions required before further flight).","References to external service/maintenance documents (Learjet and Bombardier Service Bulletins) for inspection and replacement procedures.","Applicability limited to defined serial-number ranges, requiring fleet-specific applicability checks.","Option to use maintenance-records review instead of physical inspection if P/N can be conclusively identified.","Mechanism that ends repetitive inspections upon installation of approved parts, creating a binary compliance outcome.","Prohibition on future installation of older P/Ns from the effective date, affecting parts procurement and inventory.","Operational and administrative burdens: part identification, record-keeping, aircraft downtime and parts availability/installation logistics."],"plain_english_summary":"This directive requires operators of Gates Learjet 24 and 25 series (specified serial ranges) to inspect tip-tank flapper valves, determine their part numbers (by marking or maintenance records), and replace any deteriorated or disallowed parts. Fitting the approved new flapper or assembly ends the previous repetitive inspections; installing certain older part numbers is forbidden. It affects aircraft owners/operators and maintenance organisations, who bear inspection, replacement and downtime costs. The stated safety purpose is to prevent lateral-control reduction from wing fuel imbalance."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":6,"scope_assessment":{"changed":true,"description":"The original directive (effective 1996) required only repetitive inspections and time-based replacements. This amendment significantly expands the scope by introducing a 'terminating action' concept — allowing operators to permanently resolve the issue by installing improved parts, thereby ending the inspection cycle. It also adds part-number-specific requirements, record-review alternatives, and an installation prohibition that didn't exist in the original. The directive evolved from a pure inspection regime to a comprehensive inspection-plus-modification framework with multiple compliance pathways."},"complexity_factors":["Multiple overlapping compliance timelines (50 hours, 600 hours, 5 years, 2,400 hours, 90 days) that interact differently depending on aircraft history","Six distinct requirements with sub-requirements (1a, 1b, 5a, 5b) creating conditional logic paths","Cross-references to external documents (Learjet Service Bulletin SB 23/24/25-28-2 and Bombardier Service Bulletin SB 23/24/25-28-7 Revision 2)","Part number tracking requirement (P/N 2323006-5, 2323006-6, 2323006-801, 2323006-802) with different actions for each","Alternative compliance methods (physical inspection vs. maintenance records review)","Termination conditions for repetitive inspections that depend on specific replacement actions","Reference to prior directive history and FAA AD 2005-16-09 for context"],"plain_english_summary":"This CASA Airworthiness Directive targets tip‑tank flapper valves on specific Gates Learjet 24 and 25 serial numbers to prevent fuel draining that can cause dangerous lateral imbalance and loss of control. It requires regular inspections, immediate replacement of deteriorated valves, mandatory life‑limit replacements, and removal of older problematic part numbers.\n\nInstalling improved valve parts (PNs 2323006‑801/‑802) eliminates recurring inspections, reducing cost while restoring safe fuel balance."}},"importantCases":[],"_links":{"self":"/api/acts/ad-learjet-36-amdt-1-tip-tank-flapper-valves","history":"/api/acts/ad-learjet-36-amdt-1-tip-tank-flapper-valves/history","analysis":"/api/acts/ad-learjet-36-amdt-1-tip-tank-flapper-valves/analysis","conflicts":"/api/acts/ad-learjet-36-amdt-1-tip-tank-flapper-valves/conflicts","importantCases":"/api/acts/ad-learjet-36-amdt-1-tip-tank-flapper-valves/important-cases","documents":"/api/acts/ad-learjet-36-amdt-1-tip-tank-flapper-valves/documents"}}