{"id":"F2005L02833","name":"AD/LEARJET 35/32 Amdt 1 - Tip Tank Flapper Valves","slug":"ad-learjet-35-32-amdt-1-tip-tank-flapper-valves","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":37801,"registerId":"commonwealth-F2005L02833-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Gates Learjet 35 and 36 Series Aeroplane","sectionType":"division","heading":"Gates Learjet 35 and 36 Series Aeroplanes","content":"### Gates Learjet 35 and 36 Series Aeroplanes\n\n| AD/LEARJET 35/32 Amdt 1 | Tip Tank Flapper Valves | 11/2005 |\n| ----------------------- | ----------------------- | ------- |\n\n| Applicability: | Model 35 airplanes 35-002 through 35-676 inclusive.Model 36 airplanes 36-002 through 36-063 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 35/36-28-10, 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 35/36-28-10.(b) If any flapper valve is found to be deteriorated, replace it with a new flapper valve in accordance with Learjet Service Bulletin SB 35/36-28-10.2. Replace both flappers of the tip tank in each wing with new flappers in accordance with Learjet Service Bulletin SB 35/36-28-10.3. 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 35/36-28-10.4. 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. |\n\n|             | (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 35/36-28-10 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| ----------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\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. |\n\n|             | 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| ----------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\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 35/32 Amdt 1","sectionType":"part","heading":"AD/LEARJET 35/32 Amdt 1","content":"## AD/LEARJET 35/32 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":{"kimi_summary":{"content_quality":"ok","complexity_score":6,"scope_assessment":{"changed":true,"description":"The original 1996 directive required only repetitive inspections and replacements. This 2005 amendment significantly expanded the scope by introducing a 'terminating action' pathway — allowing operators to permanently resolve the issue by installing improved parts (P/N 2323006-802), thereby ending the repetitive inspection cycle. It also added part number identification requirements and explicit prohibitions on installing certain old parts, transforming the directive from a pure maintenance burden into a fleet modification mandate."},"complexity_factors":["Multiple nested compliance pathways with cross-references between Requirements 1-6","Time-based and flight-hour-based compliance triggers that interact (e.g., 'whichever occurs later', 'whichever occurs earlier')","Conditional logic: different actions required depending on inspection findings (deteriorated vs. undeteriorated, specific part numbers found)","Four different part numbers to track with different regulatory consequences for each","References to external documents (Learjet Service Bulletin SB 35/36-28-10 and Bombardier Service Bulletin SB 35/36-28-10 Revision 2) that are incorporated by reference but not reproduced","Amendment structure requires reading alongside original directive (multiple 'Remains unchanged' references)","Specific serial number ranges for applicability rather than blanket coverage","Alternative compliance methods (physical inspection vs. maintenance records review)"],"plain_english_summary":"This CASA Airworthiness Directive requires owners/operators of specified Gates Learjet 35 and 36 series (affected serial ranges) to inspect tip‑tank flapper valves and replace any cracked, warped or deteriorated units to prevent fuel imbalance and loss of lateral control. It prohibits continued use of older part numbers (P/N 2323006‑5 and ‑6) and provides a permanent compliance option: fit the improved flapper (P/N 2323006‑802) to end repetitive inspections."},"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":true,"description":"This amendment narrowed the ongoing scope of mandatory work compared with the original Directive by adding a targeted part‑number identification and replacement pathway. The original Directive required repeated inspections of tip-tank flappers and broad follow-on actions. The amendment requires operators to identify installed flappers/assemblies (by inspection or records) and, if the approved P/Ns are installed, allows operators to cease repetitive inspections (Requirement 5(a)). It also prohibits future installation of deprecated P/Ns and requires replacement where older P/Ns are found (Requirement 5(b) and 6). Mechanically, the Directive therefore shifts from a perpetual repetitive-inspection regime to a regime where installing the improved, approved parts ends the repetitive inspection obligation — reducing recurring burden for aircraft that adopt the approved parts but imposing one‑off replacement costs for those aircraft using legacy parts."},"complexity_factors":["Six numbered substantive Requirements (1–6) with multiple sub-parts and follow-on actions","Multiple conditional branches (e.g. (a)/(b) outcomes within Requirements 1 and 5)","Several time-based thresholds and intervals (50 flight‑hours, 600 flight‑hours, 2,400 hours, 5 years, 90 days)","Cross-references to multiple external documents: Learjet Service Bulletin SB 35/36-28-10, Bombardier SB 35/36-28-10 Revision 2 (9 May 2001), and FAA AD 2005-16-09","Three distinct part-number groupings with different required actions (approved P/Ns 2323006-802/2323006-801; deprecated P/Ns 2323006-5/2323006-6)","Option to use maintenance‑record review in lieu of physical inspection, conditional on conclusive determination of P/N","Repetitive-inspection regime that can be terminated by compliance with replacement requirements (rules that change the applicability of other rules)","Legacy compliance dates (effective date and historic deadlines) that require interpreting elapsed-time conditions against installation dates"],"plain_english_summary":"**What this Directive does (mechanically)**\n\n- Requires inspection and, where necessary, replacement of the rubber \"flapper\" valves found in the tip fuel tanks on both wings of Gates Learjet Model 35 and 36 aeroplanes (see Requirement 1–4).  \n- Requires identification (by part number stamped on the item or by maintenance records) of the installed flappers and flapper assemblies (Requirement 5).  \n- Allows operators to stop the repetitive inspections if the new, approved flappers/flapper assemblies (specific P/Ns) are installed; it also forbids installation of the outdated parts (Requirement 5(a),(b) and Requirement 6).  \n- Cross-references specific Learjet/Bombardier Service Bulletins for the inspection, corrective actions and replacement procedures.\n\n**Who this affects**\n\n- Owners and operators of Learjet Model 35 aeroplanes with serial numbers 35-002 through 35-676 and Model 36 aeroplanes 36-002 through 36-063.\n- Licensed maintenance organisations and engineers who perform inspections and parts replacement under the relevant Bombardier/Learjet service bulletins.\n\n**Key compliance mechanics and timing (plain terms)**\n\n- Initial repetitive inspections: within 50 flight-hours after 29 February 1996 or before 600 flight‑hours accumulated since installation of the flapper, whichever is later; then repeat every 600 flight‑hours (see Requirement 1 and Compliance).  \n- If a flapper shows deterioration (cracks, cuts, breaks, splits, warpage) it must be replaced per the Service Bulletin (Requirement 1(b)).  \n- Replacement of both flappers in each wing is required under certain age/time conditions or when deterioration is found (Requirement 2 and 3).  \n- Identification of part numbers must be done within a stated compliance window (Requirement 5 and Compliance). If the aircraft already has the approved P/Ns (2323006-802 for flappers and 2323006-801 for assemblies), repetitive inspections can stop. If outdated P/Ns (2323006-5 or 2323006-6) are found, they must be replaced following Bombardier SB Revision 2 (Requirement 5(b)).  \n- From the effective date, operators must not install the deprecated P/Ns (Requirement 6).\n\n**Why the regulator says it matters**\n\n- The regulator states the actions prevent a significant loss of lateral control caused by fuel imbalance between wings if flapper valves fail or are degraded (Background). That is the stated safety risk motivating inspection and replacement.\n\n**Costs, incentives and trade-offs (practical assessment)**\n\n- Who pays: aircraft owners/operators pay for inspections, parts and labour. Replacement involves buying approved new flappers or assemblies and the shop time to fit them (Requirements 1–3, 5 and Compliance).  \n- Who decides: maintenance providers perform inspections and decide, per the Service Bulletin instructions, whether corrective action or replacement is needed; the operator ultimately authorises work. Compliance is mandatory under the Directive.  \n- Incentives created: installing the updated approved P/Ns removes the need for ongoing repetitive inspections, so operators have a clear incentive to replace older parts promptly (Requirement 5(a),(b)).  \n- Opportunity costs/trade-offs: replacing parts to avoid inspection hours trades a one‑off parts-and-labour cost for reduced recurring inspection burden. Operators must balance short‑term cash outlay against long‑term maintenance time saved.  \n- Implementation risk and compliance burden: the Directive references specific service bulletins and requires part-number verification; this adds administrative steps (record reviews or physical inspections) and creates reliance on correct maintenance records. Identification can be done by visual stamp reading or by maintenance records (Requirement 5).  \n- Effects on private choice and market activity: independent maintenance organisations can perform the work using the referenced Bombardier/Learjet service instructions; the Directive does not mandate a single supplier but does require parts that meet the approved P/N or approved modification (Requirement 5(b)).  \n- Capture, rent-seeking, or concentrated benefits: the commercial benefit (ending repetitive inspections) is concentrated to aircraft owners who pay for replacement; no explicit subsidy or exclusive sourcing is mandated in the text, but work must follow the maker's service bulletins (cross-referenced).  \n- Unintended consequences/substitution effects: operators might defer inspection costs by relying on maintenance-record reviews where records are poor — the Directive accepts records only if they \"conclusively determine\" the P/N (Requirement 5), which could generate disputes or require physical inspection.\n\n**Concrete behavioural changes required**\n\n- Maintenance staff must inspect flappers at the stated intervals, replace any deteriorated parts, and document part numbers (Requirements 1–4 and 5).  \n- Operators with older part numbers must procure and fit approved new or modified assemblies to stop the repetitive inspections (Requirement 5(b)).  \n- No aircraft may receive the deprecated flapper parts after the Directive’s effective date (Requirement 6).\n\n**Where to look in the Directive for details**\n\n- Inspection and corrective-action rules: Requirement 1 and 4.  \n- Replacement timing and when replacement is mandatory: Requirements 2 and 3, and Compliance section time thresholds.  \n- Part-number identification, end-of-inspection rules, and forbidden installations: Requirement 5 and Requirement 6.  \n- For exact procedures, follow Learjet Service Bulletin SB 35/36-28-10 (and Bombardier SB 35/36-28-10 Revision 2 dated 9 May 2001) as cited in the Directive.\n\nNote: the regulator’s stated purpose is accident-prevention (avoid lateral-control impairment due to fuel imbalance). The above describes the mechanical steps the Directive imposes, who pays, who acts, and the main trade-offs between recurring inspections and one-off replacement costs (see Requirements 1–6 and 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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-learjet-35-32-amdt-1-tip-tank-flapper-valves","history":"/api/acts/ad-learjet-35-32-amdt-1-tip-tank-flapper-valves/history","analysis":"/api/acts/ad-learjet-35-32-amdt-1-tip-tank-flapper-valves/analysis","conflicts":"/api/acts/ad-learjet-35-32-amdt-1-tip-tank-flapper-valves/conflicts","importantCases":"/api/acts/ad-learjet-35-32-amdt-1-tip-tank-flapper-valves/important-cases","documents":"/api/acts/ad-learjet-35-32-amdt-1-tip-tank-flapper-valves/documents"}}