{"id":"F2005L02391","name":"AD/B727/196 - Fuel Tank Float Switches","slug":"ad-b727-196-fuel-tank-float-switches","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":36825,"registerId":"commonwealth-F2005L02391-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 727 Series Aeroplanes","sectionType":"division","heading":"Boeing 727 Series Aeroplanes","content":"### Boeing 727 Series Aeroplanes\n\n| AD/B727/196 | Fuel Tank Float Switches | 10/2005 |\n| ----------- | ------------------------ | ------- |\n\n| Applicability: | Model 727, 727C, 727-100, 727-100C, 727-200 and 727-200F series aeroplanes.                                                                                                                                                                                                                                                                                                                                      |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Inspect the wing and auxiliary fuel tanks to determine if any float switches are present. Instead of an inspection of the fuel tanks, a review of aeroplane maintenance records is acceptable if the presence of any float switch can be conclusively determined from that review. If float switches are not present, further action is not required.                                                         |\n|                | 2. If any float switch is present, inspect to identify the float switch models. Instead of an inspection of the fuel tanks, a review of aeroplane maintenance records is acceptable if the identity of the float switch can be conclusively determined from that review.                                                                                                                                         |\n|                | 3. If a float switch other than an Ametek Model F8300-146 float switch is installed - Install a liner system inside the float switch electrical cable conduit in the fuel tanks in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin (ASB) 727-28A0127, dated 26 August 2004.                                                                                                     |\n|                | 4. If any Ametek Model F8300-146 float switch is installed - Replace the float switch with a new switch and install a liner system inside the float switch electrical cable conduit in the fuel tanks in accordance with the Accomplishment Instructions of ASB 727- 28A0127.                                                                                                                                    |\n|                | Note 1: ASB 727-28A0127 segregates the work into nine work packages for the six fuel tank configurations identified in the service bulletin. The work packages do not have to be completed sequentially. Each work package can be done independently or simultaneously. However, all work packages, as applicable for each fuel tank configuration, must be done to complete the requirements of this Directive. |\n|                | 5. Ametek Model F8300-146 float switches may not be installed in any fuel tank on any aeroplane as a replacement spare.                                                                                                                                                                                                                                                                                          |\n|                | Note 2: FAA AD 2005-16-07 Amdt 39-14212 refers.                                                                                                                                                                                                                                                                                                                                                                  |\n| Compliance:    | For Requirement 1 - Within 48 months after the effective date of this Directive.                                                                                                                                                                                                                                                                                                                                 |\n|                | For Requirement 2 - Before further flight, after the Requirement 1 inspection/determination.                                                                                                                                                                                                                                                                                                                     |\n\n|             | For Requirement 3 - Before further flight, after the Requirement 2 inspection/determination.                                                                                                                                                                                                                                                                                                                                                                                                                                                      |\n| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n|             | For Requirement 4 - Before further flight, after the Requirement 2 inspection/determination.                                                                                                                                                                                                                                                                                                                                                                                                                                                      |\n|             | For Requirement 5 - As of the effective date of this Directive.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |\n|             | This Airworthiness Directive becomes effective on 29 September 2005.                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |\n| Background: | Boeing has received reports of contamination of the fueling float switch by moisture or fuel, together with chafing of the float switch wiring against the fuel tank conduit. This Directive, which requires an inspection to determine if float switches are installed and, if necessary, the installation of new float switches and protective sheathing in the electrical cable conduit; is issued to prevent the contamination and chafing, which could present an ignition source inside the fuel tank that could cause a fire or explosion. |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n18 August 2005","sortOrder":0},{"sectionNumber":"AD/B727/196","sectionType":"part","heading":"AD/B727/196","content":"## AD/B727/196","sortOrder":1},{"sectionNumber":"Fuel Tank Float Switches","sectionType":"part","heading":"Fuel Tank Float Switches","content":"## Fuel Tank Float Switches","sortOrder":2},{"sectionNumber":"10/2005","sectionType":"part","heading":"10/2005","content":"## 10/2005","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This AD maintains focused scope on fuel tank float switch safety in Boeing 727 aircraft. The requirements align with the stated background of preventing ignition sources in fuel tanks. No evidence of scope creep beyond original aviation safety purpose."},"complexity_factors":["Multiple conditional pathways: 5 distinct requirements with interdependent sequencing (Requirement 2 depends on 1, Requirements 3-4 depend on 2)","Alternative compliance methods: Permits maintenance record review instead of physical inspection for Requirements 1-2, creating conditional logic","Nested applicability: Nine work packages across six fuel tank configurations referenced from external Boeing document (ASB 727-28A0127)","External document incorporation: Heavy reliance on Boeing Alert Service Bulletin for technical implementation details not reproduced in the AD","Model-specific exceptions: Different treatment for Ametek Model F8300-146 versus other float switches","Staggered compliance deadlines: Mix of 48-month window and 'before further flight' immediate action requirements"],"plain_english_summary":"This CASA Airworthiness Directive requires operators and maintenance organisations of Boeing 727 series aircraft to inspect fuel tanks for certain float switches and identify switch models. Problematic installations that risk wiring chafing and sparks must be corrected: non-Ametek switches get conduit liners; Ametek Model F8300-146 switches must be replaced and barred from future spare use.\n\nThe rule prevents ignition sources in fuel tanks, addressing a serious fire/explosion hazard."},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":false,"description":"The Directive applies only to the listed Boeing 727 series models and addresses float-switch contamination/chafing risks by requiring inspection, liner installation, replacement of a specific switch model, and a ban on that model as a spare. It does not broaden applicability beyond the named aircraft types or add obligations outside the ASB-directed corrective work."},"complexity_factors":["Multiple discrete requirements (inspect, identify, liner install, replace, spare ban) with differing triggers (Requirements 1–5).","Staggered compliance times: 48 months for initial inspection, 'before further flight' for corrective actions, and immediate ban on certain spares.","Permits record-review in lieu of physical inspection if conclusive, creating evidence/verification considerations for operators.","Mandates work to be done in accordance with Boeing ASB 727-28A0127, which divides tasks into nine non-sequential work packages—operational planning required.","Cross-reference to FAA AD 2005-16-07 and reliance on external service bulletin for technical detail increases regulatory-technical coupling.","Direct operational consequence: replacement and installation work may ground aircraft until completed, affecting scheduling and costs for operators.","Prohibition on installing a particular spare (Ametek F8300-146) imposes ongoing procurement and inventory controls for maintenance organisations."],"plain_english_summary":"This Airworthiness Directive requires operators of Boeing 727 series aircraft to check wing and auxiliary fuel tanks for float switches, identify their models, and, where needed, install protective liners and replace unsafe Ametek F8300-146 switches following Boeing ASB 727-28A0127. It also bans fitting Ametek F8300-146 switches as replacement spares. Operators must carry out an initial inspection within 48 months and any required replacements or liner installations before further flight; the measure aims to remove potential ignition sources inside fuel tanks."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-196-fuel-tank-float-switches","history":"/api/acts/ad-b727-196-fuel-tank-float-switches/history","analysis":"/api/acts/ad-b727-196-fuel-tank-float-switches/analysis","conflicts":"/api/acts/ad-b727-196-fuel-tank-float-switches/conflicts","importantCases":"/api/acts/ad-b727-196-fuel-tank-float-switches/important-cases","documents":"/api/acts/ad-b727-196-fuel-tank-float-switches/documents"}}