{"id":"F2007L02135","name":"AD/B717/21 - Fuel System Lightning Protection","slug":"ad-b717-21-fuel-system-lightning-protection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":67299,"registerId":"commonwealth-F2007L02135-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 717 Series Aeroplanes","sectionType":"division","heading":"Boeing 717 Series Aeroplanes","content":"### Boeing 717 Series Aeroplanes\n\n| AD/B717/21 | Fuel System Lightning Protection | 8/2007 |\n| ---------- | -------------------------------- | ------ |\n\n| Applicability: | Model 717-200 aeroplanes, as identified in Boeing Service Bulletin (SB)717-28-0004, Revision 3, dated 21 June 2006.                                                                                                                                                                                                                                                                                                                                                                |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Replace the lightning critical clamp bases of the fuel tank vent system with improved clamp bases, in accordance with Table 1 of Figure 1 of the Accomplishment Instructions of SB 717-28-0004, Revision 3.                                                                                                                                                                                                                                                                     |\n|                | 2. Check the electrical bond of the modified self-bonding mounting clamps in accordance with the Accomplishment Instructions of the service bulletin.                                                                                                                                                                                                                                                                                                                              |\n|                | 3. If any electrical bond fails the check, repair the electrical bond of the mounting clamp in accordance with the SB 717-28-0004, Revision 3; or according to a method approved by the Manager, Los Angeles Aircraft Certification Office (ACO), United States Federal Aviation Administration (FAA). Chapter 28-00-00 of the Boeing 717 Aircraft Maintenance Manual and Chapter 20-50-01 of the Boeing DC, MD, and 717 Standard Wiring Practices Manual are one approved method. |\n|                | Actions accomplished before the effective date of this Directive in accordance with Boeing SB 717-28-0004, Revision 2, dated 11 March 2005, are acceptable for compliance with the requirements of this Directive.                                                                                                                                                                                                                                                                 |\n|                | Later revisions of the above SB, approved by the FAA as an Alternate Method of Compliance (AMOC) to FAA AD 2006-20-12, are considered acceptable for compliance with the equivalent requirements of this Directive.                                                                                                                                                                                                                                                                |\n|                | Note: FAA AD 2006-20-12 Amdt 39-14782 refers.                                                                                                                                                                                                                                                                                                                                                                                                                                      |\n| Compliance:    | For Requirement 1 - Within 68 months after the effective date of this Directive.                                                                                                                                                                                                                                                                                                                                                                                                   |\n|                | For Requirement 2 - Before further flight after the replacement of the clamp bases.                                                                                                                                                                                                                                                                                                                                                                                                |\n|                | For Requirement 3 - Before further flight after the Requirement 2 check.                                                                                                                                                                                                                                                                                                                                                                                                           |\n|                | This Airworthiness Directive becomes effective on 2 August 2007.                                                                                                                                                                                                                                                                                                                                                                                                                   |\n\n| Background: | The FAA has advised that an investigation has revealed the aluminium foil strip on the nylon base of the ground clamps can fracture or separate from the base. This Directive is issued to ensure that the fuel pipes are properly bonded to the aeroplane structure. Improper bonding could prevent electrical energy from a lightning strike from dissipating to the aeroplane structure, which could result in a fuel tank explosion. |\n| ----------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nDavid Punshon  \nDelegate of the Civil Aviation Safety Authority\n\n19 June 2007","sortOrder":0},{"sectionNumber":"AD/B717/21","sectionType":"part","heading":"AD/B717/21","content":"## AD/B717/21","sortOrder":1},{"sectionNumber":"Fuel System Lightning Protection","sectionType":"part","heading":"Fuel System Lightning Protection","content":"## Fuel System Lightning Protection","sortOrder":2},{"sectionNumber":"8/2007","sectionType":"part","heading":"8/2007","content":"## 8/2007","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The Directive implements the FAA-referenced corrective actions for fuel‑system bonding on Model 717-200s identified in Boeing SB 717-28-0004 Rev 3 and accepts earlier (Rev 2) or later FAA‑approved SB revisions as compliant. It therefore preserves the original safety scope—ensuring proper bonding of fuel pipes to dissipate lightning energy—without broadening affected aircraft or requirements beyond the SB/FAA framework (Applicability; Actions accomplished... Revision 2 acceptable; Later revisions... AMOC acceptable; Note: FAA AD 2006-20-12)."},"complexity_factors":["Narrow applicability to Model 717-200 identified by a specific service bulletin reduces scope but requires cross-checking the SB (Applicability: Boeing SB 717-28-0004, Revision 3).","Three-step prescriptive actions (replace, check, repair) are technically straightforward but require certified maintenance work and access to parts and manuals (Requirement 1–3).","Fixed compliance deadlines create scheduling and cost obligations for operators (Compliance: 68 months for Requirement 1; before further flight for Requirements 2 and 3).","Accepts prior work done under an earlier SB revision and FAA-approved later revisions as compliant, which eases transitional compliance but requires records validation (Actions accomplished... Revision 2 acceptable; Later revisions approved by FAA as an AMOC acceptable).","Limited administrative discretion: repairs may follow the SB or a method approved by the Manager, Los Angeles ACO (Requirement 3), introducing reliance on FAA approval for alternative methods.","Safety rationale and technical cause identified (aluminium foil strip separation on nylon base), focusing interventions narrowly on bond integrity (Background)."],"plain_english_summary":"This directive requires operators of Boeing 717-200 aeroplanes (as listed in Boeing SB 717-28-0004 Rev 3) to replace specific fuel‑tank vent system clamp bases, verify electrical bonding of the modified clamps, and repair any failed bonds per the service bulletin or FAA‑approved methods. It imposes time-limited work, inspections and repairs to ensure lightning current can safely dissipate from fuel pipes to the airframe."},"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":3,"scope_assessment":{"changed":false,"description":"This directive maintains its original narrow scope — addressing a specific lightning protection defect in Boeing 717-200 fuel systems. The reference to alternative FAA-approved methods and prior acceptable work represents standard aviation regulatory practice for harmonisation, not scope creep."},"complexity_factors":["Short, single-purpose directive with only 3 requirements","Heavy reliance on external technical documents (Boeing Service Bulletin 717-28-0004) rather than spelling out procedures in the text itself","Cross-reference to US FAA Airworthiness Directive 2006-20-12 for alternative compliance methods","Conditional logic only in Requirement 3 (\"If any electrical bond fails...\")","Minimal defined terms — only standard aviation acronyms (AD, SB, ACO, FAA, AMOC)","Clear compliance deadlines with no nested exceptions"],"plain_english_summary":"This CASA Airworthiness Directive requires operators of Boeing 717-200s to replace degraded fuel‑tank vent clamp bases, verify electrical bonding of the new clamps, and repair any failures. Work must be completed within 68 months, with immediate checks before flight after replacements.\n\nIt matters because aluminium foil strips on the old clamps can fail, risking inadequate lightning grounding and potential ignition inside the fuel tank. The AD adopts an equivalent FAA safety order."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b717-21-fuel-system-lightning-protection","history":"/api/acts/ad-b717-21-fuel-system-lightning-protection/history","analysis":"/api/acts/ad-b717-21-fuel-system-lightning-protection/analysis","conflicts":"/api/acts/ad-b717-21-fuel-system-lightning-protection/conflicts","importantCases":"/api/acts/ad-b717-21-fuel-system-lightning-protection/important-cases","documents":"/api/acts/ad-b717-21-fuel-system-lightning-protection/documents"}}