{"id":"F2006B02715","name":"AD/B727/190 - Electrical Bonding","slug":"ad-b727-190-electrical-bonding","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42031,"registerId":"commonwealth-F2006B02715-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# ![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\n![](image.001.png)  \n\nBoeing 727 Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/B727/190 Electrical Bonding 8/2004","sectionType":"part","heading":"AD/B727/190 Electrical Bonding 8/2004","content":"# AD/B727/190 Electrical Bonding 8/2004\n\nApplicability: Model 727-100 and \\-200 series aeroplanes as listed in Boeing Alert Service Bulletin (ASB) 727-29A0067 dated 7 June 2001.\n\nRequirement: 1. Prepare the electrical bonding faying surfaces for the tubing penetrations of the hydraulic heat exchanger on the forward and aft surfaces of the rear spars of the fuel tanks of the left and right wings, together with carrying out a one-time measurement of the electrical bonding resistances between the penetration fittings of the hydraulic heat exchanger and the rear spars; and between the heat exchanger tube and the lower wing stringer surfaces, per the Accomplishment Instructions of ASB 727-29A0067.\n\n    2. If the bonding resistance is incorrect, repeat the preparation of the electrical bonding faying surface for the tubing penetrations of the hydraulic heat exchanger on the forward and aft surfaces of the rear spar of the fuel tanks of the left and right wings as necessary to achieve a bonding resistance below the threshold specified in the Accomplishment Instructions of ASB 727-29A0067.\n\n    3. Apply fillet sealant and protective finishes around the penetration fittings of the hydraulic heat exchanger in accordance with the Accomplishment Instructions of ASB 727-29A0067 (Figure 4 refers).\n\n    4. Service and pressurize the hydraulic systems and examine for signs of hydraulic fluid leakage. Service the fuel tank and examine for signs of fuel leakage. All these actions are to be accomplished in accordance with ASB 727-29A0067.\n\n    5. Repair any leaks found, during the Requirement 4 examination, in accordance with ASB 727-29A0067.\n\nNote: FAA AD 2004-10-06 Amdt 39-13636 refers.\n\nCompliance: For Requirement 1 \\- Within 60 months after the effective date of this Directive.\n\nFor Requirement 2 \\- Before further flight after the Requirement 1 bonding resistance check.\n\nFor Requirement 3 \\- Before further flight after completing Requirements 1 and 2.","sortOrder":1}],"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":4,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive maintaining its original scope: addressing a specific unsafe condition (electrical bonding deficiencies) in specific aircraft models. The directive remains focused on the original safety issue without expansion into unrelated areas."},"complexity_factors":["Technical aviation terminology throughout (e.g., \"faying surfaces\", \"stringer surfaces\", \"fillet sealant\") requiring specialized knowledge","Multiple cross-references to external Boeing Alert Service Bulletin ASB 727-29A0067 for detailed instructions rather than including them in the directive itself","Sequential conditional logic: Requirement 2 only applies if Requirement 1 finds incorrect resistance; Requirement 3 must follow completion of 1 and 2","Nested compliance deadlines with dependencies (Requirement 2 compliance triggers before further flight after Requirement 1, etc.)","Reference to corresponding FAA AD 2004-10-06 indicating harmonization with international regulations"],"plain_english_summary":"This CASA Airworthiness Directive requires operators of certain Boeing 727-100/-200s to inspect and, if needed, restore electrical bonding where hydraulic heat-exchanger tubes pass through wing fuel tanks, then seal and pressure-test fittings and repair any leaks.  \n\nDone within five years of effect and before further flight if defects are found, the actions prevent sparks near fuel vapour and reduce risk of fire or explosion."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This Directive stays narrowly targeted to a single technical issue — electrical bonding and associated sealing/leak checks at hydraulic heat exchanger penetrations on specified Boeing 727 wing rear spars. It implements a corrective maintenance requirement consistent with Boeing ASB and the FAA AD it references. It does not broaden the regulatory scope beyond that original technical purpose (no new operational limitations, no expansion to other aircraft types or unrelated systems)."},"complexity_factors":["Short, focused directive with 5 discrete requirements","Single applicability class: Boeing 727-100 and -200 series as listed in the ASB","Cross-reference to an external technical document (Boeing ASB 727-29A0067) that contains thresholds and detailed instructions","Conditional repetition: Requirement 2 requires repeating surface preparation until resistance is below an external threshold","Sequenced compliance timing (one-time measurement within 60 months; corrective actions before further flight)","Dependence on calibrated measurement methods (operational complexity not spelled out in the AD)","Reference to FAA AD for related context (non-technical cross-reference)"],"plain_english_summary":"**What this directive does (mechanically)**\n\n- Applies to Boeing 727-100 and 727-200 series aircraft listed in Boeing Alert Service Bulletin (ASB) 727-29A0067.  (See the ASB for the exact aircraft/serials.)\n- Requires a one-time preparation and electrical-bonding resistance measurement for the hydraulic heat exchanger tubing penetrations where they pass through the rear spar of each wing fuel tank.  Specifically, measure electrical bonding resistance between: the penetration fittings and the rear spars, and between the heat-exchanger tube and the lower wing stringer surfaces. (Requirement 1.)\n- If a measured bonding resistance is above the threshold in the Boeing ASB, repeat surface preparation and re-measure until the resistance is below the ASB threshold. (Requirement 2.)\n- After achieving acceptable bonding, apply fillet sealant and protective finishes around the penetration fittings as shown in the ASB. (Requirement 3.)\n- Pressurize and service the hydraulic systems and the fuel tank, inspect for hydraulic fluid and fuel leaks, and repair any leaks found following the ASB instructions. (Requirements 4–5.)\n- Timing: the initial bonding-resistance measurement must be done within 60 months from the Directive’s effective date. If a resistance check fails, corrective work must be completed before the aircraft’s next flight; sealant application and finishes must also be completed before further flight after the check(s) are done.\n\n**Who this affects**\n\n- Aircraft owners/operators of the specified Boeing 727-100/-200 airframes. \n- Maintenance organisations and licensed technicians doing the required inspections, measurements, repairs and sealing per Boeing ASB 727-29A0067.\n\n**Why it matters (official purpose and operational effect)**\n\n- The Directive implements an airworthiness action intended to ensure correct electrical bonding where hydraulic tubing penetrates wing structures and to verify there are no resultant fluid leaks. Adequate bonding reduces the risk that electrical potential differences or stray currents could cause damage, and the sealing/inspection requirement addresses risk of hydraulic or fuel leakage at the penetration points.\n\n**Who pays, who decides, and what changes in behaviour**\n\n- Aircraft operators/owners pay for the inspections, labour, materials (sealants, finishes, any replacement fittings), and any downtime. \n- The CASA delegate issues the Directive; the detailed technical steps and the threshold values for bonding resistance are specified in Boeing ASB 727-29A0067, which maintenance personnel must follow.\n- Maintenance providers must schedule and perform the one-time measurement, do surface preparation and repeat it if necessary, apply sealant/finishes, pressurize and test hydraulic and fuel systems, and carry out any repairs before further flight where required.\n\n**Costs, incentives and trade-offs**\n\n- Direct costs: labour for measurement and preparatory work, sealant and protective material, potential replacement of fittings or local structure if cleaning cannot achieve the required bonding resistance, testing equipment calibration, and aircraft downtime while work is carried out.\n- Incentives: maintenance providers and parts suppliers will receive work from operators complying with the Directive. Operators face an incentive to schedule the work into existing maintenance checks to reduce incremental downtime costs; if an aircraft is near retirement or expensive to repair, an operator may weigh retirement or storage as an alternative.\n- Trade-offs: the Directive prioritises a one-time corrective inspection and remediation (with immediate repairs required if failures are found) rather than recurring monitoring. That concentrates up-front cost on operators but reduces ongoing inspection burden if the one-time action is successful.\n\n**Implementation and compliance risks**\n\n- The AD relies on Boeing ASB 727-29A0067 for measurement thresholds and detailed steps; operators must have access to and correctly follow those instructions. The AD does not repeat the numeric threshold values, creating a dependency on the ASB.\n- Accurate bonding-resistance measurement requires appropriate equipment and calibrated test methods; inconsistent measurement practice could create disputes about compliance.\n- If access to the penetrations or parts is difficult, labour hours and downtime could be higher than expected. If acceptable bonding cannot be achieved without replacement parts or structural work, repair costs and out-of-service time increase.\n\n**Effects on competition and market behaviour**\n\n- The requirement creates demand for licensed maintenance providers familiar with Boeing procedures and for materials specified by the ASB; this is likely to benefit specialist MROs (maintenance, repair and overhaul organisations).\n- The Directive does not change ownership, certification rights, or operating rules; it only imposes a technical maintenance obligation on affected aircraft.\n\n**Other practical points**\n\n- The AD is time-limited for the initial measurement (60 months). Subsequent required corrective actions (if a resistance is out of spec) must be completed before the aircraft can fly again.\n- The Directive cross-references FAA AD 2004-10-06 and the Boeing ASB for technical details; operators must consult those documents to perform the required work.\n\n(References: Requirements 1–5 and Compliance times as stated in AD/B727/190 Electrical Bonding; see Boeing ASB 727-29A0067 for the technical thresholds and step-by-step instructions.)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-190-electrical-bonding","history":"/api/acts/ad-b727-190-electrical-bonding/history","analysis":"/api/acts/ad-b727-190-electrical-bonding/analysis","conflicts":"/api/acts/ad-b727-190-electrical-bonding/conflicts","importantCases":"/api/acts/ad-b727-190-electrical-bonding/important-cases","documents":"/api/acts/ad-b727-190-electrical-bonding/documents"}}