{"id":"F2008L01917","name":"AD/B737/330 - Boost Pump Control Relay Ground Block Corrosion","slug":"ad-b737-330-boost-pump-control-relay-ground-block-corrosion","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":74143,"registerId":"commonwealth-F2008L01917-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 737 Series Aeroplanes","sectionType":"division","heading":"Boeing 737 Series Aeroplanes","content":"### Boeing 737 Series Aeroplanes\n\n| AD/B737/330 | Boost Pump control RelayGround Block Corrosion | 7/2008 |\n| ----------- | ---------------------------------------------- | ------ |\n\n| Applicability: | Model 737-600, -700, -700C, -800 and -900 series aeroplanes, as identified in Boeing Special Attention Service Bulletin 737-28-1257, Revision 1, dated 28 November 2007.                                                                                                                                                                                                                  |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Carry out a general visual inspection of ground blocks GD261 and GD264 for corrosion, measure the electrical bond resistance and separate the ground wires for the fuel boost pump circuit between ground blocks GD261 and GD264 in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin (SB) 737-28-1257, Revision 1, dated 28 November 2007. |\n|                | 2. Rectify any discrepancies detected during any inspection, measurement or any other action, carried out in accordance with Requirement 1, in accordance with SB 737-28-1257, Revision 1.                                                                                                                                                                                                |\n|                | Actions accomplished before the effective date of this Directive in accordance with SB 737-28- 1257, dated 26 February 2007, are acceptable for compliance with the corresponding requirements of this Directive.                                                                                                                                                                         |\n|                | Later revisions of SB 737-28-1257, approved by the United States Federal Aviation Administration (FAA) as an Alternate Method of Compliance (AMOC) to FAA AD 2008-09-14, are considered acceptable for compliance with the equivalent Requirements of this Directive.                                                                                                                     |\n|                | Note: FAA AD 2008-09-14 Amdt 39-15495 refers.                                                                                                                                                                                                                                                                                                                                             |\n| Compliance:    | For Requirement 1 - Within 24 months after the effective date of this Directive.                                                                                                                                                                                                                                                                                                          |\n|                | For Requirement 2 - Before further flight after complying with Requirement 1.                                                                                                                                                                                                                                                                                                             |\n|                | This Airworthiness Directive becomes effective on 3 July 2008.                                                                                                                                                                                                                                                                                                                            |\n| Background:    | The United States Federal Aviation Administration (FAA) has received a report of random flashes of the six fuel pump low pressure lights and intermittent operation of the fuel boost pumps. We are issuing this AD to prevent the simultaneous malfunction of all six fuel boost pumps, which could cause the engines to operate on suction feed and potentially flame out.              |\n\n|     | This Directive requires inspecting ground blocks GD261 and GD264 for corrosion, measuring the electrical bond resistance between the ground blocks and the aeroplane structure, separating the ground wires for the fuel boost pump circuit between ground blocks GD261 and GD264 and, if necessary, carrying out corrective actions if necessary. |\n| --- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n22 May 2008","sortOrder":0},{"sectionNumber":"AD/B737/330","sectionType":"part","heading":"AD/B737/330","content":"## AD/B737/330","sortOrder":1},{"sectionNumber":"Boost Pump control RelayGround Block Cor","sectionType":"part","heading":"Boost Pump control RelayGround Block Corrosion","content":"## Boost Pump control Relay  \nGround Block Corrosion","sortOrder":2},{"sectionNumber":"7/2008","sectionType":"part","heading":"7/2008","content":"## 7/2008","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This Directive stays within the original safety objective described by the FAA: to detect and fix corrosion/poor grounding that could cause simultaneous fuel boost pump malfunction. It does not add unrelated obligations or expand to other systems or aircraft types. It accepts earlier compliance under the previous Boeing service bulletin and permits FAA‑approved AMOCs, which are procedural flexibilities rather than scope expansions."},"complexity_factors":["Short, single-issue directive with two principal actions (inspection/measurement/separation; corrective action).","Applicability limited to specific 737 models as identified by an external Boeing service bulletin (one cross-reference).","References and reliance on external documents: Boeing SB 737-28-1257 Revision 1, earlier SB dated 26 Feb 2007, and FAA AD 2008-09-14 (three external cross-references).","Two distinct time-based compliance requirements (within 24 months; before further flight for corrections).","Provision allowing prior compliance and subsequent FAA‑approved AMOCs adds limited conditional flexibility.","Technical requirements (bond resistance measurement, wire separation) require specialised equipment and procedures but are not legally complex."],"plain_english_summary":"**What this directive requires (mechanics)**\n\n- It applies to Boeing 737-600, -700, -700C, -800 and -900 series aircraft as identified in Boeing Special Attention Service Bulletin (SB) 737-28-1257, Revision 1 (28 November 2007).\n\n- Two actions are required:\n  - Requirement 1: Do a general visual inspection of two ground blocks (labelled GD261 and GD264) for corrosion; measure the electrical bond resistance between those ground blocks and the aeroplane structure; and separate the ground wires for the fuel boost pump circuit that run between GD261 and GD264. Carry out these tasks following the Boeing SB listed above.\n  - Requirement 2: If the inspection, measurements, or separation show any discrepancies (corrosion, poor bonding, incorrect wiring, etc.), fix them in accordance with the same Boeing SB before the aircraft flies again.\n\n- Timing: the initial inspection and measurements must be completed within 24 months of the Directive taking effect. Any required corrective work must be completed before the next flight of the aircraft.\n\n- Compliance flexibility: If the same work was done before the effective date using Boeing SB 737-28-1257 dated 26 February 2007, that is acceptable. Later revisions of the SB that the FAA has approved as an Alternate Method of Compliance (AMOC) to FAA AD 2008-09-14 are also acceptable for meeting this Directive.\n\n**Why the regulator issued it (official rationale)**\n\n- The FAA received reports of random flashes of the six fuel pump low‑pressure lights and intermittent operation of the fuel boost pumps. The declared safety concern is that corrosion or poor grounding could cause simultaneous malfunction of all six boost pumps, which could let the engines run on suction feed and risk flame‑out.\n\n**Who is affected and who pays**\n\n- Affected parties: operators and owners of the listed 737 models identified in the Boeing service bulletin.\n- Who pays: the operator/owner must fund inspections, electrical measurements, wiring separation and any repairs. These are maintenance actions performed by maintenance organisations authorised to work on the aircraft.\n\n**Practical effects and implementation points**\n\n- Operators must schedule an inspection within two years and, if defects are found, ground the aircraft until repairs are done (repairs required before further flight).\n- The work requires access to Boeing SB 737-28-1257 Rev 1, measurement equipment for bond resistance, and competent maintenance personnel. Separating ground wires may involve access to wiring runs and minor rewiring.\n- The Directive accepts prior compliance done under an earlier Boeing SB and allows FAA‑approved AMOCs, which gives limited flexibility on how compliance is achieved.\n\n**Trade-offs, costs and risks (mechanism-focused analysis)**\n\n- Costs and downtime: the main costs are labour, any replacement parts, specialised test equipment/time to measure bond resistance, and possible aircraft downtime while defects are rectified. These are borne by operators.\n- Concentrated benefit: safety improvement accrues to operators and passengers of affected aircraft; the regulation concentrates the expense on the relatively smaller number of operators flying the listed 737 variants.\n- Compliance incentives and discretion: FAA‑approved AMOCs and acceptance of prior work reduce the compliance burden and allow operators some discretion, subject to regulator approval.\n- Implementation risk: accurate bond resistance measurement requires the correct procedure and equipment; incorrect separation of grounds or improper repairs could create other electrical faults if not done per the Boeing instructions.\n\n(Official safety purpose attributed to the FAA/CAA is reported above; the directive’s mechanics implement that purpose by mandating inspection, measurement, wire separation and repair per the Boeing service bulletin.)"},"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":3,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive with a narrow, well-defined scope. It addresses a specific safety issue (ground block corrosion affecting fuel boost pumps) on specific aircraft models. The scope remains tightly focused on the original safety concern without expansion into unrelated areas."},"complexity_factors":["Short, single-purpose directive focused on one specific maintenance task","Only 2 main requirements with clear sequential logic (inspect first, repair if needed)","References external technical documents (Boeing Service Bulletin 737-28-1257) rather than reproducing detailed instructions","Contains one conditional compliance pathway (earlier work under February 2007 SB acceptable)","Limited defined terms — relies on standard aviation terminology","Simple compliance timeline (24 months for inspection, immediate for repairs)","No nested exceptions or complex conditional logic"],"plain_english_summary":"This CASA Airworthiness Directive mandates inspection and testing of two electrical ground blocks in the fuel boost‑pump circuit on certain Boeing 737 Next Generation aircraft. It affects operators and maintenance crews and requires corrosion checks, resistance tests, and corrective action; faults must be repaired before the next flight and inspections completed within 24 months.\n\nThe AD aims to prevent simultaneous fuel‑pump failure that could cause engine flameout and a serious flight‑safety hazard."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-330-boost-pump-control-relay-ground-block-corrosion","history":"/api/acts/ad-b737-330-boost-pump-control-relay-ground-block-corrosion/history","analysis":"/api/acts/ad-b737-330-boost-pump-control-relay-ground-block-corrosion/analysis","conflicts":"/api/acts/ad-b737-330-boost-pump-control-relay-ground-block-corrosion/conflicts","importantCases":"/api/acts/ad-b737-330-boost-pump-control-relay-ground-block-corrosion/important-cases","documents":"/api/acts/ad-b737-330-boost-pump-control-relay-ground-block-corrosion/documents"}}