{"id":"F2006B02877","name":"AD/B737/173 - Power Distribution Panels","slug":"ad-b737-173-power-distribution-panels","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42219,"registerId":"commonwealth-F2006B02877-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 CAR 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 737 Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/B737/173 Power Distribution Panels 2/","sectionType":"part","heading":"AD/B737/173 Power Distribution Panels 2/2002","content":"# AD/B737/173 Power Distribution Panels 2/2002\n\nApplicability: Model 737-600, -700, and -800 series aeroplanes, equipped with power distribution panels (PDP) bearing any of the following Boeing part numbers, as listed in the \"Existing Part Number'' column of the table under paragraph 2.E., \"Existing Parts Accountability,'' of Boeing Service Bulletin (SB) 737-24-1128, dated 29 April 1999.\n\n| S281A601-1000 | S281A601-1074 | S281A601-2003 | S281A601-2199 |\n| ------------- | ------------- | ------------- | ------------- |\n| S281A601-1001 | S281A601-1108 | S281A601-2007 | S281A601-2216 |\n| S281A601-1002 | S281A601-1110 | S281A601-2032 | S281A601-2217 |\n| S281A601-1003 | S281A601-1111 | S281A601-2038 | S281A601-2220 |\n| S281A601-1018 | S281A601-1120 | S281A601-2039 | S281A601-2222 |\n| S281A601-1020 | S281A601-1122 | S281A601-2055 | S281A601-2226 |\n| S281A601-1045 | S281A601-1128 | S281A601-2057 | S281A601-2228 |\n| S281A601-1054 | S281A601-1162 | S281A601-2109 | S281A601-2234 |\n| S281A601-1055 | S281A601-1216 | S281A601-2110 | S281A601-2275 |\n| S281A601-1056 | S281A601-2001 | S281A601-2111 | S281A601-2434 |\n| S281A601-1057 |               |               |               |\n\nRequirement: 1. Unless previously accomplished, perform a one-time general visual inspection to verify proper installation of the power feeder terminals and associated hardware located in power distribution panels (PDP) P91 and P92, in accordance with the following procedures:\n\nUsing a flashlight, inspect each of the six power feeder terminals by looking into the access holes located in the plastic cover of the rigid bus assembly. The holes are located on the aft face of PDPs P91 and P92. (Refer to the Boeing 737-600, -700, -800, -900 Aeroplane Maintenance Manual (AMM), Section 24-21-71, Page 402, Figure 401 (Sheet 1), for the location of PDP P91 and P92.) On PDP P91, the holes are adjacent to terminal blocks TB5001 and TB5002. On PDP P92, the holes are adjacent to terminal blocks TB5005 and TB5006. There are a total of six holes per PDP. (Refer to the Boeing 737- 600, -700, -800, -900 AMM, Section 24-21-71, Page 403, Figure 401 (Sheet\n\n2), for the location of the access holes on the PDPs.) Note that although each PDP has nine power feeder terminals, only the six terminals adjacent to the access holes require inspection.","sortOrder":1}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD confines its scope to specified 737 models fitted with the listed PDP part numbers and requires a one‑time visual verification of six terminals on PDPs P91 and P92 (Applicability; Requirement: 1). The text contains no language indicating an expansion or narrowing from a prior scope; it references Boeing SB 737‑24‑1128 and the Boeing AMM for locating the PDPs, so scope is defined by those part lists and maintenance‑manual locations. Operators pay for and schedule the inspection; CASA (via a delegate under subreg 39.1(1) of CAR 1998) mandates compliance."},"complexity_factors":["Narrow technical scope: applies only to 737‑600/‑700/‑800 models fitted with PDPs listed by Boeing part numbers in the AD's Applicability (Applicability).","Multiple specific part numbers to check (long list in Applicability), which requires operators to cross‑reference aircraft configuration records against Boeing SB 737‑24‑1128 (Applicability: “Existing Part Number'' table, SB 737‑24‑1128, 29 Apr 1999).","Procedure simplicity: requirement is a one‑time general visual inspection using a flashlight through access holes on PDPs P91 and P92 (Requirement: 1).","Localization of inspection: only six of nine feeder terminals per PDP (the ones adjacent to specified terminal blocks) require inspection, so personnel must identify correct terminals using Boeing AMM references (Requirement: 1; Boeing AMM Section 24‑21‑71 figures cited).","Cross‑references to manufacturer documents (Boeing AMM and Service Bulletin) add compliance steps — operators must obtain and follow those documents as part of meeting the AD (Requirement: 1; Applicability).","Regulatory authority and enforcement: issued by a CASA delegate under subregulation 39.1(1) of CAR 1998, which makes compliance mandatory for affected operators (preamble).","Compliance burden: operational cost is likely limited to technician time and access to the PDPs; no complex dismantling or specialised equipment is specified, but access logistics may vary by aircraft configuration (Requirement: 1)."],"plain_english_summary":"This Airworthiness Directive requires operators of Boeing 737‑600/‑700/‑800 aeroplanes fitted with specified power distribution panels to carry out a one‑time visual check of six power‑feeder terminals on PDPs P91 and P92 to confirm proper installation. The inspection is visual, performed with a flashlight through access holes in the PDP covers, and must follow Boeing maintenance documentation referenced in the AD. It affects aircraft operators (who must schedule and bear the inspection) and is issued by CASA under CAR 1998."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD appears tightly scoped to its original safety purpose. It targets a specific technical issue (power distribution panel terminal installation) on specific aircraft models with identified part numbers. There is no evidence of scope creep; the directive maintains the typical narrow focus of airworthiness directives on particular unsafe conditions."},"complexity_factors":["Heavy reliance on external technical documents (Boeing Service Bulletin 737-24-1128 and Aircraft Maintenance Manual Section 24-21-71) without reproducing their content","Precise part number identification required (37 specific part numbers listed in table format)","Technical terminology specific to aviation maintenance (terminal blocks, rigid bus assembly, power feeder terminals)","Specific spatial instructions (aft face, adjacent to TB5001/TB5002, six holes per PDP but only six terminals to inspect despite nine existing)","Single conditional requirement ('Unless previously accomplished')","Cross-references to figure numbers and sheet numbers in external manuals"],"plain_english_summary":"This AD mandates a one-time visual inspection, using a flashlight through access holes, of six specified power-feeder terminals in each of two P91/P92 power distribution panels on certain Boeing 737-600/700/800 aircraft.  \n\nIt addresses a potential unsafe condition from improperly installed or loose electrical connections that could cause power failures or fires. Affected operators and maintenance crews must comply or face enforcement."},"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-b737-173-power-distribution-panels","history":"/api/acts/ad-b737-173-power-distribution-panels/history","analysis":"/api/acts/ad-b737-173-power-distribution-panels/analysis","conflicts":"/api/acts/ad-b737-173-power-distribution-panels/conflicts","importantCases":"/api/acts/ad-b737-173-power-distribution-panels/important-cases","documents":"/api/acts/ad-b737-173-power-distribution-panels/documents"}}