{"id":"F2006B09423","name":"AD/ELECT/48 Amdt 3 - Mechanical Products Inc - Circuit Breakers","slug":"ad-elect-48-amdt-3-mechanical-products-inc-circuit-breakers","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":53812,"registerId":"commonwealth-F2006B09423-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/ELECT/48 Amdt 3 - Mechanical Products Inc - Circuit Breakers","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 107 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nElectrical Equipment\n\nAD/ELECT/48\n\nAmdt 3\n\n  \nMechanical Products Inc \\- Circuit Breakers 9/89\n\nApplicability: 1. Mechanical Products Inc. circuit breakers as follows:\n\n| Series Part No         | Military Designator | Rating - Amps | Manufacturers Date Code |\n| ---------------------- | ------------------- | ------------- | ----------------------- |\n| 4001                   | MS22073             | 1 thru 5      | 8501 thru 8636          |\n| 4200                   | MS26574             | 0.5 thru 5    | 8430 thru 8636          |\n| 4310-0001 and 4310-019 | MS3320              | 1 thru 5      | 8605 thru 8636          |\n| 8500                   | Nil                 | 1 thru 5      | 8514 thru 8636          |\n\n    2. Mechanical Products Inc. circuit breakers commercialised by E.C.E. Co. as follows:\n\n| Mechanical Products Series P/N | Equivalent ECE Reference No | Rating - Amps | Manufacturers Date Code |\n| ------------------------------ | --------------------------- | ------------- | ----------------------- |\n| 4001-001-( )                   | 120DU01###                  | 1 thru 5      | 8501 thru 8636          |\n| 4001-004-( )                   | 124DU01###                  | 1 thru 5      | 8501 thru 8636          |\n| 4001-007-( )                   | 125DU01###                  | 1 thru 5      | 8501 thru 8636          |\n| 4310-001-( )                   | 170/171DU01###              | 1 thru 5      | 8605 thru 8636          |\n\nNote 1. ( ) may be any digit in the range 1 thru 5. # may be any three digits in the range 010 thru 050.\n\nNote 2. The first two digits of the date code are the year of manufacture and the second two digits are the week in that year.\n\nNote 3. All the above circuit breakers may be identified by their blue or black base colour. Mechanical Products circuit breakers commercialised by ECE have an ECE reference number on the body of the circuit breaker.\n\nNote 4. This Directive does not apply to circuit breakers produced or installed prior to 23 July 1984, (the thirtieth week of 1984), or to circuit breakers which have been inspected by the manufacturer, found free of defect, marked with a white inverted Z or a T painted on the terminal end, and have an additional date code with an “R” prefix.\n\nAs an example the unit may have the additional date code of R8642, where “R” designates a retest by Mechanical Products.\n\nNote 5. Aircraft which may be fitted with circuit breakers commercialised by E.C.E. Co. include but are not limited to Aerospatiale SA 330 helicopters.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 107 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nNote 6. FAA AD 87-06-09 and DGAC AD 87-073-IMP(AB)RI refer.\n\nRequirement: Remove from service circuit breakers which fall within the area designated in the applicability statement. Some approved alternate Part No's are as follows:\n\nMechanical Products Inc Equivalent Part Numbers\n\n| Suspect Part Numbers | Klixon        | Mechanical Products Inc |\n| -------------------- | ------------- | ----------------------- |\n| 8500-005-1           | 7274-55-1     | 8500-002-1              |\n| 8500-005-105         | 7274-55-1 1/2 | 8500-002-105            |\n| 8500-005-2           | 7274-55-2     | 8500-002-2              |\n| 8500-005-3           | 7274-55-3     | 8500-002-3              |\n| 8500-005-5           | 7274-55-5     | 8500-002-5              |\n\nCompliance: For Mechanical Products Inc circuit breakers; within 100 hours time in service after 31 May 1987.\n\nFor Mechanical Products Inc circuit breakers commercialised by E.C.E Co; within 100 hours time in service after 10 August 1989.\n\nBackground: 1. Mechanical Products Inc. have advised that a quantity of circuit breakers have been shipped which may be improperly manufactured. An internal contact carrier may rotate within these units which may create an electrical shock hazard or cause the circuit breaker to not fulfil its protection function.\n\n2 Amendment 2 to this Directive is issued to include Mechanical Products Inc. circuit breakers commercialised by E.C.E. Co.\n\n    3. Amendment 3 to this AD is issued to:\n\n    clarify the applicable series of ECE commercialised circuit breakers;\n    provide additional information to aid in identifying ECE commercialised circuit breakers;\n\n    revise the compliance date for ECE commercialised circuit breakers; and\n    clarify which Mechanical Products circuit breakers in the 4310 series are affected.","sortOrder":0}],"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"},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"The AD's scope has expanded from the original instrument. The original directive targeted Mechanical Products Inc. circuit breakers; Amendment 2 added Mechanical Products circuit breakers commercialised by E.C.E. Co., increasing the range of affected parts and aircraft (see Note 5). Amendment 3 further broadened and clarified which E.C.E. commercialised series are included, added identification guidance for those E.C.E. units, revised the compliance date for the E.C.E. units, and clarified which 4310-series units are affected. These amendments increased the population of parts subject to removal and adjusted the compliance timeline for a subset of them."},"complexity_factors":["Multiple tables listing series/part numbers, ratings and date-code ranges (4 tables / lists in Applicability and Requirement).","Several conditional exclusions and identification notes (Notes 1–5) including an R-prefixed retest date-code exception.","Two different compliance dates depending on whether units are Mechanical Products branded or commercialised by E.C.E. Co.","Cross-reference to foreign airworthiness directives (FAA AD 87-06-09 and DGAC AD 87-073-IMP(AB)RI).","Amendment history: prior amendments expanded applicability (Amendment 2) and Amendment 3 made clarifications and a revised compliance deadline.","Alternative approved equivalent part numbers provided rather than a single replacement option (mapping table).","Identification relies on a combination of markings, date codes and physical colour—introducing potential ambiguity in field inspections."],"plain_english_summary":"**What this instrument does (mechanics first)**\n\n- This is an Airworthiness Directive that requires certain Mechanical Products Inc. circuit breakers — and certain units the company commercialised through E.C.E. Co. — to be removed from service because they may be improperly manufactured. (See: \"Applicability\", \"Requirement\".)\n\n- The AD identifies affected units by series/part number, amp rating and manufacturer date code (tables in \"Applicability\"). It also gives visual and marking clues to help identify them (base colour and ECE reference number on the body, and the date-code format: YYWW). (See: Notes 1–3.)\n\n- There are two compliance windows: for Mechanical Products Inc. branded units, removal is required within 100 hours time-in-service after 31 May 1987; for the Mechanical Products units sold by E.C.E. Co., removal is required within 100 hours time-in-service after 10 August 1989. (See: \"Compliance\".)\n\n- Some units are explicitly excluded: circuit breakers produced or installed before week 30 of 1984 (23 July 1984), and units that the manufacturer has inspected, found defect-free, marked with a white inverted Z or a T on the terminal end and given a retest date code prefixed by “R” (for example R8642). (See: Note 4.)\n\n- The AD lists some approved alternate/replacement part numbers (equivalent Klixon and Mechanical Products references) that operators can use when replacing the removed units. (See: \"Requirement\" – equivalent part number table.)\n\n**Why it matters (official rationale reproduced, then practical consequences)**\n\n- Official rationale: Mechanical Products Inc. reported that some shipped circuit breakers may have been improperly manufactured so an internal contact carrier can rotate. That defect can create an electrical shock hazard or cause the breaker to fail to protect the circuit (i.e. fail to trip when required). (See: \"Background\" ¶1.)\n\n- Practical consequences for operators and maintainers:\n  - Aircraft owners/operators and maintenance organisations must inspect fleets for the listed part numbers/date codes, identify any affected units (using the tables and notes), and remove them from service within the stated time limits. (\"Applicability\", \"Compliance\", \"Requirement\".)\n  - Removing and replacing breakers imposes direct costs (parts and labour) and indirect costs (aircraft downtime, scheduling). If replacements are scarce, procurement costs and delays may rise.\n  - Maintenance organisations decide whether to replace an affected unit with an approved equivalent part (tables of equivalent part numbers are provided) or another approved alternative. (\"Requirement\" table.)\n\n**Key implementation details and identification aids**\n\n- Date-code format: first two digits = year, next two = week number (YYWW). (Note 2.)\n- Colour: affected units may be identified by a blue or black base. (Note 3.)\n- E.C.E.-commercialised units carry an ECE reference number on the body; the AD lists which E.C.E. references map to Mechanical Products series/part numbers. (Applicability tables; Note 5.)\n- Exemptions: pre-23 July 1984 units and manufacturer-inspected-and-marked units with an R-prefixed retest date code are not covered. (Note 4.)\n\n**What changed in this amendment (Amendment 3)**\n\n- Amendment 3 clarifies which E.C.E.-commercialised series are included, adds identification information to help spot E.C.E. units, revises the compliance date for the E.C.E. units, and clarifies which 4310-series Mechanical Products breakers are affected. (See: final paragraph of the AD.)\n\n**Costs, incentives and trade-offs (analyst’s lens)**\n\n- Who pays: aircraft operators and maintenance providers bear the direct costs of inspection, removal and replacement, and the indirect cost of aircraft downtime. Parts suppliers and maintenance shops may receive additional business from replacement demand.\n\n- Who decides: approved maintenance organisations and certificated engineers decide whether a unit is an affected item (using the AD’s identification criteria) and which approved replacement to fit. The regulator (Civil Aviation Safety Authority/CASA) enforces compliance through airworthiness oversight. (\"Applicability\", \"Requirement\", \"Compliance\".)\n\n- Incentives and substitution effects: operators may substitute to the listed approved equivalent part numbers in the AD’s table, which shifts demand to suppliers of those parts. If the equivalent parts are more expensive or scarce, that raises operator costs and may increase aircraft out-of-service time.\n\n- Compliance burden and implementation risk: the AD requires fleet-wide checking of specific part/date-code combinations and visual markings within a short flight-hour window (100 hours). Risks include misidentification (date-code or marking errors), incomplete record-keeping of installed parts, and logistic delays in sourcing replacements. The exclusion for retested/marked units reduces replacement demand but requires accurate evidence of the manufacturer’s retest marking.\n\n- Effects on competition and private enterprise: independent maintenance organisations retain freedom to carry out the inspections and replacements subject to airworthiness approvals. Suppliers of approved equivalents may see concentrated demand, which could affect prices temporarily; the AD does not prescribe a single supplier or mandate proprietary parts. (See: \"Requirement\" – equivalent part numbers.)\n\n- Opportunity costs: time and money spent complying with this AD displace other maintenance or investment activity. For operators with many affected breakers, scheduling and parts budgeting will be necessary.\n\n**Implementation notes for operators**\n\n- Use the tables and Notes 1–5 to identify suspect units and check date codes in aircraft records and on the physical breaker. \n- Where doubt exists, treat the breaker as suspect and take it out of service until confirmed otherwise by manufacturer inspection or acceptable evidence of retest marking.\n\n(References in this summary: Applicability; Notes 1–6; Requirement; Compliance; Background; Amendment 3.)"},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":true,"description":"Originally applied only to Mechanical Products Inc. circuit breakers (Amendment 1). Amendment 2 expanded scope to include E.C.E. Co. commercialised versions. Amendment 3 further expanded/clarified the E.C.E. scope, added identification guidance, and revised compliance dates. The directive has grown from a simple manufacturer-specific recall to a multi-source, multi-deadline safety directive covering rebranded/supply-chain variants."},"complexity_factors":["Multiple overlapping applicability tables (2 main tables with sub-variants)","Date code interpretation required (YYWW format with specific ranges)","Wildcard notation in part numbers requiring decoding (parentheses and hash symbols with defined ranges)","Nested exemption conditions (Note 4 has multiple cumulative requirements: inspection + marking + date code prefix)","Dual compliance deadlines based on manufacturer vs. commercialised versions","Cross-references to foreign aviation directives (FAA AD 87-06-09 and French DGAC AD)","Amendment history tracking (Amendment 3 changes from previous versions)"],"plain_english_summary":"This Airworthiness Directive requires owners/operators to remove specific Mechanical Products Inc. circuit breakers (and certain E.C.E.-rebranded units) made in 1984–1986 because an internal part can rotate and prevent tripping or cause shock hazards. It affects aircraft and helicopter operators and maintenance engineers and mandates removal within specified service-hour deadlines to prevent electrical fires, equipment failures, or in-flight hazards. Exemptions include pre‑July 1984 units and factory‑inspected, marked, retested units."}},"importantCases":[],"_links":{"self":"/api/acts/ad-elect-48-amdt-3-mechanical-products-inc-circuit-breakers","history":"/api/acts/ad-elect-48-amdt-3-mechanical-products-inc-circuit-breakers/history","analysis":"/api/acts/ad-elect-48-amdt-3-mechanical-products-inc-circuit-breakers/analysis","conflicts":"/api/acts/ad-elect-48-amdt-3-mechanical-products-inc-circuit-breakers/conflicts","importantCases":"/api/acts/ad-elect-48-amdt-3-mechanical-products-inc-circuit-breakers/important-cases","documents":"/api/acts/ad-elect-48-amdt-3-mechanical-products-inc-circuit-breakers/documents"}}