{"id":"F2006B02836","name":"AD/B737/135 Amdt 1 - Refuel Valve Actuator Suppression Diodes","slug":"ad-b737-135-amdt-1-refuel-valve-actuator-suppression-diodes","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42178,"registerId":"commonwealth-F2006B02836-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B737/135 Amdt 1 - Refuel Valve Actuator Suppression Diodes","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \n![](image.002.png)  \nBoeing 737 Series Aeroplanes\n\nAIRWORTHINESS DIRECTIVE\n\n![](image.002.png)\n\n![](image.002.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/B737/135 and issues the following 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\nAD/B737/135\n\nAmdt 1\n\n  \nRefuel Valve Actuator Suppression Diodes 9/2000\n\nApplicability: Model 737-100, \\-200, \\-300, \\-400 and \\-500 series aeroplanes, line numbers 1 through\n\n3016.\n\nRequirement: 1. For Group 1 aeroplanes, as identified in Boeing Service Bulletin (SB) 737-28- 1115, dated 4 March 1999 or Revision 1 dated 11 May 2000 - Install a transient suppression diode, part number (P/N) 69-58806-4, in the wire bundle (W264) of the refuelling valve-to-float switch of each fuel tank, in accordance with either service bulletin.\n\n    2. For Groups 2, 3, and 4 aeroplanes, as identified in SB 737-28-1115 or Revision 1 dated 11 May 2000 - Replace the existing transient suppression diode, P/N 69- 58806-1 or 69-58806-3, installed in the wire bundle (W264) of the refuelling valve-to-float switch of each fuel tank, with an improved diode, P/N 69-58806-4, in accordance with either service bulletin.\n\n    3. Following accomplishment of either Requirements 1 or 2, perform a functional test to verify proper installation of each diode in accordance with SB 737-28-1115 or Revision 1 dated 11 May 2000. If any discrepancy is detected during any functional test replace the discrepant diode and repeat the functional test.\n\n    4. Transient suppression diodes having either P/N 69-58806-1 or 69-58806-3 may not be installed on any aeroplane.\n\nNote: FAA AD 99-23-20 Amdt 39-11416 and Alternate Method of Compliance (AMOC) 140S-00-188 dated 26 April 2000 refer.\n\nCompliance: For Requirement 1 \\- Remains unchanged as “Within 12 months from the effective date of the original issue of this Directive”.\n\nFor Requirement 2 \\- Remains unchanged as “Within 12 months from the effective date of the original issue of this Directive”.\n\nFor Requirement 3 \\- Prior to further flight.\n\nFor Requirement 4 \\- As of the effective date of this Directive.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nThis Amendment becomes effective on 7 September 2000.\n\nBackground: Boeing has advised of two incidents of electrical fire during fuelling of Boeing Model 737 aeroplanes. Investigation revealed that these incidents were due to a short circuit and overheating of a transient suppression diode.\n\nThe original issue of this Directive was intended to prevent the short circuit and overheating from occurring. Those conditions, if not corrected, could result in electrical arcing and ignition of fuel vapours at the refuelling receptacle for the fuel tanks, together with the possibility of fire during fuelling.\n\nThis amendment introduces an AMOC which allowed a revised SB to be utilised.\n\nThe original issue of this Airworthiness Directive became effective on 24 February 2000.\n\n![Signature of Eugene Paul Holzapfel, Delegate of the Civil Aviation Safety Authority.](image.003.png)  \n\nEugene Paul Holzapfel\n\nDelegate of the Civil Aviation Safety Authority 27 July 2000\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 9 August 2000.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment does not expand the substantive scope of the original safety objective (prevent diode shorting/overheating and possible ignition during fuelling). It revokes the original AD and issues an amended AD that implements the same corrective measures (install/replace diode and test) but introduces and recognises an AMOC allowing use of a revised Boeing service bulletin. In short, the change is procedural (alternate compliance pathway and formal amendment), not an expansion of affected aircraft, affected systems, or the safety issue addressed."},"complexity_factors":["Single narrow technical subject (transient suppression diodes in W264 refuel-valve-to-float wiring)","Four discrete requirements (install, replace, functional test, prohibition)","Three part numbers to track (P/N 69-58806-1, 69-58806-3, 69-58806-4)","Applicability limited by model and line numbers (737 -100/-200/-300/-400/-500, line 1–3016)","Dependence on an external document for detail and group identification (Boeing SB 737-28-1115 and Revision 1)","Cross-reference to FAA AD and an AMOC (alternate method of compliance)","Different compliance timing rules (within 12 months for R1/R2; prior to further flight for R3; immediate ban for R4)"],"plain_english_summary":"**What this directive does (mechanically)\n\n- Requires modification of the refuelling electrical wiring on certain Boeing 737 aeroplanes so that an improved transient suppression diode (part number 69-58806-4) is fitted in the W264 wire bundle that runs between the refuel valve and the float switch in each fuel tank. (A transient suppression diode is an electrical component that prevents voltage spikes.)\n\n- For aeroplanes designated Group 1 in Boeing Service Bulletin (SB) 737-28-1115 (or Revision 1): install P/N 69-58806-4.\n\n- For aeroplanes designated Groups 2, 3 and 4 in that SB: remove and replace any existing diodes with P/N 69-58806-1 or 69-58806-3 and fit P/N 69-58806-4 instead.\n\n- After installation or replacement, perform a functional test described in the SB to verify each diode is correctly fitted; if the test shows a problem, replace the faulty diode and repeat the test.\n\n- Prohibits installation of the older diode part numbers (P/N 69-58806-1 or P/N 69-58806-3) on any affected aeroplane.\n\n- Compliance timing: installations/replacements for Requirements 1 and 2 are to be done within 12 months of the original AD’s effective date; the functional test (Requirement 3) must be performed prior to further flight after the work; the ban on older parts (Requirement 4) is effective immediately.\n\n- Aircraft affected: Boeing 737-100, -200, -300, -400 and -500 series aeroplanes, line numbers 1 through 3016 (see SB for group definitions) (Applicability).\n\n\nWhy the rule was issued (the stated safety concern)\n\n- Boeing reported two incidents in which a transient suppression diode short‑circuited and overheated during fuelling. The stated risk is electrical arcing at the refuelling receptacle that could ignite fuel vapours — the AD is issued to prevent that unsafe condition (Background).\n\n\nWho pays, who decides, and what changes in behaviour\n\n- Who pays: aircraft operators/owners pay for the parts (P/N 69-58806-4) and labour to install or replace diodes and to perform the functional test (Requirement 1–3).\n\n- Who decides: the regulator (CASA delegate) mandates the action; compliance is carried out by approved maintenance organisations following the Boeing SB or an approved AMOC (alternate method of compliance) where accepted (Note/Background).\n\n- Behavioural change: maintenance programmes must add the diode installation/replacement and a mandatory functional test; maintenance records must document compliance; operators must not install the older diode part numbers on any aeroplane.\n\n\nCosts, incentives, trade-offs and operational effects (practical implementation notes)\n\n- Direct costs: purchase of replacement diodes and labour time for removal/installation and testing. Those costs fall on the aircraft operator or owner.\n\n- Operational cost: aircraft may be out of service while the work and functional testing are performed; the functional test must be completed before returning the aircraft to flight.\n\n- Supply chain and inventory effect: operators and MROs must source P/N 69-58806-4 and remove older stock of P/N 69-58806-1 and -3 from service (Requirement 4).\n\n- Compliance pathway: the AD references Boeing SB 737-28-1115 (and Revision 1), and it also notes an FAA AD and an AMOC — operators may use an approved alternate compliance method if authorised by the regulator (Note).\n\n- Administrative/implementation risk: correct identification of aircraft Group (as defined in the SB) is necessary to determine whether to install or replace diodes; reliance on the SB for grouping and test procedures means accuracy of SB instructions is material to safe, compliant work (Requirement sections and Note).\n\n\nCross-references used by the AD\n\n- The AD requires following Boeing SB 737-28-1115 (or Revision 1) for both the work and the functional test (Requirements 1–3).\n- The AD notes related FAA AD 99-23-20 and an AMOC (Background/Note).\n\n\nBottom line\n\n- If you operate one of the affected 737s (line 1–3016), you must ensure the improved suppression diode P/N 69-58806-4 is fitted in the refuel-valve-to-float switch wiring of every fuel tank, that each installation is functionally tested before further flight, and that the older diode part numbers are not used on any aeroplane. The measure is framed as preventing diode overheating and the associated risk of electrical arcing during fuelling (Requirements 1–4; Background)."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment remains tightly focused on its original purpose: preventing electrical fires in 737 fuel tank refuelling systems. The amendment simply incorporates an approved alternative compliance method (AMOC) allowing use of a revised Boeing Service Bulletin, without expanding the scope beyond the specific diode replacement issue."},"complexity_factors":["Short, single-purpose document (4 requirements only)","Minimal defined terms (only standard aviation abbreviations like P/N for part number, SB for Service Bulletin)","Clear grouping structure (Groups 1-4) with straightforward conditional logic","Simple cross-references (only to Boeing Service Bulletin and FAA AD for context)","No nested exceptions or complex temporal conditions beyond standard compliance deadlines","Technical but not legally convoluted — complexity is in the engineering, not the drafting"],"plain_english_summary":"Australia’s aviation regulator (CASA) orders owners/operators of older Boeing 737s (Series -100 to -500, line numbers 1–3016) to install or replace transient suppression diodes in refuelling-valve wiring, test them before flight, and stop using specified faulty diode models.  \n\nThe measure targets diodes that can short and overheat during refuelling vapour conditions—addressing past electrical fires to prevent fuel-tank fires or explosions."},"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-b737-135-amdt-1-refuel-valve-actuator-suppression-diodes","history":"/api/acts/ad-b737-135-amdt-1-refuel-valve-actuator-suppression-diodes/history","analysis":"/api/acts/ad-b737-135-amdt-1-refuel-valve-actuator-suppression-diodes/analysis","conflicts":"/api/acts/ad-b737-135-amdt-1-refuel-valve-actuator-suppression-diodes/conflicts","importantCases":"/api/acts/ad-b737-135-amdt-1-refuel-valve-actuator-suppression-diodes/important-cases","documents":"/api/acts/ad-b737-135-amdt-1-refuel-valve-actuator-suppression-diodes/documents"}}