{"id":"F2006B02977","name":"AD/B737/76 - Flight Control Cable Guards","slug":"ad-b737-76-flight-control-cable-guards","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42336,"registerId":"commonwealth-F2006B02977-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B737/76 - Flight Control Cable Guards","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)  \nBoeing 737 Series Aeroplanes\n\nAD/B737/76 Flight Control Cable Guards 5/93\n\nApplicability: Model 737-100, \\-200, \\-300, and \\-400 series, with all line numbers through to 1869.\n\nRequirement: a. Replace plastic flight control cable guards with aluminium cable guards in accordance with Boeing Service Bulletin 737-27A1164 Revision 1.\n\nb. Remove any previously-installed aluminium cable guards located at right buttock line (RBL) 6.60, between body stations (BS) 947.5 and 967, and relocate the aluminium cable guards to RBL 14.75, between BS 947.5 and 967; and verify that grommets are properly installed at all locations; in accordance with Boeing Service Bulletin 737-27A1164 Revision 1.\n\nNote: FAA AD 93-01-27 Amdt 39-8481 refers.\n\nCompliance: Prior to 9 March 1997.\n\nBackground: The FAA had received a report of locked elevator controls and horizontal stabiliser trim; caused by plastic cable guards that had melted onto the control cables.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive’s scope, as stated in this instrument, is limited and specific: it covers certain Boeing 737 series up to line number 1869 and prescribes replacement of plastic cable guards with aluminium guards, relocation of aluminium guards at a specified location, and verification of grommets (Applicability; Requirement a and b). The Background identifies the safety event motivating the AD (melting plastic guards causing locked controls). The instrument does not expand or narrow that stated technical response beyond prescribing the actions and the manufacturer service bulletin; therefore the scope set out here is consistent with the directive’s stated purpose and does not indicate a change from that purpose within the text provided (Requirement a and b; Background)."},"complexity_factors":["Limited aircraft applicability to specific Boeing 737 models and line numbers (Applicability).","Clear, prescriptive technical actions: replace plastic guards with aluminium; remove and relocate aluminium guards at specified RBL and BS coordinates; verify grommets (Requirement a and b).","Mandatory reference to an external manufacturer document (Boeing Service Bulletin 737-27A1164 Revision 1) for the technical procedure (Requirement a and b).","Fixed compliance deadline (Prior to 9 March 1997) creating a time-constrained operational requirement (Compliance).","Cross-reference to a related FAA AD, requiring awareness of parallel regulatory action (Note)."],"plain_english_summary":"The Civil Aviation Safety Authority requires operators of Boeing 737-100/200/300/400 series (line numbers through 1869) to replace plastic flight-control cable guards with aluminium, relocate specific aluminium guards and verify grommets, all per Boeing Service Bulletin 737-27A1164 Revision 1. Work must be completed by 9 March 1997 after incidents where melted plastic guards caused locked elevator controls and stabiliser trim."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-limited safety directive addressing a specific mechanical defect. It has not expanded beyond its original purpose of preventing flight control cable jams on specific Boeing 737 models."},"complexity_factors":["Very short document (under 300 words)","Only 4 defined technical terms (RBL, BS, line numbers, body stations) that are standard aviation references","Single compliance deadline with no conditional exceptions","Clear two-part requirement structure (replace plastic guards; relocate specific aluminium guards)","References only one external technical document (Boeing Service Bulletin) and one related FAA directive","No nested conditions, no alternative compliance methods, no partial applicability clauses"],"plain_english_summary":"This is a **safety order** issued by Australia's Civil Aviation Safety Authority (CASA) requiring specific repairs to Boeing 737 aircraft.\n\n**What it does:**\n- Orders airlines and aircraft owners to replace **plastic cable guards** with **aluminium ones** on certain Boeing 737 models (the -100, -200, -300, and -400 series, up to production line number 1869).\n- Also requires moving some existing aluminium guards to a different location and checking that protective rubber rings (\"grommets\") are properly installed.\n\n**Why it matters:**\nThe US aviation regulator (FAA) discovered that **plastic cable guards could melt onto flight control cables**, causing the elevator and horizontal stabiliser controls to jam. This is extremely dangerous—it could prevent pilots from controlling the aircraft's pitch (nose up or down). The aluminium guards won't melt.\n\n**Who must comply:**\nAnyone operating the affected Boeing 737 models in Australia had to complete these modifications **before 9 March 1997**.\n\n**Key terms explained:**\n- **Airworthiness Directive (AD):** A mandatory safety order—like a recall notice, but legally enforceable. You cannot fly the aircraft until it's done.\n- **Cable guards:** Protective brackets that keep control cables in place.\n- **RBL/BS:** Technical measurements showing exactly where on the aircraft body the work must happen."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-76-flight-control-cable-guards","history":"/api/acts/ad-b737-76-flight-control-cable-guards/history","analysis":"/api/acts/ad-b737-76-flight-control-cable-guards/analysis","conflicts":"/api/acts/ad-b737-76-flight-control-cable-guards/conflicts","importantCases":"/api/acts/ad-b737-76-flight-control-cable-guards/important-cases","documents":"/api/acts/ad-b737-76-flight-control-cable-guards/documents"}}