{"id":"F2006B02998","name":"AD/B737/98 - Krueger Flap Actuator Support Fitting","slug":"ad-b737-98-krueger-flap-actuator-support-fitting","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42357,"registerId":"commonwealth-F2006B02998-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B737/98 - Krueger Flap Actuator Support Fitting","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/B737/98 Krueger Flap Actuator Support Fitting 13/96\n\nApplicability: Model 737 -100 and -200 series aircraft, line positions 001 through 813. Requirement: Action in accordance with the technical requirements of FAA AD 96-17-04 Amdt\n\n39-9712.\n\nCompliance: As specified in the Requirement Document.\n\nNote: Replacement of the support fitting with a steel fitting and modification of the actuator aft attachment in accordance with Boeing Service Bulletin 737-57-1129 Revision 1, as revised by Notices of Status Change 737-57-1129NSC1; 737-57- 1129NSC2; and 737-57-1129NSC3; constitutes terminating action for the repetitive inspections required by this Directive.\n\nBackground: The FAA received reports of cracking due to fatigue and stress corrosion of the support fittings of the Krueger flap actuator.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive addressing a specific mechanical defect in a defined aircraft population. It has not expanded beyond its original safety purpose."},"complexity_factors":["Very short document (under 300 words)","Only 4 defined structural elements: Applicability, Requirement, Compliance, and Background","Single cross-reference to external FAA directive (AD 96-17-04)","One conditional pathway (terminating action via Boeing Service Bulletin)","No nested exceptions or complex conditional logic","Technical aviation terminology assumes specialist knowledge but is standard for the field"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific Boeing 737 aircraft.\n\n**What it does:**\n- Requires owners and operators of early-model Boeing 737-100 and -737-200 aircraft (serial numbers 001 through 813) to follow a specific safety procedure issued by the US Federal Aviation Administration (FAA AD 96-17-04).\n- The procedure addresses a dangerous problem: **cracking in the Krueger flap actuator support fittings** caused by metal fatigue and stress corrosion. These fittings are critical components that help control the aircraft's leading-edge flaps during takeoff and landing.\n\n**Who it affects:**\n- Operators of older Boeing 737 aircraft (the \"Classic\" -100 and -200 series, first produced in the 1960s-1980s).\n- Maintenance organisations servicing these aircraft in Australia.\n\n**Why it matters:**\n- Cracked support fittings could lead to **flap system failure**, potentially causing loss of control during critical flight phases.\n- The directive mandates **repetitive inspections** until a permanent fix is installed.\n- Operators can \"terminate\" the repetitive inspections by installing a redesigned steel fitting and modifying the actuator attachment per Boeing's specified service bulletin.\n\n**Key takeaway:** This is a **safety-critical maintenance requirement** — non-compliance means the aircraft cannot legally fly in Australian airspace."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive’s scope, as stated in the instrument, is to address reported cracking of Krueger flap actuator support fittings on specified 737-100 and -200 aircraft by imposing inspections and allowing a defined terminating modification (Applicability; Requirement; Note; Background). The text gives no indication that the legal or technical scope has been expanded or narrowed away from that stated purpose; it limits applicability by model and line position and ties required actions to the referenced FAA AD and Boeing service bulletin."},"complexity_factors":["Cross-reference to an external FAA Airworthiness Directive (FAA AD 96-17-04 Amdt 39-9712) for the technical inspection and corrective-action requirements (Requirement).","Reliance on a manufacturer service bulletin (Boeing Service Bulletin 737-57-1129 Revision 1) and multiple Notices of Status Change to define the terminating modification (Note).","Narrow applicability to specific aircraft models and line positions (737-100 and -200, line positions 001–813) requiring operators to check fleet records to determine applicability (Applicability).","Operational complexity: choice between recurring inspections or scheduling a one-time modification with parts and qualified labour implications (Requirement; Note).","Compliance depends on access to and correct interpretation of external technical documents, increasing compliance friction (Requirement; Note).","Implementation risks tied to inspection effectiveness, parts availability and maintenance capacity (Background; Note)."],"plain_english_summary":"This AD requires operators of Boeing 737-100 and 737-200 (line positions 001–813) to follow the FAA AD’s inspection and corrective-action regime for Krueger flap actuator support fittings after reports of fatigue and stress‑corrosion cracking. It makes operators responsible for costs and compliance, and offers a terminating modification—replacement with a steel fitting plus the Boeing service‑bulletin attachment change—that ends repetitive inspections if accomplished."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-98-krueger-flap-actuator-support-fitting","history":"/api/acts/ad-b737-98-krueger-flap-actuator-support-fitting/history","analysis":"/api/acts/ad-b737-98-krueger-flap-actuator-support-fitting/analysis","conflicts":"/api/acts/ad-b737-98-krueger-flap-actuator-support-fitting/conflicts","importantCases":"/api/acts/ad-b737-98-krueger-flap-actuator-support-fitting/important-cases","documents":"/api/acts/ad-b737-98-krueger-flap-actuator-support-fitting/documents"}}