{"id":"F2006B04804","name":"AD/BO 105/15 - Transmission Flange Shimming","slug":"ad-bo-105-15-transmission-flange-shimming","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44592,"registerId":"commonwealth-F2006B04804-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BO 105/15 - Transmission Flange Shimming","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Eurocopter BO 105 Series Helicopters\n\n \n\nAD/BO 105/15 Transmission Flange Shimming 8/92\n\nDM\n\n \n\nApplicability: All model BO 105 helicopters S/No S 1 up to and including S 876.\n\n \n\nRequirement: Unless previously carried out action in accordance with MBB (Eurocopter) Alert Service Bulletin No ASB-BO 105-30-104.\n\n \n\nNote: German AD 92-273 MBB/Eurocopters dated 29 April 1992 refers.\n\n \n\nCompliance: As specified in the requirement document.\n\n \n\nBackground: The manufacturer has advised that shims fitted to the input/output shaft, installed in the main transmission, intermediate or tail rotor gearbox, may be incorrectly installed. If this condition exist, the pinion gear teeth will suffer rapid wear which if undetected will result in loss of tail rotor drive.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The AD's text matches its stated purpose in the Background: to detect and correct incorrectly installed transmission shims on specified BO 105 helicopters. It applies to the serial-number range S 1–S 876 and requires action per the manufacturer's Alert Service Bulletin (Applicability; Requirement; Background), so there is no indication the scope was broadened or narrowed from that stated intent."},"complexity_factors":["Narrow, clearly defined applicability (serial numbers S 1–S 876) (Applicability)","Technical action is delegated to an external document (MBB Alert Service Bulletin ASB-BO 105-30-104) rather than detailed in the AD (Requirement)","Safety-critical mechanical inspection and possible corrective work (Background)","Compliance timing and procedural detail are contained in the referenced service bulletin rather than in the AD itself (Compliance)","No additional regulatory exceptions, alternatives or implementation mechanisms specified in the AD (AD text)"],"plain_english_summary":"This Airworthiness Directive requires operators of Eurocopter BO 105 helicopters (serial numbers S 1 to S 876) to inspect and, if necessary, correct shims on transmission input/output shafts in accordance with MBB (Eurocopter) Alert Service Bulletin No ASB-BO 105-30-104 (Requirement; Applicability). The manufacturer states incorrect shim installation can cause rapid pinion gear wear and loss of tail-rotor drive; the inspection and any corrective work and its timing are the responsibility and cost of the aircraft owner/operator (Background; Compliance)."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in a defined aircraft population. It has not expanded beyond its original purpose of mandating corrective action for the transmission flange shimming issue."},"complexity_factors":["Very short document (approximately 200 words)","Only 4 operative sections: Applicability, Requirement, Note, and Compliance","Single cross-reference to manufacturer service bulletin and German AD","No defined terms section","No conditional logic or nested exceptions","Straightforward command structure: identify affected aircraft, specify required action, cite source document"],"plain_english_summary":"This CASA Airworthiness Directive mandates inspection and correction on all Eurocopter BO 105 helicopters (S 1–S 876) to fix incorrectly installed shims in transmission/gearbox shafts. Left uncorrected, the defect can cause rapid gear wear and loss of tail-rotor drive—an immediate crash risk. Operators must comply with the manufacturer’s Alert Service Bulletin on the specified schedule."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bo-105-15-transmission-flange-shimming","history":"/api/acts/ad-bo-105-15-transmission-flange-shimming/history","analysis":"/api/acts/ad-bo-105-15-transmission-flange-shimming/analysis","conflicts":"/api/acts/ad-bo-105-15-transmission-flange-shimming/conflicts","importantCases":"/api/acts/ad-bo-105-15-transmission-flange-shimming/important-cases","documents":"/api/acts/ad-bo-105-15-transmission-flange-shimming/documents"}}