{"id":"F2006B06301","name":"AD/PMTV/1 - Blade Root Lag Screws","slug":"ad-pmtv-1-blade-root-lag-screws","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47399,"registerId":"commonwealth-F2006B06301-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PMTV/1 - Blade Root Lag Screws","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)  \nPropellers \\- Variable Pitch \\- MT\n\nAD/PMTV/1 Blade Root Lag Screws 4/99 DM\n\nApplicability: MTV-3-B-C/L250-21 and MTV-9-B-C/CL250 or /CL260-27 model propellers manufactured prior to 31 December 1998 and installed on Vedeney M-14-P or M-14- PF engines.\n\nRequirement: Check lag screw torque in accordance with MT-Propeller Service Bulletin (SB) 17, Revision A, dated 5 March 1999.\n\nIncorporation of new blade root lag screws in accordance with SB 17, Revision A, constitutes terminating action for this check.\n\nNote 1: LBA ADs 1999-081/2 and 1999-082/2 also refer.\n\nNote 2: Propellers inspected per the original issue of SB 17 satisfy the intent of this Directive.\n\nCompliance: Unless previously accomplished, prior to next flight after effective date of this airworthiness directive. Thereafter at intervals of 100 hours time in service or 12 months, whichever occurs first.\n\nThis Airworthiness Directive becomes effective on 17 March 1999.\n\nBackground: This airworthiness directive is prompted by reports of broken blade root lag screws in certain models of MT propellers installed on aerobatic aircraft. Lag screw breakage is attributed to loss of torque. Fractured lag screws can lead to blade separation and loss of control of the aircraft.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, narrowly-targeted airworthiness directive addressing a specific mechanical defect in specific equipment. The scope remains tightly constrained to the identified safety issue with MT propeller lag screws."},"complexity_factors":["Single, specific technical requirement (torque check) with clear reference to external manufacturer document","Limited applicability — only 2 specific propeller models on 2 specific engine types, with manufacturing date cutoff","Simple compliance structure: one-time immediate check plus recurring interval (100 hours/12 months)","Clear terminating action (replacement of screws per Service Bulletin)","No nested definitions, cross-references to other legislation, or conditional exceptions","Total length: approximately 200 words"],"plain_english_summary":"This CASA Airworthiness Directive mandates safety action for owners/operators of certain MT-Propeller models (manufactured before 31 Dec 1998) when fitted to Vedeney M‑14‑P/PF engines—commonly on aerobatic aircraft. It requires an immediate torque check of the blade root \"lag screws\" before next flight and repeat checks every 100 flight hours or 12 months until the redesigned screws from the manufacturer's Service Bulletin 17 (Rev A) are installed.  \n\nThe AD responds to reported broken lag screws that can cause blade separation, loss of control, and potential crashes."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive's scope is narrowly focused on identified propeller models manufactured before 31 December 1998 and installed on specified engines, matching the stated safety concern about broken lag screws. It does not expand to other models or dates and offers terminating action and recognition of prior inspections (Applicability; Requirement; Note 2; Background)."},"complexity_factors":["Targeted applicability to specific propeller models and a manufacture cut‑off date (Applicability).","Requirement references an external technical document (MT‑Propeller Service Bulletin 17, Revision A) for the inspection and for terminating action (Requirement).","Immediate compliance timing: inspection required prior to next flight after the directive becomes effective, creating urgent operational disruption risk (Compliance).","Recurring compliance intervals (100 hours or 12 months) create ongoing maintenance burden and scheduling needs (Compliance).","Terminating action is replacement of screws per SB 17, shifting costs from inspections to parts and labour where operators choose replacement (Requirement).","Notes allow prior inspections under the original SB 17 to satisfy the directive and cross‑refer to related foreign ADs, introducing potential variation in compliance evidence accepted (Note 2; Note 1).","Safety risk is concrete and mechanical: loss of torque → fractured lag screws → possible blade separation (Background).","Administrative qualifier 'unless previously accomplished' creates limited operator discretion about whether immediate action remains necessary (Compliance)."],"plain_english_summary":"This airworthiness directive requires an immediate torque check of blade-root lag screws on specified MT propeller models (manufactured before 31 Dec 1998) installed on Vedeney M-14-P or M-14-PF engines, and repeating the check every 100 flight hours or 12 months until the lag screws are replaced per MT‑Propeller Service Bulletin (SB) 17 Rev A. Replacing the screws according to SB 17 is the terminating action for the checks. It affects aircraft owners/operators and maintenance providers because they must inspect, repeat inspections, and pay for parts and downtime in response to reported lag‑screw failures that can cause blade separation."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pmtv-1-blade-root-lag-screws","history":"/api/acts/ad-pmtv-1-blade-root-lag-screws/history","analysis":"/api/acts/ad-pmtv-1-blade-root-lag-screws/analysis","conflicts":"/api/acts/ad-pmtv-1-blade-root-lag-screws/conflicts","importantCases":"/api/acts/ad-pmtv-1-blade-root-lag-screws/important-cases","documents":"/api/acts/ad-pmtv-1-blade-root-lag-screws/documents"}}