{"id":"F2009L03654","name":"AD/F27/26 - RPM Control System - Gustlock Interference System - Improvement - CANCELLED","slug":"ad-f27-26-rpm-control-system-gustlock-interference-system-improvement-cancelled","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":141488,"registerId":"commonwealth-F2009L03654-current","compilationNumber":null,"startDate":"2026-04-03","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Fokker F27 Series Aeroplanes","sectionType":"division","heading":"Fokker F27 Series Aeroplanes","content":"### Fokker F27 Series Aeroplanes\n\n| AD/F27/26 | RPM Control System - GustlockInterference System - Improvement | 11/2009 |\n| --------- | -------------------------------------------------------------- | ------- |\n\n| Requirement: | CANCELLED.                                                                                                                                                                                                                                                                                               |\n| ------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n|              | This AD is cancelled on 22 October 2009.                                                                                                                                                                                                                                                                 |\n| Background:  | This AD, raised in 1960 against Fokker Service Bulletin F-9, required modifications to improve the reliability of the gustlock/RPM control interference system. Compliance was required before 1 January 1961.As all affected aircraft would have been modified long ago, this AD is no longer required. |\n\n![](image.001.png)\n\nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n9 September 2009","sortOrder":0},{"sectionNumber":"AD/F27/26","sectionType":"part","heading":"AD/F27/26","content":"## AD/F27/26","sortOrder":1},{"sectionNumber":"RPM Control System - GustlockInterferenc","sectionType":"part","heading":"RPM Control System - GustlockInterference System - Improvement","content":"## RPM Control System - Gustlock  \nInterference System - Improvement","sortOrder":2},{"sectionNumber":"11/2009","sectionType":"part","heading":"11/2009","content":"## 11/2009","sortOrder":3}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":2481},"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":true,"description":"The instrument has shifted from imposing mandatory aircraft modifications and safety requirements (its original 1960 purpose) to solely removing those obligations as obsolete. The current version contains no operative mandates or compliance duties."},"complexity_factors":["Single operative provision consisting only of cancellation","No defined terms, interpretation section, or cross-references to other legislation","No conditional logic, exceptions, or compliance requirements","Extremely short length (one substantive sentence plus background)","Contains only historical context and cancellation instructions"],"plain_english_summary":"This document officially cancels an obsolete aircraft safety rule (an **Airworthiness Directive**) for Fokker F27 aircraft.\n\n**Background:** The original 1960 rule required physical modifications to prevent the **gustlock** (a device that locks the plane's steering surfaces when parked) from interfering with the engine speed (**RPM**) controls. Aircraft owners had to comply by 1 January 1961.\n\n**Why it matters:** Since all affected aircraft were modified nearly 50 years ago, the rule is redundant. This instrument simply removes the outdated requirement, cleaning up the regulations without affecting any current aircraft operations."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f27-26-rpm-control-system-gustlock-interference-system-improvement-cancelled","history":"/api/acts/ad-f27-26-rpm-control-system-gustlock-interference-system-improvement-cancelled/history","analysis":"/api/acts/ad-f27-26-rpm-control-system-gustlock-interference-system-improvement-cancelled/analysis","conflicts":"/api/acts/ad-f27-26-rpm-control-system-gustlock-interference-system-improvement-cancelled/conflicts","importantCases":"/api/acts/ad-f27-26-rpm-control-system-gustlock-interference-system-improvement-cancelled/important-cases","documents":"/api/acts/ad-f27-26-rpm-control-system-gustlock-interference-system-improvement-cancelled/documents"}}