{"id":"F2008L01937","name":"AD/F100/88 - Engine Controls - Reverse Thrust Control Normal Maximum (Second) Detent","slug":"ad-f100-88-engine-controls-reverse-thrust-control-normal-maximum-second-detent","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":74172,"registerId":"commonwealth-F2008L01937-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Fokker F100 (F28 Mk 100) Series Aeroplan","sectionType":"division","heading":"Fokker F100 (F28 Mk 100) Series Aeroplanes","content":"### Fokker F100 (F28 Mk 100) Series Aeroplanes\n\n| AD/F100/88 | Engine Controls - Reverse Thrust Control Normal Maximum (Second) Detent | 7/2008 |\n| ---------- | ----------------------------------------------------------------------- | ------ |\n\n| Applicability: | Fokker Services B.V. F28 Mark 0100 aircraft, fitted with Rolls-Royce (Deutschland) TAY650-15 engines. |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n| Requirement: | 1. Unless accomplished previously, remove the normal maximum (second) detent for the reverse-thrust control in accordance with the instructions of Fokker Services Service Bulletin (SB) SBF100-76-014 at any revision status; and2. Concurrent with the modification as required by Requirement 1 of this AD, amend the Airplane Flight Manual (AFM) as specified in Fokker Services Manual Change Notification - Operational Documentation (MCNO) F100-032 Rev 1 dated 21 Sep 2007 or using AFM pages supplied by Fokker Services.Note: EASA AD No. 2008-0089 dated 13 May 2008 refers. |\n| Compliance: | Requirement 1 and 2: Within 12 calendar months after the effective date of this AD. |\n| | This Airworthiness Directive becomes effective on 3 July 2008. |\n| Background: | All F28 Mark 0100 aircraft with TAY650-15 engines were standard equipped with a normal maximum (second) detent on the reverse-thrust controls. The second detent was intended to provide the flight crew with an easy reference position for the selection of normal maximum reverse thrust for daily use if more than idle reverse thrust was required. Later, investigation revealed that stabilized operation in the N1 speed range of 57% to 75% in reverse thrust could lead to too high stresses on the fan blades of TAY650-15 engines, ultimately leading to structural damage of the fan blades.Consequently, AD/F100/58 was issued in 2003 requiring amendment of AFM for F28 Mark 0100 aircraft fitted with TAY650-15 engines, prohibiting stabilized operation in the 57%-75% N1 speed range in reverse thrust. Because selection of the second detent could result in stabilized operation in the prohibited speed range, a number of operators decided to remove the normal maximum (second) detent in accordance with (recommended) Fokker SBF100-76-014.However, since the introduction of the operational limitation as required by AD/F100/58, occurrences have been reported of inadvertent selection of the second detent, still present on unmodified (pre-mod SBF100-76-014) aircraft. |\n\n| | For the reasons described above, this AD requires the removal of the normal maximum (second) detent and the introduction of related AFM changes on all TAY650 equipped F28 Mk0100 aircraft. |\n| --- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png) \nJames Coyne \nDelegate of the Civil Aviation Safety Authority\n\n22 May 2008","sortOrder":0},{"sectionNumber":"AD/F100/88","sectionType":"part","heading":"AD/F100/88","content":"## AD/F100/88","sortOrder":1},{"sectionNumber":"Engine Controls - Reverse Thrust Control","sectionType":"part","heading":"Engine Controls - Reverse Thrust Control Normal Maximum (Second) Detent","content":"## Engine Controls - Reverse Thrust Control Normal Maximum (Second) Detent","sortOrder":2},{"sectionNumber":"7/2008","sectionType":"part","heading":"7/2008","content":"## 7/2008","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope. It addresses a specific mechanical modification to address a known safety issue with a particular engine-airframe combination. The background explains the evolution from operational limitations (previous AD) to physical modification (this AD), but this represents a logical progression of the same safety issue rather than scope creep."},"complexity_factors":["Single, clearly defined applicability (one aircraft type with one specific engine)","Two straightforward requirements with no conditional logic or exceptions","No defined terms section — technical terms (detent, AFM, N1) are explained in context or are standard aviation terminology","No cross-references to other legislation beyond a single note about the related EASA directive","Clear, linear structure: Background → Requirement → Compliance","Single compliance deadline with no phased implementation or alternative methods of compliance (AMOCs) mentioned"],"plain_english_summary":"This Airworthiness Directive from CASA mandates physical modification and doc changes for Fokker F100 (F28 Mk 0100) aircraft with Rolls‑Royce TAY650‑15 engines: remove the second detent on the reverse‑thrust lever and amend the Airplane Flight Manual per Fokker Service instructions. The detent permitted selecting reverse thrust at 57–75% N, causing excessive fan‑blade stress and risk of blade damage; removing it prevents accidental selection. Both actions were required within 12 months of 3 July 2008."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Scope changed from the earlier measure (AD/F100/58) that imposed an AFM operational limitation prohibiting sustained reverse N1 57–75% to a mandatory physical modification plus AFM amendment. The AD moves from relying solely on procedural/operational controls to requiring a hardware change and concurrent documentation update (Requirement 1 and 2; Background)."},"complexity_factors":["Single defined hardware modification: remove second detent per Fokker SBF100-76-014 (Requirement 1)","Concurrent mandatory documentation change: amend AFM as specified in MCNO F100-032 Rev 1 (Requirement 2)","Compliance deadline and verification tracking: complete within 12 calendar months (Compliance)","Interaction with earlier AD/F100/58 (Background) — changes an operational limitation into a physical cockpit change","Safety-critical nature increases regulatory oversight and recordkeeping despite limited technical scope","Operational impact on flight crews: change in control feel and procedures requiring crew awareness/training","Dependence on manufacturer service instructions increases reliance on Fokker Service Bulletin availability and accuracy"],"plain_english_summary":"Requires removal of the \"normal maximum\" (second) detent on reverse‑thrust levers and a concurrent Airplane Flight Manual (AFM) amendment for Fokker F28 Mark 0100 aeroplanes fitted with Rolls‑Royce TAY650‑15 engines. CASA mandates the modification per Fokker Service Bulletin within 12 months. Mechanically this eliminates a lever position that can produce sustained reverse N1 in the 57–75% range, which investigations linked to fan‑blade overstress. Aircraft operators pay for and implement the modification and update operational documentation."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-f100-88-engine-controls-reverse-thrust-control-normal-maximum-second-detent","history":"/api/acts/ad-f100-88-engine-controls-reverse-thrust-control-normal-maximum-second-detent/history","analysis":"/api/acts/ad-f100-88-engine-controls-reverse-thrust-control-normal-maximum-second-detent/analysis","conflicts":"/api/acts/ad-f100-88-engine-controls-reverse-thrust-control-normal-maximum-second-detent/conflicts","importantCases":"/api/acts/ad-f100-88-engine-controls-reverse-thrust-control-normal-maximum-second-detent/important-cases","documents":"/api/acts/ad-f100-88-engine-controls-reverse-thrust-control-normal-maximum-second-detent/documents"}}