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AD/F100/88 - Engine Controls - Reverse Thrust Control Normal Maximum (Second) Detent
Fokker F100 (F28 Mk 100) Series AeroplanFokker F100 (F28 Mk 100) Series Aeroplanes
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Fokker F100 (F28 Mk 100) Series Aeroplanes
| AD/F100/88 | Engine Controls - Reverse Thrust Control Normal Maximum (Second) Detent | 7/2008 |
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| Applicability: | Fokker Services B.V. F28 Mark 0100 aircraft, fitted with Rolls-Royce (Deutschland) TAY650-15 engines. |
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| 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. |
| Compliance: | Requirement 1 and 2: Within 12 calendar months after the effective date of this AD. |
| This Airworthiness Directive becomes effective on 3 July 2008. | |
| 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. |