AMC 25.149(g) Minimum Control Speed with Two Inoperative Engines during Approach and Landing (VMCL-2)

• ED Decision 2020/024/R found in: CS-25 Amdt 27 - Large Aeroplanes (Jan 2023)

AMC 25.149(g) Minimum Control Speed with Two Inoperative Engines during Approach and Landing (VMCL-2) ED Decision 2020/024/R (a) For aeroplanes with three or more engines, VMCL-2 is the minimum speed for maintaining safe control during the power or thrust changes that are likely to be made following the failure of a second critical engine during an approach initiated with one engine inoperative. (b) In accordance with [CS 25.149(g)(5)](#_DxCrossRefBm1709820669) for propeller-driven aeroplanes, the propeller of the engine that is inoperative at the beginning of the approach may be in the feathered position. The propeller of the more critical engine must be in the position it automatically assumes following an engine failure. (c) Tests should be conducted using either the most critical approved one-engine-inoperative approach or landing configuration (usually the minimum flap deflection), or at the option of the applicant, each of the approved one-engine-inoperative approach and landing configurations. The following demonstrations should be conducted to determine VMCL-2: (1) With the power or thrust on the operating engines set to maintain a -3 ° glideslope with one critical engine inoperative, the second critical engine is made inoperative and the remaining operating engine(s) are advanced to the go-around power or thrust setting. The VMCL-2 speed is established with the flap and trim settings appropriate to the approach and landing configurations, the power or thrust on the operating engine(s) set to the go‑around power or thrust setting, and compliance with all the VMCL-2 requirements of [CS 25.149(g) and (h)](#_DxCrossRefBm1709820669) must be demonstrated. (2) With the power or thrust on the operating engines set to maintain a -3 ° glideslope, with one critical engine inoperative: (i) Set the airspeed at the value determined in paragraph (c)(1) above and, with a zero bank angle, maintain a constant heading using trim to reduce the control force to zero. If full trim is insufficient to reduce the control force to zero, full trim should be used, plus control deflection as required; and (ii) Make the second critical engine inoperative and retard the remaining operating engine(s) to minimum available power or thrust without changing the directional trim. The VMCL-2 determined in paragraph (c)(1) is acceptable if a constant heading can be maintained without exceeding a 5 ° bank angle and the limiting conditions of [CS 25.149(h)](#_DxCrossRefBm1709820669). (iii) Starting from a steady straight flight condition, demonstrate that sufficient lateral control is available at VMCL-2 to roll the aeroplane through an angle of 20 ° in the direction necessary to initiate a turn away from the inoperative engines in not more than five seconds. This manoeuvre may be flown in a bank-to-bank roll through a wings-level attitude. (d) At the option of the applicant, a two-engine-inoperative landing minimum control speed, VMCL‑2 (2 out) may be determined in the conditions appropriate to an approach and landing with two engines having failed before the start of the approach. In this case, only those configurations recommended for use during an approach and landing with two engines inoperative need be considered. The propellers of the inoperative engines, if applicable, may be feathered throughout. The values of VMCL-2 or VMCL-2 (2 out) should be used as guidance in determining the recommended procedures and speeds for a two-engine inoperative approach and landing. [Amdt 25/26]