AMC
25.107(e)(1)(iv) Take-off speeds
ED Decision 2003/2/RM
VMU Testing for Geometry Limited Aeroplanes.
1 For aeroplanes that are geometry limited (i.e., the minimum possible VMU speeds are limited by tail contact with the runway), CS 25.107(e)(1)(iv)(B) allows the VMU to VLOF speed margins to be reduced to 108% and 104% for the all-engines-operating and one-engineinoperative conditions, respectively. The VMU demonstrated must be sound and repeatable.
2 One acceptable means for demonstrating compliance with CS 25.107(d) and 25.107(e)(1)(iv) with respect to the capability for a safe lift-off and fly-away from the geometry limited condition is to show that at the lowest thrust-to-weight ratio for the all-engines-operating condition:
2.1 During the speed range from 96 to 100% of the actual lift-off speed, the aft under-surface of the aeroplane should be in contact with the runway. Because of the dynamic nature of the test, it is recognised that contact will probably not be maintained during this entire speed range, and some judgement is necessary. It has been found acceptable for contact to exist approximately 50% of the time that the aeroplane is in this speed range.
2.2 Beyond the point of lift-off to a height of 11m (35 ft), the aeroplane’s pitch attitude should not decrease below that at the point of lift-off, nor should the speed increase more than 10%.
2.3 The horizontal distance from the start of the take-off to a height of 11 m (35 ft) should not be greater than 105% of the distance determined in accordance with CS 25.113(a)(2) without the 115% factor.