14 CFR §23.2115

1. (a)The applicant must determine airplane takeoff performance accounting for—
   1. (1)Stall speed safety margins;
   2. (2)Minimum control speeds; and
   3. (3)Climb gradients.
2. (b)For single engine airplanes and levels 1, 2, and 3 low-speed multiengine airplanes, takeoff performance includes the determination of ground roll and initial climb distance to 50 feet (15 meters) above the takeoff surface.
3. (c)For levels 1, 2, and 3 high-speed multiengine airplanes, and level 4 multiengine airplanes, takeoff performance includes a determination of the following distances after a sudden critical loss of thrust—
   1. (1)An aborted takeoff at critical speed;
   2. (2)Ground roll and initial climb to 35 feet (11 meters) above the takeoff surface; and
   3. (3)Net takeoff flight path.