INTRODUCTION In this Item@ the increment in lift coefficient at zero angle of attack@ due to the deployment of trailing-edge split flaps on a wing@ is derived from the increment due to the deployment of the split flap on an aerofoil section that is representative of the wing. For wings with full-span trailing-edge split flaps a factor@ dependent on planform geometry@ is applied to allow for three-dimensional effects. For wings with part-span trailing-edge flaps additional factors are introduced@ that are dependent on the wing geometry. Wings with single-slotted@ double-slotted and plain trailing-edge flaps@ are dealt with in Item Nos 93019@ 95021 and 97011 (References 17@ 19 and 21). At low speeds@ the increment in lift coefficient at zero angle of attack@ ??CL0tw @ due to the deployment of a full-span trailing-edge split flap on a high-aspect-ratio rectangular wing is strongly dependent on the corresponding value@ ??CL0t@ for an aerofoil/split flap combination appropriate to the mid-semispan location. The main parameters that can influence ??CL0t are the flap angle@ chord of the flap@ the aerofoil maximum lower-surface ordinate and its chordwise location@ the flow Reynolds number and Mach number. For trailing-edge split flaps on wings the additional parameters that can influence ??CL0tware the wing planform geometry (aspect ratio@ taper ratio and sweep)@ and the spanwise extent of the flap. The effects of wing planform geometry are largely accounted for in terms of their effect on the wing lift-curve slope. Provision is made for the case of an extended split flap. In the application of the method a number of other Data Items may be required@ and these are listed in Section 3. Section 4 describes the prediction method. Section 5 discusses Mach number and Reynolds number effects. The accuracy and applicability of the method are addressed in Section 6. The Derivation and References are given in Section 7. Section 8 presents a worked example that illustrates the steps of the calculation.