The An-14Sch was an experimental version of the An-14. It featured an test started with the Kubischev KB An-714. It was developed on through a tethered test rig. The An-14Sch flew at a height of 15-20 metres. It was fitted with an air cushion device powered by a TA-6A-1 APU located inside the cabin as a lift engine.
A test-bed, known as the An-14Sh, was developed for air cushion effect system which was intended to he used on large cargo aircraft types. To reduce the pressure on the surface, the air cushion unit (ShVP) comprised of an inflatable ring or skirt with four pairs of inner rings, located around the areas, where the compressed air was to be expelled. The energy of the air expelled was less than that in the ShVP with flexible skirt (like on the earlier An-714). The ShVP was folded in a special housing, beneath the fuselage, which reduced the drag. The An-14Sh could land in the conventional aircraft mode if the skirt was not deployed. During tests, the An-14Sh was tested on both paved and unpaved surfaces.
The design was explained in detail and illustrated in the magazine Aviastii Vreyma [Ukrainian Aviation Magazine] (1/96) [Page 11] and the book History of Aircraft Design in USSR 1951-1965 (Edited by Yu V Zaspkin and K Yu Kosminkov).
I understand that the An-14Sh trials started around 1983. It seems that years before (1970) an An-14 was tested with some floatation gear (not air cushion) under the An-714 company (see photo).
The An-714 carried a civil registration, whereas the An-14Sh was apparently a military example.