Phönix-Aviatechnica LKhS-4

The Phönix-Aviatechnica LKhS-4 (also transliterated Phoenix-Aviatechnica LKhS-4 or Feniks-Aviatechnica LKhS-4; in Cyrillic script Феникс-Авиатехника ЛХС-4) was a 1990s Russian design for a civil utility aircraft of unusual configuration. Its designation is an acronym of Legkiy Khozyaystvennyy Samolet (Легкий Хозяйственный Самолет) — "light utility aircraft" in Russian. In addition to general aviation purposes, the LKhS-4's intended use was air-taxi and commuter roles throughout the CIS and it was therefore designed to be able to operate from soft snow or mud.

It was to have been produced by an international joint venture between Russia and Bulgaria. Construction of a prototype began in 1992. First flight was anticipated by 1993, then by 1994, but did not eventuate at all.

Design and development
Although designed in the 1990s, the LKhS-4 was a single-bay, equal-span, unstaggered biplane design. The wings were braced with I-struts at mid span, and were designed to fold backwards for storage. The fuselage was to have a pod-and-boom layout, with a conventional tail  and fixed, tricycle undercarriage. Seating for a pilot and three passengers was to be provided in two rows of two seats inside an enclosed, extensively-glazed cabin. Power was to be provided by two piston engines mounted to the fuselage sides in the interplane gap, driving pusher propellers. At one stage, the engines were specified as VAZ-3187 two-cylinder engines of 60 kW each, but the LOM M132 was also considered.

Construction was to be a light alloy frame, with wing spars of steel tube, covered in panels of composite material.

In September 1990, Bulgarian aircraft engineering company Aviatsionna Tehnika (a division of VMZ) and Russian aircraft engineering company Interavia signed an agreement to develop and manufacture light aircraft. This led to the foundation of Phönix-Aviatechnica as a joint company the following year, with 51% Bulgarian and 49% Russian ownership. The two designs selected for production were the LKhS-4 and SL-90.

Production of the LKhS-4 was planned to start in May 1994 at Aviation Repair Factory ARZ-411 in Mineralnye Vody, Russia, but the aircraft would never be completed, much less manufactured.