The PZL-106 “Kruk” is the first Polish-designed specialist agricultural aircraft, designed at WSK PZL Warszawa Okecie under the direction of Andrzej Frydrychewicz, MSc Eng. It is a single-engine, strut-braced low-wing monoplane of all-metal construction.
It has a fixed undercarriage with a tailwheel. The fuselage is welded from steel tubes and contains space for the chemical tank, which is positioned ahead of the pilot’s cockpit. Particular attention was paid to pilot safety. The cockpit is a separate integral unit, attached to the fuselage truss. Behind the pilot’s cockpit there is a separate compartment for a mechanic, used during ferry flights. The cockpit is sealed and pressurised, and the incoming air is filtered.
To prevent the consequences of collisions with power lines, wire-cutting knives are mounted on the main undercarriage and in front of the pilot’s cockpit, and a deflector cable runs from the top of the cockpit to the top of the vertical stabiliser. Below the cockpit is a cargo space where agricultural equipment is secured on appropriate mounts during longer ferry flights. The wing in the A version is a two-spar design. The torsion box is sheet-metal skinned, and the trailing portion is fabric-covered. A fixed slot extends along the entire wingspan.
— When I finally hit those trees, I understood why the cockpit was so large — the pilot later testified before the commission — in a Gawron I would have long since smashed my head into the instrument panel. I only felt the bent stick slide across my chest; in a Gawron I would already have been like a butterfly pinned on a needle… — after: Andrzej Kardymowicz*
The basic component of the aerial application equipment is the chemical tank. It is made of epoxy laminate reinforced with glass fibre. It is placed in the fuselage truss between the engine and the pilot’s cockpit. In its upper part, the tank has a loading opening for dry chemicals, closed by a pneumatically operated hatch controlled from the cockpit. In its lower part, the tank has an outlet fitted with locks for attaching various versions of underwing equipment. Dry-material equipment consists of a dispenser mounted on the tank and a tunnel spreader suspended from fuselage fittings. Liquid equipment consists of a pumping-filtering unit, an under-fuselage pipe for filling the tank with working fluid, and spray bars with 90 fittings for shut-off valves with interchangeable spray nozzles. The bars are suspended on booms behind the trailing edge of the wing.
The exhibited aircraft, serial number 05005, is one of 7 pre-production units with a “T” horizontal stabiliser. The aircraft with a PW R-1340 engine was first flown by W. Lukomski in March 1975, and subsequently with a Lit-3S engine in May of that year by J. Wojnar. The latter prototype powerplant was derived from the Lit-3 helicopter engine produced at WSK PZL Rzeszow. This engine became the precursor of the PZL-3S and SR engines used on production PZL-106 aircraft. In 1975–76, factory flight tests of various powerplant units and agricultural equipment were conducted on these aircraft. One of the aircraft took part in operational trials in Egypt. The aircraft bearing the registration SP-PBK was donated to the Polish Aviation Museum by EADS PZL Warszawa-Okecie on 7 October 2007.
| year of production | 1975 |
| wingspan | 14.8 m |
| length | 8.9 m |
| height | 3.32 m |
| empty weight | 1685 kg |
| take-off weight | 3000 kg |
| cruise speed | 160 km/h |
| working speed | 145 km/h |
| max speed | 211 km/h |
| service ceiling | 4000 m |
| range | 680 km |
| take-off/landing run | 240/210 m |
| spraying width | 35 m |
| powerplant | 7-cylinder air-cooled radial piston engine Lit-3S (PZL-3S) rated at 600 HP (441 kW) with a 4-blade laminate propeller US 129000 |
