This photo was taken at the Transavia factory at Seven Hills, c.1979. Visible are the V-shaped spray bar supports under the port wing, and one of the load dump doors under the fuselage. The hopper took up most of the centre fuselage, and the pilot sat just in front of the c/g and above the engine. Most of the basic fuselage was a maze of tough welded chrome-molybdenum steel tubing carrying the stainless-steel hopper, with everything else hanging off it. From memory, a lot of the stub wing was also chrome-moly. Wings, tail assemblies, and cockpit front panel were aluminium alloy, fuel tanks were welded and riveted aluminium, and the cowling, cockpit sides and roof and the rear fuselage were fibreglass.
I believe this was the first Airtruk to be fitted with the Lycoming O-540 engine, which would later be used to power the upgraded Airtruk T300 Skyfarmer. In fact, this airframe may have become the Skyfarmer prototype. At the time this photo was taken the design team were trying to see if a better carburettor alternate air source could be found, in case of air filter blockage. A 4″ square-to-round 45 degree alloy duct was made to fit in the very confined space – no easy task – but after a lot of effort a different system was used. Around this time the side cowlings were also modified, with large vents, in an effort to improve engine cooling for the Lycoming. In case of fire, this would have blown the flames onto the unprotected fuel pipes; but as it turned out the idea didn’t work anyway. The side panels weren’t reshaped again, though. The air exits were simply blocked off. Which is why some Airtruks have odd bulges in the cowling sides.
The cockpit was entered from the starboard side, and the door was attached to the steel frame using piano hinge. In the event of a rollover the frame would most likely buckle, bending the hinge. The possibly-injured pilot was then expected to kick his way through the fibreglass door to escape. If the accident happened on landing, the lowered flaps blocked the only exit door for the passengers in the rear. I always felt this showed a surprising lack of sympathy for the unfortunate occupants.