By Boran Pivčić All photos (and some screwdriver work) author
About a month or so back, I got the almost-unique opportunity to peek into the internal workings of two Air Tractor AT-402 cropdusters (9A-DKG and -DKJ) sitting around at Lučko. Having been parked there for a good part of eight years, they finally went up for sale and some prospective buyers wanted to have a looksee under the hood. Through a long chain of events, I ended up being there – and of course didn’t miss the opportunity to have a photo field day :). Going to the airfield without my camera… bah!
A bit about the planes themselves first – as their name suggests, these are rough-and-tough utility machines, designed for continuous 24/7 back-water, dirt-strip torture. As such, they’re built to last, utilising proven, classic technology. Designed to be dismantled with little more than a screwdriver (and liberal amounts of WD40 in our case), ATs of all marks – 300s, 400s, 500s and 800s – hold few surprises under the skin. But they’re simple and uncluttered and a good showcase of aircraft structural solutions.
The 402 version came about when someone decided to ditch the earlier versions’ 600 HP Pratt&Whitney R-985 9 cyl piston radial and replace it with a more reliable – and far simpler – turboprop. Since the 400 series, all ATs have been produced in this configuration, with engines of varying outputs to cater for increasing weights. The current standard is the AT-802 wheeled model and the AT-802AF Fire Boss amphibian. Despite being designed primarily for cropdusting, most 802s today are used for firebombing. Indeed, the Croatian Air Force operates both variants down at the coast (one wheeled, three Fire Bosses) with notable success.
And now, a step-by-step condensed lesson in aircraft structures :).