Aerial operations in the Colchagua Valley, Chile

by Jose Ignacio Caminos
ignaciocaminos@hotmail.com
Ops. Manager, Aero Santa Cruz, LTDA

We are a company based in Santa Cruz, Chile in the Colchagua Valley, 110 nm to the south of Santiago, one of the most beautiful wine growing region of Chile.

Today, aerial applications consist mainly of sulphur dusting on vineyards and insecticides on seed corn. Almost daily, government regulations affect aerial applications. To make an application, Aero Santa Cruz has to send a fax to the Health Environment Service, 48 to 72 hours before the application. In some regions, the aerial applications are prohibited altogether. The future of aerial application in Chile is a complicated one.

Aero Santa Cruz has one Ag-Cat and two Pawnees. The company makes seven to ten sulphur dusting applications on the vineyards, from October to February. The applications begin at sunrise and usually stop by 11:00a due to the risk of a fire from atmospheric conditions. The sulphur dust used is very combustible. It has a very low ignition point and is highly combustible when atomized with air, which occurs during dusting operations. Due to its excellent dielectric properties, sulphur picks up electrical charges readily, which under atmospheric conditions of low relative humidity and high air temperature, may result in combustion. The dust also irritates the eyes, not unlike when you cut an onion.

Therefore, it is of vital importance to use extreme care in sulphur dusting operations. Aircraft have to be kept as clean as possible at all times. The engine exhaust system has to be maintained free from leaks. Due to the fact that the pull-up at the end of the field directs the exhaust downward towards the dust swath, the hopper gate is closed prior to the pull-up at the end of the field to minimize the possibility of fire. This reduces the efficiency of the dusting operations slightly, however, the pilot always makes a trip across the ends to spread dust on the parts of the field missed by closing the gate early.

Extra care has to be taken while loading the hopper in order to prevent foreign matter, such as wire, paper, etc., from getting in the hopper. Smoking in the vicinity of sulphur dust is never is permitted.

Relative humidity is usually at its lowest during the late morning and early afternoon. Therefore, as a further precaution against sulphur dust fires, applications are made only in the early morning.

The engine throttle is opened slowly, except in the case of an emergency. A sudden blast of exhaust could throw sparks from the exhaust into the dust swath. This is one reason only the best grades of lubricating oil are used in order to reduce carbon formation.

We have to pay special attention to electrical circuits to prevent sparks from short circuits or other sources such as unsealed circuit breakers. Every possible precaution is taken to minimize the hazards of sulphur dusting.

Aero Santa Cruz’s season continues into March with insecticide on seed corn, with three applications per field. Altogether, we make about 100,000 acres of sulphur dusting and 30,000 acres of spraying on seed corn.

For a tour of the Colchagua Valley, visit: www.santacruzchile.cl.