In a slight variation from normal agricultural operations, a helicopter operator in The Netherlands has been carrying out some interesting and ecologically advantageous spreading operations over recent months, as Jimmy van Drunen reports.

It is quite a novelty, finding a heliport sited amongst all the agricultural activity in the Dutch village of Harskamp. Still, the helicopter company HeliAir is appropriately located in this area and has been active since 2012. In the early days, the company only conducted sightseeing flights, but competition in the market caused HeliAir to diversify and it now offers many products; including training courses at their own flight school, film flights with their own Cineflex cameras, inspection flights, firefighting, external cargo operations and more. HeliAir offers courses for commercial pilot licenses - either CPL or ATPL - as well as the private pilot license (PPL), under the guidance of experienced instructors and the fleet has grown to nine helicopters; most equipped with luxurious and comfortable interiors.

Unique Project

The company has been working on a unique project that has never before been carried out in the Netherlands in this manner, and was implemented in September, after being prepared over the preceding months in conjunction with various agencies. In recent years, extensive experience has been gained with the spreading of lime and stone meal (ground rock) over heath and forests, using either tractors or helicopters. In recent months, HeliAir has scattered tons of shell grit and stone meal over various nature reserves in the Netherlands to support the restoration of nature and the new project involves spreading stone flour over the Hoge Veluwe National Park to enrich the soil. It was an entirely accidental discovery that stone flour has a positive effect on the acidified soil, which came about when it was realized the heather at the site of a World War II airport is of better quality than heather in other areas. Moreover, more rare plants grow on the site of the former airport. It turns out that stone and concrete residues make a positive contribution to the soil. Despite being just ground rock, the stone meal seems to breathe new life into an impoverished and acidified landscape as the minerals it contains slowly end up in the soil. With this program, the Hoge Veluwe intends to tackle soil acidification and it is believed that it will be about twenty years ahead with the 1,450 tons of stone dust that has now been scattered over the park. It should be noted that the stone meal is a supplement and not a solution to the underlying nitrogen problem, but the park hopes to get plants, insects and birds back to the area by spreading the stone flour.

In addition to the stone flour that was scattered at the Hoge Veluwe National Park, flights were also carried out to spread shell dust over the forest and heathland area of ​​The Ginkel. Shell grit from the North Sea was chosen for this specific area in the municipality of Ede, where there is mainly a lack of calcium. The shell grit has a similar effect to stone flour, as the lime from the shell grit makes the soil less acidic but the ground rock contains more minerals and is used to restore the total soil mineral balance. Unlike stone meal, the birds can eat the shell grit and the oak trees and great tits in the area, for example, benefit greatly from this. Various measures to assist nature are being taken in the municipality of Ede, under a policy aimed at preserving, restoring and enhancing biodiversity. ‘Liming’ is a part of that biodiversity policy as the acidified soil in the forest and heathland washes away important nutrients, with detrimental consequences for animals, plants and trees. The effects of the acidification is made apparent by such examples as young great tits that sag through their legs due to a lack of calcium in the bones, and the death of oak trees.

A total of 385 hectares of woodland and nature area has been treated in The Ginkel and the entire forest and heathland area in question was closed to the public during the work because of the dust, noise and falling grit particles, while traffic wardens, enforcers and forest rangers kept a close eye on everything. In times of the COVID pandemic, this was quite a challenge and when someone was spotted, the helicopter was temporarily grounded in order to ensure safety. There was no spreading over houses and gardens of houses. The dispersal pattern with shell grit is different to that of stone flour, as the material blows out less and falls in a much narrower swathe, leaving clearly visible tracks in the forest. The helicopter flew lower, more closely spaced runs to get better coverage and while the shell grit was spread as evenly as possible, with stone flour it is a bit easier.

The advantage of shell grit is that it can be handles and spread in the rain, whereas stone flour clumps together when wet and clogs the spreader. The electric-powered spreading unit hangs twenty meters below the helicopter and you can't just give it a thump if the supply is blocked. The scattering of shell dust took place outside the breeding season, in the first weeks of November and only after the end of the red deer rut and the hustle and bustle of the autumn holidays. The exercise took about three weeks during which more than eighty tons of shell grit per day went out with the helicopter. The municipality of Ede and the province of Gelderland will monitor the effects over the coming years, observing aspects such as soil biology, soil chemistry, flora and fauna. In this way it is hoped to successfully preserve the natural areas for the future.

Unique Spreader

HeliAir conducts the spreading operations with an AS350-B3 Ecureuil, slinging a self-made and purpose-built spreading bucket from the belly hook. While the cargo hook must be inspected annually, what is suspended from the hook is not defined by any rule or legislation, making possible the use of their own unique bucket. A wiring harness connected to the bucket lets the pilot open the spreader with the press of a cockpit-mounted button and determine the amount of grit to be spread, while a camera system attached to the skid provides real-time imaging of the bucket. Not only does this let the pilot see where the material is scattering, but also more importantly, where it comes to rest upon landing for loading. Arno van der Craats, one of the owners of HeliAir, led the project on behalf of HeliAir and he operates the loader that fills the bucket. Two pilots conduct the flights, Matti Rutgers and Björn Hazzelhekke, with Hazzelhekke belonging to the list of highly experienced helicopter pilots in the Netherlands. His boyhood dream to be an F-16 pilot ended when he was rejected from the Elementary Military Pilot Training School at Woensdrecht Air Base after one year, but he did work for some years at the Royal Netherlands Air Force on the HAWK rockets. After a period of other work, he rolled back into the aviation world when, after a trial lesson on a helicopter, he realized that he wanted to become a helicopter pilot. He obtained his CPL(H) license in 1994 on the Robinson R22 and now has type ratings on several types, including the Robinson R22 and R44, Airbus EC120, EC130, AS.350, AS355N and F2, Bell 206, Aérospatiale SA341 Gazelle and Schweizer SC330.

An average of 110 flights was flown on each suitable day, spreading the entire 385-hectare area in two to three weeks and dispersing a total of 1,125 tons of shell dust on approximately 1,200 flights over the De Ginkel nature reserve. The spreading operation is weather-dependent, as it must be dry with sufficient visibility and the wind must not blow too hard. About 950 kilograms of litter is lifted on each flight and a load indicator in the cockpit lets the pilot see how much weight is in the bucket at any given time. Refueling is carried out on location each hour, taking about 170-200 kilograms of fuel on board for each sortie and the B3 has proved to be a great platform for the program, with plenty of power and performance to safely carry out the work.