On checking towing winches it was established that lack of maintenance has led to a
malfunction of the cutting arrangement. The reason for this was a heavy build up of dirt
on the cutting knife that prevents a guaranteed cutting operation.
To be sure of cutting the towing line at the least suitable point (Pressnipple)
can only guaranteed when the cutting edge of the cutting tool is free of dirt and lightly
greased and an operation test has been carried out to the manufacturers recommendations
before beginning towing operations. The set up of the cutting knife is to be checked at
In agreement with the representative of the manufacturer, Matthias Betsch, the DHV has
therefore, as a precaution, reached the following safety measures:
- Before beginning a towing operation a check of the functioning of the cutting
arrangement is to be carried out according to the manufacturers instructions. The set up
of the cutting knife has to be checked. If necessary the cutting area of the knife and
other moving parts are to be oiled or greased as required according to the manufacturers
- To protect the cutting knife spring the tension in the cutting installation is to be
released after the towing operation.
This airworthiness instruction comes into force when published in the News for
Paragliders and Hang Gliders (NfGH).