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LTL TATM LTL - Vol 1
Issue 1.0
15
3.5.1 Ground Fan
The ground fan should be used during high winds and in case of ballonet fan failure. It can also be
used to save battery power when the balloon is low moored overnight or if it is not operational for a
long period.
It is essential to maintain pressure when the balloon is moored during windy conditions to prevent the
envelope from indenting, and reduce wind drag and balloon movement.
To speed up pressure recovery in gusty conditions when ballonet air is blown out of the pressure relief
valve, the ground fan has a higher performance than the ballonet mounted fan.
If the ground fan was operated continuously there is a danger that the balloon could be over-
pressurised and helium vented. To prevent this the fan is linked into the pressure sensing system
displayed in the instrument box which switches the fan in and out to limit pressure.
The ground fan is powered by mains or generator A C supply either 240 V or 110 V this means there
is a continuous supply and no drain on the on board batteries, which can be charged.
The ground fan must be disconnected before the balloon is flown or raised to the high
mooring position.
3.5.1.1 Ground Fan Installation
Locate fan on the platform outside the gondola.
Lead the duct over the top of the gondola and under the mooring ring.
Couple the duct up to the connection under the ballonet fan using the four ‘over centre’ catches.
Mains lead - plug in to mains (or generator) supply socket.
The connection of the ground fan controller lead to the control panel is the responsibility of the
supervisor. He must also connect the battery charger to ensure overnight charging.
3.5.1.2 Emergency Operation
If there is a failure in the automatic system or in severe storm conditions the fan may be plugged
directly into the mains supply and operated continuously.
In this case an operator should monitor the ballonet and helium pressure closely. If the ballonet
pressure exceeds 14 mm WG, or He pressure exceeds 38 mm WG, the fan should be switched off
until the pressure drops around 3 mm WG before switching on again.
If there is a mains power failure the ground fan can be connected and operated from the internal
lighting generator.
3.5.1.3 Ballonet Fan Reconnection
Before the balloon is flown or raised from the low mooring position the ground fan must be
disconnected.