GE ADTS552F, User Manual

Page: 86 / 153

M
ANUAL
V
ENTING OF THE
A
IRCRAFT
P
ITOT AND
S
TATIC
S
YSTEMS
K0553 Revision D 76 [EN] English
Manual Venting of the Aircraft Pitot and Static
Systems
ADTS status on power failure
On removal of power, the main output valve linking external ports Pt and Ps to the internal pres-
sure controllers will automatically close. The aircraft pitot and static systems remain safe but
with the last applied pressures now isolated and maintained in the hoses.
ADTS status on restoration of power
When power is restored to the ADTS the normal self test routine for the ADTS will be performed
and at the end of this the ADTS will exactly equalize the internal manifold pressures to match
those of the external aircraft hoses and then the output valves will be reopened. This process will
at all times protect the aircraft pitot and static systems from adverse pressure transients, differ-
entials or excessive rates.
When the output valves are fully opened, the normal parameter measurement screens become
available from the Dashboard and full control is again available. The testing may then either
continue from the same point (when the power failure occurred) or the aircraft pitot and static
systems may be safely controlled back to ground pressures.
Actions if power cannot be quickly restored
Two courses of action are possible at this point:
1) Leave the ADTS connected to the aircraft pitot and static systems with pipes safely isolated
but maintaining trapped pressures until such time as power can be restored.
2) Use the manual let-down valves on the ADTS front panel to safely bleed the trapped hose
pressures back to ambient ground. This must be carried out in a way that ensures the Pt to
Ps differential pressure remains at zero while the whole connected system is brought to
ground pressure.
Open the valves slowly while monitoring the cockpit gauges for any excessive rate of change.