GE ADTS542F User Manual page 65

ADTS542F/552F/553F/554F User Manual
Altimeter and Airspeed Indicator Testing
Limits Protection Checks
The ADTS will automatically power up with the HELICOPTER limits in force. This table enforces the
most restricted control range on the ADTS output pressures, so this default configuration is the
safest of the three predefine limit sets if working on small, low speed aircraft.
Consult the AMM to check the approved maximum test ranges for Altitude, Rate of Climb, Airspeed
and Mach for your aircraft.
It is important to have the ADTS limits set correctly configured for the following reasons:
a) Prevents operators mistakenly entering test aims which exceed the aircraft maximums.
b) Provides early real time warnings that ranges and rates are being exceeded (due to Pitot Static
system leak etc.).
c) Will prevent inadvertent creation of excessive Mach conditions due to selection of inappropriate
altitude and airspeed combinations.
d) Will ensure that the ADTS can successfully reach any extended range test points as required.
Consult the ADTS limits values for the three predefined tables, HELICOPTER, FIXED WING and MAX
AERO in the SETTINGS menu (see section 3.6). If a suitable protective limits match cannot be found
in one of the three predefined tables then choose CREATE NEW LIMITS and edit your own custom
limits table name and preferred values from the offered starting values. This protected operation
will require use of the Supervisor PIN code. Any attempt to enter limit values greater than the ADTS
pneumatic control maximums will create a warning to the user requesting a lower value. Before
attempting to create a new custom named limit, first check that there are no more than 4 existing
user named tables. A maximum of 5 only are allowed, but old unused tables can be deleted as
required.
Leak Checks
Since the leak status of the aircraft is initially likely to be unknown, it is recommended to perform a
preliminary assessment at low altitude and airspeed stimulus so as to minimise risk to the aircraft
instruments, should a high rate leak be present.
It is strongly recommended to enable the ADTS "AUTO LEAK RECOVERY" function. This will
automatically attempt to regain control of the aircraft pressures if the measured rates of change
(leak rate) exceed 3000 feet/min or 600 knots/min.
If no specific leak check procedure is described in the AMM, first select safe rates of parameter
change for the Ps and Pt channels according to aircraft type. It is suggested to start with
simultaneous aims of 2000 feet and 200 knots, following the procedure described for the standard
equipment serviceability test described in section 6.2.
Correct any leak issues found with the hose connections or aircraft systems before proceeding
with further testing. The leak status of the ADTS alone may be verified using the procedures in
section 6.3.
K0553 Revision C
3-31