GE ADTS 542 Instruction Manual page 110

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 automati-
cally 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 service-
ability test described in section Standard Serviceability Test.
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
ADTS Leak Check.
Typical Aircraft Instrument Performance Checks
The required aircraft specific procedures will be detailed in the AMM but the following generic test is
provided purely as an example of how the ADTS facilities might be best utilised.
The ADTS produces controlled altitudes based on the standard sea level pressure (zero feet reference)
that is defined in the ICAO international standard atmosphere model. In order to correctly check the
aircraft instruments for accuracy against the ADTS, it is vital that the altimeter baroscale datum
adjustment is set to the same 1013.25 mbar (29.92 inHg).
Systematically enter the required aims for the Ps and Pt channel from each row of the test table. Aims
may be entered either in aeronautical units or absolute/differential pressure units according to the
requirements of the AMM. For each of the six test row conditions, allow the ADTS to approach and
stabilise the aims until the ADTS Touch shows each measurement in green record the difference
between the ADTS and the Aircraft instrument under test.
Altitude
Test Point (feet)
1 0
2 5,000
3 15,000
4 *29,000
Ps Pressure Airspeed
(mbar Abs.)
1013.25 90.0
843.07 130.0
571.82 250.0
314.85 310.0
E B A
XAMPLE ASIC IRCRAFT
Pt Pressure
(Knots) (mbar Abs.)
1026.44
870.73
676.80
479.37
T O ADTS542F
EST PERATION USING THE
Qc Diff.
Press. (mbar)
13.19
27.66
104.98
164.52
108