CM170407AMA
SECTION 7 ADVANCED OPERATIONS
7.1 SPECIFIC PITOT PRESSURE VALUE COMMAND
When the MPS49 is displaying pressures (see chapter 4.1), the Status Screen (FIG 5) can
show either the dynamic (Qc) pressure or the total pressure. The display mode can be
changed by touching the orange button Qc/Pt or by pressing
SHIFT
+ 7.
NOTE
While in Pt, pressure, control mode, it is possible to command and achieve negative
Qc values, i.e. a Pt value lower than the Ps value.
NOTE
The orange button
Qc/Pt
only switches the display mode. In order to change the
control mode, the Operator must select the Pt/Qc rate and then touch the
Eu/Au
green button.
7.2 LEAK TEST
The MPS49 can perform a leak test of the static, pitot and AoA lines using a built-in timing
function. Leak rates for pitot and static lines are calculated every second and are
automatically shown in the selected units in the Leak Screen.
NOTE
the AoA channel is tested for leaks if the AoA pressure is not zero. Otherwise, the
Ps and Ps2 lines are connected inside the MPS49, and any leak on the AoA
pneumatic circuit will be measured as a Ps leak.
The MPS49 can perform three kinds of leak tests:
1. “Free-running”, without time limit.
2. Timed.
3. Fully automatic, at pre-programmed altitude/Ps and airspeed/Qc/Pt values.
All kinds of leak tests are enabled by pressing the
LEAK
key. The Leak Screen (paragraph
4.3.2) will appear.
NOTE
The leak test can be performed either in aeronautical or pressure units. FIG 7 is an
example of the Leak Screen in aeronautical units.
NOTE
The pneumatic circuit inside the MPS49 consists of a small volume (0.07 liter for
Ps, Pt and AoA). For this reason, any leak test conducted on the MPS49 without
any pneumatic load and high rate values may give unexpected results, due to the
fast change of the temperature inside the pneumatic circuitry. In order to conduct a
leak test of the MPS49 alone, please refer to the Final Inspection and Calibration
Certificate for the rate values and stabilization time required.
7.2.1 FREE-RUNNING LEAK TEST
When the
LEAK
key is pressed, the MPS49 starts a free-running leak test: it begins
counting the seconds and displaying the leak rates for the pitot and static circuits.
For the best measurement results, wait until the values in the Leak Screen are stabilized
after pressing the
LEAK
key. Typically this will happen after one minute. When the
stabilization has occurred, press the
LEAK
key once again to reset the clock for a fresh
start of a leak test.
7.2.2 TIMED LEAK TEST
A timed leak test can be prepared by touching either the time indication in the lower-left part
of the display, or the Time button. After setting the leak test time, the Leak Screen will be
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