Engine Pressure Ratio (Epr) - GE Druck ADTS 405 R/F Mk2 Instruction Manual

Chapter 3. OPERATION
3.5.6.3 Airspeed Switch test
The following example shows how an airspeed switch can be functionally checked.
Note: For low airspeed switches (i.e. 130 knots) the Pt Only facility could be used.
Example
a. Press LEAK MEASURE/CONTROL to enter control mode. Press SPEED/Qc.
b. If necessary, press RATE and enter a change of airspeed low enough to observe switch
operation.
c. Enter an Aim value below the operating limits of the switch (i.e., airspeed switch operating
at 130 knots ±2 knots set 127 knots).
d. Press ENTER and observe the airspeed changing.
e. Using the nudge facility, set to an appropriate step value, increase the Aim value.
f. Increase the Aim until the switch operates (contacts close) and record the value.
g. Change the Aim to above the airspeed operating range (i.e. 133 knots). Repeat the steps 3
to 5, decreasing the Aim value until the airspeed switch operates (contacts open) and
record value.
This procedure can be repeated. If many operations of a switch are required use the oscillating
facility detailed in Full Set-up, see 6.2.30. The above method (steps a. to g.) can be applied for the
other parameters:
Examples:
Altitude switch
Mach switch

3.5.7 Engine Pressure Ratio (EPR)

The ADTS 405 may be used to check EPR sensors and indicators. Use Ps for INLET pressure and Pt
for OUTLET pressure. To carry out an EPR check, the display must be showing pressure units e.g,
mbar or in Hg.
3.5.7.1 Example EPR
To enter an EPR of 1.8 with inlet pressure of 500 mbar (15 inHg), proceed as follows:
a. If the display shows "Leak Measure", press LEAK MEASURE/CONTROL to regain control.
Note: The pressure/vacuum pumps must be switched on.
b. Press ROC/Ps RATE to select rate of change of static.
c. Enter required rate of change e.g, 1000 mbar/min, (30 inHg/min).
34 | ADTS 405 Mk2 Instruction Manual-English
• Low altitude warning
• Landing gear configuration warning
• Height lock
• Speed brake scheduling
• Mach cruise lock
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