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Engine Pressure Ratio only operates in units of pressure measurement (mbar, inHg etc.) with
a set of pre-defined limits, see section 1. The ADTS 505 can be used to check EPR sensors,
indicators and EPR data for engine control systems.
Altitude correction applies to EPR values, make sure this correction does not adversely
affect accuracy. The difference in height between the ADTS 505 and the EPR sensor may
be different to the altitude correction previously set for the aircraft instruments.
For EPR testing, use Ps as INLET pressure and EPR to set the ratio of OUTLET pressure (Pt) to
INLET pressure (Ps).
Before entering a new EPR aim, the rate of change should be set by selecting [EPR Rate] on
the Main Menu.
When in Control Mode (AIM display), a new EPR aim can be entered using the numeric keys.
Use LEAK MEASURE/CONTROL to change between Control and Leak Measure mode.
When in Control Mode (AIM display), the rate of pressure change can be set using the
numeric keys. Use LEAK MEASURE/CONTROL to change between Control and Leak Measure
Selecting [HOLD] causes a changing pressure to instantaneously hold. Selecting [HOLD]
again releases the pressure to continue to the aim value. The [HOLD] facility applies to both
[HOLD] automatically releases when LEAK MEASURE/CONTROL is pressed entering Measure
Changes the current aim value [
This facility can be used to align a pointer of an instrument to a precise indicated value and
compare this indicated value with the measured value.
This facility may be used for pressure switch testing as follows:
Aim for a pressure just below the expected operating point.
When the pressure is achieved, repeatedly press
Record the pressure reading shown on the display.
Repeat this procedure using the
section 3 for an example.
K0260 Issue No. 8
] by a set increment value (2 ft, 0.2 kts, Mach 0.02).
until the switch returns to its original condition, refer to
Reference and Specification
until the switch operates.