barfield DPS1000 - ENGINE PRESSURE RATIO (EPR) TEST; EPR Test Procedure

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Note: For an airspeed switch with a 140 kts ± 2 kts trip point, start with a CAS Target
of ~136 kts.
4. If necessary change the RtCAS Target low enough to observe the switch operation.
5. Wait for initial CAS Target to be achieved.
6. Select CAS touch zone, on Target keypad select “Nudge Mode”.
7. Use the Nudge Up key to slowly increase the CAS Target value until the Airspeed
switch trip point is determined.
Note: If required the Nudge value “CAS Nudge = 0.x kts” can be changed by
selecting the Define Nudge soft key.
8. Record the trip point where the switch contacts closed.
9. Use the Nudge Down key to slowly decrease the CAS Target value until the
Airspeed switch operates (opens).
10. Record the trip point where the switch contacts open.
11. On completion of the Airspeed switch testing select the Go To Ground function and
wait for the “Unit Safe at Ground” message to be displayed.
Note: The above Nudge feature can be used with any of the Controlled Target
parameters such as ALT, ROC, MACH, RtCAS, Ps, Pt, EPR.
12. ENGINE PRESSURE RATIO (EPR) TEST
Note: This test is limited by Test Set airspeed range (650 knots).
A. Preliminary
1. Connect the PITOT (Pt) port (red band) to the PT7 (Hi) port of the EPR transmitter to be
tested.
2. Connect the STATIC (Ps) port (blue band) to the PT2 (Lo) port of the EPR transmitter
to be tested.
B. Test
1. The EPR function of the DPS1000 allows the display of the EPR Ratio PT7/PT2 and
also pressures of PT2 and PT7 individually. The units of measure available for the PT2
and PT7 pressure display are: inHg, mb, or Altitude (ft or m) and Airspeed (kts or km/h).
To set up the EPR display to desired units of measure, refer to Table 6.