Druck ADTS 505 User Manual 3 - 21
K0260 Issue No. 8
3
3.7.6 Airspeed Switch Test
The following example shows how an airspeed switch can be functionally checked.
Note: For low airspeed switches (i.e. 130 knots) Pitot only could be used, 3.7.2.
• Press LEAK MEASURE/CONTROL to enter control mode. Press SPEED/Qc.
• Enter an Aim value below the operating limits of the switch (i.e., airspeed switch operating at 130
knots ±2 knots set 127 knots).
• If necessary, press RATE and enter a change of airspeed low enough to observe switch operation.
• Press ENTER and observe the airspeed changing.
• Using the NUDGE facility, to step-increase, at a fixed increment (0.2 knots), the Aim value.
• Increase the Aim until the switch operates (contacts close) and record the value.
• Change the Aim to above the airspeed operating range (i.e. 133 knots). Repeat the steps, decreasing
the Aim value until the airspeed switch operates (contacts open) and record value.
• On completion of testing, select GROUND and wait for the `Safe at Ground' message to be displayed,
see 3.7.8., refit the pitot and static blanking caps.
• This procedure can be repeated.
• The above method can be used for the other parameters:
Examples:
Altitude switch - low altitude warning
- landing gear configuration warning
-height lock
Mach switch - Speed brake scheduling
- Mach cruise lock
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