INSTRUCTION MANUAL
DPS400
56-101-01180-C
1-4
Page 21
November 5, 2003
D. PROTECTION CIRCUIT RESET INSTRUCTIONS
(1)
Altitude Limits Exceedance
(a)
Close static RATE CONTROL/LEAK TEST and pitot LEAK TEST valves fully.
Caution:
Do not use unnecessary force to adjust set valve. Positive stop
spacers have been installed on all needle valves to permit firm
closing of the valves without damage. However, excessive
force can overcome the knob setscrew and result in valve
damage. Use the same caution applies when using the knob on
the pressure regulators.
(b)
Open the STATIC VENT valve slowly until the displayed altitude is 2000 feet
below the programmed limit, then close STATIC VENT valve. Readjust the
static regulator to a value 1000 ft below the programmed altitude limit.
Caution: Do not exceed programmed VSI rates while venting the system or
the VSI rate protection circuit will trip.
(c)
Press
F4
. The message "Limit Exceeded F4:-RESET-" replaces the message
"Protection Enabled F1: View Limits" and the protection circuit resets.
(d)
If a higher altitude is desired, reprogram the altitude limits and continue with
normal testing.
(e)
Readjust the STATIC CONTROL to an altitude within the programmed altitude
limit.
(f)
Slowly reopen the static RATE CONTROL/LEAK TEST valve. Do not exceed
programmed VSI limits. Continue with normal testing.
(2)
VSI Rate Limit Exceedance
(a)
Close the static RATE CONTROL/LEAK TEST valve fully.
(b)
Allow the VSI rate to drop below the programmed limit. Press
F4
. The
message "Limit Exceeded, F4:-RESET-" replaces the message "Protection
Enabled F1: View Limits" and the protection circuits resets.
Note:
The display will show variations of altitude and VSI after the
protection circuits have tripped due to pressure transients. This is a
result of the instantaneous readings sensed by the transducers
(which respond much quicker than analog instruments) and do not
affect the aircraft systems to which the tester is connected. Once
the protection systems are tripped, the aircraft systems remain fully
isolated until they are reset by the operator.