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3.5.4 Aircraft system protection
The ADTS 405 protects the aircraft system against user error and leaks in the aircraft system.
Note: The pumps must be switched on.
The system protection operates by:
•
Limit checking of user entered set-points.
•
Automatic regain of control if leak rate is over limit during leak testing.
•
Automatic regain of control if a leak takes the system pressures outside of limits.
3.5.4.1 Auto recovery facilities
The pressure controllers in the ADTS 405 can "feed" a leak in an aircraft system. When first testing
an aircraft system, a leak test must be carried out at low altitude and airspeed.
• If, during a leak test, a leak in the system produces a rate of climb greater than the
rate set in limits or a rate of change of airspeed greater than the rate set in limits,
then the pressure controllers automatically regain control to minimise damage to
the aircraft system. This AUTO LEAK RECOVERY facility can be disabled.
•
If a leak causes the system pressures to exceed any limit during a leak test, the
pressure controllers automatically regain control. This AUTO LIMIT RECOVERY
facility can be disabled.
•
If negative airspeed (or Qc) occurs in measure mode, the zero valve is
automatically opened for one second to balance the airspeed. This only applies
when the minimum CAS (or Qc) limit is zero.
• Limits cannot be changed with SETUP switched off or Limit Lock enabled.
3.5.5 Limit Checking
The system checks all data entered against minimum and maximum limits set for the particular
limit set in use. If these limits are exceeded, the data entry is ignored and a warning message
displayed showing the minimum and maximum values that can be entered. The system also checks
all limits of associated parameters. If these limits are exceeded when a new value is entered, the
display shows the name of the associated parameter, e.g. If a Mach limit is exceeded when entering
an airspeed value the display shows "Mach" and the equivalent maximum and minimum limits as
airspeed values.
Similarly, if an ARINC 565 limit is exceeded when entering a value and ARINC limits are enabled, the
display shows `ARINC'.
3.5.5.1 Select the limits in use:
a.
Press SETUP.
b.
Select [LIMITS].
c.
Use [NEXT] or [PREV] to select the limits required. Each set of limits is identified by its
name, including the pre-defined sets of limits ("Standard", "Civil" and "Max" see section 1.3,
Operating Limits).
d.
Select [SEL] to select the limits.
e.
Press QUIT/CLEAR to return to the pressure display.
© 2015 General Electric Company – All rights reserved.
Operating Procedures
ADTS 405 Mk2 Instruction Manual-English | 31
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