BENDIX/KING
KAP 140
Page 2--13
Revision 2, Dec/2002
CS:15574F02.IDU
2.9 BUILT--IN TEST
The AFCS provides Built--In--Test capabilities to assist service personnel in installing and
troubleshooting the system. This capability is accessed via an RS232 port in the cockpit, using
a portable PC or dumb terminal.
2.9.1 MANUAL ADJUSTMENTS
The FCC contains a single adjustment potentiometer, which is used to make user/installer
adjustments. To make an adjustment, the operator selects the appropriate mode, as shown in the
following table. This activates the adjustment pot to adjust the selected offset/parameter.
MODE
OFFSET/PARAMETER
ROL (default)
Rate gyro/Roll servo command
VS mode engaged, ALT and DN switches
pressed
Pitch servo command
AP engaged and AP switch pressed
Display Brightness (minimum and slope)
AP disengaged and AP switch pressed
Backlighting Brightness
2.9.2 OFFSET COMPENSATION
The FCC also provides offset compensation for the following parameters: Heading Datum, Course
Datum, VOR Deviation, Localizer Deviation, GPS Deviation, and Glideslope Deviation. This
compensation is accomplished by storing the actual input value when the parameter is at the
desired zero condition. These values are stored in nonvolatile memory.
2.9.3 POWERUP TESTS
After application of DC power, the FCC will automatically perform tests of program memory and
RAM. Checksum tests will also be performed on all nonvolatile parameters.
2.9.4 PREFLIGHT TEST
After Powerup tests have passed, the FCC will initiate a preflight test sequence to check
monitoring hardware for possible latent failures. The accelerometer, acceleration monitor, MET
monitor, autotrim/runaway monitor and the trim disable function of the trim servo (if installed) are
tested. The maximum trim servo voltage is also checked against the certification value. A minimum
of 6.0 VDC is also required from the trim servo, to ensure continuity. If all PFT tests pass, the test
ends with a 2.0 second tone on the AFCS Alert output and a flashing visual alert. A lamp test will
be performed on the display and annunciators at the same time. If any PFT tests fail, modes
associated with the tests will not be allowed. Failure of PFT tests for the acceleration monitor will
prevent pitch axis engagement, as indicated by a pitch LED and dashed pitch coupled field, but
roll axis will still be allowed. Failures in trim monitoring, indicated by “PT”, will allow autopilot
engagement, but autotrim and MET will not be allowed. Manual trim indications will still be
presented to the pilot during autopilot operation.
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