TM 1–1520–238–T–1
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Change 5
1–5
FD/LS OPERATION – GENERAL (cont)
1–5
(2) When boresight correctors are entered via the DEK
(ADC) or CDU (ADD) the checksum for these values is
calculated for each system. These checksums are monitored
continuously following power-up.
(3) Upon detection of a checksum error, a high-action-
display (HAD) message is displayed to the appropriate crew
member in the sight status or weapon status character field.
The affected system(s) boresight correctors for the system(s)
defaults automatically to zero until the operator intervenes.
(4) In order not to mask lower priority weapon status
messages, the boresight (BST) message is blinked. The
messages to be displayed are correlated to the systems
affected as follows:
System In Use
Message
TADS
TADSBST?
PNVS
PNVSBST?
GUN
GUN BST?
ROCKETS/
MISSILES
PYLNBST?
(5) For checksum errors, FD/LS does not set the
system status indicators signifying a failure for the respective
system. Therefore, invalid boresight correctors do not result in
lighting of caution and warning indicators, or display of system
failure messages.
(6) When the flashing FD/LS prompt is initiated (ADC)
or FDLS message appears on the CDU (ADD), the
operator sets the DATA ENTRY switch to the FD/LS position
(ADC) or selects the FDLS FAB on the CDU (ADD). Typical
boresight checksum error related FD/LS continuous messages
and corresponding maintenance messages are as follows:
