TM 1-1520-238-10 4-16 Change 9 4.14 SYMBOL GENERATOR. The symbol generator receives data from the bus control- ler and creates the symbols on the video image. The sym- bol generator also serves as the video switching unit for the helicopter. The symbol generator receives incoming video from the TADS, PNVS and video recorder and routes them to crew stations as requested by the crew members. The symbol generator will display video and symbology or symbology only on any of the displays; IHADSS, TADS ORT, or VDU. The symbol generator re- ceives 115 vac power from the No. 1 Essential Bus and is protected by the SYM GEN circuit breaker on the pilot overhead circuit breaker panel. The symbol generator is continuously monitored by FD/LS; the on command test (test 13-SYMG) will fault isolate to the LRU. 4.15 FAULT DETECTION/LOCATION SYSTEM (FD/LS). The FD/LS is contained within the fire control computer (FCC) program. The continuous monitor functions when- ever power is applied to the FCC. If the BBC is the primary bus controller, no FD/LS capability exists. The function of the FD/LS is to detect faults in the subsystems monitored and announce the NO-GO conditions to the flight crew or FCC repairman. The FD/LS identifies the NO-GO subsys- tem component and its location within the helicopter. For FCC software, the CDU is used to access the FD/LS and/or BST functions. For and FCC software, the DEK is used to access the FD/LS and/or BST func- tions. There are two modes of the FCC operation: continu- ous monitor; and on-command initiated. Most weapon, sensor, and fire control subsystems have a continuous check on their status and report their status to FD/LS with- out an on-command initiated test. If the FD/LS detects a NO-GO condition during the continuous monitor of any of the weapons, TADS or PNVS, the results are displayed on the pilot and CPG caution/warning panels. If the exact sta- tus information regarding the NO-GO condition for and software is desired, the DEK switch must be set to FD/LS. For software the CDU FDLS FAB must be pressed. The FD/LS will automatically display the status of all NO-GO subsystem components. An asterisk will be displayed to the left of the fault message that initiated the FD/LS annuniciator / . The status list may be paged by pressing the SPACE key on the DEK for and software or the SPC key on the CDU for software. The FD/LS MENU will be displayed when press- ing any other key. The list is completed when the message ANY KEY FOR FD/LS MENUS appears on the display. WARNING Prior to initiating AWS FD/LS check, en- sure the pilot ground override (PLT/GND ORIDE) switch is in the OFF position. Failure to perform this action may result in uncommanded gun turret slewing or uncommanded gun firing during a AWS FD/LS manual abort. 4.15.1 FD/LS On-Command Tests. Most command initiated tests are fully automatic and do not require any intervention between initiation and completion. There are certain tests which do require some interaction between the initiator and the fire control system. Interaction may re- quire either switch actuation or evaluating a specific pa- rameter or function and the decision regarding its accept- ability. The interaction is fully prompted for all switch actions or evaluations. The on-command initiated tests are displayed as a menu of the specific tests. There are two pages of the test menu. They are: 01–ADS 05–HARS 09–PNVS 02–DASE 06–IHDS 10–PYLN 03–DICE 07–MSL 11–RKT 04–GUN 08–MUX 12–STAB 13–SYMG 17–APU 33–CDU 14–TADS 18–GEN 34–DNS 15–UTIL 19–TRAN 35–DTU 16–ETE 32–TAGA 36–EGI These tests are initiated by entering the corresponding two-digit number for the test; tests 32 – 36 are for only. Any required intervention is fully prompted and the results of the test are displayed on the TADS ORT, VDU and helmet mounted displays. The results may be paged by pressing the SPC key on the CDU ; or the SPACE key on the DEK for and ; this should be done until the message ANY KEY FOR FD/LS MENUS is dis- played. The FD/LS status or on-command initiated test may be accomplished without turning the TADS on. The TADS heads out display can be used independently of the