Symbol Generator Failure.

Section III. CAUTION/WARNING LIGHT EMERGENCY PROCEDURES - TM-1-1520-238-10_574

TM-1-1520-238-10 Helicopter Attack AH-64A Apache Manual
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TM 1-1520-238-10 Change 10 9-21 9.16.5 DELETED. 9.16.6 Symbol Generator Failure. Failure of the symbol generator will result in the loss of video to the VDU and video recorder. Both the PLT and CPG HDUs will automatically revert to PNVS FLIR-2 (PNVS video with no symbology). The ORT, HOD or HDD, as se- lected, will automatically revert to TADS FLIR-2 (TADS FLIR video). If the CPG VID SEL switch is positioned to TADS, the LOS reticle and the IAT gates (if operational) symbology from the TEU will be displayed. If the CPG VID SEL switch is set to PNVS, these symbols will not be displayed. The AND display will continue to operate normally. The pilot may continue flight in a degraded mode without flight or weapon symbology. The CPG may continue weapons engagement in a degraded mode without range information. 9.16.7 TADS Electronic Unit (TEU) Failure. Com- plete failure of the TEU will cause the CPG’s displays to lose imagery and the AND to blank. The pilot may be limited to 75 degrees in azimuth on the PNVS and the message PNVS DIRECT will be displayed in the HAD sight status section. 9.16.8 FLIR Cooler Failure. Failure of the PNVS or TADS FLIR cooler normally occurs during FLIR cool- down prior to flight. However, the cooler may fail in flight. Cooler failures are indicated by a loss of resolution on the FLIR. Resolution loss occurs gradually initially, and becomes more rapid as detector temperatures increase until resolution is lost completely. In the event of a PNVS cooler failure, proceed as indicated in PNVS failure emergency. 9.16.9 FCC Failure. Failure of the FCC (primary MUX BUS Controller) will be indicated by illumination of the MASTER CAUTION and PRI MUX caution segment lights in the pilot and CPG stations. MUX BUS control will be automatically assumed by the BBC. In addition to the degradations listed in Chapter 4, the following ef- fects will be present: DASE channels may disengage causing temporary instability; range inputs thru the DEK range page will be accepted but will have no effect on ordnance delivery; laser designator codes may not transfer to BBC registers and boresight correction data will not be available in the BBC. In the event of a PRI MUX failure, DASE channels should be re-engaged. The MUX switch should be placed in SEC. If weapons system use is necessary, correct laser codes should be confirmed and outfront boresight alignment should be checked prior to weapons systems engagements.

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