VOR Failure - P-12850102

T-45C TS & ADV BIFP-09

Instrument Failures

VOR FAILURE 1.8.1.9.8.2

Once a selected NAV control panel (FWD/AFT command on the HSI MFD) is turned on

and a valid VOR frequency is selected, VOR feeds data to the DEU.

Until a tuned VOR station is locked-on and the CDI mode is selected, there will be no

VOR indications shown on the HSI display system: no digital bearing data, no bearing

pointer, no CDI, no alert notices. Once a VOR lock-on occurs, digital VOR bearing

information is displayed in the upper left-hand corner of the HSI preceded by a “V,” and

a VOR bearing pointer and tail is displayed on the HSI compass card. If VOR steering

mode is also selected [VOR boxed], the VOR CDI will also be displayed. A selected

VOR station must be within range before the system can lock-on, and the pilot must be

in the CDI mode.

The T-45C system is designed so that a VOR station may be tuned anytime, and kept

in the ON position without entailing a cockpit distraction. When within range of a tuned

station, it will lock-on and VOR data will be displayed—but, only in CDI mode.

If a locked-on VOR fails, the aural identification tone will be lost. The digital “V” and

digital bearing data will be removed. The VOR bearing pointer will no longer be

displayed, and if VOR steering had been previously selected, the CDI will go away.

Unlike most analog systems, no VOR warning “flags” appear on the HSI display if the

VOR fails or breaks lock.

The procedure for dealing with a VOR failure is:

1. Reset the desired frequency.

2. Cycle the NAV control panel to OFF and back to PWR.

2. Check with ATC to see if the subject VOR is in operation, or select another VOR that

is known to be in operation and within range.

3. Use TACAN [if available], waypoints [non-IFR conditions], or request radar vectors.

TACAN BEARING/DME FAILURE 1.8.1.9.4.2

Once a selected TACAN control panel (FWD/AFT command on the HSI MFD) is turned

on and a valid TACAN station is selected, the TACAN feeds data to the DEU.

Until a tuned TACAN station locks-on, there will be no TACAN data shown on the HSI

display page: no digital bearing data, the bearing pointer will rotate in a search mode,

no DME, and no TACAN symbol. Once the TACAN locks-on, TACAN bearing, slant-

range DME, and slant-range time-to-go will be digitally displayed in the upper left-hand

corner of the HSI page. The TACAN bearing pointer will lock-on and point to the

TACAN station and the TACAN symbol will be displayed. If TACAN is selected as the

(8-99) Original

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