IRS DISPLAY PANEL (UPPER)

Question 1

Display Selector KNOB

- 5 positions -

TEST

TK/GS

PPOS

WIND

HDG/STS

- inner knob -

BRT

Answer 1

• Displays are for the IRS selected by the SYS DLPL switch
• TEST:
  
  • spring loaded to TK/GS, all lights (display and mode select unit) illuminate
  • 10 sec self test (use ONLY during alignment)
  • disabled in flight or ATT mode
  • illuminates MC and IRS annunciator panel (about 3 seconds)
• TK/GS:
  
  • Left Window (LW) - true trk Right Window (RW) - present gnd spd
• PPOS:
  
  • LW: present LAT RW: present LONG
• WIND:
  
  • LW: present INFLT TRUE WIND DIR RW: present INFLT Wind Speed
• HDG/STS:
  
  • LW: present TRUE Hdg RW: maint status codes
  • RW: during alignment it shows time (in min) till alignment is complete (15 min max - if greater it will stay at 15 until there is 14 min left) - then counts down in 1 min intervals.
• BRT:
  
  • adjust brightness of data displays

Question 2

System Display Selector

• 2 position -

L or R

Answer 2

• SYS DSPL
• L: selects Left IRS for the data display
• R: selects Right IRS for the data display

Question 3

ENTER - Key

Answer 3

• Illuminated White: when direction or hdg keys are entered - N, S, E, W or H
• When Pushed: Valid information sent to each IRS after self-test for reasonableness

Question 4

CLEAR - key

Answer 4

• Illuminated (white) - an ENT attempt has failed (ie not accepted by the IRS - did not pass unreasonable test)
• Push - clears data display of any displayed info not entered into the IRS, if cue lights are on - they will go out
• Illuminated - will also illuminate when 2 or more MAINT codes are active

Question 5

Data Display Window

Answer 5

• 2 windows (Left & Right) display IRS data requested from the system display selector
• last digit is tenths

Question 6

Keypad

Answer 6

• Alpha keys and Numeric keys
• Alpha keys: N, S, E, W or H (heading) - these arm the numeric keys
• Numeric keys:
  
  • permit manual entry of present position when ALIGN light illuminated
  • permit manual entry of magnetic heading when either mode selector is in ATT

System Notes:

• the inertial system display unit (ISDU) supplies initial position and hdg to the ADIRU’s
• ISDU powered by 28v DC from left and right ADIRU
• 2 IRU’s contain 3 laser gyros and 3 accelerometers