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initiated BIT (IBIT), and displays a BIT status message. See figure 2-61 for the DISPLAYS BIT
sublevel display.
2.22.5.1 Start-up BIT (SBIT). When the HMD system is turned on, SBIT starts automatically and
the internal software is loaded in the EU. SBIT can be stopped at any time by pressing STOP (PB 10)
on the DISPLAYS BIT sublevel display. PBIT GO or DEGD, as appropriate, is displayed when SBIT
is completed.
2.22.5.2 Initiated BIT (IBIT). IBIT is performed when the HMD (PB 11) option is selected on the
DISPLAYS BIT sublevel display. IBIT can be stopped at any time by pressing STOP (PB 10).
After the IBIT is completed, a series of four HMD test patterns are displayed and automatically
changed each second. See figure 2-62. The test patterns are displayed until the STOP (PB 10) option
is selected. If the ALL (PB 6) option is selected, IBIT is initiated, and HMD test patterns are
displayed.
Figure 2-61. Displays BIT Sublevel
A1-F18EA-NFM-000
I-2-178 CHANGE 1
Figure 2-62. HMD Test Patterns
A1-F18EA-NFM-000
I-2-179 CHANGE 1
2.22.5.3 Status Messages. Refer to the following for status messages and associated descriptions:
STATUS MESSAGE
DESCRIPTION
MUX FAIL Equipment ready discrete is high but the EU is
not communicating on either MUX bus to the
MC
NOT RDY Equipment ready discrete is low and the EU is
not communicating on either MUX bus to the
MC
IN TEST Initiated BIT in progress
RESTRT Re-initiate BIT, EU did not respond to the
IBIT command or IBIT did not complete
within 30 seconds
DEGD EU has detected a failure which degrades system
performance
OVRHT EU has reported a component as overheated
DEGD+OVRHT EU has detected a failure and EU has reported
a component as overheated
GO EU responded with no failures.
OP GO EU has detected a failure which does not degrade
system performance
PBIT GO EU responded with no failures prior to performing
IBIT
2.22.5.4 BIT Recording On The Memory Unit. The MC records any failure or degrade reported by
the EU to the memory unit for fault reporting and isolation.
2.22.5.5 Overheat Condition. The system has the capability to detect an equipment overheat
condition. When an overheat condition is detected the system is automatically shut down to prevent
equipment damage.
A1-F18EA-NFM-000
I-2-180 CHANGE 1
2.22.6 HMD Maintenance. The HMD MAINT option is displayed at PB 17 of the DISPLAYS BIT
sublevel display. See figure 2-63. Pressing PB 17 boxes the option and displays STEP PAGE and STEP
LINE at PBs 14 and 15 respectively. Selecting either STEP PAGE or STEP LINE sends the
appropriate BIT data to the EU. With HMD MAINT boxed, pressing PB 17 removes the STEP PAGE
and STEP LINE displays and unboxes the HMD MAINT option.
2.22.7 JHMCS Alignment. The JHMCS must be boresighted (aligned) with the aircraft prior to
every flight. Selecting the ALIGN (PB 20) option on the HMD format boxes ALIGN, selects coarse
alignment mode, and displays the FINE (PB 1) alignment option after the coarse align function is
complete. See figure 2-64.
2.22.7.1 Coarse Alignment. An alignment cross is displayed on the HUD and in the HMD. See figure
2-64. The pilot moves the HMD to superimpose the alignment cross on the HMD over the alignment
cross on the HUD. Once aligned, the cage/uncage switch is pressed and held until ALIGN OK is
displayed in the HMD. When coarse alignment is complete, fine alignment is automatically selected.
Fine alignment (PB 1) can also be manually selected.
Figure 2-63. HMD Error Log Display
A1-F18EA-NFM-000
I-2-181 CHANGE 1
Figure 2-64. Coarse Alignment
A1-F18EA-NFM-000
I-2-182 CHANGE 1
2.22.7.2 Fine Alignment. When the FINE (PB 1) option is boxed an alignment cross is displayed in
the HUD, and two alignment crosses are displayed on the HMD in the vicinity of the HUD alignment
cross. See figure 2-65. The display indicates which axis is being aligned. If azimuth and elevation is
indicated (FA DXDY), the pilot moves the TDC either left or right to align in azimuth, up or down to
align in elevation. The pilot presses and releases the cage/uncage switch when satisfied with the quality
of the azimuth and elevation alignment. This causes the display to toggle to roll alignment mode. With
the roll axis indicated (FA DROLL), TDC inputs to the left or right are used to rotate the HMD
alignment symbols to align with the HUD alignment cross. The pilot presses and releases the
cage/uncage switch when satisfied with the quality of the roll alignment. Pressing and releasing the
cage/uncage switch continues to toggle between these two modes until the pilot deselects FINE to
return to coarse alignment or exits alignment.
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本文链接地址：
NATOPS Flight Manual 飞行手册 1(121)
