Honeywell SPZ-8000 Maintenance Manual page 59

I
The IRS is an all attitude inertial sensor system which provides aircraft
attitude, heading, and flight dynamics information to the PFD and ND, flight
control (DAFCS), weather radar antenna platform, and other aircraft systems
and instruments.
The inertial reference unit (IRU) is the primary component of the IRS and
provides the following digital outputs:
. Primary attitude
Body linear accelerations
. Body angular rates
Inertial velocity vectors
. Magnetic and true north reference
. Present position data
Wind data
The IRU requires a dedicated +24 volt dc backup battery, which the user must
supply.
The triple-channel mode select unit (MSU) enables the flightcrew to select
the mode of system operation for three IRUS, provides status indication for
each system, and test initiation for each IRU.
The optional IRU 3 is used in triple IRS installations in place of the
attitude heading reference unit (AHRU).
The form, fit, and function of the AHRU are identical to those of the IRU
except that the AHRU does not provide navigation outputs on the digital bus
interfaces. The AHRU provides continuous comparison monitoring in which its
internally computed attitude, angular rate, and acceleration signals are
compared to those same signals transmitted on the ASCB data bus from IRU 1
and IRU 2.
The AHRU also provides backup attitude, heading, rate, and
acceleration outputs.
The inertial system display unit (ISDU) selects data from any one of three
IRUS for display and provides position or heading data to three IRUS.
LASERTRAK@ is an extension of the Honeywell Laseref Inertial Reference System
(IRS). The function is resident in a navigation display unit (NDU) which
replaces the ISDU normally found in IRS installations. The NDU retains the
ISDU functionality and gives the pilot a means of entering a nine-waypoint
flight plan. Waypoints are entered using lat/long designations. Flight plan
progress is monitored on the NDU or on EFIS.
For additional information on the IRS components, 'refer to the manuals listed
in INTRODUCTION.
22-14-00
Page 11
Apr 15/93
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