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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
737-300/400/500MAINTENANCE MANUAL
L. AIRPLANES WITH IRU -109 AND PREVIOUS; Built-in test equipment (BITE) circuits isolate faults to the LRU level. Faults are indicated by the yellow fault ball on the front of the IRU, the amber FAULT light on the MSU, and a status bit on the data buses to the user systems. The user systems may record an inflight fault based upon the fault from the IRU. In addition, status words are stored in a non-volatile memory in the IRU for at least the previous nine flights. Contents of the non-volatile memory can be extracted on the ground for maintenance.
M. AIRPLANES WITH IRU -110 AND SUBSEQUENT; Built-in test equipment (BITE) circuits isolate faults to the LRU level. Faults are indicated by the amber FAULT light on the MSU, and a status bit on the data buses to the user systems. The user systems may record an inflight fault based upon the fault from the IRU. In addition, status words are stored in a non-volatile memory in the IRU for at least the previous nine flights. Contents of the non-volatile memory can be extracted on the ground for maintenance.
N. Parameters continuously monitored by the BITE include the laser gyros, accelerometer and power supply outputs, computer and memory operation, and temperature. When the IRU is initially turned on, the battery power is tested. The ON DC indication displays during the battery check.
O. The manual test is initiated by pressing the test switch on the IRU or by holding the display selector in TEST position. The test is also performed as part of the IRS BITE from the FMCS CDU. The test can be done in ALIGN mode, or in NAV mode when ground speed is less than 20 knots. It is inhibited in ATT mode.
6. FMCS-CDU IRS Functions______________________
A. Initialization Functions
(1) The IRS is initialized (present position entered) by selecting IRS pages on the FMCS-CDU keyboard. For detailed operation of the FMCS-CDU, refer to AMM 34-62-01/001. The FMCS-CDU(s) are located in the forward electronics panel, P9.
B. IRS Related CRT Displays
(1)
The POS INIT page is selected to enter the initial reference position for IRS alignment.
(2)
The POS REF 2/2 page displays current position as computed by the FMC and each IRU.
(3)
The MAINTENANCE INDEX provides access to pages of data from which maintenance personnel can check IRU performance data.
7. Digital/Analog Adapter (DAA)____________________________
A. The digital to analog adapter (DAA) is a component of the inertial reference system (IRS) but is interfaced with other airplane systems for processing signals independent of the status of the IRS. The two DAAs accept inputs in various formats, primarily ARINC 429, and convert them to outputs compatible with various airplane systems and instruments. The DAAs accept ARINC 429 inputs from the IRUs and convert the 429 format into analog signals with associated valids to control the presentations on various displays.
B. The DAA's are installed on the E1-2 rack in the electrical and electronic compartment.
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. AIRPLANES WITH EFIS ú
34-28-01
ú ú 02 Page 20 ú Nov 12/00
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
737-300/400/500MAINTENANCE MANUAL
CAUTION:_______THE UNIT CONTAINS STATIC SENSITIVE DEVICES. OBSERVE PRECAUTIONS FOR HANDLING ELECTROSTATIC SENSITIVE DEVICES. FAILURE TO OBSERVE ELECTROSTATIC DISCHARGE PRECAUTIONARY PROCEDURES WHEN HANDLING THE DAA MAY RESULT IN DEGRADATION OR FAILURE OF THE DAA.
C. The DAA is a 1/2 ATR box that weighs 23.5 pound (10.66 kgms). Two holddown hooks are used to secure the DAA in its mount. There are no external controls or indictors on the front face. Internally, the module contains 13 card assemblies inlcuding two cards supplying unit power. A dual, rear mounted connector interfaces the unit with airplane wiring.
D. The DAA contains the following internal processing circuits for converting these signals:
(1)
Computer
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