MIL-PRF-83419E

Abstract

This specification covers integrally-lighted altimeters that have an elctromechanical servo driven pointer and a digital display of corrected altitude. The altimeters operate in the normal mode to display altitude transmitted by altitude computers or central air data computers. The altimeters incorporate an integral pressure sensor with electronic outputs to aid operation in the normal mode and to provide altitude inputs for the electronic display of pressure altitude when operated in the standby mode. The altimeters also incorporate an electrical output of barometric pressure setting which is required by some aircraft. A method is provided on the bezel of the altimeter for the selection of barometric setting to be displayed in either inches of mercury (in. hg) or millibars (mb). The altimeters are designed to operate from the following power sources: 115V, 400Hz (primary), 28V DC (secondary), and 18V DC (battery mode) from an optional rear mounted battery module. Altimeters meeting the requirements of this specification are interchangeable with AAU-19/A, AAU-19A/A, and AAU-19B/A, AAU-34/A, and AAU-37/A Altimeters.<b><u>Intended Use:</u></b> The AAU-34B/A Altimeter is intended to replace the AAU-19/A, AAU-19A/A, AAU-19B/A, AAU-34/A and AAU-37/A Altimeters. The AAU-34B/A Altimeter incorporates all functions of the altimeters it replaces. The AAU-34C/A Altimeter incorporates night vision compatible Type A, NVIS "Green A" lighting and "blue filtered" white lighting. The two altimeters covered by this specification are intended for use with altitude computers CPU46/A and CPU66/A, Central Air Data Computers, and Standard Central Air Data Computers (SCADCs) to provide a display of static pressure defect corrected altitude in the normal mode and uncorrected pressure altitude in the standby mode. The installation of a battery on the rear of the altimeter case enables altimeter operation for a limited time when all aircraft power is lost to the altimeter. This capability was developed primarily for use by the Navy. In the unlikely event that loss of both 115V AC 400Hz and 28V DC aircraft power occurs during carrier launch, a battery back-up power capability is available.<br>