TEST CHAMBER ASSEMBLY, MODEL 452 OPERATION UNDER USUAL CONDITIONS

TM 10-1670-305-23&P TEST CHAMBER ASSEMBLY, MODEL 452 0009 00 OPERATION UNDER USUAL CONDITIONS - CONT INITIAL ADJUSTMENT BEFORE USE – CONT 2. Verify that ON/OFF switch (5) of the test chamber is in OFF position and CLIMB/FALL/COCK switch (8) in FALL position (centered). 3. Plug power cord (16) into 110 VAC outlet. NOTE Record test data on maintenance log (WP 0042 00). CAUTION To avoid damaging the test chamber do not switch the test chamber on/off switch to on while the air compressor or vacuum pump is under load (while the altitude chamber is under vacuum or the air cylinder is pressurized). If it has recently been used, wait one to two minutes for pressure trapped in the system to bleed off. 4. Position ON/OFF switch (5) on test chamber to ON. The indicator light (6) will illuminate, and the air compressor and vacuum pump will start. When switching the test chamber ON, immediately look under the transparent altitude chamber at the ends of both air compressor and vacuum pump to ensure that the cooling fans are spinning on both units. If either fan is not spinning, immediately cycle the CLIMB/FALL/COCK switch (8) between FALL and COCK until the fans spin. Move the CLIMB/FALL/COCK switch (8) on test chamber to CLIMB position and adjust the altitude control regulator (14) to an altitude of 6,500 feet. NOTE Pressure vs. rate of fall varies greatly with altitude; as altitude increases, the rate of fall will also increase for a given pressure reading on the gauge. To be sure of the exact rate of fall, always check it with a stop watch over the 1,000-foot interval from 500 feet above to 500 feet below the dial setting of the AR2. NOTE Check pressure vs. rate of fall values shown on FUNCTIONS decal once each hour with a stop watch to verify accuracy. These checks should be conducted between 6,000 and 5,000 feet simulated altitude with a barometric pressure adjustment of 29.92 on the altimeter. Values shown on the FUNCTIONS decal correspond approximately to rate of fall indicated thereon. The AR2 rate-of-fall mechanism senses rate of pressure change (PSI/sec), which corresponds to its rate of fall. To obtain correct rate-of-fall data, always install an AR2 in the altitude chamber before testing. NOTE It is not necessary to wait for the AR2 to stabilize since these checks do not result in actuation. Change 1 0009 00-4