TEST CHAMBER ASSEMBLY, MODEL 452
UNIT MAINTENANCE - CONT
1. Install replacement vacuum pump (14) using three washers (34) and screws (33).
2. Connect tubing (9) to elbow (3) on vacuum pump (14) and secure with compression nut
3. Route and reconnect electrical leads to vacuum pump (14) as identified at disassembly and
4. Install replacement air compressor (13) using three washers (32) and screws (31).
5. Connect tubing (10) to elbow (12) on air compressor (13) and secure with compression nut
6. Route and reconnect electrical leads to air compressor (13) as identified at disassembly and
7. Use lint-free cleaning cloth and isopropyl alcohol (anhydrous) to clean areas where decals
were mounted. Install new identification decal (1), making sure to transfer serial number
identification of test chamber, WARNING decal (5), CONNECTIONS decal (15), and
FUNCTIONS decal (7) by peeling protective back from new decals and pressing new decals
firmly in position.
8. Peel protective backing off the right end (as it would be installed on the altitude chamber) of
the gasket (30). Carefully align gasket and gently press in place. Continue to peel off
protective backing as the gasket is installed. Use care not to develop any wrinkles in the
gasket (30) or adhesive since they may cause a leak.
9. If necessary, install elbow (20) in replacement altimeter (26). Lubricate O-ring packing (23)
sparingly using MIL-G-27617 lubricant. Turn elbow (20) into the threaded opening (boss) of
altimeter (26) by hand until back-up washer (24) contacts the face of the boss. Position
elbow (20) by backing it out (NOT MORE THAN ONE TURN COUNTERCLOCKWISE) until it
is oriented correctly as observed at disassembly. Hold elbow (20) stationary, using a 5/8-in.
back-up wrench, and tighten lock nut (25) with a 11/16-in. wrench until back-up washer (24)
is pressed against the face of the boss of replacement altimeter (26). DO NOT
OVERTIGHTEN. Joint is sufficiently tight if elbow (20) cannot be rotated with fingers.