Pressurization

STUDENT GUIDE T-39N/G NATOPS

c. Aircraft ceiling is 45,000' MSL.

2. Dump valve prevents cabin pressure from exceeding 9.1 + .1 above outside pressure.

3. Cabin pressure dumps with weight on wheels.

4. AFT FUS HOT light if bleed air leak (135C).

-select RAM below 15K

-select EMER PRESS above 15K

5. CABIN AIR HOT light on if air downstream of mixing valve exceeds 130C - select MAN

COLD

NOTE: Expect this light if EMER PRESS is selected

6. Door seal will remain pressurized with dual gen fail (DC Essential power available); cabin

pressure will dump if TOTAL electrical failure.

7. Emergency pressurization from unconditioned RH bleed air; INOP ON DECK or if RH FIRE

handle pulled. Control air temperature with throttle position.

8. CABIN AIR SELECT switch controls bleed air valves

a. OFF - closes both shutoff valves.

b. BOTH ENG - Both bleed air shutoff valves open (normal position).

c. LH/RH ENG - single engine operations or contamination suspected.

d. RAM - closes both shutoff valves and opens ram air supply valve.

e. AM AND DUMP - same as RAM but dumps cabin pressure as well.

f. EMER PRESS - closes both shutoff valves and opens the emergency valve from RH

engine.

NOTE: In RAM or OFF, pressure will bleed off; RAM/DUMP = immediate depressurization.

9. CABIN TEMP switch/ AUTO CONTROL rheostat

a. OFF/AUTO/MAN HOT/MAN COLD (spring-loaded to OFF from MAN HOT or MAN

COLD).

b. Rheostat only operative if BOTH or LH/RH ENG is selected on CABIN AIR SELECT

switch.

c. Auto temp range of 60-80F

10. CABIN PRESS FAIL red light if cabin altitude exceeds 10,000 + 400 feet. Will also get a

FASTEN SEAT BELT light.

7-2

ENVIRONMENTAL SYSTEMS