TM 55-1510-220-MTF
SECTION IV. SPECIAL PROCEDURES
GENERAL
This section contains the special procedures that were referenced in section II.
*A.
PRESSURIZATION SYSTEM.
Check as follows:
1.
Bleed air valve switches (2) - OPEN.
2.
After takeoff - Establish a climb.
3.
Cabin altimeter - After takeoff the cabin altimeter needle should stabilize at selected altitude +250 feet
and the cabin differential pressure needle should continue climbing. The cabin altimeter needle should
remain at selected altitude until the maximum pressure differential of 6. 0 1 is reached. At this point
(approximately 16, 600 feet pressure altitude) the cabin altitude should increase while the differential
pressure remains constant.
4.
Cabin pressurization leak rate - Check within limits as follows:
a.
Level off aircraft when pressure differential reaches 6.0+.1.
b.
Bleed air valve switches (2) - ENVIRO OFF.
c.
Cabin rate-of-climb indicator - Read and record cabin rate of climb. Cabin rate of climb (cabin
pressurization leak rate) should not exceed 2200 feet per minute.
5.
Bleed air valve switches (2) - OPEN. Reestablish 6.0+.1 PSI cabin pressure differential.
6.
Left bleed air valve switch - ENVIRO OFF.
7.
Slowly retard the right power lever and record the minimum N1 speed that the right engine must be
operated at to maintain the cabin pressure differential at 6.0 1. N1 should not exceed 85%, and the
minimum desirable N1 is 80%.
4-1
