737 MAX Flight Crew Operations Manual
Landing Gear -
System Description
MN-FLT-OH-201
14.20.7
Tire Pressure Monitoring System
1B785, 1J585 - 1J594
(as installed)
Tire pressures of each main landing gear (MLG) and nose landing gear (NLG) tire
are displayed on the MDS System page. When an abnormal tire pressure condition
exists, the display turns to amber, and the TIRE PRESSURE light on the forward
electronic panel illuminates. Abnormal conditions are defined by low pressure; a
25% difference between MLG tires on the same axle; or a 12% difference between
NLG tires.
Air/Ground System
In flight and ground operation of various airplane systems are controlled by the
air/ground system.
The system receives air/ground logic signals from six sensors, two on each
landing gear. These signals are used to configure the airplane systems to the
appropriate air or ground status.
Air/Ground System Logic Table
SYSTEMS
NORMAL INFLIGHT
OPERATION
NORMAL ON GROUND
OPERATION
REFER
TO CH
Emergency
Exit Doors
Flight locks engaged
when either engine N2 is
more than 50% and 3 or
more Entry/Service
doors are closed.
Flight locks disengaged
when either thrust lever is
set below approximately
53 degrees.
1
Pack Valves
With one pack
operating, regulates to
high flow with flaps up.
With one pack operating,
regulates to high flow only
when pack is operating
from the APU and both
engine bleed switches are
OFF.
2
Pressurization Allows programmed
pressurization in the
automatic modes.
Allows pressurization
only at high power
settings.
2
Ram Air
Ram Air fans operate
whenever air
conditioning packs
operate.
Ram Air fans operate
whenever air conditioning
packs operate. Deflectors
are extended.
2
March 1, 2021
