How many hydraulic backup systems for the flight controls does a Boeing 737 have?

Posted by admin on March 15th, 2010 and filed under systems |

A 737-NG has System A and System B, wich controls pretty much everything. But what about the standby or backup systems. How many does it have and what do they control?

There is a standby hydraulic system. If all system pressure is lost:
1) Ailerons and Elevators go to manual reversion, and are "flown" by control tabs
2) Rudder, leading edge flaps and slats(extend only), and thrust reversers are powered by standby hydraulics
3) Nose steering, ground and flight spoilers, yaw dampers, and autopilots are inop.
4) Trailing edge flaps are extended electrically using, as I recall, trapped fluid
5) Inboard and outboard wheel brakes have accumulator pressure only (limited number of applications)
6) Gear will be extended manually
7) Autobrakes inop
8) Landing will be with flaps 15–this is in case a go around is required
9) The approach speed will be around 9 kts higher than a normal flap 30 landing, and the landing distance will increase somewhat. This will not be a problem on a normal runway that serves jets, but probably wouldn’t try Midway, LaGuardia, DCA, TGU, etc.

5 Responses

  1. kelly_f_1999 Says:

    System A and System B or crash only just a wild guess
    References :

  2. Karhu100 Says:

    look here

    http://www.smartcockpit.com/plane/boeing/B737/

    or here

    http://www.b737.org.uk/aircraftsystems.htm

    can i have best answer please

    thanks
    References :
    A/C Engineer

  3. Joe G Says:

    It has a standby reservoir that actually is serviced when servicing the B reservoir. And it can power the rudder, extend the flaps/slats, and deploy the thrust reversers, some may wonder why not the brakes, but the brakes have an accumulator that provide enough pressure to come to a stop.
    References :

  4. Charles B Says:

    737’s have A system hydraulic, B system hydraulic, a battery driven back up system, and manual control if all else fails. The European subsidized air bus has no real back up if all the electric and hydraulic systems fail. Buy and Fly Boeing. Help your country and live longer.
    References :

  5. RickH Says:

    There is a standby hydraulic system. If all system pressure is lost:
    1) Ailerons and Elevators go to manual reversion, and are "flown" by control tabs
    2) Rudder, leading edge flaps and slats(extend only), and thrust reversers are powered by standby hydraulics
    3) Nose steering, ground and flight spoilers, yaw dampers, and autopilots are inop.
    4) Trailing edge flaps are extended electrically using, as I recall, trapped fluid
    5) Inboard and outboard wheel brakes have accumulator pressure only (limited number of applications)
    6) Gear will be extended manually
    7) Autobrakes inop
    8) Landing will be with flaps 15–this is in case a go around is required
    9) The approach speed will be around 9 kts higher than a normal flap 30 landing, and the landing distance will increase somewhat. This will not be a problem on a normal runway that serves jets, but probably wouldn’t try Midway, LaGuardia, DCA, TGU, etc.
    References :

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