Originally Posted by
dave.rooney
A couple of questions for 737 drivers or mechanics.
- What systems on a 737-800 would be affected by losing engine 2?
- What antenna does ADS-B use?
The sudden loss of ADS-B data and no apparent mayday call from the crew indicate that whatever happened was immediate and catastrophic.
Firstly, thoughts and prayers for the families of this tragedy.
ADS-B uses output from the Dual GPS.
Hydraulics:
3 Systems: SYSTEM A, SYSTEM B, STANDBY SYSTEM
SYSTEM A & B operates independently
SYSTEM B and STANDBY are connected through a hydraulic servicing line
The Bleed air supplies air pressure to System A & B reservoir.
Fuel in the main wing tank help cool the hydraulic fluid A & B with help of a Heat Exchanger.
An engine driven pump supplies about 6 times the volume of hydraulic fluid of an electric driven pump.
SYSTEM A
Powered by Engine 1 hydraulic pump and an electric pump powered by IDG 2. It supplies power to :
- Primary flight controls (Ailerons, Elevator & Feel, Rudder)
- Engine 2 thurst reverser
- Autopilot A
- Two flight spoilers on each wing
- Ground spoilers
- Nose wheel steering
- Alternate Brakes
- Landing Gear
- Power Transfer Unit
LOSS OF SYSTEM A
With the loss of system A the following systems are inoperative :
- Autopilot A
- 2 Flight spoilers on each wing and all ground spoilers
- Normal landing gear extention and retraction
Considerations :
- Single autopilot = CAT III not available
- Plan a manual gear extension
- Once extended the gear will not retract again ( decreased G/A performance, additional fuel burn )
- Ground spoilers unavailable, increased landing distance
POWER TRANSFER UNIT
When System B pressure is low, In flight with flaps 1 - 15, PTU control valve opens and supplies power
from system A to system B with help of standby fluid.
The purpose of the PTU is to supply power to operate the autoslats and the leading edge flaps and slats.
SYSTEM A FLUID LEAK
Hydraulic fluid to the engine 1 hydraulic pump is supplied by the system A reservoir via a standpipe.
Should a leak occur in the engine 1 hydraulic pump the system A level would decrease to about 20%.
Should a leak occur in the system A electric hydraulic all system A pressure is lost.
A leak in engine 1 hydraulic pump would not prevent operation of the PTU
SYSTEM B
Powered by Engine 2 hydraulic pump and an electric pump powered by IDG 1. It supplies power to :
- Primary flight controls (Aileron, Elevator & Feel, Rudder)
- Engine 2 thrust reverser
- Autopilot B
- Autoslats, Leading edge flaps and slats
- Trailing edge flaps
- Two flight spoilers on each wing
- Normal brakes
- Alternate Nose Wheel Steering
- Landing Gear Transfer Unit
- Yaw Damper
LOSS OF SYSTEM B
With the loss of system B the following systems are inoperative :
- Autopilot B
- 2 Flight spoilers on each wing
- Yaw damper
- Normal leading edge and trailing edge flaps
LANDING GEAR TRANSFER UNIT
In case of engine 1 failure during takeoff, with the landing gear lever selected up and either main landing
gear not up and locked system A assists landing gear retraction via the landing gear transfer unit.
SYSTEM B FLUID LEAK
Any leak downstream of the system B resevoir will cause the loss of system B pressure.
However there remains sufficient fluid for the operation of the PTU.
STANDBY SYSTEM
The standby system is linked to the system B reservoir.
If a leak occurs in the standby system, the system B reservoir level will decrease to approx 72%.
A standby electric pump provides backup hydraulic power to :
- Engine 1 & 2 thrust reversers
- Standby rudder
- Leading edge flaps & slats ( extension only )
- Standby yaw damper ( loss of system A & B )