Fuel Leak
Any time an unexpected fuel quantity indication, FMC or EICAS fuel message, or imbalance condition is experienced, a fuel leak should be considered as a possible cause. Maintaining a fuel log and comparing it to the flight plan can help the pilot recognize a fuel leak.
Significant fuel leaks, although fairly rare, are difficult to detect. The non-normal checklist assumes the leak is between the strut and the engine. There is no specific fuel leak annunciation on the flight deck. A leak must be detected by discrepancies in the fuel log, by visual confirmation, or by some annunciation that can occur because of a leak. Any unexpected change in fuel quantity or fuel balance should alert the crew to the possibility of a leak. If a leak is suspected, it is imperative to follow the non-normal checklist.
Low Fuel
A low fuel condition exists when the FUEL CONFIG light illuminates and the EICAS message LOW FUEL is displayed.
Approach and Landing
With a low fuel quantity, the clean configuration should be maintained as long as possible during the descent and approach to conserve fuel. However, initiate configuration change early enough to provide a smooth, slow deceleration to final approach speed to prevent fuel running forward in the tanks.
A normal landing configuration and appropriate airspeed for the wind conditions
are recommended. Runway conditions permitting, heavy braking and high levels of reverse thrust should be avoided to prevent uncovering all fuel pumps and possible engine flameout during landing roll.
Go-Around
If a go-around is necessary, apply thrust slowly and smoothly and maintain the minimum nose-up body attitude required for a safe climb gradient. Avoid rapid acceleration of the airplane. If any wing tank fuel pump low pressure light illuminates, do not turn off fuel pump switches.
Hydraulics
Proper planning of the approach is important. Consideration should be given to the effect the inoperative system(s) has on crosswind capabilities, autoflight, stabilizer trim, control response, control feel, reverse thrust, stopping distance, go-around configuration and performance required to reach an alternate airfield.
Note: Autolands are not certified with any hydraulic system inoperative.
Hydraulic System(s) Inoperative - Landing
If the landing gear is extended using the alternate gear extension, the gear cannot be raised. Flaps can be extended or retracted using the alternate flap drive system. However, the rate of flap travel is significantly reduced.
Flaps 20 and an adjusted VREF are used for landing with multiple hydraulic systems inoperative to improve flare authority, control response and go-around capability. The airplane may tend to float during the flare. Do not allow the airplane to float. Fly the airplane onto the runway at the recommended point.
Landing Gear Landing on a Flat Tire
Boeing airplanes are designed so that the landing gear and remaining tire(s) have adequate strength to accommodate a flat nose gear tire or main gear tire. When the pilot is aware of a flat tire prior to landing, use normal approach and flare techniques, avoid landing overweight and use the center of the runway. Use differential braking as required to help with directional control. With a single tire failure, towing is not necessary unless unusual vibration is noticed or other failures have occurred.
In the case of a flat nose wheel tire, slowly and gently lower the nose wheel to the runway while braking lightly. Runway length permitting, use idle reverse thrust. Autobrakes may be used at the lower settings. Once the nose gear is down, vibration levels may be affected by increasing or decreasing control column back pressure. Maintain nose gear contact with the runway.
Flat main gear tire(s) cause a general loss of braking effectiveness and a yawing moment toward the flat tire with light or no braking and a yawing moment away from the flat tire if the brakes are applied harder. Maximum use of reverse thrust is recommended. Do not use autobrakes.
If uncertain whether a nose tire or main tire has failed, slowly and gently lower the nose wheel to the runway and do not use autobrakes. Differential braking may be required to help steer the airplane. Use idle or higher reverse thrust as required to stop the airplane.
Loss of two aft main gear tires may cause the airplane air/ground sensing system to remain in the in air mode causing loss of thrust reversers and a need to manually deploy the speedbrakes.
Partial or Gear Up Landing General
Land on all available gear. Recycling the landing gear in an attempt to extend the remaining gear is not recommended. A gear up or partial gear landing is preferable to running out of fuel while attempting to solve a gear problem.
If time and conditions permit, reduce weight as much as possible by burning off fuel to provide the slowest possible touchdown speed. Less damage occurs if the airplane is kept on a paved landing area.
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本文链接地址：757 Flight Crew Training Manual 机组训练手册(92)
