.
if both aileron and rudder control are affected, the use of asymmetrical
engine thrust may aid roll and directional control
.
if elevator control is affected, stabilizer trim, bank angle and thrust can be
used to control pitch attitude. To do this effectively, engine thrust and
airspeed must be coordinated with stabilizer trim inputs. The airplane
continues to pitch up if thrust is increased and positive corrective action is
not taken by re-trimming the stabilizer. Flight crews should be aware of
the airplane’s natural tendency to oscillate in the pitch axis if the stable
pitch attitude is upset. These oscillations are normally self damping in
Boeing airplanes, but to ensure proper control, it may be desirable to use
thrust and/or stabilizer trim to hasten damping and return to a stable
condition. The airplane exhibits a pitch up when thrust is increased and a
pitch down when thrust is decreased. Use caution when attempting to
dampen pitch oscillations by use of engine thrust so that applications of
thrust are timed correctly, and diverging pitch oscillations do not develop
.
a flight control break-out feature is designed into all Boeing airplanes. If a
jammed flight control exists, both pilots can apply force to either clear the
jam or activate the break-out feature. There should be no concern about
damaging the mechanism by applying too much force. In certain cases,
clearing the jam may permit one of the control columns to operate the
flight controls with portions of a control axis jammed. It may be necessary
to apply break-out forces for the remainder of the flight on the affected
control axis
Copyright . The Boeing Company. See title page for details.
October 31, 2003 FCT 757 (TM) 8.23
.
stall margin decreases with angle of bank and increasing load factors.
Therefore, it is prudent to limit bank angle to 15 degrees in the event
maneuvering capability is in question. Increasing the normal flap/speed
maneuvering schedule while staying within flap placard limits provides
extra stall margin where greater bank angles are necessary
.
all Boeing airplanes have the capability to land using any flap position,
including flaps up. Use proper maneuvering and final approach speeds
and ensure adequate runway is available to stop the airplane after landing.
Flight Path Control
When encountering an event of the type described above, the flight crew’s first consideration should be to maintain or regain full control of the airplane and establish an acceptable flight path. This may require use of unusual techniques such as the application of full aileron or rudder or in an asymmetrical thrust situation, reduction of power on the operating engine(s) to regain lateral control. This may also require trading altitude for airspeed or vice versa. The objective is to take whatever action is necessary to control the airplane and maintain a safe flight path. Even in a worst case condition where it is not possible to keep the airplane flying and ground contact is imminent, a “controlled crash” is a far better alternative than uncontrolled flight into terrain.
If the operation of flaps is in doubt, leading and trailing edge flap position should not be changed unless it appears that airplane performance immediately requires such action. Consideration should be given to the possible effects of an asymmetrical flap condition on airplane control, if flap position is changed. If no flap damage exists, wing flaps should be operated as directed in the associated non-normal checklist. Anytime an increasing rolling moment is experienced during flap transition, (indicating a failure to automatically shutdown an asymmetric flap situation) return the flap handle to the previous position.
Unusual events adversely affecting airplane handling characteristics while airborne may continue to adversely affect airplane handling characteristics during landing ground roll. Aggressive differential braking and/or use of asymmetrical reverse thrust, in addition to other control inputs, may be required to maintain directional control.
Recall Checklists
After flight path control has been established, accomplish the recall steps of appropriate NNCs. The emphasis at this point should be on containment of the problem. Execution of non-normal checklist actions commences when the airplane flight path and configuration are properly established.
Accomplish all applicable NNCs prior to commencing final approach. Exercise common sense and caution when accomplishing multiple checklists with differing direction. The intended course of action should be consistent with the damage assessment and handling evaluation. 中國航空網 m.k6050.com 航空翻譯 www.aviation.cn 本文鏈接地址：757 Flight Crew Training Manual 機組訓練手冊(96)
