Copyright . The Boeing Company. See title page for details.
SP.16.8 D6-30151-425 April 01, 2001
Supplementary Procedures -Adverse Weather 747 Operations Manual
Severe Turbulence
The turbulent air penetration speed of 290-310 KIAS or .82-.85 Mach provides ample protection from stall and high speed buffet, while also providing protection from exceeding the structural limit.
Flight test data substantiates important benfits are obtained from the use of the yaw dampers during turbulence penetration. Excursions in sideslip and roll are minimized and, even though the rudder control may be more active, the structural loads imposed on the vertical tail are considerably reduced.
The recommended procedures for flight in severe turbulence are summarized below.
Climb and Cruise
After takeoff and when established in a clean climb configuration, the autoflight system is recommended for flight through turbulence. To reduce pitch changes as the AFDS attempts to fly speed with elevators, climb and descend using vertical speed (speed on thrust) and cruise using altitude hold.
In extreme turbulence, it may be necessary to disconnect the autothrottles. With autothrottles disconnected, the FMC generates a target thrust setting for cruise which is displayed on EICAS. Set thrust at or slightly above the target thrust indicator. Change thrust setting only if required to reverse an unacceptable speed trend.
Descent
If severe turbulence is encountered at altitudes below 15,000 feet and the gross weight is less than the maximum landing weight, the airplane may be slowed to 250 KIAS in the clean configuration. Adequate stall margin exists under these conditions.
Delay flap extension in an area of known turbulence as long as possible because the airplane can withstand higher gust loads in the clean configuration. Diversion to another airfield is the best policy if severe turbulence persists in the area.
Manual Flight in Severe Turbulence
If manual flight in severe turbulence becomes necessary, trim the airplane for penetration speed, then do not change stabilizer position. Control the airplane pitch attitude with the elevators using the attitude indicator as the primary instrument. In extreme drafts, large attiude changes may occur. Do not make sudden large control inputs. Corrective actions to regain the desired attitude should be smooth and deliberate. Altitude variations are likely in severe turbulence and should be allowed to occur if terrain clearance is adequate. Control airplane attitude first, then make corrections for airspeed, altitude, and heading.
Copyright . The Boeing Company. See title page for details.
April 01, 2001 D6-30151-425 SP.16.9
Supplementary Procedures -Adverse Weather 747 Operations Manual
Windshear
If windshear conditions are suspected prior to takeoff, do not use the assumed temperature method for reduced thrust (i.e., entry of a SEL TEMP value on the THRUST LIM page of the FMC). Whenever possible, use maximum thrust available. Use flaps 20 for takeoff unless limited by obstacle clearance and/or climb gradient.
Windshield Washer and Rain Repellent
Note: Do not use windshield wipers or rain repellent on dry window. If rain repellent inadvertently applied, do not use windshield wipers unless windshield washer activated first.
Windshield Washer switch (As required) ...................................................................................... ON
Rain Repellent switch (As required) .................................................................................... Push Use on one window at a time.
Windshield Wiper selector .................................................... As required
Copyright . The Boeing Company. See title page for details.
SP.16.10 D6-30151-425 April 01, 2001
Dimensions........................................... 1.10.1
PrincipalDimensions .................................. 1.10.1
InstrumentPanels..................................... 1.20.1
FlightDeckPanels .................................... 1.20.1
InstrumentPanels,Overhead............................ 1.21.1
OverheadPanels...................................... 1.21.1 中國航空網 www.k6050.com 航空翻譯 www.aviation.cn 本文鏈接地址：747-441 Operations Manual 747操作手冊(56)
