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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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757
MAINTENANCE MANUAL
(h) CLB Mode
1) The CLB mode is entered two ways as follows:
a) A manual CLB request from the TMSP when the VNAV and the reverse thrust modes are disengaged. Also, the landing flaps are not set or the glide slope is not active.
b) A FMC CLB request when VNAV is engaged.
(i) CRZ Mode
1) The CRZ mode is entered two ways:
a) A manual CRZ request from the TMSP when the VNAV and the reverse thrust are disengaged and the aircraft is above 400 feet AGL. Also, the landing flaps are not set and the glide slope is not active from an Autopilot or a Flight Director.
b) A FMC CRZ request when the VNAV is engaged.
(j) REV Mode
1) The REV mode is engaged when the airplane is on the ground and the reverse thrust levers are moved to the reverse thrust position, and the autothrottle is disengaged.
(9) Thrust Limit Derate Logic
(a)
Fixed Percentage Derates are available for CLB mode only. You can push the 1 or 2 button on the TMSP to preselect a CLB derate while in a mode other than CLB. When the CLB derate mode is preselected, T/O-X shows on the EICAS (where X shows the applicable derate number in white). When CLB mode becomes active, the preselected derate mode becomes the active derate. The EICAS shows CLB-X with the color of the derate number changed to green.
(b)
When the airplane is on the ground and in the T/O mode, the TMC allows the assumed temperature entry from the TMSP or the FMC CDU for reduced T/O thrust.
(c)
The TMC normally computes a thrust limit based on ambient temperature or flat rated temperature, whichever is greater. This value is used as the computation temperature. A further manual increase in computation temperature is referred to as assumed temperature and decrease thrust.
(d)
Assumed temperature data is sent to the TMC for thrust limit calculation. If the assumed temperature is higher than flat rated and ambient temperature, the derated mode shows as a "D" adjacent to the mode display on the EICAS display unit. Assumed temperature can be set as follows: 1) Engage in a different limit mode to leave the T/O mode. 2) Push the GA switch on the throttle levers after lift off. 3) Cycle the TMC power. 4) Push the TO/GA button on the TMSP before lift off. 5) Push the 1 or 2 botton on the TMSP.
(e)
When the CLB mode is engaged, the CLB derated thrust can be selected on the TMSP. The 1 or 2 buttons on the TMSP gives a fixed decrease in thrust.
(f)
When a CLB derate is preselected and you engage the CLB thrust limit mode, it will provides the CLB derated thrust.
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
757
MAINTENANCE MANUAL
(10) Thrust Limit Calculation
(a)
The TMC calculates EPR REF and MAX EPR based on:
1) Selected mode (effects EPR REF only)
2) Environmental data
3) Engine bleed status
(b)
The TMC does these calculations regardless of A/T engagement status. Calculated limits show on the upper EICAS display unit. However, the TMC calculated MAX EPR limit only shows if the applicable EPR MAX limit from the EEC is not available.
(c)
EPR Calculation
1) The EPR limit calculation alternates between MAX EPR and EPR REF on each iteration pass of the computer. The REF calculations are based on thrust limit mode, Mach, temperature, and altitude. The MAX calculations are based on Mach, temperature, and altitude only. The temperature used for T/O and G/A thrust limit calculation is the highest value of flat rated, ambient, or assumed temperature. The temperature used for all other thrust modes is the higher of Total Air Temperature (TAT) and Static Air Temperature (SAT). Standard barometric altitude is used for altitude correction. 中國(guó)航空網(wǎng) www.k6050.com 航空翻譯 www.aviation.cn 本文鏈接地址：757 AMM 飛機(jī)維護(hù)手冊(cè) 自動(dòng)飛行 AUTOFLIGHT 2(121)
