FLIGHT FLIGHT OPERATIONS OPERATIONS ENGINEERING ENGINEERING
Reduced and Derated Thrust
Reduced and Derated Thrust
Dennis Ting
Dennis Ting
Perfo
Performance rmance EngineEngineer –er – OperaOperations tions CoursCoursee
Boeing Commercial Airplanes Boeing Commercial Airplanes
September 2009 September 2009
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Topics of Discussion
Topics of Discussion
•• BenefiBenefits of ts of using using lower lower takeoff takeoff thrustthrust •• MetMethods anhods and reguld regulatoratory requiy requiremrementsents •• EffEffect of thect of thrusrust on taket on takeoff peroff performformanceance •• The aThe assumssumed temed temperaperaturture methe methodod
•• ThThe de deraerate te metmethodhod
•• OperatiOperational onal practicpractices aes and nd consideconsiderationsrations •• PractiPractical cal exercisexercises aes and sond software ftware toolstools
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Topics of Discussion
Topics of Discussion
•• BenefiBenefits of ts of using using lower lower takeoff takeoff thrustthrust •• MetMethods anhods and reguld regulatoratory requiy requiremrementsents •• EffEffect of thect of thrusrust on taket on takeoff peroff performformanceance •• The aThe assumssumed temed temperaperaturture methe methodod
•• ThThe de deraerate te metmethodhod
•• OperatiOperational onal practicpractices aes and nd consideconsiderationsrations •• PractiPractical cal exercisexercises aes and sond software ftware toolstools
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Benefits of Using Lower Takeoff Thrust
Benefits of Using Lower Takeoff Thrust
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Internal Temperature and Pressure
5
20.9 455°
JT9D Sea Level Static Thrust 43,500 LB
Station Pt (PSIA) Tt (°C) 2 14.7 15° 2.5 32.1 99° 14 22.4 55° 3 316 470° 4 302 1075° Unlock Access to An
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Hot section life usage
Turbine metal temperature
Hot section life usage increases
exponentially
with increasing turbine metal temperature !
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Maintenance material cost (MMC)
decreases with lower EGT
Note: Specific cost savings for a particular engine model require a detailed assessment of the operator’s route structure.
Maintenance material cost (MMC)
Exhaust gas temperature (EGT)
Takeoff EGT limit
E X A
M P
L E
Industry average thrust reduction prior to regulatory revision which permits 25% maximum takeoff thrust reduction
Takeoff rating 18% 7% MMC ≈ 25% Δ MMC ≈ 40% Δ Unlock Access to An
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Shop maintenance cost decreases
with lower takeoff thrust
Full rated Derate No thrust reduction 25% thrust reduction 10 $/EFH Shop maintenance cost Thrust Unlock Access to An
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10% thrust reduction
20% thrust reduction
Saving: US$ 100000 per year
Using lower takeoff thrust will result in
significant cost savings
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Benefits of Using Lower Takeoff Thrust
• Engine manufacturers can provide specific data on reliability and cost savings related to using lower takeoff thrust
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Methods and Regulatory Requirements
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Engine and Thrust Designations
Engine Nameplate versus Rated Thrust
• Engine nameplate indicates Bill of Material • Rated Thrust defines level of maximum thrust • Rated Thrust is programmed using data plug Limitations on maximum thrust
• Combustor inlet pressure (CIP) • Turbine inlet temperature (TIT) • Fan rotation speed (RPM)
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Design Thrust Limits
Pressure Limited RPM Max TIT Max CIP T e m p e r a t u r e L i m i t e d Thrust OAT Unlock Access to AnExclusive 30
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Pressure limited T e m p e r a t u r e l i m i t e d Thrust OAT
Rated Thrust
Flat rated
Thrust break temperature
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Rated Thrust Levels
Takeoff Thrust and Go-Around Thrust
• The highest thrust level programmed for an engine; it is regulatory certified and limited to 5 minutes
(10-minute option available for engine-out takeoff) Other Rated Thrust Levels:
• Maximum Continuous Thrust (MCT); certified • Maximum Climb Thrust (MCLT); not certified • Maximum Cruise Thrust (MCRT); not certified
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Methods for Takeoff Thrust Reduction
Reduced Thrust (Assumed Temperature)
• Based on a certified takeoff rating and ambient condition, the thrust reduction achieved by selecting the rated thrust for a temperature that is higher than the outside air temperature.
Derated Thrust (Derate)
• For a given ambient condition, the thrust reduction achieved by selecting another certified takeoff rating that is lower than the maximum takeoff rating. These two methods can be combined per regulation
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Thrust OAT
Assumed Temperature
Maximum thrust Actual temperature Thrust required Assumed temperature Unlock Access to AnExclusive 30
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Thrust
OAT
Derate (Multiple Takeoff Ratings)
Full rated Derate Maximum thrust Thrust set Thrust required Actual temperature Unlock Access to An
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Types of Takeoff Derate
Fixed Derate
• A derate that is pre-defined by the engine manufacturer; the level of derate cannot be changed by the operator. • 737, 757 and 767
Variable Derate (VTR)
• A derate that can be selected from a range of ratings; the level of derate can be changed by the operator. • 747-400, 777, 717, MD-90 and MD-11
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Thrust
OAT
Takeoff Thrust Bump vs. Bump Rating
Bump rating
Full rated
Pressure bump
Temperature bump
Design limit Unlock Access to An
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Altitude
Climb Derate
Derated Climb Thrust
10000 ft CLB 1 CLB 2 “Washout” altitude Unlock Access to An
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Regulatory Requirements
Regulatory guidance
• FAA Advisory Circular (AC) 25-13
• JAR Advisory Material Joint (AMJ) 25-13 Compliance and operational approval
• AFM provides certification and authorization
• Each operator establishes operating procedures • Local regulatory authority grants final approval
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AC 25-13 and AMJ 25-13
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Regulatory Definitions
“b. Derated takeoff thrust, for an airplane, is a takeoff thrust level less than the maximum takeoff thrust, for which exists in the AFM a set of separate and independent, or clearly distinguishable, takeoff limitations and performance data that complies with all the takeoff requirements of Part 25. When operating with a derated takeoff thrust, the value of the thrust setting parameter which establishes thrust for takeoff is presented in the AFM and is considered a normal takeoff operating limit.”
“b. Derated takeoff thrust, for an airplane, is a takeoff thrust level less than the maximum takeoff thrust, for which exists in the AFM a set of separate and independent, or clearly distinguishable, takeoff limitations and performance data that complies with all the takeoff requirements of Part 25. When operating with a derated takeoff thrust, the value of the thrust setting parameter which establishes thrust for takeoff is presented in the AFM and is considered a normal takeoff operating limit.”
“c. Reduced takeoff thrust, for an airplane, is a takeoff thrust less than the takeoff (or derated takeoff) thrust. The airplane takeoff performance and thrust setting are established by approved simple methods, such as adjustments, or by corrections to the takeoff or derated takeoff thrust setting and performance. When operating with a reduced takeoff thrust, the thrust setting parameter which establishes thrust for takeoff is not considered a takeoff operating limit.”
“c. Reduced takeoff thrust, for an airplane, is a takeoff thrust less than the takeoff (or derated takeoff) thrust. The airplane takeoff performance and thrust setting are established by approved simple methods, such as adjustments, or by corrections to the takeoff or derated takeoff thrust setting and performance. When operating with a reduced takeoff thrust, the thrust setting parameter which establishes thrust for takeoff is not considered a takeoff operating limit.”
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AFM-DPI Basic Performance
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AFM-DPI Alternate Performance – Fixed Derate
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AFM-DPI – Variable Derate (VTR)
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AFM Appendix – Fixed Derate
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AFM Appendix – Variable Derate (VTR)
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AFM Appendix – No Derate
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Effect of Thrust on Takeoff Performance
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Effect of Thrust on Takeoff Performance
Level of takeoff thrust affects:
• Takeoff and stopping distances • Climb capability
• Obstacle clearance Lower takeoff thrust will:
• Increase takeoff and stopping distances • Reduce climb gradient
• Reduce obstacle clearance margin
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Minimum Takeoff Speeds Requirements
VEF V1 VR VLO V2 35 ft ≥ V1(MCG) ≤ VR V2 ≥ 1.13 VS 1G ≥ 1.05 VMCA ≥ 1.05 VMU(EO) ≥ 1.10 VMU(AE) ≥ 1.13 VS 1G ≥ 1.10 VMCA Unlock Access to AnExclusive 30
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Takeoff and Stopping Distances Requirements
VEF V1 VR Brake release V2 35 ft One engine inop VLO• Engine Inoperative Accelerate-Go distance
All engine acceleration
One engine inop acceleration
Balance takeoff field length Accel-Go = Accel-Stop VEVENT V1 VB Brake release Full stop • Accelerate-Stop distance All engine acceleration Transition to stopping Brakes applied Throttles set to idle Maximum manual braking Spoilers set
.
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Proper takeoff speeds for a balanced field length
V2 = 155 Max thrust
V1 = 135 VR = 140
Speeds same as those for max thrust would result in an unbalanced field length
V1 = 135
V2 = 155 VR = 140
Reduced thrust
Increasing V1 and VR will re-balance field length
V1 = 140 VR = 145 V2 = 150
Reduced thrust
Effect of Thrust on Speeds and Distances
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Climb gradient is reduced with reduced thrust which, along with longer takeoff distance, also reduces obstacle clearance margin
M a x t
h r u s t
R e d u c e d t
h r u s t
Effect of Thrust on Flight Path
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VMCG for derated thrust is lower than that for full rated thrust
VMCG (and V1MCG) varies with thrust rating
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Derated thrust requires more Nose-up trim than full rated thrust
Stab trim setting varies with thrust rating
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Effect of Thrust on Speeds and Controllability
• Reduced / derated thrust requires increased speeds (V1 and VR) to maintain a balance field length
• Derated thrust lowers minimum control speed on the ground (VMCG) and minimum V1 (V1MCG)
• Derated thrust requires more Nose-up stabilizer trim
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The Assumed Temperature Method
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Certificate Limitations (Basic AFM)
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40% Limit Option (777-300ER/200LR/200F)
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Certificate Limitations (AFM Appendix)
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FAR / JAR Takeoff Performance Requirements
1
2
3
Field length
• One engine inoperative takeoff distance • Accelerate-stop distance
• 115% all-engine takeoff distance Climb gradient
• 1st segment – positive (2-engine airplanes)
• 2nd segment – 2.4% (2-engine airplanes)
• Final segment – 1.2% (2-engine airplanes) Obstacle clearance
• Net flight path must clear obstacle by 35 ft
• Net is gross reduced by 0.8% (2-engine airplanes) 35 ft 2 1 . 35 ft Obstacle N e t 3 G r o s s ( a c t u a l ) Unlock Access to An
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Assumed Temperature Concep
Assumed Temperature Concep
t
t
Thrust Thrust
MTOW
MTOW
Max TOW Max TOW Max thrust Max thrust Reduced thrust Reduced thrust 25% reduction 25% reduction Maximum Maximum assumed temperature assumed temperature Minimum Minimum assumed temperature assumed temperature Actual TOW Actual TOW Unlock Access to AnExclusive 30
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FCOM Takeoff Speeds
TOW = 70000 kg Flaps 5
Pressure Altitude Sea Level
Temp V1 VR V2 30 141 143 152 40 142 144 151 50 144 146 150 60 145 147 149 C C C C Unlock Access to An
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Determining Proper Takeoff Speeds
Balanced Plus (or Standard) takeoff speeds:
• V1, VR, and V2 should be obtained from the FMC or FCOM based on the actual takeoff weight and
the selected assumed temperature
• V1MCG must be based on the actual OAT Optimized V1 or Improved Climb:
• Speeds must be obtained either from a takeoff analysis chart for the specific runway, or …
• Real-time performance calculations tool (OPT)
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Factors Affecting Max Assumed Temp
Maximum allowable assumed temperature depends on the following factors:
• Actual takeoff weight
• Runway (length, slope, wind, and obstacles) • Airport elevation and pressure (QNH)
• Runway surface condition (dry or wet) • Flaps setting
• Thrust rating
• Engine bleed configuration
• Performance option (Improved Climb, V1 policy …)
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Wet Runway Performance Requirements
Two types of wet runway surface:
1. Normal – smooth hard surface; well soaked without significant areas of standing water. 2. Skid Resistant (SK-R) – conform to AC 150/5320-12C or equivalent. Typically grooved
and porous friction course runways might qualify as a skid resistant runway. All engine acceleration Transition stopping VEF V1 VR Brake release V2(at 35 ft) One engine inop VLO
• Engine Inoperative Accelerate-Go distance
All engine acceleration
One engine inop acceleration
Balance takeoff field length Accel-Go = Accel-Stop VEVENT V1 VB Brake release Full stop • Accelerate-Stop distance Brakes applied Throttles set to idle
Maximum manual braking (wet) operative thrust reverser Spoilers set
.
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737-800 TAKEOFF PERFORMANCE KSEA RWY 34R LENGTH 11900 FT CFM56-7B26 STANDARD CONFIGURATION SEA-TAC INTL ELEV 430 FT FLAPS 5 NO WIND, STANDARD QNH RWY COND DRY
TEMP NORMAL IMPROVED CLIMB (C) MTOW V1 VR V2 MTOW V1 VR V2 50 67600 143 143 148 71600 165 168 172 48 68800 144 144 149 72800 165 169 172 46 70000 145 145 150 74100 166 169 173 44 71200 146 146 151 75200 165 168 172 42 72500 147 148 153 76200 164 167 171 40 73700 148 149 154 77300 163 166 171 38 75000 149 150 155 78400 163 166 170 36 76300 150 151 156 79400 162 165 169 34 77600 151 152 157 80300 161 164 169 32 78900 152 153 159 81300 160 163 168 30 80100 153 154 160 82200 160 163 168
737-800 TAKEOFF PERFORMANCE KSEA RWY 34R LENGTH 11900 FT CFM56-7B26 STANDARD CONFIGURATION SEA-TAC INTL ELEV 430 FT FLAPS 5 NO WIND, STANDARD QNH RWY COND DRY
TEMP NORMAL IMPROVED CLIMB (C) MTOW V1 VR V2 MTOW V1 VR V2 50 67600 143 143 148 71600 165 168 172 48 68800 144 144 149 72800 165 169 172 46 70000 145 145 150 74100 166 169 173 44 71200 146 146 151 75200 165 168 172 42 72500 147 148 153 76200 164 167 171 40 73700 148 149 154 77300 163 166 171 38 75000 149 150 155 78400 163 166 170 36 76300 150 151 156 79400 162 165 169 34 77600 151 152 157 80300 161 164 169 32 78900 152 153 159 81300 160 163 168 30 80100 153 154 160 82200 160 163 168
Assumed Temp with Improved Climb
OAT 30 TOW = 75000 kg C Unlock Access to An
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OAT
Thrust, EPR, and %N1 Relationship
%N1 EPR Thrust Unlock Access to An
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737-800 TAKEOFF PERFORMANCE KBFI
CFM56-7B26 STANDARD CONFIGURATION BOEING FIELD ELEV 17 FT FLAPS 5 NO WIND, STANDARD QNH RWY COND DRY
MAXIMUM TEMP MAX ALLOWABLE TAKEOFF WEIGHT (KG) / V-SPEEDS %N1 (C) RUNWAY 13R RUNWAY 31L 97.2 50 66900 141 142 147 68400 143 144 149 97.4 48 68100 142 143 148 69700 144 145 150 97.7 46 69200 143 144 150 71000 145 146 151 98.0 44 70400 144 145 151 72200 146 147 152 98.3 42 71500 145 146 152 73500 147 148 154 98.6 40 72700 146 147 153 74700 148 150 155 98.9 38 73800 147 148 154 76000 149 151 156 99.3 36 75000 147 149 155 77300 150 152 157 99.6 34 76200 148 150 156 78600 151 153 158 99.9 32 77400 149 152 158 80000 152 154 160 100.3 30 78500 150 153 159 81300 152 155 161 99.5 25 78900 150 153 159 81500 153 156 161 98.8 20 79200 150 153 159 81700 153 156 161 98.0 15 79500 151 153 160 81800 153 156 161 97.2 10 79800 151 154 160 82000 153 156 162 737-800 TAKEOFF PERFORMANCE KBFI
CFM56-7B26 STANDARD CONFIGURATION BOEING FIELD ELEV 17 FT FLAPS 5 NO WIND, STANDARD QNH RWY COND DRY
MAXIMUM TEMP MAX ALLOWABLE TAKEOFF WEIGHT (KG) / V-SPEEDS %N1 (C) RUNWAY 13R RUNWAY 31L 97.2 50 66900 141 142 147 68400 143 144 149 97.4 48 68100 142 143 148 69700 144 145 150 97.7 46 69200 143 144 150 71000 145 146 151 98.0 44 70400 144 145 151 72200 146 147 152 98.3 42 71500 145 146 152 73500 147 148 154 98.6 40 72700 146 147 153 74700 148 150 155 98.9 38 73800 147 148 154 76000 149 151 156 99.3 36 75000 147 149 155 77300 150 152 157 99.6 34 76200 148 150 156 78600 151 153 158 99.9 32 77400 149 152 158 80000 152 154 160 100.3 30 78500 150 153 159 81300 152 155 161 99.5 25 78900 150 153 159 81500 153 156 161 98.8 20 79200 150 153 159 81700 153 156 161 98.0 15 79500 151 153 160 81800 153 156 161 97.2 10 79800 151 154 160 82000 153 156 162
Assumed Temp Reduced %N1
OAT 10 TOW = 72000 kg C Unlock Access to An
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OAT 10 altitude sea level assumed temperature: 40
Max assumed temp 66
Max %N1 for 40 98.6
Min assumed temp 30
%N1 reduction 4.4 Reduced %N1 94.2 C, C C C C
OAT 10 altitude sea level
assumed temperature: 40
Max assumed temp 66
Max %N1 for 40 98.6
Min assumed temp 30
%N1 reduction 4.4
Reduced %N1 94.2
FCOM Reduced %N1 Calculation
C, C C C C Unlock Access to An
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Assumed Temp Reduced EPR
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OAT 15°C Actual 40 Assumed 40 EPR 1.376 1.376 V1 (IAS / TAS) 147 / 153 147 / 147 VR (IAS / TAS) 155 / 162 155 / 155 V2 (IAS / TAS) 162 / 169 162 / 162 Thrust at V1 (LB) 30960 31210 Thrust at VR (LB) 30610 30880 Thrust at V2 (LB) 30300 30570
Engine-Out Takeoff Distance (ft) 9800 9050
All-Engine Takeoff Distance (ft) 8800 8100
Accelerate – Stop Distance (ft) 9800 9050
Assumed Temperature is
Inherently
Conservative!
Extra field length margin due to the true airspeed effect!
C C
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The Derate Method
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Certificate Limitations In AFM
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Determining Allowable Takeoff Derate
OAT MTOW Full rated Derate 1 Derate 2 Derate 1 Actual TOW Max TOW Actual temperature Maximum allowable takeoff derate Unlock Access to AnExclusive 30
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OAT Thrust
Derate Combined with Assumed Temperature
Full rated Derate 1 Derate 2 Max thrust Actual temp Thrust required Assumed temp Unlock Access to An
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Derate can
increase
max takeoff weight !
Field length limit weight Runway length F u l l r a t e d D e r a t e V1MCG Higher Weight Unlock Access to An
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Derate can
expand
aft CG limit (737NG)
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Operational Practices and Considerations
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737NG FMC N1 LIMIT Page
An assumed temperature can be entered and/or a derate selected. If a takeoff derate is selected, the corresponding climb derate will be armed automatically.
N1 LIMIT 1 / 1 SEL / OAT / + 20°C 26K <T O 24K DERATE
<TO - 1 <ACT> <SEL>
22K DERATE <TO - 2 27K BUMP <TO - B <PERF INIT 26K N1 98.8/ 98.8 CLB > CLB -1> CLB -2> TAKEOFF> — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — Unlock Access to An
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737NG Upper Center Display Panel
Assumed temperature and target %N1 setting display ENG 1 START VALVE OPEN OIL FILTER BYPASS LOW OIL PRESSURE EGT FF N1 ENG 2 START VALVE OPEN OIL FILTER BYPASS LOW OIL PRESSURE 663 663 87.7 94.2 10 TAI 8 6 4 2 0 87.7 94.2 10 TAI 8 6 4 2 0 TAT +22C D - TO + 45C 3.80 3.80 FUEL KG 1 900 3 CTR 2 900 3 600 7 Unlock Access to An
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737 Classic FMC TAKEOFF REF Page
An assumed temperature can be entered on either page 1/2 or 2/2. Takeoff derate can be selected on page 2/2.
TAKEOFF REF 2 / 2 SEL TEMP + 4 0 ° C 104 °F 2 0 K DERA TE 91.3 / 91.3% <INDEX RED 22K N1 92.2 / 92.2% 18.5K DERATE 89.1 / 89.1% — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — Unlock Access to An
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737 Classic EIS Panel
Thrust Mode display for reduced thrust REVERSER
UNLOCKED A/T LIM
REVERSER UNLOCKED EGT °C N1 %RPM 94.5 94.5 MAN SET R - TO 3 92.5 4 10 12 8 6 4 2 0 5 83.4 3 3 92.5 4 10 12 8 6 4 2 0 5 83.4 3 Unlock Access to An
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777 FMC THRUST LIM Page
An assumed temperature can be entered and/or a derate selected. If a takeoff derate is selected, the corresponding climb derate will be armed automatically.
THRUST LIM
SEL OAT
45°C 20°C
<TO < SEL> <ARM>
TO 1 < – 10% TO 2 < – 20% <INDEX D – T O N1 97.3% CLB > CLB 1> CLB 2> TAKEOFF> — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — Unlock Access to An
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777 Upper EICAS Panel
N1 75.6 97.3 75.6 97.3 EGT 587 587 TAT + 22C D - TO + 45C TOTAL FUEL 94.3 TEMP +10c KGS X 1000 DOWN GEAR F L A P S 15Assumed temperature and target %N1 (or EPR) setting display
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757 and 767 Thrust Mode Select Panel (TMSP)
An assumed temperature can be dialed in, and/or a paired derate selected. If 1 is pushed, then TO 1 and CLB 1 will be selected; if 2 is pushed, then TO 2 and CLB 2 will be selected.
2 2 TEMP SEL TEMP SEL 1 1 CLB CLB TO TO CRZ CRZ CON CON GA GA Unlock Access to An
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757 / 767 Upper EICAS Panel
EPR EGT N1 599 597 90.7 90.6 TAT + 22°C D - TO + 45C V V V V V V V V V 1.64 1.64 2.0 1.5 1.0 2.0 1.5 1.0 1.64 1.64Assumed temperature and target EPR (or %N1) setting display
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757 and 767 FMC (PIP and PEGASUS)
T A K E O F F R E F P R E – F L T S T A T U S T E M P S E L 4 5° C T O E P R 1 . 6 4 D – T O < P O S I N I T < P E R F I N I T < I N D E X V 1 V R V 2 R O U T E > D E P A R T U R E > — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —An assumed temperature can be entered and target EPR (or %N1) setting displayed
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FMC/TMC Takeoff Power Setting Constraints
• FMC/TMC protects the 25% thrust reduction limit and overboost
– If an assumed temperature higher than the assumed temperature for 25% thrust reduction is entered, the assumed temperature and power setting for 25% thrust reduction will be displayed and set.
– If an assumed temperature lower than the thrust break temperature (or lower than OAT) is entered, the power setting for OAT will be displayed and set; but the temperature entered will still be displayed.
– 757 & 767 TMC also limits the reduced takeoff power setting to no lower than the armed climb power setting
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FMC/TMC Takeoff & Climb Power Setting Constraints
• The 757-200 TMC limits the thrust reduction to 25% based on the full rated takeoff thrust only
• If the option is enabled in the FMC, the 40% thrust reduction limit for 777-300ER/200LR/200F is based on the full rated takeoff thrust only
• Assumed temperature reduced thrust is not available for takeoff bump rating
• The FMC (except on 757 & 767) will automatically select a lower climb rating if the reduced takeoff power setting is lower than the power setting for the currently selected climb rating
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OAT Thrust
Thrust Increase from Takeoff to Climb
TO TO 1 TO 2 Takeoff thrust selected CLB CLB 1 CLB 2
Actual temperature Assumed temperature
Thrust increase Climb thrust armed Except on 757 & 767 Unlock Access to An
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Firewall in an Emergency (Assumed Temp) !
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Firewall in an Emergency (Derate) ?
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Other Considerations
• Reduced / derated takeoff thrust may increase the airplane-to-ground noise level as a result of the lower flight path
• Reduced / derated takeoff thrust should not be considered as a means to continue the use of a
defective engine (repeated EGT exceedence), neither should re-rate or engine swap.
• Using climb derate will increase trip fuel and trip time as a result of the longer time in climb to reach cruise altitude
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Sources of Operational Data
Computerized system:
• Software tool (such as OPT)
• Integrated dispatch / departure control system Paper-based system requires:
• Takeoff analysis charts
• Takeoff speeds data (such as FCOM or FMC)
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FMC Takeoff Speeds
Balanced Plus (or Standard) takeoff speeds:
• Balanced field length, except when V1 must be unbalanced to comply with V1MCG ≤ V1 ≤ VR.
FMC takeoff speeds DO NOT include:
• V1 adjustment for unequal clearway and stopway • V1 adjustment for slippery or contaminated runway • V1 adjustment for inoperative equipment (MEL)
• Optimized (unbalanced) V1 for obstacles or VMBE • Improved Climb or Alternate Forward CG speeds
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FMC and FCOM Takeoff Speeds
T A K E O F F R E F 1 / 2 F L A P S ° 2 6 K N 1 9 8 . 8 / 9 8 .8% C G T R I M 22.5% 5 . 2 5 R U N W A Y < P E R F I N I T Q R H V 1 V R V 2 G W / T O W S E L E C T QRH OFF> — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —Balanced+ (Standard) speeds only. No Improved Climb or Alt Fwd CG !
FMC speeds, plus V1 adjustments for clearway and stopway, slippery and contaminated runways, and some inoperative systems. No optimized V1, Imp Climb or Alt Fwd CG speeds.
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Practical Exercises and Software Tools
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Summary
Summary
The benefits of using lower takeoff and climb thrust are: The benefits of using lower takeoff and climb thrust are:
•• RedReduceuced cost on pad cost on parts anrts and maind maintenatenancence •• IncreasIncreased ened engine gine reliabreliability ility and land lifeife
•• ImproveImproved oped operating rating safety safety and eand efficiefficiencyncy
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Summary (continued)
Summary (continued)
There are two methods for takeoff thrust reduction: There are two methods for takeoff thrust reduction:
•• Reduced Reduced Thrust Thrust (Assume(Assumed Td Temperaturemperature)e) •• DerDerated ated ThrThrust ust (Der(Derate)ate)
•• The twThe two methodo methods can bs can be combine combined for aed for all Boell Boeinging FMC-equipped models, except MD models
FMC-equipped models, except MD models
Regulatory requirements and certificate limitations Regulatory requirements and certificate limitations can be found in:
can be found in:
•• FAA FAA AC 25AC 25-13 a-13 and JAnd JAR AMR AMJ 25-J 25-1313 •• AFM AFM (AF(AFM-DM-DPI or ApPI or Appendpendiceices)s)
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Summary (continued)
Summary (continued)
•
• MaximuMaximum of 25% m of 25% thrust thrust reductireduction from on from the full the full rated or rated or
derated thrust (40% option from the full rated thrust for
derated thrust (40% option from the full rated thrust for
777-300ER/200LR/200F)
777-300ER/200LR/200F)
•
• RequireRequires takes takeoff peroff performance formance data odata only fonly for the r the ratingrating
to be used (full rated or a derate)
to be used (full rated or a derate)
•
• A range A range of tempof temperatures eratures allows allows flexibflexible thrusle thrust reduct reductiontion
•
• Extra Extra field field length mlength margin duargin due to the e to the true aitrue airspeed erspeed effectffect
•
• May be usMay be used wited with Imprh Improved Coved Climlimb perfob performanrmancece
•
• AllowAllowed on wed on wet runwet runway if way if wet rwy et rwy perf daperf data is ata is availabvailablele
•
• ProProhibihibited on cted on contaontaminminated rated runwunwaysays
The Assumed Temperature Method
The Assumed Temperature Method
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Summary (continued)
• May increase takeoff weight capability if limited by V1MCG • Permitted on contaminated runways
• Better trimmed for rotation and climbout
• May improve aircraft loadability for 737NG models • More thrust reduction for equivalent performance
• Separate takeoff performance data required for each rating • Increases trip fuel and trip time if climb derate is also used
The Derate Method
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