BIG ENGINES

7/30/2019 BIG ENGINES

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Big Engines and

Directional Control

Big Engines and

Directional Control

WARNING: Export ControlledThis document contains technical data whose export is restricted by the ExportAdministration Act of 1979, as amended, Title 50, U.S.C.; App. 2401, et seq.Violators of these export laws are subject to severe criminal penalties.Diversion contrary to U.S. law is prohibited.Controlled by ECCN: 9E991 Date: 11January2008



BigEnginesBigEngines..22


BIG engines………BIG engines………





IntroductionsIntroductions

3 Boeing representatives for this topic:

Captain Suzanna P. Darcy-Hennemann777 Chief Pilot

Captain Gregory G. Botch777 Chief Technical Pilot

Paul J. Bolds-Moorehead777 Stability & Control Lead Engineer

3 Boeing representatives for this topic:

Captain Suzanna P. Darcy-Hennemann777 Chief Pilot

Captain Gregory G. Botch777 Chief Technical Pilot

Paul J. Bolds-Moorehead777 Stability & Control Lead Engineer





● Concept

● Situation

●

Effect

● Plan

● Summary

● Concept

● Situation

●

Effect

● Plan

● Summary

● Concept

● Situation

●

Effect

● Plan

● Summary

● Concept

● Situation

● Effect

● Plan

● Summary

AgendaAgenda





The ConceptThe Concept● Thrust on twin-engine airplanes tends to grow significantly

over the life of the fleet

● Rarely do vertical tail and rudder sizes grow with this thrustgrowth

● High thrust asymmetry (engine failure) challenges directionalcontrol

● Thrust on twin-engine airplanes tends to grow significantlyover the life of the fleet

● Rarely do vertical tail and rudder sizes grow with this thrustgrowth

● High thrust asymmetry (engine failure) challenges directionalcontrol

Yawing moment due toaerodynamic directional

stability and controls

Yawing moment due toaerodynamic directionalstability and controls

Large thrust commandedfrom operating engine

Large thrust commandedfrom operating engine

Yawing moment due tothrust asymmetry

Yawing moment due tothrust asymmetry

Failed EngineFailed Engine





The Concept (continued)The Concept (continued)

● Loss of directional control at a given airspeed in thisenvironment is defined by:

– Inability to reliably fly a specific bank angle

– Inability to precisely control the heading

● Large displacements of control wheel and rudder pedals will be

noticeable to the flight crew as this speed is approached

● The certified minimum control speeds (VMCA /VMCL) are alwaysgreater than the airspeed for loss of directional control

● Operational airspeeds (V2 /VREF) are always greater thanor equal to minimum control speeds

● “Stretched” airplanes are less susceptible to this phenomenon(longer tail moment arm)

● Loss of directional control at a given airspeed in thisenvironment is defined by:

– Inability to reliably fly a specific bank angle

– Inability to precisely control the heading

● Large displacements of control wheel and rudder pedals will be

noticeable to the flight crew as this speed is approached

● The certified minimum control speeds (VMCA /VMCL) are alwaysgreater than the airspeed for loss of directional control

● Operational airspeeds (V2 /VREF) are always greater thanor equal to minimum control speeds

● “Stretched” airplanes are less susceptible to this phenomenon(longer tail moment arm)





A i r s p e e d

A i r s p e e d

WeightWeight

The Concept (continued)The Concept (continued)

S t a l l W a r n

i n g ( s t i c k s h a k e

r )

S t a l l W a r n

i n g ( s t i c k s h a k

e r )Loss of Directional Control (now)Loss of Directional Control (now)

VMCAVMCA

Loss of Directional Control (then)Loss of Directional Control (then)

However, higher thrust asymmetry may cause a loss of directionalcontrol at airspeeds greater than that for stall warning

Thrust growthThrust growth

before big engines

invented, Loss of control

speed (independent from

weight) was smaller than

stall (so first stall, then

loss of control)

Thrust growth carried theline here. This means at

certain weights you may

losse conytrol even befoire

stall





The Concept: Takeoff Procedure ReviewThe Concept: Takeoff Procedure Review

Limited Max availableLimited Max availableThrust afterengine failure

Based upon derated thrust

level

Determinedby full thrust

Based upon derated

thrust level

Determinedby full thrust

VMCA / VMCG /V2 airspeeds

Combination

AssumedTemperature

Method(ATM)

Fixed

derate Full thrust

Takeoff Thrust Setting Method





The Concept: Go-Around Procedure ReviewThe Concept: Go-Around Procedure Review

● Pilot initiates go-around with TOGA push (single or double push)

– Single push gives thrust for ~2000 fpm climb – Double push gives full GA rated thrust

● Pilot changes flap setting to go-around flap (typically flaps 20)

● On achieving positive rate-of-climb, pilot raises landing gear

● Should engine failure occur during go-around, continuenormal procedures

● Maintain VREF speed as minimum during the go-around

● Follow Flight Director guidance to maintain recommendedairspeed

● Pilot initiates go-around with TOGA push (single or double push)

– Single push gives thrust for ~2000 fpm climb – Double push gives full GA rated thrust

● Pilot changes flap setting to go-around flap (typically flaps 20)

● On achieving positive rate-of-climb, pilot raises landing gear

● Should engine failure occur during go-around, continuenormal procedures

● Maintain VREF speed as minimum during the go-around

● Follow Flight Director guidance to maintain recommendedairspeed





● Concept

● Situation

● Effect

● Plan

● Summary

● Concept

● Situation

● Effect

● Plan

● Summary

● Concept

● Situation

● Effect

● Plan

● Summary

● Concept

● Situation

● Effect

● Plan

● Summary

AgendaAgenda





Reduced Directional Control Example - 777Reduced Directional Control Example - 777

● The 777 airplane family meets all certification regulations

(including minimum control speeds, VMC)

● There have been no reported 777 directional control incidentsin Boeing flight test or airline revenue service

● Decelerating enough to reach engine-out loss of directionalcontrol airspeeds is an extremely improbable event for 777airplanes

● Flying at approved operating airspeeds and followingrecommended procedures will maintain directional control

● The 777 airplane family meets all certification regulations

(including minimum control speeds, VMC)

● There have been no reported 777 directional control incidentsin Boeing flight test or airline revenue service

● Decelerating enough to reach engine-out loss of directionalcontrol airspeeds is an extremely improbable event for 777airplanes

● Flying at approved operating airspeeds and followingrecommended procedures will maintain directional control





Defining “Loss of Directional Control”Defining “Loss of Directional Control”

● The airspeed at which it is no longer possible to reliably control bankangle and heading defines a loss of directional control airspeed

Note: For all Boeing models, this speed is always less than VMCA

● For example, with the 777 family:

– On some of the minor models for lighter weight operations only,the speed for loss of directional control is greater than stall

warning speed – While meeting all VMC regulations, decided to enhance operational

speed margins

● Operations near ground in high thrust asymmetry conditions

(single-engine go-arounds and single-engine takeoffs) arethe areas of primary interest

● Again, flying at approved operating airspeeds and followingrecommended procedures will maintain directional control

● The airspeed at which it is no longer possible to reliably control bankangle and heading defines a loss of directional control airspeed

Note: For all Boeing models, this speed is always less than VMCA

● For example, with the 777 family:

– On some of the minor models for lighter weight operations only,the speed for loss of directional control is greater than stall

warning speed – While meeting all VMC regulations, decided to enhance operational

speed margins

● Operations near ground in high thrust asymmetry conditions

(single-engine go-arounds and single-engine takeoffs) arethe areas of primary interest

● Again, flying at approved operating airspeeds and followingrecommended procedures will maintain directional control





● Concept

● Situation

● Effect

● Plan

● Summary

● Concept

● Situation

● Effect

● Plan

● Summary

● Concept

● Situation

● Effect

● Plan

● Summary

● Concept

● Situation

● Effect

● Plan

● Summary

AgendaAgenda





Determining “Loss of Directional

Control” Airspeeds

Determining “Loss of Directional

Control” Airspeeds

Determination procedure:

1. Fail one engine and command

full thrust on operating engine(against Standard OperatingProcedure for Fixed Derate orFixed Derate/ATM takeoffs)

2. Decelerate while maintaining

constant heading using rudderand wheel deflections

3. Airspeed at which bank/headingis no longer controllable islabeled the “loss of directionalcontrol” airspeed

4. Large wheel and rudderdisplacements are readilyapparent, even though crewproximity to this regimeis not specifically annunciated

Determination procedure:

1. Fail one engine and command

full thrust on operating engine(against Standard OperatingProcedure for Fixed Derate orFixed Derate/ATM takeoffs)

2. Decelerate while maintaining

constant heading using rudderand wheel deflections

3. Airspeed at which bank/headingis no longer controllable islabeled the “loss of directionalcontrol” airspeed

4. Large wheel and rudderdisplacements are readilyapparent, even though crewproximity to this regimeis not specifically annunciated

S t a l l W a r n

i n g

S t a l l W a r n

i n g Loss of Directional Control (high-thrust engines)Loss of Directional Control (high-thrust engines)

VMCAVMCA

Loss of Directional Control (ideal)Loss of Directional Control (ideal)

ThrustGrowthThrustGrowth

WeightWeight

A i r s p e e d

A i r s p e e d





S t a l l W a r n

i n g

S t a l l W a r n

i n g Loss of Directional Control

(full thrust)

Loss of Directional Control

(full thrust)

VMCA (full thrust)VMCA (full thrust)

Airspeed Margins (Takeoff)Airspeed Margins (Takeoff)

●What is the desired marginbetween V2 and the loss

of directional control? – Minimum V2 speeds obtained

assuming largest fixed derateswhere thrust lever push is notallowed (not an issue for

full-thrust or assumedtemperature takeoffs)

●Establishing guidelines for themargin between Minimum V2

and the loss of directional controlairspeed for all models

● For the takeoff scenario:

– May result in a V2 airspeed

floor being implemented

●What is the desired marginbetween V2 and the loss

of directional control? – Minimum V2 speeds obtained

assuming largest fixed derateswhere thrust lever push is notallowed (not an issue for

full-thrust or assumedtemperature takeoffs)

●Establishing guidelines for themargin between Minimum V2

and the loss of directional controlairspeed for all models

● For the takeoff scenario:

– May result in a V2 airspeed

floor being implemented

V2 floorV2 floor

Note: Only an issue if pilot pushes thrust levers past fixed derate level disregarding training

M a r g i n

M a r g i n

M i n i m u

m V 2

( f i x e d d

e r a t e ) M i n

i m u m V 2

( f i x e d d

e r a t e )

WeightWeight

A i r s p e e d

A i r s p e e d





Airspeed Margins (Takeoff) – Proper TechniqueAirspeed Margins (Takeoff) – Proper Technique

S t a l l W

a r n i n g

S t a l l W

a r n i n g Loss of Directional Control

(fixed derate)


(fixed derate)

VMCA (fixed derate)VMCA (fixed derate)

M i n i m u

m V 2

( f i x e d d e

r a t e ) M i n

i m u m V 2

( f i x e d d e

r a t e )

WeightWeight

S t a l l W

a r n i n g

S t a l l

W a r n i n

g Loss of Directional Control

(full thrust)


(full thrust)

VMCA (full thrust)VMCA (full thrust)

V 2 ( f u

l l t h r u s t )

V 2 ( f u

l l t h r u s t )

WeightWeight

A i r s p e e d

A i r s p e e d

Adequate marginAdequate margin

Adequate marginAdequate margin





Airspeed Margins (Landing/Go-Around)Airspeed Margins (Landing/Go-Around)

● What is the acceptable marginbetween VREF and the loss of

directional control?

● Establishing guidelines for themargin between VREF and theloss of directional controlairspeed for all models

● For the landing/go-aroundscenario:

– May result in a VREF airspeedfloor being implemented

● What is the acceptable marginbetween VREF and the loss of

directional control?

● Establishing guidelines for themargin between VREF and theloss of directional controlairspeed for all models

● For the landing/go-aroundscenario:

– May result in a VREF airspeedfloor being implemented

WeightWeight

A i r s p e e d

A i r s p e e d

S t a l l W a r n

i n g

S t a l l W a r n

i n g Loss of Directional ControlLoss of Directional Control

VMCLVMCL

VREF floorVREF floor

M a r g i n

M a r g

i n

S t a l l - B a

s e d V R E F

S t a l l - B a

s e d V R E F





Operational speed margin affected for

takeoff below ~380Klb/~172000Kg andlanding below ~400Klb/~181000Kg

RR 895

GE90-94B777-200ER

NONE(ALL)777-300 / -300ER

Operational speed margin affected fortakeoff below ~445Klb/~202000Kg(~465Klb/~211000Kg for the 115BL)

GE90-110B1L

(GE90-115BL)

777-200LR

777-Freighter

Operational speed margin affected forlanding only below ~365Klbs/~165500 Kg

PW4090

RR 892

GE90-90B

777-200ER

NONE

PW4074, 4077, 4084

RR 877, 884

GE90-76B, -85B

777-200 / -200ER

AffectEngineMinor Model

Airspeed Margins - 777 Fleet ExampleAirspeed Margins - 777 Fleet Example





● Concept

● Situation

● Effect

● Plan

● Summary

●

Concept

● Situation

● Effect

● Plan

● Summary

● Concept

● Situation

● Effect

● Plan

● Summary

●

Concept

● Situation

● Effect

● Plan

● Summary

AgendaAgenda





The PlanThe Plan● Simulation study across all Boeing models in process

– 777 study portion now complete

● Establishing margin guidelines for all Boeing models

– 777 preliminary results: 10 knots for takeoff, 17 knotsfor landing

● Reviewing all manuals for clarity

– 777 Flight Crew Training Manual revised October, 2007

● Make modifications as warranted

– TakeoffÆ Modify V2 for affected 777-200ER, 777-200LR,and 777F

– Go-AroundÆ Modify VREF for affected 777-200ER(V

REF

floor already in place for 777-200LR/F)

● Simulation study across all Boeing models in process

– 777 study portion now complete

● Establishing margin guidelines for all Boeing models

– 777 preliminary results: 10 knots for takeoff, 17 knotsfor landing

● Reviewing all manuals for clarity

– 777 Flight Crew Training Manual revised October, 2007

● Make modifications as warranted

– TakeoffÆ Modify V2 for affected 777-200ER, 777-200LR,and 777F

– Go-Around Æ Modify VREF for affected 777-200ER(V

REF

floor already in place for 777-200LR/F)





● Concept

● Situation

● Effect

● Plan

● Summary

●

Concept

● Situation

● Effect

● Plan

● Summary

● Concept

● Situation

● Effect

● Plan

● Summary

●

Concept

● Situation

● Effect

● Plan

● Summary

AgendaAgenda





SummarySummary

● Provide heightened operator awareness of the affect of increasedasymmetric thrust

– On some of the minor models for lighter weight operations only,the speed for loss of directional control is greater than stallwarning speed

● Emphasize the importance of following published procedures

– Flying at Boeing-recommended airspeeds and followingBoeing-recommended procedures maintains directional control

– Manage thrust as recommended (respect derated takeoffs)

● Evaluate entire Boeing fleet to establish appropriate V2 / VREF

margins to loss of directional control airspeed

● Available tomorrow for breakout sessions on this topic uponrequest

● Provide heightened operator awareness of the affect of increasedasymmetric thrust

– On some of the minor models for lighter weight operations only,the speed for loss of directional control is greater than stallwarning speed

● Emphasize the importance of following published procedures

– Flying at Boeing-recommended airspeeds and followingBoeing-recommended procedures maintains directional control

– Manage thrust as recommended (respect derated takeoffs)

● Evaluate entire Boeing fleet to establish appropriate V2 / VREF

margins to loss of directional control airspeed

● Available tomorrow for breakout sessions on this topic uponrequest




SeattleSeattle

Bringing Flight Operations to YouBringing Flight Operations to You

Big Engines and

Directional Control

Big Engines and

Directional Control

BIG ENGINES

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