Asymetric Flight

Question 1

Critical Engine

Answer 1

The engine that if it fails the other engines produces the most yaw

Question 2

Clockwise rotating twin AC - Critical Engine

Answer 2

In clockwise rotating propellers the left engine failing would give the greatest yaw due to right engine having a greater moment arm from the cg

Asymmetric blade effect

Question 3

What effects yawing moments for asymmetric flight

Answer 3

Density
Thrust setting
How far engines are from CG
Propeller drag (windmilling)

Question 4

Outboard engines are always

Answer 4

The critical engine

Question 5

Secondary effect of yaw in asymmetric flight if not stopped will be

Answer 5

Roll in the same direction as more lift on wing with live propeller (slipstream effect also)

Question 6

What causes the unbalanced force after applying rudder in asymmetric flight

Answer 6

Drift is caused by the corrective rudder force which causes a diversion from flight path due to sideway force being generated

Wings level method
Or
Wings down method

Required

Question 7

Wings Level Method

Answer 7

Using additional rudder to sideslip in opposite direction to the failed engine to create a side ware component of thrust

Question 8

Wings Level Method - Advantages and disadvantages

Answer 8

+ Comfortable and more suitable for IMC (turn/slip coordinator are seated naturally)

• Not suitable for light twins as unable to generate enough force to overcome
• extra drag leading to more fuel needed
• higher AOA on fin risk of stalling

Question 9

Banking Method

Answer 9

Creating a side ware component of lift to balance the weight by banking towards the live engine

Question 10

Banking Method Advantages and Disadvantages

Answer 10

+Less drag therefore better performance

+ Better rudder authority less chance of thin stall

• Not used on large CAT AC
• increased risk of disorientation
• attitude indicator may re erect itself to a false datum

Question 11

What is the limit of bank when using the banking method

Answer 11

5 degrees to prevent additional lift requirements to overcome the bank angle

Question 12

Why is the left engine the critical engine on a clockwise prop

Answer 12

Due to the asymmetric blade effect which inclines the thrust line further to the right therefore yawing the ac left

Reinforced by the slipstream effect
Rolling left due to torque reaction

Question 13

Where is it worst to have a crosswind from when you have an engine failure

Answer 13

Crosswind from dead engine will give you a weathercock effect yawing you into the wind further

Question 14

Counter rotating propellers advantage

Answer 14

Do not suffer from slipstream or asymmetric blade effect

Although critical engine will still be the into wind engine

Question 15

What do you need to consider on a go around with one engine

Answer 15

A much larger yawing moment when pitching up (gyroscopic effect) and asymmetric blade effect) + slipstream effect

Question 16

Minimum control speed CS23

Answer 16

Vmc is the the minimum speed at which full deflection of the rudder can oppose the yaw

Question 17

Factors which increase VMC

Answer 17

Crosswind from failed engine side

Lower altitude/cold temp (density/thrust)

Go around (idling to go around)

Higher AOA reducing margin of control

Question 18

CS25 minimum control speeds

Answer 18

Vmca
Vmcg
Vmcl

Question 19

Vmca + what happens to vmca when you bank

Answer 19

Minimum control speed at cruise altitude

Refer to directional control

Banking 2-5 degrees reduces rudder input therefore more contlability decrease VMCA

Question 20

Vmcg

Answer 20

Minimum control speed on the ground

Must not deviate more than 30ft from centreline

Question 21

Vmcl

Answer 21

Minimum speed to control yaw + minimum roll rate requirements

(Need to be able to manoeuvre ac to runway in roll)

20 degree roll within 5 seconds

Question 22

Vmca vs Vmcg

Answer 22

Vmcg is greater as a smaller arm to rudder when on the ground (wheel assembly)

Vmcg will always be faster

Question 23

Vmca must never exceed

Answer 23

1.13V

Question 24

How is Vmca measured

Answer 24

Worst situations on T/O
Max thrust on operating engine
Most unfavourable CG position
Ac trimmed for TO
Max TO weight
Most critical takeoff config (without gear)

Question 25

How is Vmcl Measured

Answer 25

Worst config on landing
Flaps etc

Question 26

Wing level method will show a what to the turn indicator and slip indicator

Answer 26

Both will be neutral as wings are level and rudder input balances the yaw

Question 27

If engine failures the secondary effect is to roll towards the dead engine further roll is increase by

Answer 27

The loss of lift behind the dead engine

Question 28

Vmcl is determined under the following config

Answer 28

Landing Flaps and trimmed for all engines operating + gear down

Question 29

Asymmetric blade effect descending

Answer 29

Up going blade on a clockwise propeller will produce thrust from the left side

Question 30

Mass vs asymmetric flight

Answer 30

Greater the weight the greater the induced side slip and greater rudder effectiveness