multi flying in the DA42

Question 1

What are the 3 assymetries when OEI

Answer 1

• lift
• drag
• thrust

Question 2

what is the main control problem when OEI?

Answer 2

Yaw

Question 3

what are the 3 factors affecting control OEI?

Answer 3

• speed
• drag on dead engine
• thrust on live engine

Question 4

what are light twins not required to have by law in the event of an engine failure?

Answer 4

positive rate of climb

Question 5

what is the purpose of a propellor?

Answer 5

to convert engine power into thrust

Question 6

what is disc-ing?

Answer 6

when drag from the prop affects forward speed

Question 7

what is the angle between the chord line and plane of rotation on a prop?

Answer 7

incidence angle

Question 8

what is the angle between the chord line and the relative airflow?

Answer 8

angle of attack

Question 9

what is the angle between the relative airflow and the plane of rotation?

Answer 9

angle of advance

Question 10

what is propellor torque?

Answer 10

the combination of the drag vector and the lift opposed to the plane of rotation

Question 11

where does lift act from the propellor?

Answer 11

at 90 degrees to the aerofoil. drag acts at 90 degrees to the lift

Question 12

when will a propellor run at constant speed?

Answer 12

when propellor torque matches torque from the engine

Question 13

what happens to AOA on a fixed pitch prop as forward speed increases?

Answer 13

AOA reduces

Question 14

what is fixed on a fixed pitch prop?

Answer 14

angle of incidence

Question 15

what is the most efficient prop AOA?

Answer 15

2-4 DEGREES

Question 16

what happens to AOA as prop rotation speed increases?

Answer 16

AOA increases

Question 17

what happens to a fixed pitch prop when the nose is raised?

Answer 17

RPM reduces because the AOA and propellor torque is increased

Question 18

what happens to RPM as forward speed increases?

Answer 18

RPM increases as the torque reduces.

Question 19

why is washout used?

Answer 19

speed of the propellor increases from root to tip. without washout the AOA and difference would lead to unbalanced lift and drag from root to tip

Question 20

how does washout work?

Answer 20

chord length and thickness is reduced progressively from root to tip, to ensure equal thrust along the blade. the blade is coarse at the root and fine at the tip/

Question 21

how will asymmetric blade effect make the aircraft yaw when pitched up?

Answer 21

the down going blade has further to travel meaning the RAF encountered is faster which increases the lift and thrust from the blade. this yaws the aircraft. (greater the angle of the prop axis from the horizontal, the greater the yaw)

Question 22

what is the effect of aerodynamic moments on a prop?

Answer 22

aerodynamic moments create most lift from the base of the prop, forward of the centre of rotation. meaning it has a tendency to coarsen the blade. A negative AOA will cause the opposite effect (windmilling)

Question 23

what is the effect of centrifugal force on a prop?

Answer 23

twisting moments about the centre of rotation that want to fine off the prop

Question 24

what force is used to assist fining a prop on a VP propellor?

Answer 24

centrifugal force

Question 25

what needs to be considered if full rudder deflection can't be achieved?

Answer 25

a higher critical speed

Question 26

on a multi-lever ME aircraft, how would we carry out a CSU RPM check?

Answer 26

with relatively high power, bring the rpm lever back until there is an RPM drop of about 200, the advance back to full RPM. do this 3 times, but not too far as to not overload the engine.

Question 27

on multi lever ME aeroplanes, how would we carry out a feather check?

Answer 27

choose a low power setting then pull the RPM lever fully back to observe a large drop in rpm. do not hold the lever back for to long other wise the feathering locks may move into place.

Question 28

on multi lever ME aeroplanes, why is the RPM pushed all the way forward for takeoff?

Answer 28

in order to allow maximum power without overloading the engine

Question 29

what causes roll in asymmetric flight?

Answer 29

- loss of lift behind the failed engine - secondary effect of yaw - the failed side being lower than the live side, exacerbating the roll

Question 30

where is the relative airflow from in uncorrected asymmetric flight?

Answer 30

the live side

Question 31

what forces assist the pilot in asymmetric flight?

Answer 31

fin side force (lift) and fuselage drag

Question 32

why do we bank into the live engine?

Answer 32

the lift vector is tilted to produce a sideways component of life to oppose the yaw. if banked too far the fin could stall however.

Question 33

recite the standard control recovery for an engine failure

Answer 33

- rudder to prevent yaw - aileron to level the wings - pitch as necessary to maintain speed

Question 34

what opposes the rudder force in stable asymmetric flight?

Answer 34

- fuselage sideforce - yaw from asymmetric thrust - drag from dead engine

Question 35

why is the rudder less effective in stable asymmetric flight?

Answer 35

the RAF is on the dead side, meaning the angle of attack of the Raf acting on the rudder is less

Question 36

what effect do leg/rudder forces have in stable asymmetric flight?

Answer 36

they increase the AOA of the fuselage in relation to the RAF, creating a greater drag force as the aircraft is pushed into the RAF. this further reduces the speed

Question 37

how does power affect asymmetric flight?

Answer 37

the more thrust from the live engine, the greater the yawing moment will be towards the dead engine. rudder should be applied or reduced in line with power changes on the same side.

Question 38

how do we check the yaw situation when maintain stable asymmetric flight?

Answer 38

the heading and slip ball

Question 39

when is the rudder least effective?

Answer 39

high power/low IAS

Question 40

what is critical speed? (Vmc)

Answer 40

the lowest speed at which multi-engine aeroplane at constant asymmetric thrust and at a particular configuration can be kept under control by a particular pilot

Question 41

what are the conditions for Vmca?

Answer 41

- MTOM - Max take off power - critical engine windmilling - most aft CG - gear up, flap T/O - 5 degrees bank into live engine