NATOPS Chapter 11

Question 1

Normal Hover Attitude

Answer 1

Approximately 4-5* nose up and 2-3* left-wing down

Question 2

Ground Effect

Answer 2

Within one rotor diameter of the ground

45’ for 60 (based on rotor being higher than RADALT sensors)

Question 3

Dissymmetry of Lift

Answer 3

Compensated for with blades on advancing side of rotor disc flaps up, decreasing AOA and reducing the lift generated–retreating blade flaps down, increasing AOA and generating additional lift

Question 4

Stab in Slow Flight

Answer 4

Below 30 KIAS, stab full down at 42*

CLAP inputs have no effect below 30 KIAS (when programming begins)

Question 5

Tailwinds

Answer 5

Require more power when forward flight is started, doesn’t matter for just hovering

Question 6

Level Flight Up To?

Answer 6

Stab maintains approximately level nose attitude up to 130 KIAS

Question 7

Blade Stall

Answer 7

Retreating blade stalls because blade tip is traveling at the rotational velocity minus forward speed of helicopter (as in-air velocity decreases, AOA must increase)

Starts at blade root where AOA highest and most likely to occur at high speed, gross weight, D and power

Maneuvers, acceleration or turbulent air all increase g-loading, inducing blade stall by reducing airspeed at which blade stall will occur

Fully developed, pitch upward and to the left–use of forward cyclic to control pitch will aggravate situation (increases AOA of retreating blade)

Question 8

Eliminate Blade Stall (SCAARG)

Answer 8

Severity of maneuver - decrease

Collective pitch - decrease

Airspeed - decrease

Altitude - decrease

Rotor RPM - increase

Gross Weight - decrease

Question 9

Loss of Tail Rotor Authority

Answer 9

Issue of power

Usually high gross weight and/or high density altitude

Left pedal may be sluggish and may cause Nr droop (torque increases while power available decreases)

Question 10

Loss of Tail Rotor Effectiveness

Answer 10

Inability of the tail rotor to provide sufficient force to maintain yaw controllability

Function of operating rpm and tail rotor AOA

Caused by wind direction, low-speed/high-power maneuvering, operating rpm, gross weight and DA

Question 11

LTE (AOA Reduction)

Answer 11

060-120* - Winds from the right tend to decrease AOA, reducing effectiveness requiring additional left pedal to maintain heading

Question 12

LTE (Vortex Ring)

Answer 12

210-330* - Winds from left increase AOA for a given pitch setting and may increase effectiveness; however, if excessive, disturbed airflow around tail rotor may develop

Question 13

LTE (Weather Vaning)

Answer 13

120-240* - will weather-vane the nose into the wind

Helo makes un-commanded left or right turn

If yaw already established, acts to accelerate the yaw as tail passes through the wind

Question 14

LTE (Main Rotor Vortex)

Answer 14

280-330* (less frequently 030-080*) - causes main rotor vortex onto the tail rotor changing AOA; thrust can vary significantly

Question 15

LTE Recovery

Answer 15

Altitude permitting, lower collective to reduce torque and assist in arresting right yaw; however, if a significant rate of descent is established, the additional power required to arrest the rate of descent may aggravate or reinitiate LTE

Using forward cyclic to increase airspeed and if necessary turning into direction of rotation (reduction in tail rotor thrust required and produces streamlining effect)

At very low speed or in a hover, applying full left pedal may arrest yaw