Flight Controls

Question 1

What does the AUTO FLIGHT CONTROL system consist of?

Answer 1

Stabilator
SAS
Boost servos
Flight directors
Trim

Question 2

What does the GO ARND button give you?

Answer 2

750fpm climb at 70kts

Question 3

What does the mixing unit provide?

Answer 3

Control mixing functions that minimize inherent control coupling

Question 4

What are the four types of mechanical mixing functions?

Answer 4

Collective to pitch: compensates for the changes in rotor downwash on the stabilator. Main rotor will tilt forward as collective is increase and aft as it is decreased

Collective to yaw: compensates for the changes in torque effect due to changes in the collective. As collective is increase, T/R pitch is increased. As collective decreases, so does the pitch of the T/R

Collective to roll: compensates for translating tendency caused by changes in T/R thrust. As collective is increased, the M/R disk tilts left, decreased it tilts right

Yaw to Pitch: Compensates for changes in the vertical thrust components of the canted T/R. As the T/R pitch is increased, the M/R system tilts after, as its decreased, slightly forward

Question 5

What is collective/airspeed to yaw or electronic coupling?

Answer 5

2 FCC commands the yaw trim actuator

Helps compensate for torque effect caused by changes in collective.

As airspeed increases, pitch of the T/R decreases and the cambered fin becomes more effective.

Maximum mixing occurs 0-40kts. Above 40 kts, mixing decreases until 100kts

Question 6

What do the switches in the pedals provide?

Answer 6

Below 50kts, heading hold
Above 50kts, heading hold and turn coordination

Question 7

What are the 3 boost servos?

Answer 7

Pitch
Yaw
Collective

Question 8

What are the subsystems of AFCS?

Answer 8

SAS
Trim
FPS
Stabilator
Coupled Flight Director

Question 9

What does the stabilator do?

Answer 9

Improves flying quality by positioning the stabilator through electromagnetic actuators in response to collective, airspeed, pitch rate and lateral acceleration inputs

Question 10

What does SAS provide?

Answer 10

Stability Augmentation System. Provides short term rate dampening in pitch, roll, and yaw axes

Question 11

What is trim?

Answer 11

Control positioning and force gradient functions

Question 12

What does AFCS provide?

Answer 12

Heading hold
Pitch and roll attitude hold
Cyclic, collective, pedal trim
Stabilator control
Pitch, roll, and yaw stability augmentation
Pitch and toll hover augmentation
Turn coordination
Fault detection
Coupled FD integration

Question 13

What controls the AFCS?

Answer 13

The 2 FCCs

Question 14

What is the inner loop and outer loop control?

Answer 14

Inner loop (SAS) employs rate dampening to improve stability. It is fast in response, has limited authority, doesn’t move flight controls

The outer loop (trim) provides long term inputs. Can drive the controls through their full range of motion at a limited rate of 10% per second

Question 15

With SAS 1 or SAS 2 off, how much is the authority reduced?

Answer 15

by 1/2 or 5%

Question 16

What drives the trim actuators?

Answer 16

2 FCC, there is no backup

Question 17

What is a stabilator?

Answer 17

Variable angle of incidence that enhances qualities in the pitch axis in forward flight

Question 18

What are the 5 functions of the stabilator?

Answer 18

-Align stab to M/R downwash in low speed flight to minimize nose up attitude
-Decrease angle of incidence with increase in stability
-Provide collective coupling to minimize pitch attitude excursions, begins at 30kts
-Pitch rate feedback for gusts, sudden pitch up will cause the stabilator to trail down
-Sideslip to pitch coupling to reduce gusts, from M/R downwash on the stabilator. Nose left, trails down. Nose right, trails up