Mod 7-8-9

Question 1

vibration ranges 3 types ?

Answer 1

-Low
Vibrations less than 500 Hz Example: Main Rotor
-Medium
Vibrations between 500 Hz and 2000 Hz Example: �2 per Rev� Main rotor or airframe vibrations
-High
Vibrations above 2000 Hz Example: Tail Rotor, Drive Shafts, Fan Shafts, and cooler blowers

Question 2

They will be low frequency because of the RPM of the main rotor (less than 500 RPM). Main Rotor vibrations can show up in two forms:

Answer 2

Lateral

Vertical

Question 3

The blades are considered aligned when the_________________________ of the blade is aligned with the feathering axis for the blade.

Answer 3

center of pressure

Question 4

which balance should be adjusted first?

Answer 4

chord wise as it will have an effect on the span wise balance.

Question 5

Never sweep a blade________ of the alignment position. A move of the alignment position may cause the rotor system to become unstable.

Answer 5

forward, forward

Question 6

where you add weight for Chord wise Balance:

Answer 6

Blade can be swept aft of alignment position

Weight may be added to the main rotor hub

Question 7

where you add weight for Span wise Balance:

Answer 7

Weight is added to the blade bolts

Question 8

track is adjusted two ways:

Answer 8

Pitch Links

Blade Tabs

Question 9

If a low frequency vertical vibration is consistent from a hover to high-speed forward flight, it indicates that a ________ should be adjusted.

Answer 9

pitch link

Question 10

If a low frequency vertical vibration increases with airspeed, it is an indication that a ___ should be adjusted.

Answer 10

tab

Question 11

Static balance of the tail rotor is commonly done one of two ways

Answer 11

Horizontally (Marvel Universal balancer)

Vertically (Knife Edge Stand)

Question 12

vibration management static balance ?

Answer 12

part is fully assemble but not installed

Question 13

vibration management dynamic balance ?

Answer 13

part is installed and aircraft is running and sometimes flying

Question 14

vibration management final acceptance ?

Answer 14

autorotation RPM adjustment

Question 15

what is target ?

Answer 15

the reference blade or point

Question 16

what is blank?

Answer 16

opposite to the target

Question 17

what is clock angle ?

Answer 17

location of the vibration

Question 18

what is ips

Answer 18

inches per second. level of vibration

Question 19

helicopter stability Dynamic stable means ?

Answer 19

the helicopter will recover to its original position , oscillations decrease to nothing

Question 20

helicopter stability Dynamic unstable means ?

Answer 20

the helicopter will not recover from its original position, oscillations get worse

Question 21

helicopters are naturally ?

Answer 21

Dynamically unstable

Question 22

_________ change the tip path plane of the blades through out all speeds

Answer 22

pitch links

Question 23

_________ change the tip path plane of the blades at higher speeds

Answer 23

tab

Question 24

if the vibration changes with speed we called that ?

Answer 24

speed sensitive -adjust with tab

Question 25

vibration non speed sensitive are adjusted by ?

Answer 25

pitch link

Question 26

flight directors are for __________

Answer 26

navigation

Question 27

autopilots are for ________

Answer 27

stability

Question 28

Basic autopilot modes are

Answer 28

SAS, ATT and CPL

Question 29

The autopilot cannot couple to the _____________

Answer 29

flight director in SAS

Question 30

Flight director commands can be______________ while the autopilot is engaged in the ATT mode

Answer 30

flown manually

Question 31

SAS is a _________ mode and ATT is a ________mode

Answer 31

hands-on, hands-off

Question 32

Coupled (CPL) Mode

Answer 32

the autopilot(s) follow flight director lateral and vertical steering commands to achieve the pilots desired flight path. In coupled flight, the AFCS computer is truly flying the helicopter.

Question 33

ATT (Attitude Retention Mode)

Answer 33

designed to be a hands-off mode. In the ATT mode, the autopilot pitch and roll channels are engaged to maintain the attitude existing at the moment of autopilot engagement.

Question 34

SAS (Stability Augmentation System)

Answer 34

it supplies short-term attitude and attitude rate stabilization for use in hands-on flying.

Question 35

what would mean that the center of mass of the rotor system is not in line with the center of rotation?

Answer 35

In industry a lateral vibration may be referred to as a �shuffle�

Question 36

what is the name of the movement when blades are allowed to move on a vertical hinge.

Answer 36

This movement is known as �hunting�.

Question 37

Vertical Vibrations are?.

Answer 37

an out of Track condition and are referred to as a �Hump�

Question 38

The weights on the pitch horns are used to correct for ________on non-hydraulic tail rotor systems.

Answer 38

�pedal creep�

Question 39

a condition where aerodynamic twisting force or centrifugal twisting force will attempt to change the pitch of the tail rotor, causing the tail rotor pedals to move away from the neutral position.

Answer 39

PEDAL CREEP