Rfh-11

Front 1

define autorotation

Back 1

descending maneuver where the engine is disengaged from the main rotor system and the rotor blades are driven solely by the upward flow of air through the rotor

Front 2

reasons for autorotation

Back 2

- engine failure
- complete tail rotor failure (because there is virtually no torque produced in an autorotation)
- to recover from settling with power

Front 3

what is the freewheeling unit?

Back 3

a mechanical device that automatically disengages the engine from the main rotor anytime the engine r.p.m. is less than the rotor r.p.m.

Front 4

when does the freewheeling unit disengage

Back 4

anytime the engine r.p.m. is less than the rotor r.p.m.

Front 5

what produced thrust during autorotative descent?

Back 5

upward flow of air through the rotor provides sufficient thrust to maintain rotor r.p.m. throughout the descent

Front 6

lowering the collective during an autorotation does what to lift, drag, and thrust?

Back 6

reduces lift and drag, causing an immediate descent, which produces an upward flow of air through the rotor system, providing sufficient thrust to maintain rotor r.p.m. throughout the descent

Front 7

what drives the tail rotor during an autorotation?

Back 7

the main rotor (transmission)

Front 8

factors that affect the rate of descent in autorotation

Back 8

- density altitude
- gross weight
- rotor r.p.m.
- airspeed
- wind (speed and direction)

Front 9

your primary control of the rate of descent in autorotation

Back 9

airspeed

Front 10

rate of descent is slowest at which airspeeds?

Back 10

50-60 kts

Front 11

what control adjusts airspeed in autorotation

Back 11

cyclic pitch control
forward = nosedive = faster
aft = flare/balloon = slower

Front 12

during an autorotation, what is the (kinetic) energy in the rotating blades used for?

Back 12

to decrease the rate of descent and make a soft landing

Front 13

why is it important nail your recommended airspeed during an autorotation?

Back 13

rate of descent increases for airspeeds beyond (higher or lower) than the range which gives minimum rate of descent (50-60 kts)

Front 14

why are higher airspeeds bad for an autorotation?

Back 14

higher airspeeds increase
- rate of descent (which decreases decision-making time)
- amount of rotor energy required to stop (you may not have the rotor energy you need)

Front 15

how is airspeed for autorotations established for each type of helicopter?

Back 15

on the basis of average weather and wind conditions and normal loading (which you may not have when you're forced to do an auto)

Front 16

best performance autorotation airspeed with heavy loads, in high density altitude, or gusty wind conditions

Back 16

slightly faster than recommended

Front 17

best performance autorotation airspeed with light loading or low density altitude

Back 17

slightly slower than recommended

Front 18

which controls should be used to make turns during an autorotation?

Back 18

cyclic only, not pedals

Front 19

why shouldn't pedals be used to make turns in an autorotation?

Back 19

use of pedals causes loss of airspeed and downward pitching of the nose

Front 20

how should pedals be used in an autorotation?

Back 20

to maintain straight flight and prevent yawing

Front 21

how is r.p.m. managed/controlled during an autorotation?

Back 21

the collective is raised to lower r.p.m. and lowered to raise r.p.m. to keep it within the normal operating range (green arc)

Front 22

during an autorotation, why does r.p.m. increase during a turn?

Back 22

increased airflow through the rotor disc. The tighter the turn and the heavier the gross weight, the higher the r.p.m.

Front 23

how do you initiate a practice autorotation?

Back 23

- choose your landing zone
- lower the collective full down
- roll off the throttle and keep it closed
- split the needles

Front 24

rate and amount of flare determine what?

Back 24

speed at touchdown and the resulting ground run

Front 25

a higher degree of flare or holding the flare longer results in

Back 25

slower touchdown speed and shorter the ground run

Front 26

conditions prior to initiating a straight-in auto

Back 26

- level flight at recommended airspeed
- 500-700 ft AGL, 0 VSI
- heading into the wind, upwind

Front 27

straight-in auto procedure (up to the flare)

Back 27

- smoothly lower collective full down
- maintain r.p.m. in green arc with throttle
- right pedal to maintain trim
- aft cyclic to maintain airspeed and attitude for best glide distance and rate of descent
- cross check airspeed, r.p.m., LZ, attitude, trim
- roll off throttle to split the needles (but keep above normal idle)
- maintain r.p.m. in the green arc with the collective (aft cyclic inputs will increase r.p.m.)

Front 28

straight-in auto flare

Back 28

- 40-100 ft (50 ft.) AGL, begin the flare with gentle aft cyclic to reduce airspeed and rate of descent
- pull in a little collective
- maintain heading with pedals
- 8-15 ft (10 ft) AGL level out of the flare
- avoid nose high or tail low attitude below 10 ft AGL
- increase collective and roll on throttle coming out of the flare to cushion the landing
- add right pedal to counteract increased throttle (and torque)
- touch down in a level attitude

Front 29

power recovery from an auto procedure

Back 29

- at 8 to 15 ft (10 ft) AGL, level the helicopter
- avoid nose high or tail low attitude below 10 ft AGL
- increase collective and throttle to join the needles (too much/fast throttle = overspeed; too little/slow throttle = rotor r.p.m. decay)
- use pedals to maintain heading
- add right pedal to counteract increased throttle (and torque)
- hover, descend to a landing
- or forward cyclic for a go-around

Front 30

why are 90, 180, or 360 autos (aka. autos with turns) made

Back 30

- to land into the wind
- avoid obstacles
- hit a landing zone (available LZ may be behind you)

Front 31

180 auto entry point

Back 31

- flight path 700 ft AGL, parallel to LZ, 200 ft away
- initiate abeam the LZ (1500 MSL, better than 60 kt, 0 VSI)

Front 32

2nd 180 turn should be completed

Back 32

- to roll out on the centerline
- prior to 100 ft AGL

Front 33

setup for hovering autos

Back 33

- normal hovering attitude
- headed into the wind
- hold maximum allowable r.p.m.

Front 34

hovering auto procedure

Back 34

- roll throttle into spring-loaded override position
- right pedal (to counteract loss of torque, then pedals neutral)
- right forward cyclic (to counteract left drift from loss of tail rotor thrust)
- level attitude and vertical descent on entry using the cyclic
- allow helicopter to settle
- pull collective (full up) at 1 ft AGL to cushion the landing
- keep throttle closed to prevent rotor from reengaging
- when the weight of the helicopter is entirely on the skids, full down collective

Front 35

define height-velocity diagram (long answer)

Back 35

- aircraft-specific chart published by the manufacturer showing an aircraft's performance capabilities (advisory performance info, not a limitation, flight in avoid areas not restricted)
- shaded or cross-hatched portions indicate critical combinations of altitude and airspeed to be avoided from which an average pilot would not have time to safely transition from powered flight to autorotation
- two sides: low speed (left, A), high speed (right, B), with a recommended takeoff profile in between
- right side is arguably more critical, since high speed, low altitude flying greatly limits reaction time
- overall, the 50/50 rule is to keep airspeed above 50 kt until below 50 ft AGL
- chart errs on the side of caution, because to develop the diagram, the aircraft is loaded to maximum gross weight and worst center of gravity (HAI Rotor magazine, 2002)

Front 36

why is engine failure in a climb after takeoff most critical?

Back 36

a helicopter is operating at higher power settings and blade angle of attack (vs. lower power settings and AOA during landing)

Front 37

define height-velocity diagram (short answer)

Back 37

chart showing critical combinations of altitude and airspeed from which you may not have enough time to perform a safe and successful autorotation

Front 38

define gross weight vs. density altitude chart

Back 38

aircraft-specific chart published by the manufacturer showing an aircraft's autorotative capability during takeoff and climb (advisory in nature, not a restriction to gross weight)

Front 39

define settling with power (short answer)

Back 39

when the helicopter settles in it's own downwash
you could also think of it as loss of main rotor efficiency (LME)

Front 40

define settling with power (long answer)

Back 40

- aerodynamic condition where a helicopter's rate of descent is accelerating by reingesting it's downwash
- power from the engine is wasted in accelerating the air in a doughnut pattern around the rotor
- also known as vortex ring state or toroidal ring state (toroid from the Latin torus for bulge or knot)