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10 Cards in this Set

  • Front
  • Back
Low Rotor RPM
- Anytime The Rotor RPM Is Below 101%
(Below The Green
-> Green Arch: 101% To 104%

- Over Pitch For The Power Available

- So Much Drag The Engine Can Not Keep Up (Engine Does Not Have Enough Power To Overcome Drag)

- The Slower The Blade Spins, The Larger The Angle Of Attack Needed To Create The Same Amount Of Lift

- As The Rotor Rpm Decreases Engine RPM Will Decrease Intrinsically
-> 10% Less Rotor RPM Equals
-> 10% Less Engine RPM
-> Crack House Analogy

- Pulling Pitch To Make More Power Creates More Drag
-> Further Exacerbating The Situation

- Finally The Airflow Will Serpate From the Airfoil
-> Causing A Stall
-> (ROT) Stall Occurs @ 80% Plus 1% Per 1000 Ft
Blade Stall
- All Lift Is Lost
**NO RECOVERY / Fatal**
- So Much Drag There Is NO Aerodynamic Way To Recover

- Retreating Blade Will Stall First
Blowback / Tailboom Chop
- Byproduct Of Low Rotor RPM Blade Stall

- Nose Low Attitude
-> Results In FWD CG
-> Air Stiking The Rear Stabilizer From Underneath

- Pilot Will Try To Correct With Full Aft Cyclic
-> Disc Tilts Rearward
-> Nose Low Attitude
-> Tailboom Chop

Leading Causes:
- High DA, High GW
-> Engine Already @ Max Power
-> More AA = More Drag
- Kung Foo Grip On Throttle
-> Holding Power Back
- Lazy Governor

- LT Nose Yaw
- Engine Quiet
- Low Horn & Light
- Tachs

- Simultaneous Down Collective & On Throttle

- Down Collective Alone Will Not Correct Problem
-> B/C Engine & Rotor RPM Are Intrinsically Linked
-> B/C Of The Correlator
-> Down Collective = Lower Throttle

- Make Sure Low H/L Warning System Is Operational
- Make Sure Governor Is On & Working
- No Kung Foo Grip
Low G Pushover
- Anytime The Helicopter Is Placed In A Weightless State

- Weightless State = Less Than 1x The Force Of Gravity

- Unloads The Rotor System
- Loss Of Pendular Action

- Helicopter Is Free To 'Float' Independent Of The Rotor System

- Tail Rotor (Still Loaded)
-> Causes Roll In The Direction Of TR Thrust
-> Right Roll

Leading Causes:
- Any Condition That Unloads The Rotor System
- Abrupt FWD Cyclic
- Leveling Off Too Quickly After A Climb
- Turbulance (Wind Shear)
- Collision Avoidence
Mast Bumping
- Byproduct Of Low G

- In The RT Roll
-> Caused By Loss Of Pendular Action and
-> Tail Rotor Thrust

- Pilot Uses Hard LT Cyclic To Recover From RT Roll
-> Since NO Pendular Action
-> Helicopter Remains In The RT Roll
-> While The Disc Is Tilted Full LT
-> The Rotor Blades Then Contact The Rotor Mast On Every Revolution
-> Ultimately Severing Rotor System

- This Only Occurs In UNDERSLUNG Rotor Systems

- Gentle Aft Cyclic To reload The Rotor System
- Roll Out Of The Turn

- No Abrupt FWD Cyclic
- Slow Down For Turbulence
-> Reduces FWD Momentum
-> Less Nose Low Attitude
-> Lower Tail = Less TR Thrust Vector For RT Roll
- Gradual Level Off After Climb
- Turn For Collision Avoidence
Ground Resonence
- Occurs In A Helicopter With A Fully Articulated Rotor System
- When Blades Become Out Of Phase With Each Other
- Thru The Lead & Lag Hindge
-> Used To Fix Coreolis Effect
-> R22 Uses Underslung
- Due To Shock Contact With The Ground
-> Rough Landing
-> Usually In Wheeled Helicopters
- Ultimately Shaking The Helicopter Apart
-> Washing Machine Analogy

- Fully Articulated Rotor System
- Ground Contact

Leading Causes:
- Rough / Hard Landing
- Bad Dampeners (Make It Worse)

- If Rotor RPM Is Still In The Green Arch
-> Pick Helicopter Up
-> Blades Should Rephase Themselves
- If Rotor RPM Is Out Of The Green Arch
-> Get It On The Ground
-> Shut It Down Immediately
Dynamic Rollover
- The Tendency Of The Helicopter To Continue Rolling Past Its Critical Angle
-> Critical Angel = 15 Degrees
- With A Pivot Point
-> Usually A Stuck Skid
- Some Lift In Use
- A Rolling Moment
-> Momentum Of The Helicopter Rolling

- Pivot Point
- Some Lift In Use
-> Enough Pitch To Create Lift
- Rolling Moment

- Immediate Down Collective

Contributing Factors:
- Poor Preflight
-> Check Skids
- Obstacle Clearance
-> Hover High Enough
- Rushed Pickup
- Failure To Consider Wind & CG
-> Mitch & TB v. Mitch & Jeff

- @ 15 Degrees The Max Thrust Vector For Rollover Is Reached
- 15 Degrees = Critical Angle

- Cyclic Travel Only Has 9 Degrees Of Travel
- Therefore, Opposite Cyclic Will Not Correct The Problem
- B/C There Is Not Enough Cyclic Travel

- Good Preflight
-> Check Skids
- Stay Clear Of Obstacles
-> Hover High Enough
- 2 Step Pickup
- Consider Wind & CG
Retreating Blade Stall
- Caused By Excess Flapping
- Leads To Exceeding The
Critical AA On Retreating Side Of The Rotor System
- Causing Blade Stall

Leading Causes:
*Excess Flapping*
- Flapping Compensates For Dissymetry Of Lift
- Leads To An Increased Angle Of Attack
- Critical Angle Is Reached
- Blades Stalls
- Blades Stall Starts @ The Tip
-> B/C Ret. Blade Tip Is The Lowest Downflapped Portion
-> Works Its Way In

- Deep Low Vibes
- Nose Pitch Up (Gyro)
- Lt Roll (Ret. Blade Is Stalling)

Leading Causes:
- High FWD Airspeed
-> The Slower The Retreating Blades Gets
- Abrupt Lt Cyclic Turns
-> Lower Dip (Flap) Of The Ret. Side
-> The Slower The Ret. Side Gets (Rt Turns)
- Turbulence (Wnd Shear)
-> Tail To Head Wind
-> Slows The Ret. Side More
- Low Rotor RPM
-> Slows The Ret. Side More

- Down Collective / Aft Cyclic
- Whatever Input Was Made - Take It Out
-> IE: Too Fast - Slow Down
-> IE: Abrupt Turn - Roll Out

- Retreating Blade Moves Out Of The Wind
- Retreating Blade Is Slower
- Retreating Blade Flaps Down
- Retreating Blade Has A Larger AA

- Advancing Blade Moves Into The Wind
- Advancing Blade Is Faster
- Advancing Blade Flaps Up
- Advancing Blade Has A Smaller AA

- Blade Flapping Occurs To Compensate For Dissymetry Of Lift

- Nose Pitch Up Is Caused By Gyroscopic Procession
-> Stall Displacement Will Be Felt 90 Degrees After The Stall Starts

- Lt Roll Occurs B/C Ret. Blade Continues To Flap Down
Settling With Power
Vortex Ring State
- A Condition In Downward Flight In Which The Helicopter Decends In Its Own Vorticies

Leading Causes:
- Steep Approach
- Low FWD Airspeed
- Less Than ETL (> 30 KIAS)
- High DA / High GW
- Low Airspeed With A Tailwind
- Hover Out Of OGE Ceiling
- Flopping (Ballooning) Auto

- Sudden Rapid Descent
- Pitching & Yawing
- Mushy Controls

- Down Collective / FWD Cyclic
-> Down Collective Reduces Vorticies (Less Drag)
-> FWD Cyclic Moves Helicopter In Front Of Vorticies
- Once Airspeed Is Established
-> Pull Pitch & Climb Out

3300 Rule
-> Don't Loose 30 KIAS Until ROD Is > 300 FPM

- Settling With Power Becomes Worst When Wind Shifts From Being Sucked Down Thru The Rotor To Being Pushed Up Thru
-> Creating A Second Set Of Vorticies Closer To The Center Of The Rotor System
-> Further Reducing Lift
Loss Of Tail Rotor Effectiveness
(4 Types)
- Unanticipated Yaw B/C Of Diminished Or Lost Tail Rotor Thrust
- Not Related To Equipment Malfunction

4 Types:

1. Main Rotor Disc Interference
- Caused By A Left Quartering Headwind
- Main Rotor Vorticies Are Blown Back Into The Tail Rotor

2. Weather Cock Instability
- Caused By A Tailwind
- Tail Wants To Yaw With The Wind
- The Wind Trys To Force The Nose Into The Wind

3. Tail Rotor Vortex Ring State
- Caused By A Left Crosswind
- Vorticies Of The Tail Rotor Get Blown Back Into The Tail Rotor

4. LTE @ Altitude
- The Air Is Not Thick Enough For The Tail Rotor To Maintain Sufficiant Thrust

- Uncommanded Yaw

- High FWD Airspeed / High Power

Contributing Factors:
- Low Rotor RPM
- Tail Wind
- Not Paying Attention To Wind Direction

- Immediate Opposite Pedal
- FWD Cyclic To Get Out Of Vorticies

- Fly Into The Wind