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10 Cards in this Set
- Front
- Back
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Low Rotor RPM
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- Anytime The Rotor RPM Is Below 101%
(Below The Green Arch) -> 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 |
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Blade Stall
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- All Lift Is Lost
**NO RECOVERY / Fatal** - So Much Drag There Is NO Aerodynamic Way To Recover Note: - Retreating Blade Will Stall First |
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Blowback / Tailboom Chop
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- Byproduct Of Low Rotor RPM Blade Stall
Why: - 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 Recognition: - LT Nose Yaw - Engine Quiet - Low Horn & Light - Tachs Recovery: - Simultaneous Down Collective & On Throttle Note: - Down Collective Alone Will Not Correct Problem -> B/C Engine & Rotor RPM Are Intrinsically Linked -> B/C Of The Correlator -> Down Collective = Lower Throttle Prevention: - Make Sure Low H/L Warning System Is Operational - Make Sure Governor Is On & Working - No Kung Foo Grip |
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Low G Pushover
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- Anytime The Helicopter Is Placed In A Weightless State
Note: - 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 |
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Mast Bumping
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- 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 Note: - This Only Occurs In UNDERSLUNG Rotor Systems Recovery: - Gentle Aft Cyclic To reload The Rotor System - Roll Out Of The Turn Prevention: - 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 |
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Ground Resonence
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- 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 Requirements: - Fully Articulated Rotor System - Ground Contact Leading Causes: - Rough / Hard Landing - Bad Dampeners (Make It Worse) Recovery: - 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 |
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Dynamic Rollover
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- 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 Requirements: - Pivot Point - Some Lift In Use -> Enough Pitch To Create Lift - Rolling Moment Recovery: - 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 Note: - @ 15 Degrees The Max Thrust Vector For Rollover Is Reached - 15 Degrees = Critical Angle Note: - Cyclic Travel Only Has 9 Degrees Of Travel - Therefore, Opposite Cyclic Will Not Correct The Problem - B/C There Is Not Enough Cyclic Travel Prevention: - Good Preflight -> Check Skids - Stay Clear Of Obstacles -> Hover High Enough - 2 Step Pickup - Consider Wind & CG |
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Retreating Blade Stall
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- 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 Recognition: - 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 Recovery: - Down Collective / Aft Cyclic - Whatever Input Was Made - Take It Out -> IE: Too Fast - Slow Down -> IE: Abrupt Turn - Roll Out Note: - Retreating Blade Moves Out Of The Wind - Retreating Blade Is Slower - Retreating Blade Flaps Down - Retreating Blade Has A Larger AA Note: - Advancing Blade Moves Into The Wind - Advancing Blade Is Faster - Advancing Blade Flaps Up - Advancing Blade Has A Smaller AA Note: - Blade Flapping Occurs To Compensate For Dissymetry Of Lift Note: - Nose Pitch Up Is Caused By Gyroscopic Procession -> Stall Displacement Will Be Felt 90 Degrees After The Stall Starts Note: - Lt Roll Occurs B/C Ret. Blade Continues To Flap Down |
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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 Recognition: - Sudden Rapid Descent - Pitching & Yawing - Mushy Controls Recovery: - 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 Note: 3300 Rule -> Don't Loose 30 KIAS Until ROD Is > 300 FPM Note: - 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 |
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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 Recognition: - Uncommanded Yaw Conditions: - High FWD Airspeed / High Power Contributing Factors: - Low Rotor RPM - Tail Wind - Not Paying Attention To Wind Direction Recovery: - Immediate Opposite Pedal - FWD Cyclic To Get Out Of Vorticies Prevention: - Fly Into The Wind |
