Potential Hazards/Emergencies Flashcards
Settling with power
A condition of powered flight in which the helicopter settles in its own downwash (vortices)
- *Caused by a vertical or near vertical descent rate of at least 300ft/min depending on:
- gross weight,
- rotor RPM,
- density altitude.
- *Using 20% to 100% available engine power with insufficient power remaining to arrest the descent. **Slow forward airspeed, less than ETL.
- *— know the numbers above —**
Flight conditions:
- hovering above max hover ceiling
- OGE hover within hover ceiling, but failing to maintain constant altitude
- formation flights (turbulence)
- mask/unmasking
- downwind approaches
- steep approach with high rate of descent
- Recovery procedures:*
- increase airspeed with cyclic
- reduce collective pitch as altitude permits
- adjust rotor RPM to normal operating range
Autorotation
Autorotation is a flight condition during which no engine power is supplied and the main rotor is driven only by the action of the relative wind
A/C transmissions are designed to allow the rotor to rotate freely, providing a method of landing if the engine were to fail
- Rotor RPM stabilizes when rotor system reaches aerodynamic equilibrium
- RPM will remain stable unless there is a change in the up flow of relative wind entering the rotor system
- rotor RPM will increase during autorotative turns (tilted disk, higher rate of descent, pilot prevents overspeed with cyclic)
Dynamic Rollover Condition
A helicopter’s susceptibility to lateral rolling tendency
- Pivot Point
- Rolling motion
- exceed critical angle
- Pivot point - skid, wheel, or portion of A/C in contact with ground. Sluggish and less effective lateral cyclic response: failure to remove tiedown, skid/wheel contact with fixed object, gear stuck in ice/mud, slope operations
- Rolling motion - roll rate is vital, as the roll increases, critical angle is reduced, in a fully articulated system, all three flight controls can contribute to rolling motion
- Exceed Critical Angle
- static angle: the point where A/C CG is located over the pivot point.
- critical angle: when a rolling motion is present, the dynamic rollover angle is introduced and is called the critical angle.
- Rolling on level ground: skid/wheel is stuck, becomes pivot point
- Rolling downslope: slope causes aircraft to tip beyond lateral cyclic limits
- Rolling upslode: during takeoff when aviator applies too much cyclic into the slope to hold the skid/wheel firmly on the slope, the. Improperly applies collective
- PHYSICAL FACTORS: (know this, not bullets)
- main rotor thrust
- center of gravity
- tail rotor thrust
- crosswind component
- ground surface
- sloped landing area
- in some A/C low fuel condition causes CG to move
- HUMAN FACTORS: (know this, not bullets)
- inattention
- inexperience
- failure to take timely action
- inappropriate control input
- loss of visual reference
Contributing factors:
- failure to detect lateral motion during landing
- abrupt cyclic displacement (with or without thrust) in fully articulated systems
- large/uncoordinated anti-torque pedal inputs
- performing slope landings/takeoffs using rapidly increasing or decreasing collective control
ONE RECOVERY METHOD: A smooth, moderate collective reduction
Stall
Aerodynamic stall occurs when an increase in the angle of attack results in a decrease in the coefficient of lift (separation layer moves forward)
Caused when the angle of attack exceeds the critical angle of attack. All stalls are corrected by reducing angle of attack lower than the critical angle
Retreating blade stall:
- retreating blade operates at a lower relative wind than advancing
- greater angle of attack is applied to retreating blade to compensate
- effect of the stall is displaced aft due to gyroscopic precession
RBS Factors (minus DA, same factors as blade coning)
- Primary: excessive airspeed
- Contributing: high GW, high DA, High “G” maneuvers, low rotor RPM, Turbulence
RBS Symptoms:
- abnormal vibration
- pitch up of nose
- tendency to roll toward stall (left) side
- loss of control (if corrective action not applied)
RECOVERY: (initial response**)
- Reduce collective
- regain control of the aircraft
