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PTS Spin Awareness
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Contents:
...D. Task: SPIN AWARENESS; ...Sources of Inadvertent Stalls Becoming Spins;
...Endorsement For Spin Awareness;
…Spinning out of the Clouds;
…Inadvertent Spin Causes; …Intentional Spins Prohibited; …Placards; …Spin
Training and Parachutes; …Types
of Spins; …
REFERENCES; AC 61-21, AC 61-67, operating handbook, flight manual
P 1. Knows flight situations where unplanned spins may occur.
P 2. Recognizes unintentional incipient spin and knows procedure
for recovery
P 3. Explains recovery procedure for aircraft used for the practical
test.
SPIN AWARENESS REQUIREMENT
Flight situations where spins may occur recognize recovery techniques, recovery procedure for aircraft used on the test. An established spin is an aggravated stall with developed autorotational forces. Gravity causes a helical path during the descent. The aerodynamic and inertial forces are balanced. You must upset this balance to recover. The stall, which has directional control, occurs at an angle of attack near 17 degrees. In a spin the down wing may have an angle of attack of 70-80 degrees while the up wing will be between 30 and 40 degrees. The stall prelude to the spin lacks directional control (rudder). Stall/spins account for 12% of general aviation accidents, but 25% of fatal accidents. And upwards of 20% of the fatal stall/spins occur with CFI's on board! Find out what you need to know to avoid stall/spin
ANGLE OF ATTACK Angle the wing chord line has when it meets the relative wind.
The CRITICAL ANGLE OF ATTACK---Will always result in a stall. The flow of air cannot follow the curve of the wing. For a given flying surface the critical angle of attack never changes. The airspeed at which a flying surface will stall depends on aircraft weight, balance, and load factor.
RELATIVE WIND Speed and direction of wind caused by aircraft movement. Velocity of relative wind is equal but opposite to speed of aircraft.
Normal category aircraft are placarded against spins but they
are factory/FAA tested to one turn (or three seconds) with a one-turn
recovery when controls are used correctly.
1. Speeds and load factors are not to be exceeded.
2. Flaps may be retracted.
3. No uncontrollable spins possible.
4. No acrobatics or spins allowed.
5. The weight and CG certification of the aircraft will determine
its spin characteristics and recovery procedures.
6. Beyond one turn even correct control input may not work.
Normal category aircraft that are placarded against spins must
be considered as being non-recoverable from spins.
Certification today does not include ability to recover from a
fully developed stabilized spin. The required one turn recovery
is only the incipient stage of the spin. Aerobatic aircraft have
not been tested beyond six turns.
Sources
of Inadvertent Stalls Becoming Spins
1. Inadequate rudder application in steep climbs. Climb power
raises nose, decreases airspeed and increases P-factor.
2. False concept of air speed when on base due to a tailwind.
Peripheral vision can sense the illusion and send it to the brain.3.
Letting nose pitch up and airspeed drop when applying power.
4. Having aircraft enter 'reverse command' area in pattern. A
speed so slow and power so high that the only recourse is to lower
the nose for flying speed.
5. Use of rudder to increase rate of turn from base to final.
Keep ball centered during turns.
6. Distractions from primary purpose of aircraft control. This
is now a required part of the flight test.
7. Trying to stretch a glide at a speed below best glide speed.
If you don't know best glide, use best climb. It will be close.8.
Attempting to return to runway after engine failure. Practice
at altitude and then add 50% fudge factor.
Stalls do not cause spins. A spin is initiated where the pilot includes or fails to include, rudder, aileron, or power individually or in combination during a stall. Auto rotation occurs from an asymmetrical stall and a sideslip. There is an abrupt loss of control when leaving the stall and entering the spin. The untrained pilot will always react instinctively and apply controls incorrectly thus aggravating the spin entry.
An incipient phase occurs when the foregoing stall is accompanied by uncoordinated yawing. The yaw induces a roll due to increased asymmetric lift on the wing opposite to the applied rudder. The aerodynamic differences from uncoordinated stalled flight causes the nose to drop. The autorotation to follow is quite varied as long as the dynamic and inertial forces are unbalanced. Airspeed will be changing but the faster the entry the longer it takes to stabilize the spin. By the second turn we may be in a developed (stabilized) spin. IAS will be pegged a few miles above 1G stall speed. Descent will vary but can reach 7500' fpm.
Know how to recognize the beginning of a spin. Quickly apply the proper control input. Get out of the incipient spin before it has a chance to develop. In a developed spin an aircraft prohibited for spins may be unrecoverable. To prevent this development from occurring the recognition and recovery from an incipient spin is a desirable training goal. The first turn of a spin causes the greatest loss of altitude, as much as 800' to 1000'. High-density altitude causes faster rate of spin and greater loss of altitude.
Recovery: Immediately, power off, opposite rudder, forward on yoke always in this sequence. If rudder is effective yoke forward may not be necessary. Otherwise, hold full application of controls until recovery. Check turn coordinator for direction if in doubt. The proper recovery from the incipient spin must be initiated at once or the yaw rate will become faster and the nose more toward the vertical.
Endorsement For Spin Awareness
(Required logbook endorsement)
I certify that I have given _____holder of pilot certificate # ________ ground and flight instruction in stall awareness, spin entry, spins and spin recovery technique and find that he/she meets the knowledge requirements required under FAR61....see above.
Dated...
Signed..
Spinning
Out of the Clouds
A spiral dive or a spin have very much the same instrument
indication. You will be in a higher rate of descent. The turn
coordinator and attitude indicator will show a steep bank. The
AI will show nose down. Airspeed will tell you the
difference. High to redline speeds indicate a spiral. Below stall
speed means you are in a spin.
PARE for recovery.
Power off
Ailerons neutral
Rudder opposite to TC
Elevator forward
Inadvertent
Spin Cause
Any time the critical AOA is exceeded while inappropriate
rudder effect exists to either side; a stall/spin situation is
precipitated.
---Airspeed indicator and altimeter are unreliable.
---Yaw can occur due to asymmetric thrust of propeller blade
---Go-around or short field takeoff
---Cross controls applied during turn with the spin direction
of the rudder
---In a skid with aileron and rudder in the same direction spin
will be in direction of the controls.
---In a slipping turn with opposite controls applied the spin
will be opposite to the applied aileron.
Intentional
Spins Prohibited
In 1974, 45% of fatal accidents were attributed to stall/spin
causes. Some aircraft are placarded against intentional spins
because the aircraft may become uncontrollable in a spin. In the
year 2000 the original document has quadrupled in size.
Changes are highlighted. A spin is a maneuver in which the airplane
descends in a helical path while at an AOA greater
then the critical AOL. A spin cannot occur until a stall occurs.
At the stall the introduction of yaw will cause the spin out
of either a skid or slip.
---Normal Category:
Able to recover from one-turn of three-second spin in one additional
turn using normal recovery. Recovery may not have
excessive back pressure during recovery and be impossible to enter
an uncontrollable spin. Flaps are retracted during
recovery only when rotation has ceased. 2-G load limit applies
with flaps extended. Controls or characteristics
must not prevent prompt recovery. Part 23 certified aircraft
must be placarded against doing spins.
Placards
Part 23 requirement:
--Normal category, "No acrobatics or spins."
--Utility category, Placarded list of what is allowable."
Some placarded against spins.
--Acrobatic category: Allowed maneuvers and entry speeds. Notation
about inverted flight. Additional placards giving
spin recovery SOP and quitting if spiral or more than six turns
unless placarded for more turns.
Spin
Training and Parachutes
Any maneuver that exceeds 60 degrees of bank or 30 degrees
in pitch is prohibited unless occupants have parachutes.
Does not apply if qualified instructor is doing required maneuvers
of pilot certificate of rating. Solo pilots may perform these
maneuvers without parachutes.
Flight instructor applicant must have flight training in stall
awareness, spin entry, spins, and spin recovery. Applicant must
possess and demonstrate instructional proficiency in these areas.
Parachutes are not required for this training.
---Acrobatic Category
Able to recover any time from spin in not more than 1 1/2 additional
turns using normal recovery control.
Spin test must be for the longer time up to six-turns or six
seconds. With flaps extended time of the longer of one turn or
three seconds. Beyond three turns discontinue if spiral
characteristics appear with flaps retracted. Flaps not
to be
retracted during recovery. Load limits may not be exceeded.
No uncontrollable spin using controls or engine must
be possible. No spin characteristic can cause disorientation
or incapacitation of the pilot.
---(Utility) Category
Approved list of maneuvers on placard. Notation if not for
inverted flight. An aircraft approved for spins in the utility
category may not be able to recover if loaded in the normal category.
Types
of spins
--Incipient Spin:
Aircraft is stalled and wing is dropped but rotation has not started.
Opposite rudder will lift the wing and prevent
rotation.
--Fully Developed and Steady State Spin:
A vertical descent in with there is a stabilized rate of rotation,
constant airspeed and constant vertical speed.
--Flat Spin:
Having a near level attitude in both pitch and roll. CG near center
of aircraft. May be unrecoverable..
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