Page 2.6 (1,729)
PTS Spin Awareness
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...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; Spin Recovery Conundrum; ...Base Turn Spin; Flat Inverted Spin; ...Spin Direction: ...
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 auto-rotational 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.
of Inadvertent Stalls Becoming Spins
1. Inadequate rudder application in steep climbs. Climb power raises nose, decreases airspeed and increases P-factor. Hazard in modified C-172s
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. (Modified C-172s)
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. (Try no flap full nose up trim to get 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 skid. 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, flaps up before spin, 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.
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.
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.
Rudder opposite to TC
Any time the critical AOA is exceeded while inappropriate rudder effect exists to either side; a stall/spin situation is
---Airspeed indicator and altimeter are unreliable.
---Yaw can occur due to asymmetric thrust of propeller blade (Modified C-172)
---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. This means that the high wing is stalled and must drop through level. Catch the wing at level with rudder and you will not spin.
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.
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.
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.
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.
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.
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.
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.
Having a near level attitude in both pitch and roll. CG near center of aircraft. May be unrecoverable..
Spin Recovery Conundrum
--The easier an aircraft is to spin, the easier it is to make a spin recovery
--The more difficult it is to make an aircraft spin the more likely that the spin recovery will be difficult.
Actually the stall/spin sequence on the base to final turn is NOT a result of a steep turn. It is rather the result of trying to hurry a shallow turn. Even a coordinated LEVEL forty-five degree banked turn only increases your stall speed by fourteen percent. You normal approach speed is approximately thirty percent above stall speed. You STILL have a fifteen percent margin if you bank steeply and remain coordinated.
The problem arises when you attempt to maintain the bank at thirty degrees and turn as sharply as you would with a forty-five degree bank. That required excessive inside rudder to rush the turn, which tends to stall the inside wing. It then begins to drop and the normal reaction is to use aileron to pick it up, aggravating the stall condition developing on the inside wing. Prompt application of TOP rudder would instantly move the inside wing out of the stall region and avoid the problem as you return to coordinated flight. Of course, it would also cause you to widen the turn to correspond with your shallow bank and leave you out of position for your final approach.
The easy way to avoid the situation is to remain coordinated and never attempt to hurry a turn with inside rudder. Remember that an airplane is turned by BANK. The rudder is only there to counteract the adverse yaw that generally occurs with aileron deflection. :-)
It is quite possible to design an airplane with NO rudder
pedals. Ercoupe anyone!
Flat Inverted Spin
……Snip…..I watched an aerobatic pilot demonstrate an inverted flat spin. Now, my understanding (which may be wrong) of the peculiar aerodynamics of a flat spin is that the control surfaces are ineffective, so I'm presuming that what allowed the pilot to successfully come out of the flat spin was the result of having such a high horsepower engine. Is this a correct assumption?
Also, my understanding regarding our regular G.A. planes is that only a severe C.G. imbalance would allow a regular G.A. airplane to enter a flat spin. Is this correct?
I'm thinking you saw Jimmy Franklin. He's the only person I know who does these as part of a routine. I am not an expert, but from what I've learned about his maneuver is that he "forces" himself into it with application of power. Then throughout the maneuver he adds and reduces power as he revolves in the spin. Managing his power keeps him in the flat spin. When he comes out of it, I believe he does not add power which allows the nose to fall a little, which in turn allows the wings to once again do their thing (fly). He is then in a normal spin, rides that out for a few revolutions and pulls out.
If anyone else has more knowledge, I'd sure like to learn about this. No plans on doing them in my life time, but the maneuver is amazing, and Jimmy is one of the best flyers I've ever seen!
Inverted spin characteristics differ somewhat from type to type, and the recovery is type specific to be sure. Also, the spin can be simply inverted, flat inverted, or accelerated inverted. In all cases, the application of power would NEGATE recovery rather than cause it. Power is used to accelerate a flat inverted spin. Pro spin aileron and forward stick are used to flatten. Recovery requires backing off all throttle or you'll screw the airplane right into the ground. In other words, although some airplanes have a flatter spin mode than others, (spin axis stabilized past incipient) you have to MAKE the airplane go flat in the real flat spin sense, and that requires power. Keep the power in and the airplane won't recover. As for the cg and GA airplanes, having the cg out will change the normal spin axis for a specific airplane...any airplane! It's entirely possible to get an out of cg aircraft into a non recoverable spin both erect and inverted.
For spin direction, especially in high performance jets, we ALWAYS use the turn NEEDLE for spin direction, NOT the ball!
The ball will NOT always swing left. It could swing either way. However, the direction the ball moves has to do with the center of the spin axis and the location in the airplane of the indicator. It does NOT indicate the direction of the spin. The turn needle, however, ALWAYS indicates the direction of the spin and can be used for recovery.
To recover from a spin on partial panel do the following:
---Use rudder to center the turn needle and hold it centered.
---Then alter pitch until you stop the airspeed indicator momentarily.
---Hold that pose. Eventually things will settle out in level flight!
---Believe it or not. :-)
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