Compressor stall - Compressor stalls may be characterized
by an audible change in engine noise (a loud bang or backfire) with fluctuations
in torque, ITT, N1, and fuel flow. Additionally, flames and smoke may be visible
from the engine exhaust stacks. A severe compressor stall may result in engine
damage and/or flameout. Compressor stalls may be caused by damaged or degraded
compressor or turbine blades, disrupted airflow, or compressor bleed valve malfunction.
If compressor stalls occur, proceed as follows:
- PCL - SLOWLY RETARD TO JUST BELOW STALL THRESHOLD TO CLEAR STALL
- Cockpit environmental control - FULL FORWARD
- PCL - SLOWLY ADJUST TO DESIRED POWER SETTING
WARNING - Avoid unnecessary PCL movement. Advancing the PCL
may result in further compressor stalls and engine flameout. Retarding the
PCL further may limit maximum power available.
If sufficient power is available:
- PEL - EXECUTE
If sufficient power is insufficient to execute a PEL:
- Proceed to the nearest suitable landing field and execute the
- ENGINE FAILURE procedure.
WARNING - Use of manual fuel control will only aggravate
compressor stalls and could lead to flameout.
WARNING - When the engine is so underpowered that high rates
of descent occur, any delay in feathering the propeller may result in insufficient
altitude to reach a suitable landing site.
NOTE - If the situation permits, record the altimeter, OAT,
max ITT, and duration of compressor stall.
NOTE - If resultant power is sufficient to maintain a rate
of descent less than the feathered condition (600-800 fpm clean), consideration
should be given to allowing the engine to operate until the field is made.
high power - The bearings or shaft in the FCU could fail without prior
fluctuations, causing fuel flow to go to maximum, resulting in a very high-power
condition that will be unresponsive to PCL movements. If torque, N1, and fuel
flow go to maximum and the engine is unresponsive to PCL movements, proceed
- PEL - EXECUTE (climb or accelerate to a suitable paved field).
WARNING - Certain failures can cause wide power surges from
maximum to as low as minimum fuel flow. Engagement of the EPL in this case
will have no effect on the high end of the power fluctuations, but may raise
the low end of the surges, thus reducing the magnitude of the fluctuations.
- Friction lock knob - FULL DECREASE
- Condition lever - RAPIDLY RETARD TO FUEL OFF
CAUTION - When retarding the condition lever, do not hesitate
in the FEATHER detent because high power from the engine with the propeller
in FEATHER may cause sever airframe vibration and very high torque applied
to the propeller and reduction gearbox.
NOTE - Altitude permitting, the pilot may elect to shutdown
the engine with the emergency fuel shutoff handle. The engine may continue
running for as long as 30 seconds after the handle is pulled.
- Execute ENGINE FAILURE procedures.
New Maneuvers for this event:
VFR wide or straight-in approaches
This type of approach may be used at both military and civilian airfields
when use of the “break” (or “overhead at civil fields) would be precluded or
impractical due to weather, traffic, or local procedures. They may also be used
in conjunction with certain emergencies (i.e., inflight damage).
- ATC - communicate intentions/request. If at a tower controlled field, contact
tower prior to entering the Airport Traffic Area.
"____Approach/Tower, Ranger _____, Pt. Shamrock inbound [extended base
leg / straight-in approach] for full-stop"
- Fast cruise (170 kts) at altitude to position 2-3 miles from runway on extended
- Transition LAC by slowing to 150 kts. Gear, Landing Chk no later than one-mile
final. Lower/hold flaps as appropriate.
- Radio calls to the tower or RDO (Report 2 mile final) as required.
- If at a tower controlled field, obtain landing clearance prior to landing.
Check the winds.
- Intercept a standard glideslope at 85/95 kts, 1200-1500 feet of straightaway
and 100-150’ AGL, wings level.
- Continue approach & landing using normal procedures.
- Not establishing radio contact with ATC soon enough.
- Transitioning to the landing configuration too late.
- Not making requested report to the tower.
- Landing without a clearance.
Low altitude power loss from the pattern (LAPL(P)) The simulated
Low Altitude Power Loss (LAPL) in the pattern will be initiated above 800’ AGL
by the instructor reducing the power to 200 ft-lbs torque and informing the
student there is a simulated power loss.
The power loss on takeoff will require immediate reaction to prevent catastrophic
results. About the only recourse for the pilot in this situation is to land
straight ahead changing direction only to avoid major obstacles. Do not try
to turn back to the runway from which you departed. Making a crash landing straight
ahead with the aircraft under control affords a much higher likelihood of survival
than an uncontrolled crash. Depending upon your altitude, you may be able to
reach an off duty runway if it is forward of the wings. On entry to any airfield,
an alert pilot will take notice of the options available in the event a failure
occurs ANYWHERE in the pattern. Obviously, the most critical area is that from
takeoff until commencing the crosswind turn. Thereafter, your options will greatly
improve as an off duty runway will probably be within gliding distance IF THE
FIRST SIX PROCEDURES OF THE LAPL ARE EXECUTED.
- DUMP. Obtain a safe flying speed by lowering the nose. If in a climb with
the gear and/or flaps down, the aircraft will rapidly decelerate toward stall
speed. Immediate forward stick is required while you simultaneously asses
(CHECK) the engine difficulty.
- If a rollback condition exists, use the EPL for power.
- SUCK. FEATHER. If not, feather the prop and raise the gear and flaps while
you are setting up for the landing.
- LOCK. Check your harness locked prior to landing.
- Altitude permitting, disconnect the fuel source by placing the condition
lever to fuel off and pulling the t-handle.
- CONFIGURE THE AIRCRAFT AS APPROPRIATE. Lower the flaps whenever the landing
site is made. Or gear if able to make it to an off-duty runway.
- BROADCAST. MAYDAY report:
ICS “MAYDAY, MAYDAY, MAYDAY, Ranger _____, Engine Failure, [location], plan
to land on runway ________.”
- CANOPY Blown.
- BATTERY OFF
- Not lowering the nose to maintain safe flying airspeed - 100 kts.
- Not feathering prop (simulated).
- Not cleaning up the aircraft’s configuration.
- Failure to lower flaps when field is made.
- Poor field selections.
- Failure to intercept ELP profile when possible.
- Getting too verbose with the “MAYDAY” call. Fly the aircraft, be brief with
PPEL from the pattern (PPEL(P))
Purpose. Utilize the PEL procedure to ensure that a safe landing at a paved
field can be made if indications of an impending engine failure should occur.
Indications of an impending failure or power loss are: system malfunction, excessive
vibration, smoke or fumes, chip detector annunciator light, fuel leaks or siphoning,
prop malfunction or any other condition listed in NATOPS requiring that you
land as soon as possible due to impending engine/airframe problems. Although
the situations requiring a PEL are impending engine failures, unlike the total
power loss situations, POWER IS AVAILABLE and should be used to reach High Key,
Low Key, and the runway at a paved field. Utilize maximum power (1015 ft-lbs)
if the emergency is not related to the Oil System or strong engine vibrations,
if related, use 850 ft-lbs torque and climb at 120 knots. Realize that power
may cease at any time, anticipate forward stick to maintain flying speed should
- TURN towards the nearest paved field.
NOTE - For PPEL’s turn towards the nearest manned OLF designated
for PPEL’s. Realize that for actual conditions, you would land at the best
suitable field commensurate with altitude and gliding distance.
- CLIMB to intercept at or below HIGH KEY. LOW KEY is probably going to be
your best option. Use a 120 kt climb with 1,015 ft-lbs (850 if oil related).
In an actual emergency, use a 100 kt climb attitude to increase your rate
of climb. Once on profile, pull power to 200 ft-lbs, transition to a 100 kt
glide. Do not lose sight of your landing field by turning the aircraft away
from it (remember, you just took off a few seconds ago).
- CLEAN with gear and flaps up and report
ICS “AIRCRAFT CLEAN”
- CHECK engine and flight instruments. Try to ascertain the cause and functional
status of the aircraft.
- DETERMINE. The runway shouldn’t have changed in the last 2 mins.
- DELIVER PAN voice report using ISPI format to RDO
ICS (UHF if actual) “PAN-PAN, PAN-PAN, PAN-PAN, Ranger _______, Fuel Pressure
Light, [location, altitude], Intend to land on runway ____________”
- REDUCE torque to 200 ft-lbs and transition to a 100 kt glide when back on
profile. Drop your gear as soon as you intercept X-WIND/LOW KEY.
- REPORT landing checklist
ICS “HARNESS LOCKED, GEAR THREE DOWN AND LOCKED, BRAKES PARKING BRAKE OFF,
BRAKES PUMPED FIRM, ENGINE INSTRUMENTS CHECKED, LANDING LIGHTS ON”
- CROSSWIND (2000’ AGL, 100 KIAS) Vary your AOB to arrive 2/3 WTD out at Low
Key. This is your only valid crosscheck if you are at the proper altitude.
- LOW KEY (1200’, 100 KIAS, 2/3 WTD)
CH X “_______Tower/RDO, Ranger ________, PATTERN LOW KEY, GEAR DOWN AND LOCKED”
- FLAPS if required and the field is made
- 90 POS (600-800’ AGL, 90 KIAS)
ICS “GEAR DOWN, FLAPS (UP/DOWN), LANDING CHECKLIST COMPLETE”
- FINAL (1200-1500’ straight-away, 90/95 KIAS)
ICS “GEAR DOWN, PADDLES CHECKED”
- Reduce power to idle for the transition to touchdown at the intended point
NOTE - Touchdown is made on the main gear, then gently
lower the nosewheel as in a normal landing. The descent to final will generally
be at a greater rate than for normal touch-and-go’s. Adjust nose attitude
and power in the flare to transition to a normal landing. If making a full
stop, apply BETA and braking commensurate with runway remaining. Should
insufficient runway remaining preclude a full stop before going off the
runway execute a waveoff if in the pilot’s judgment the engine will continue
to develop sufficient power to obtain a low key position for another attempt.
If the pilot feels that the engine is not reliable for another attempt,
utilize NATOPS ABORTED TAKEOFF procedures.
NOTE - When executing a PEL with the EPL, exercise caution
in power application to prevent a compressor stall. Be sure the EPL is in
either DISCONNECT or IDLE before selecting BETA with the PCL.
Aileron roll - The aileron roll is a 360° roll about the
longitudinal axis of the aircraft. Plan your clearing turn so as to roll out
on a good section line or with the nose aimed at a prominent reference point.
When performing the maneuver make your control inputs smooth, brisk, and positive.
DO NOT MIX UP YOUR STICK CONTROLS!!!
- C: Transition to aerobatic cruise
- C: Aerobatic checklist.
- C: Clearing turn, roll out with the required ground references.
- Commence the maneuver...
- Smoothly raise the nose to place the exhaust stacks on the horizon while
keeping the wings level.
- Stop the nose movement by relaxing back stick pressure.
- Roll briskly in either direction by applying lateral stick deflection
and rudder in the same direction (rudder will counter the adverse yaw).
The amount of stick deflection will determine your rate of roll. If the
rate of roll is too slow the nose will fall below the horizon and a rolling
pullout will result.
- As you approach wings level attitude, ease out aileron and rudder pressure
to recover with the wings level and the nose attitude reset for level
- Failure to relax the back stick pressure prior to rolling. Back stick pressure
is required only to set the initial nose high attitude. Failure to relax the
back stick pressure will cause the nose to follow an arcing path rather than
having the aircraft roll about its longitudinal axis. It will also cause the
nose to drop rapidly while passing the inverted position.
- Delaying initiation of the roll once the nose high attitude is set. This
causes excessive airspeed decay which results in a sluggish roll performance.
- Failure to input sufficient rudder in the direction of roll. The high roll
rates required for the aileron roll generate considerable adverse yaw. This
must be compensated with sufficient rudder in order to maintain balanced flight.
Loop - The loop is a 360-degree turn in the vertical plane.
During the loop the aircraft is rotated at a constant rate of pitch about its
lateral axis. In this maneuver, the elevator is the principal control surface
utilized. The nose pitch rate should be constant, but the aft stick force required
to obtain this will vary with airspeed and G loading. Directional control is
maintained using rudder input as the airspeed varies, thereby maintaining balanced
- C: Transition to aerobatic cruise
- C: Aerobatic checklist.
- C: Clearing turn. Last 90° of turn:
- Lower the nose slightly, accelerate to 200 kts
- Roll out of the clearing turn on or parallel to a section line with
- Left rudder (for increased airspeed).
- Recheck the wings level and clear airspace above.
- NOTE THE ENTRY ALTITUDE. Check and report:
ICS: “ENTRY ALTITUDE IS 7,500 FT”
- PULL-UP (3.5 G’S in 2-3 seconds).
- AGSM. Commence the AGSM and immediately start a smooth straight pull
up accelerating to 3.5 G’s within 2-3 seconds.
- Do not use aileron.
- KEEP WINGS LEVEL. INCREASE RIGHT RUDDER PRESSURE AS AIRSPEED IS LOST. Recheck
the wings level as the nose passes through the horizon. Adjust stick pressure
as necessary to keep the nose moving at a constant rate. Increase right rudder
pressure as airspeed decreases.
- TILT HEAD BACK TO FIND THE OPPOSITE HORIZON. RECHECK WINGS LEVEL. Shortly
after passing the vertical position, tilt your head back and visually locate
the opposite horizon. Correct with aileron as necessary to maintain the wings
parallel to the horizon.
- RUDDER. Check the nose in relation to the section line and correct directional
deviations as necessary by adjusting the rudder input.
- KEEP THE NOSE MOVING AT A CONSTANT RATE (90-100 KIAS). Airspeed will reach
its slowest point at the top of the loop. The greatest amount of right rudder
input will therefore be required at this point in order to maintain balanced
flight. The amount of aft stick force required to maintain a constant nose
pitch rate will have decreased significantly from the initial pull up. Maintain
positive G loading and wings parallel to the horizon.
- ALLOW THE NOSE TO FALL ALONG THE SECTION LINE. Allow the nose to fall through
the opposite horizon, adjusting the amount of aft stick pressure to maintain
a constant pitch rate. Fly the aircraft’s nose along the section line, relaxing
right rudder pressure as airspeed is quickly regained.
- RELAX RUDDER PRESSURE AS AIRSPEED IS REGAINED. Continue to relax right rudder
pressure as the airspeed increases in the dive and smoothly increase aft stick
pressure as necessary to maintain a constant pitch rate. The recovery will
again require approximately 3.5 G’s, to remember to resume the AGSM.
- SCAN. Quickly scan the altimeter during recovery in order to return to straight
and level flight at approximately the same altitude, airspeed, and heading
from which the maneuver was initiated.
- Failure to check and report the altitude prior to entry. It’s hard to recover
on the same altitude when you don’t know what it is!
- Poor directional control caused by failure to maintain balanced flight with
the proper amount of right rudder as airspeed is lost and then regained. Poor
rudder control is easily detected by checking the alignment of the nose and
the section line. Remember that the required rudder input varies as airspeed
varies. Almost constant rudder adjustment will be required.
- Poor directional control caused by failure to keep the wings parallel to
the horizon throughout the maneuver. The most common tendency by far is to
pull the stick slightly to the right when pulling the nose up during the 3.5
G entry. Keep the stick centered longitudinally as the entry input is made.
Check and correct the wing attitude often.
- Poor execution of the initial pull-up with respect to G loading and/or timing.
Remember 3.5 G’s in 2-3 seconds. Scan the accelerometer. Excessive G loading
and/or loading the aircraft too quickly will cause an excessively rapid deceleration
and may result in overstress. Insufficient G loading, or taking too long to
obtain the correct acceleration, will deplete the aircraft’s energy state,
resulting in a stalled or near stalled condition when approaching the inverted
- Relaxing too much back stick pressure while passing through the inverted
position at the top of the loop. This will result in a “floating” sensation.
Remember to maintain some positive G loading throughout the entire maneuver.
Conversely, failure to relax sufficient backstick pressure over the top will
result in excessive AOA and rudder shakers. If this occurs, relax the back
stick pressure slightly.
- Failure to initiate the pull out soon enough during the second half of the
loop. This results in excessive airspeed and recovery below the initial altitude.
Wingover - The wingover is a 180 degree reversal in the direction
of flight accomplished by combining a smooth climbing turn for 90° with
a smooth diving turn for 90°. Recovery should be on the same altitude
and approximately the same airspeed at which the maneuver was started.
The wingover will develop your ability to smoothly control the aircraft in
balanced flight through constantly changing attitudes and airspeeds. The maneuver
may be initiated in either direction and is always performed in a series of
two. You should therefore complete the series on the same heading that the first
wingover was initiated. They can even serve as clearing turns when properly
executed. Once you are able to visualize the pattern, keep your scan primarily
outside of the cockpit. Use your instruments only for an occasional reference
to crosscheck your sensory impressions.
The rate of roll should be constant throughout the maneuver. The nose always
moves at a constant rate in relation to the horizon as it describes arcs, first
above and then below the horizon. Remember that turns to the right, torque and
slipstream effect must be offset with an increased amount of rudder input than
in turns to the left. The pitch and roll rates are relatively slow during the
- C: Transition to aerobatic cruise
- C: Aerobatic checklist
- C: Clearing turn
- Roll out on or parallel to a section line
- Pick a prominent reference point on horizon 90° to left or right,
in direction intended to perform the maneuver.
- On section line, with good reference point...
- CLEAR ABOVE AND REPORT ALTITUDE.
- Recheck the wings level and clear the airspace above you.
- Just prior to entry, check and report the entry altitude: ICS: “ENTRY
ALTITUDE IS 7,500 FT”
- Smoothly raising the nose while keeping the wings level.
- As the exhaust stacks pass the horizon, start a roll toward the 90 degree
- 45° NOSE UP, 45° AOB, 45° HEADING CHANGE. Control the pitch
and roll rate so as to reach 45° nose up and 45-deg AOB simultaneously.
The aircraft’s heading should also have changed approximately 45° at
- 90° AOB, 90° HEADING CHANGE, 90 KIAS. CHECK 90° REFERENCE POINT.
Continue to roll toward 90° AOB as the nose inscribes an arcing path downward
toward the horizon. Maintain orientation on your outside reference points.
Control the pitch and roll rate so as to arrive at 90° AOB with the nose
aligned with the 90° reference point. Airspeed should be approximately
90 KIAS at this point. DO NOT exceed 90° AOB.
- Allow nose to fall through the horizon, then commence the recovery by smoothly
rolling and pulling out of the diving turn. After approximately 135° of
turn, the nose will be approximately 45° below the horizon and the AOB
should again be 45° . Scan the section line for longitudinal alignment
and the horizon for pitch and roll rates.
- Control the pitch and roll rate so as to recover on the original altitude
and reciprocal heading.
NOTE - When the maneuver is completed at the same altitude it was initiated,
there is a tendency to gain about 10 kts.
- Repeat steps 3 through 8, performing the second wingover in the opposite
direction. Upon completion of the series, the aircraft should once again be
established in level balanced flight, on the original heading and altitude.
- RUSHING THE MANEUVER. Remember, the wingover is a relatively slow and gentle
- Failure to obtain 45° nose up and 45° AOB simultaneously.
This is usually caused by an excessive roll rate and/or insufficient back
stick pressure during the initial pull up. Once the AOB exceeds 45°,
it is difficult to raise the nose any higher. This type of error will result
in excessive airspeed (i.e., greater than 90 KIAS) at the 90 degree checkpoint.
- After the exhaust stack passes the horizon, keep the roll rate slow and
constant. As the aircraft rolls, smoothly increase the back stick pressure
so as to obtain 45° nose up simultaneously with 45° AOB. The
required back stick pressure reaches a maximum at approximately this point.
You must then continue to roll toward the 90 degree checkpoint at a constant
rate while beginning to relax the back stick pressure. By the time you reach
90 deg AOB, you should only have enough back stick to keep from feeling light
in your seat (i.e., slight positive G loading)
- Exceeding or not fully reaching 90° AOB.
- Holding excessive back stick pressure at the 90 degree checkpoint, thereby
“pulling” the nose through and obtaining the reciprocal heading too early
during recovery. Conversely, releasing all of the back stick pressure, thereby
inducing a zero or negative G state.
- Poor timing of the roll and pitch rate during recovery. The wings should
come level simultaneously as the nose reaches the level flight attitude.
- Commencing the second wingover in the series off airspeed, heading, altitude,
etc. Expeditiously make the necessary corrections prior to initiation of the
next wingover. There is no point practicing the maneuver if the entry parameters
Barrel roll - The barrel roll is a maneuver in which the aircraft
is rolled 360° about an imaginary point which bears 45° off the
nose of the aircraft. This maneuver is designed to develop your ability to maintain
- C: Aerobatic cruise
- C: Aerobatic checklist.
- C: Clearing turn
- Roll out on or parallel to a section line.
- Pick a prominent reference point on the horizon 90° left / right,
in the direction you intend to perform the maneuver.
- Recheck the wings level and clear the airspace above you.
- NOTE THE ENTRY ALTITUDE. Check and report the entry altitude:
ICS: “ENTRY ALTITUDE IS 7,500 FT”
- SMOOTHLY RAISE THE NOSE WHILE KEEPING THE WINGS LEVEL. As the exhaust stacks
pass the horizon, roll and pull so that the nose travels around in an arcing
path toward the selected 90° checkpoint. After 45° of turn, the AOB
should be 90° and the nose will be at its highest point during the maneuver
(approximately 55-60° above the horizon).
- Continue rolling the aircraft at a constant rate until in a wings level,
inverted attitude, heading directly at the 90° reference point on the
horizon. Your nose should be slightly above the horizon and the airspeed between
90 and 100 kts.
- Fly the aircraft through the inverted position and continue rolling at a
constant rate, completing the maneuver on the original heading and altitude
at aerobatic cruise airspeed. Maintain a positive G load throughout the maneuver.
If you exceed the G limit, it’ll most likely happen here. If performed properly,
2.0 G’s should not be exceeded at any time.
- The nose should appear to make an arcing path about the imaginary point
on the horizon 45° from your original heading. The last half of the arc
will, therefore, be the same distance below the horizon that the first half
is above the horizon. Remember, as the airspeed decreases toward the top of
the maneuver, it will be necessary to increase the deflection of the ailerons,
rudder, and elevator to maintain a constant rate of pitch and roll. Conversely,
as the airspeed increases toward the bottom of the maneuver, it will be necessary
to decrease the deflection of the ailerons, rudder, and elevator to maintain
a constant rate of pitch and roll. Notice that this roll is started as a climbing
turn, which then becomes a continuous roll at a constant rate.
- Maintain orientation throughout the maneuver by concentrating on your reference
points. Maintain a constant rate of roll and nose movement. Inscribing a small
arc above the horizon in the first half of the maneuver and a larger arc below
the horizon in the last half will result in too great an airspeed at the completion
of the maneuver or unnecessarily high G forces to recover on airspeed.
- During the rollout to the original heading, adjusting the back stick pressure
will enable you to recover on altitude and at aerobatic cruise airspeed.
- Failure to raise the nose high enough during the first 45° of turn.
Generally, this will result in a correspondingly nose low attitude and proportionally
high airspeed when recovery is made.
- Improperly coordinating the rate of roll with the rate of pitch. An insufficient
roll rate will result in an overshoot of the intended recovery heading while
an excessive roll rate will result in an undershoot. A common tendency is
to allow the roll rate to accelerate after passing the inverted position.
- Failure to maintain balanced flight. Too much or too little rudder will
produce essentially the same results as too fast or too slow a rate of roll,
- Failing to scan ahead for the reference point and/or section line and thereby
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the webmaster, Bryan Weatherup
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