Advanced Pilot Training: Aircraft Ops

Advanced Pilot Training: Propeller Operation

General

The blade angle of a fixed pitch propeller cannot be changed. The blade angle of an adjustable pitch propeller can be changed only on the ground. The useful blade angle of both of these propellers is a compromise between the high rpm needed for takeoff and the low rprn that is best for cruising. These propellers are used only on training airplanes.

A two-position propeller provides both a high rpm setting for takeoff and a low rpm setting for cruising efficiency.

The constant speed propeller permits an engine to develop full horsepower for takeoff, and allows automatic readjustment of the blade angle during flight for particular power and altitude conditions.

Feathering

Some constant speed propellers incorporate a feathering feature. Feathering a propeller permits the stopping of a disabled and vibrating engine, decreases the drag of the propeller and increases the performance of the airplane with the remaining good engine.

A feathered propeller on a twin-engined airplane increases the single engine ceiling appreciably over that which can be maintained with the useless propeller windmilling.

If necessary to maintain level flight, increase the propeller and throttle settings of operating engine, but don't exceed maximurn permissible operating limits of the engine except in an emergency.

Maximum performance at all altitudes with a feathered propeller is obtained by trimming the flight controls for level flight.

Operating Tips

1. Observe engine operating instructions.

2. Increase rpm first, then manifold pressure.

3. Decrease manifold pressure first, then rpm.

4. Keep throttle closed when unfeathering.

For maximum endurance select airspeed and reduce rpm to lowest permissible value for the manifold pressure required to maintain selected airspeed. Adjust mixture as specified by engine operating instructions.

For economical cruising reduce manifold pressure to approximate cruising value then reduce rpm to value specified by engine operating instructions. Readjust manifold pressure to specified limits.

Featheritis

Don't jump for the feathering switch the minute you think you have engine trouble.

Check these things first:

1. It may be that your tachometer is registering incorrectly.

2. Look at your airspeed.

3. Listen to sound of suspected engine.

4. Look at the exhaust.

5. Make sure the trouble is not caused by inverter failure (See PIF 5-8-3).

Remember, unless you are practicing feathering you don't want to lose an engine if you don't have to.

CURTISS ELECTRIC PROPELLER

Starting Engine

1. Before starting engine, set circuit breaker to "ON" position. Leave it "ON" at all times during flight.

2. Set selector switch to "AUTOMATIC". If propeller is not already in low pitch, the electric motor will decrease the angle when the engine is started until the minimum is reached.

3. Start engine.

Preflight Check

Manual Operation:

1. Safety switch "ON" and selector switch "OFF" (center).

2. With engine running at approximately 2000 rpm check the manual propeller operation with the selector switch first in "DECREASE" then in "INCREASE RPM," noting that the engine speed responds accordingly, but do not decrease rpm excessively (200 rpm maximum).

Automatic Operation:

1. Safety switch "ON" and selector switch to "AUTOMATIC."

2. Propeller control to takeoff rpm.

3. Open throttle to obtain 2000 rpm.

4. Pull propeller control back until you notice approximately 200 rpm reduction in engine speed.

5. Return propeller control to takeoff position noting that you again attain 2000 rpm.

6. Close throttle.

If your airplane is equipped with a feathering Curtiss Electric Propeller, immediately following the manual and automatic operation checks, and before you close throttle, perform the following feathering check:

1. Feathering switch to "FEATHER" until you notice approximately 200 rpm reduction in engine speed. (This takes only one to two seconds. Don't reduce rpm excessively.)

2. Return feathering switch to "NORMAL," noting that -you again attain 2000 rpm (because of automatic operation).

3. Close throttle.

These propeller checks can be made in sequence and concurrently with the magneto check without shutting the engine down between each check.

Takeoff, Climb, and Level Flight

I. Set selector switch to "AUTOMATIC."

2. Adjust propeller for takeoff rpm.

3. Adjust throttle to obtain desired manifold pressure. During climb and level flight, with selector switch in "AUTOMATIC", the governor holds engine speed constant by varying the pitch of propeller to suit different engine powers or flight conditions.

If a different engine speed is desired during flight, adjust the propeller slowly until tachometer registers the proper speed.

Any combination of engine rpm and manifold pressure is obtained within the operating limitations of the engine by independent adjustment of throttle and propeller.

When cruising altitude is reached, set throttle for cruising, adjust propeller to cruising rpm.

If your propeller governor fails, you may still maintain satisfactory performance by placing the selector switch in "FIXED PITCH."

Feathering

1. Close throttle.

2. Set feathering switch to "FEATHER."

3. Move mixture control to "IDLE CUT-OFF."

4. Shut "OFF" fuel supply to engine.

5. Leave ignition switch "ON" until propeller stops, then turn switch "OFF."

Unfeathering

1. Turn ignition switch "ON" with throttle closed.

2. Set propeller control to "DECREASE RPM."

3. Turn "ON" fuel supply.

4. Move mixture control to "FULL RICH."

5. Set feathering switch to "NORMAL."

6. Hold selector switch to "INCREASE RPM" until tachometer reading reaches 800 rpm; then release switch.

7. Allow engine to operate at this rpm until required operating temperature is obtained. Otherwise you may damage the engine.

8. Set selector switch to "AUTOMATIC" position and open throttle gradually to speed for which governor is set.

9. Adjust mixture, throttle, and governor to desired power and engine rpm.

Approach and Landing

Place propeller in maximum cruising rpm position to prevent overspeeding of engine if throttle is opened in an emergency. If necessary to interrupt the glide and make another landing approach, adjust throttle first, then place propeller control in "INCREASE RPM."

After landing, before stopping engine, place control in "INCREASE RPM."

Run-Away Propeller

In case of a run-away propeller, that is, one which allows engine to overspeed, check:

1. Circuit breakers.

2, Switch settings.

3. Try to reduce rpm by propeller control.

4. Hold selector switch in the "DECREASE RPM" position.

If this fails to reduce the rpm, turn the feathering switch on, then quickly off again to reduce rpm to the correct setting. Be careful not to reduce the rpm too much when using this method.

Power Failure

The battery and generator are your sources of electric power. If the generator fails in flight place the selector switch in "FIXED PITCH" to conserve electric energy. Switch it back to "AUTOMATIC" before landing, so that you will have automatic operation if you have to go around again.

Selective Fixed Pitch Operation

If you desire selective fixed pitch operation, or if the constant speed control fails:

1. Move selector switch to "FIXED PITCH".

2. Hold switch momentarily on "INCREASE RPM" or "DECREASE RPM" (as required) to obtain the rpm setting you want.

Reset Circuit Breaker

If the. circuit breaker opens because of an overload' on the propeller circuit let it cool for 10 or 15 sec-1 onds, then reset it to "ON". Otherwise, the propeller blades will remain at a fixed angle setting.

In emergencies hold the circuit breaker button full in if a continuous overload exists. It will carrv extremely high loads.

REFERENCE: T,-chnical Ordet fi,2-20B-3and Techni,~al Manual 1-412

HAMILTON STANDARD COUNTERWEIGHT TYPE PROPELLER

Starting Engine

Before starting engine, place propeller governor control in "DECREASE RPM" position. Then start engine and run for at least 1 minute. This is done to avoid starving the engine thrust bearing of oil immediately upon starting. This is opposite to the setting used for all other propellers.

Warm-up

Shift propeller control to "INCREASE RPM" position for warm-up in accordance with operating instructions for the particular type of engine.

Takeoff and Climb

Place governor control in "INCREASE RPM" position for takeoff and climb. As airplane accelerates, engine speed increases until it reaches governor setting. Setting has been adjusted previously and should be within 25 rpm of the red line on the tachometer. From this point on, rpm is held constant by the governor. As soon as safety permits, reduce manifold pressure and rprn. Always reduce manifold pressure and then rpm. Move throttle an4_ governor controls slowly.

Level Flight

Set rpm for normal level flight. It will be helconstant by the governor within close limits.

Engine Failure

In event of engine failure, place governor contr(% in "DECREASE RPM" to reduce drag.

Approach and Landing

Place governor control in maximum cruising rph position. If necessary to interrupt glide and mat another landing approach, first adjust throttle, thE place governor control in "INCREASE RPM."

Before stopping engine make sure that propell, has shifted to low rpm to prevent exposure and corosion of the propeller piston.

REFERENCE: Technical Order 03-20CB-1 a4d Technical Manual 1A

HAMILTON STANDARD HYDROMATIC PROPELLER

Preflight Check of Feathering System

1. After engine is warmed up set governor control loo approximately 1,400 rpm.

2. Open throttle until governor is functioning, i.e., engine operating at constant rpm with slight increase in manifold pressure.

3. Depress feathering button until the engine Vpeed drops to 1,200 rpm.

4. Pull feathering button out. Engine speed should return to original governing value in a few seconds.

5. If propeller does not respond as above, feather_ ing system should be checked immediately.

Takeoff and Climb

1 Place propeller governor control in "INCREASE -RPM" for takeoff and climb.

As the airplane accelerates, engine speed increases ~until it reaches the governor setting. This setting has been previously adjusted and should be within 25 rpm of the red line on the tachometer. Therelafter, rpm is held constant by governor. As soon as -safety permits, reduce manifold pressure and rpm. Always reduce manifold pressure, then rpm. Move - throttle and governor controls slowly.

Level Flight

Set rpm desired for normal level flight. The gov.ernor will hold it constant within close limits.

Approach and Landing

Place governor control in maximum cruising rpm position for approach and landing. If necessary to interrupt the glide and make another landing aproach adjust throttle first, then place governor control in high rpm position.

Feathering

1. Close throttle.

2. Depress feathering button.

3. Move mixture control to "IDLE CUT-OFF."

4. Shut "OFF" fuel supply to engine.

5. Leave ignition switch "ON" until propeller -stops, then turn switch "OFF."

In case of practice feathering while flying, don't leave propeller feathered for more than 15 minutes. Longer periods of feathering may allow enough oil to seep past the piston rings of the lower cylinders to I damage the engine when you unfeather the propeller -. and restart the engine.

Practice feathering only between 5000 and 10,000 feet above terrain over which you are flying.

Unfeathering

1. Turn ignition switch "ON" with throttle closed.

2. Set propeller control to the minimum rpm position.

3. Turn "ON" fuel supply.

4. Depress propeller feathering button. Keep closed until tachometer reading reaches approximately 1000 rpm; then release.

5. Adjust mixture control.

6. Allow engine to operate at this rpm until required temperature is obtained. Then open throttle gradually, causing engine to speed up to the minimum rpm or the speed for which governor is set.

7. Adjust throttle, mixture, and governor setting to desired power and engine rpm, and synchronize.

In flight, the propeller begins to windmill and crank engine as soon as it starts to unfeather. Engine speed increases rapidly as power is applied and automatic unfeathering proceeds.

When unfeathering a propeller after engine has cooled, idle at slow speed until engine is thoroughly warmed up. Otherwise serious damage may result. Windmilling action on unfeathering acts as a powerful cranking force and may overspeed engine beyond safe idling speed unless unfeathering is stopped while propeller still is at a high angle.

If the engine idles at too high a speed, you can reduce rpm by depressing the feathering button briefly. Pull out button when desired rpm is reached.

If. you don't pull the button out, the propeller will continue to the full feathered position at which time the button pops out.

If you hit the feathering switch accidentally, pull it out at once. Do nothing more as the propeller will return shortly to governor control.

REFERENCE: Technical Order 03-20-14 and Technical Manual 1-412.

AEROPROP

Starting Engine

Start engine with propeller control in "INCREASE RPM." This reduces the load or drag of the propeller and results in easier starting and warm-up of the engine. Also, this is normally the position of propeller prior to stopping engine.

Takeoff and Climb

Place propeller in high rpm position for takeoff and climb. As the throttle is advanced, engine rpm increases until it reaches the amount for which the high rpm stop has been set. From this point on, rpm is held constant by the governor.

As soon after takeoff as safety permits, reduce both manifold pressure and rpm. Always reduce manifold pressure first and then rpm. Move throttle and propeller controls slowly.

Level Flight

Set rpm desired for normal level flight. The governor will hold it constant within close limits.

Approach and Landing

Place propeller in maximum cruising rpm position for approach and landing. If necessary to interrupt the glide and make another landing approach, adjust throttle first and then place propeller control in "INCREASE RPM."

Stop engine with control in "INCREASE RPM."

Aeroprop Purging

If you suspect poor governing, purge the propeller by changing the manifold pressure from 20" Hg to 37" Hg (for the P-39Q-10) several times in succession. Always consult the Technical Order for the airplane operating instructions.

Dual Rotation Propellers

The operating instructions for the dual rotation Aeroprop, are the same as for conventional rotating propellers; move propeller control forward for increased rpm, backward for decreased rpm.

REFERENCE: Technical Order 03-20E-2.

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