Multi engine systems

PA44-180 Seminole


Make : Avco Lycoming

Model: Right Engine LO-360 E1A6D(turning counter clockwise from the cockpit)

Left Engine O-360 E1A6D


4 cylinders

Horizontally opposed

Carbureter equipped

Air cooled (Engine oil and fuel helps cooling)

Direct drive(Propeller is attached to the crank shaft directly without any reduction gear or transmission)

Normally aspirated(No turbo charge)

Horsepower: 180 BHP


Cowl flap: Manually operated. There are two positions; open and closed.


Make: Hartzell


Type: Constant speed, full feathering propeller

What is a constant speed prop?

The propeller which maintains the RPM selected by propeller control lever constant regardless of airplane’s pitch attitude or throttle position within some range.

The advantage of a constant speed prop.

The pilot can select the most efficient blade angle for each phases of operation. By selecting low pitch/high RPM, you can get maximum power for takeoff. By selecting high pitch/low RPM, you can fly faster at low RPM and you can save the fuel for cruise.

How does it work?

When the airplane rise it’s nose, it start climb. As it climb, airspeed goes down. The RPM is also going down due to increasing drag on the blade. However, blade angle is decreased automatically to reduce the drag to maintain the RPM constant.

When the airplane drops it’s nose, it start to descend. As it descend, airspeed will increse. The RPM is also increased due to decreasing drag on the blade. However, blade angle is increased automatically to increase the drag to maintain the RPM constant.

Where is the governor located?

In front of the engine.

What does governor do?

The fly weight inside the governor senses the change in RPM by sensing the change in centrifugal force. It opens the pilot valve. When the RPM increase, the valve opens the line without the pump. It drains the oil back from propeller hub to increase the blade angle. When the RPM decrease, the valve opens the line with the pump. The pump send the oil to propeller hub to decrease the blade angle.

What makes it high pitch?

Spring, nitrogen charged in the hub and counter weight at the root of the propeller blades.

What makes it low pitch?

High pressure of the oil and aerodynamic force on the prop.

What does pilot do when he move the prop lever in the cockpit? What will happen to governor?

It change the tension of the speeder spring. High tension requires more centrifugal force on the fly weight. It increase the RPM. Low tension requires less centrifugal force on the fly weight. It decrease the RPM.

Where is the oil from?

Engine oil reservoir at the bottom of the engine.

What will happen if you lose engine oil completely?

It become high pitch. Moves toward feathering.

How can you feather manually?

Move the propeller lever all the way down to the feather detent.

What is the purpose of feathering?

To reduce the drag caused by windmilling. To avoid further damage to the engine.

What force makes it feather?

Spring, nitrogen charged in the hub and counter weight at the root of the propeller blades.

How can you unfeather the prop?

Use starter.

How does the unfeatering accumulator work?(if it is equipped)

It has diaphragm inside. Nitrogen is charged in one side. Engine oil is pumped in on the other side from the governor during normal operation. When the propeller lever is moved down to feather position, the valve is closed to keep high oil pressure inside the accumulator(300PSI). When the prop lever is moved to high RPM position, the valve is opened and the nitrogen push the oil back. The oil is sent to the hub through the governor and crankshaft to decrease blade angle. Once the blade angle changes, the wind pick up the prop to start windmill. In this way, the engine can be restarted without stress on the cylinders(N2967D does not have unfeathering accumlator).

Will the prop feather when you shut down the engine after landing? Can you feather the prop when engine is not running?

No. There is anti-feather lock pin which prevent the prop from feathering below 950 RPM(N2967D, 800RPM for N79JT). When the RPM is high, the pin hide inside sleeve due to centrifugal force. When the RPM is low, the spring push out the pin to stop the movement of the prop.

Fuel system

What is the fuel system of the Seminole?

Fuel pump system.

How many fuel pumps are there?

4. Each engine has engine driven fuel pump and electrical fuel pump.

Also, heater has one electrical pump.

What drives fuel pumps?

Engine driven and electrical motor.

When do you use electrical fuel pump?

To start the engine.

Takeoff, climb and landing.

When the engine driven pump is inoperative.

How many fuel tanks are there?

One tank in each engine nacel. Total two tanks.

What is the capacity of each tanks( total/usable)?

55 gallons in each tanks. Total 110 gallons. 2gallons unusable each side makes usable fuel of 108 gallons.

How many fuel gauges are there?

Two. Fuel quantity gauges. Fuel pressure gauges.

Can you send the fuel from right tank to left engine? How?

Yes. Select cross feed on the left fuel selector valve. The P.O.H says fuel selector valve for the inoperative engine should be “off”.

When can you use the cross feed line?

Only in cruise.

Can you select cross feed on both engine?

P.O.H said "NO" though you can physically position it.

What is the purpose of cross feed?

To balance the weight laterally when one engine is inoperative. For longer range/endurance.

Draw the fuel system.

Refer P.O.H.

How many drains are there? Where are they located?

Two. There are two quick drains on the right side of the fuselarge. Those are the drain from the fuel filters.

What is the minimum grade of fuel?


How can you make sure you have correct fuel?

Color. 100 is green. 100 LL is blue.

Landing gear

Type of the landing gear?

Tri-cycle, retractable.

How does it work?

It is electrical-hydraulic system. Pilot can select the position(up/down) by the gear handle. The electrical motor rotate the hydraulic pump which send the hydraulic fluid from reservoir to three actuators. The fluid move the piston in each actuators to move the push-pull rod which are connected to the landing gears. Electrical limit switch stop the motor when it reached full up or full down position. When the hydraulic pressure decrease, pressure switch activate the motor to pump the oil. When the hydrauric pressure reached to certain amount, it disconnect the cercuit to stop the pump.

Where is the power pack located?

Behind the baggage compertment.

What is the color of the hydraulic fluid?


What will happen in the case of loss of hydraulic fluid?

The gear will drop by gravity and spring.

How can you make sure it is down and locked?

Three green lights and.

Is there anything to tell you the position of the nose gear?

There is a mirror on the both cowling to check nose gear position

Lock systems(up/down).

Up-No mechanical lock. Only supported by hydraulic pressure.

Down-Over center lock supported by spring and finger hook.

What is the maximum speed you can extend/retract the gear?

Vle is140KIAS. However, for retraction, it must be below 109KIAS.

Is there any system which warns you when you forget to extend the gear for a landing?

There is warning horn. When the throttle is reduced(14”) with gear up, it beeps. When the flap is extended at 25 or 40 degree with gear up, it beeps. It beeps on the ground when the gear handle is up.

And gear unsafe light (red) illuminates if it not fully down or fully up.

What will happen if you move gear handle up while you taxi on the ground?

The warning horn beeps. And gear unsafe light (red) illuminates The gear will not go up because of the squat switch located on the left main gear strut.

What would you do if you don’t see green light after you move the gear handle down?

Check master switch on, circuit breaker in, push the light bulb for test, switch the light bulb, turn the navigation light off(navigation light dims green lights). Check if you hear warning horn or not. Check unsafe light.

Explain the manual extension procedure.

Use check list.

  1. Slow down to 100 KIAS.
  2. Landing gear lever-down.
  3. Pull emergency gear extension knob.
  4. Check three green lights.
  5. Leave emergency gear extension knob pulled.

What makes gear down when you use manual extension system?

It release the hydraulic pressure. The gravity and the spring pulls gear down.

Electrical system

What is the primary source of electricity?


How many alternators are there?


What drives the alternator?


What is the voltage and capacity of the alternator?

14 volt, 60 Am

How can it maintain the voltage constant while the engine RPM changes from phase to phase?

Voltage regulator maintain it at 14 volt regardless of RPM.

How many voltage regulators are there?

Two. Each alternator has its own voltage regulator.

What is happening if you see over voltage warning light?

Over voltage relay shut down the alternater field as a result of over voltage(more than 17 volt) caused by spike or voltage regulator failure. Recycle the master switch and/or alternator.

How can you make sure one of the alternators is working or not?

Turn off the alternator one at a time. If the other load increase, the alternator you turned off was working.

What is bus bar? Location?

Bus bar is a piece of metal used for the distribution of the electricity. It simplify the wiring. It is located behind the circuit breakers.

How can you detect the alternator failure? What would you do then?

One or both load meters indicate zero. If only one indicates zero, turn off the other one to make sure it is working. If both indicate zero, check master switch on, circuit braker, recycle alternator. If it still indicate zero, turn off the master switch to conserve the battery. Also alternator announciator light on.

How many batteries are there? Location?

One battery in the nose.

What is the voltage and capacity of the battery?

12 volt, 35 amh.

How long does the battery last after losing alternator?

Depend on the load. If you use 35 am continuously, it last 1 hour. If you use 70 am continuously, it last 1/2 hour.

Flight control system

Conventional cable and pulley system.


Type of flap: Single slotted

How does it work?

Flap is actuated manually by human power.

Maximum deflection: 40 degrees

Vfe: 111KIAS.

Vacuum system


To operate the gyro instruments. AI and HI.

Source of vacuum

Two engine driven vacuum pumps.

Normal indication

5 in-hg±0.2

How to detect the failure

There are red flags on the vacuum gauge.

Stall warning system

Electrical warning horn activated with tabs. There are two tabs on the left wing. The out board is activated for flap zero and 10 degrees. Inboard one is for 25 and 40 degrees.

However, the system is off on tth ground due to the squat switch.

HeaterCombution type heater is located in nose cone. Aviation fuel is supplied from left tank with electorical fuel pump. It uses aboput 0.5 GPH.

Ice protection: Pitot heat, carb heat

Hydraulic system: Prop, Brakes, Landing gear

Draw the airspeed indicator.

V speed:KIAS

Va: 135(3,800lb) 112(2,700lb)

Vx: 82

Vy: 88

Vxse: 82

Vyse: 88


Vmc: 56

Vs0: 55

Vs1: 57


Vne: 202


Vle: 140

Vr: 75