POH 4.6 Engines

Question 1

POH.4.6.1 Detailed Information

Question 2

How’s the Seneca II powered?

Answer 2

By two Teledyne Continental six-cylinder turbocharged engines, each rated at 200 horsepower at 2575 RPM at sea level

Question 3

How are the engines cooled?

Answer 3

By air

Question 4

How is the fuel system?

Answer 4

Injected

Question 5

What are engines equipped with?

Answer 5

oil coolers with low temperature bypass systems and engine mounted oil filters

Question 6

How’s asymmetric thrust during takeoff and climb eliminated?

Answer 6

by the counter-rotation of the engines, the left engine rotating in a clockwise direction when viewed from the cockpit, and the right engine rotating counterclockwise.

Question 7

How are the engines accessed?

Answer 7

engines are easily accessible through doors in the cowlings, one on either side of each engine cowling.

Question 8

How are the engine cowlings designed?

Answer 8

for maximum aerodynamic efficiency

Question 9

How are engine mounts constructed?

Answer 9

steel tubing, and dynafocal engine mounts are provided to reduce vibration.

Question 10

POH.4.6.2 Turbocharger

Question 11

What kind of turbocharger does the Seneca II have and how is it operated?

Answer 11

Ray-Jay turbocharger on each engine is operated by exhaust gases.

Question 12

How does it work?

Answer 12

Exhaust gases rotate a turbine wheel, which in turn drives an air compressor.

Induction air is compressed (supercharged) and distributed into the engine air manifold, and the exhaust gases which drive the compressor are discharged overboard.

Question 13

How is engine induction air taken?

Answer 13

from within the cowling, is filtered, and is then directed into the turbocharger compressor inlet.

Question 14

How are cylindiers supplied?

Answer 14

with pressurized air in operation from sea level to maximum operating altitude.

Question 15

What’s the pressure relief valve?

Answer 15

protects the engine from inadvertently exceeding 42 inches Hg; 40 inches Hg is manually set with the throttles. The turbo bypass orifice is preset for 40 inches Hg at 12,000 feet density altitude at full throttle and 2600 RPM.

Question 16

POH.4.6.3 Induction Air System

Question 17

How does the intake filter air box work?

Answer 17

It incorporates a manually operated two-way valve designed to allow induction air either to pass into the compressor through the filter or to bypass the filter and supply heated air directly to the turbocharger.

Question 18

What happens when the primary source of air is blocked?

Answer 18

There is an automatic alternate air door which opens in the event that the primary air source becomes blocked

Question 19

POH.4.6.4 Fuel Injection System

Question 20

How does the metering system work in the fuel injection system?

Answer 20

measures the rate at which turbocharged air is being used by the engine and dispenses fuel to the cylinders proportionally.

Question 21

How is fuel supplied?

Answer 21

Fuel is supplied to the injector pump at a greater rate than the engine requires.

Question 22

What happens to the excess fuel?

Answer 22

The excess fuel is returned to the fuel tank by the vapor return line.

Question 23

What type of injection system is it?

Answer 23

Continuous flow type which allows excess fuel and fuel vapor separated in the injector pump to be returned to the fuel tanks.

Question 24

POH.4.6.5 Propeller

Question 25

How is balanced thrust provided by propellers?

Answer 25

Counter-rotation of the propellers provides balanced thrust during takeoff and climb and eliminates the critical engine factor in single engine flight.

Question 26

What kind of propellers does Seneca II use?

Answer 26

Three-blade, constant speed, controllable pitch and feathering McCauley.

Installed as standard equipment.

Question 27

How are the propellers mounted?

Answer 27

directly to the engine crankshafts.

Question 28

How is pitch controlled?

Answer 28

by oil and nitrogen pressure.

Oil pressure sends a propeller toward the high RPM or unfeather position;

nitrogen pressure sends a propeller toward the low RPM or feather position and also prevents propeller over speeding

Question 29

How do the governors work?

Answer 29

one on each engine, supply engine oil at various pressures through the propeller shafts to maintain constant RPM settings.

A governor controls engine speed by varying the pitch of the propeller to match load torque to engine torque in response to changing flight conditions.

Question 30

How are propellers controlled?

Answer 30

by the propeller control levers located in the center of the power control quadrant.

Question 31

How’s feathering accomplished?

Answer 31

by moving the control fully aft through the low RPM detent, into the FEATHER position.

Feathering takes place in approximately six seconds.

Question 32

How is unfeathering accomplished?

Answer 32

by moving the propeller control forward and engaging the starter until the propeller is windmilling.

Question 33

What does a feathering lock work? What does it prevent?

Answer 33

operated by centrifugal force,

prevents feathering during engine shut down by making it impossible to feather any time the engine speed falls below 800 RPM.

Question 34

What must the pilot make sure when he/she wishes to feather a propeller to save an engine?

Answer 34

when airborne, and the pilot wishes to feather a propeller to save an engine, he/she must be sure to move the propeller control into the “FEATHER” position before the engine speed drops below 800 RPM.

Question 35

POH.4.6.6 Engine Controls

Question 36

What do the engine controls consist off?

Answer 36

Throttle, a propeller control and a mixture control lever for each engine.

Question 37

Where are they located?

Answer 37

on the control quadrant on the lower center of the instrument panel where they are accessible to both the pilot and the copilot.

Question 38

What cables do the controls use?

Answer 38

The controls utilize Teflon-lined control cables to reduce friction and binding.

Question 39

What are throttle levers used for?

Answer 39

to adjust the manifold pressure.

Question 40

What’s the gear up warning horn switch?

Answer 40

activated during the last portion of travel of the throttle levers to the low power position.

If the landing gear is not locked down, the horn will sound until the gear is down and locked or until the power setting is increased.

This is a safety feature to warn the pilot of an inadvertent gear up landing.

Question 41

What are the propeller control levers used for?

Answer 41

to adjust the propeller speed from high RPM (low pitch) to feather (high pitch).

Question 42

What are the mixture control levers used for?

Answer 42

o adjust the air to fuel ratio. An engine is shut down by the placing of the mixture control lever in the full lean (idle cut-off) position.

Question 42

Where are the alternate air controls located? What are they for?

Answer 42

located on the control quadrant just below the engine control levers.

When an alternate air lever is in the up, or OFF, position the engine is operating on filtered air; when the lever is in the down, or ON. position the engine is operating on unfiltered, heated air. Should the primary air source become blocked the automatic alternate air door will
automatically select unfiltered heated air.

Question 43

Where are the cowl flap control levers located and for what are they used?

How many positions are there?

Answer 43

located below the control quadrant,

used to regulate cooling air for the engines

The levers have three positions: full open, full closed, and intermediate.

Question 44

How should all throttle operations be made?

Answer 44

All throttle operations should be made with a smooth, not too rapid movement to prevent unnecessary engine wear or damage to the engines, and to allow time for the turbocharger speed to stabilize.