PA44-180 Systems

Question 1

What are the Components of the Gear System?

Answer 1

Reservoir

• intake/return lines
• bleed line/thermo-relief line

Hydraulic Pump

SHUTTLE VALVE
[[-][down][-][up][-][up][-][down][-]]

Hydraulic Chambers
- Low pressure lines/High pressure lines

Gear Cylinders
Landing Gear
Emergency Gear Extension
Pressure Switch
Down Limit Switches

Question 2

When you place the Gear Handle in the UP position, how is Gear Retraction achieved?

Answer 2

1. Placing Gear handle in UP position turns the Hydraulic Fuel Pump ON, shifting the SHUTTLE VALVE, and sending hydraulic fluid from Reservoir down the lines and into the HIGH Pressure Hydraulic Chamber
2. In the High Pressure Hydraulic Chamber, the hydraulic fluid is directed down individual lines to the BOTTOM of the Cylinders of the L/R/Nose Gear
3. This forces the gear to move UP, as well as forcing hydraulic fluid in the TOP of the Cylinders of the L/R/Nose Gear to move back up the lines, thru the Low Pressure Hydraulic Chamber, and back into the Reservoir
4. When the PRESSURE SWITCH in the High Pressure Hydraulic Chamber reaches 1800 psi, the SHUTTLE VALVE moves back to neutral, the Hydraulic Pump turns off

Gear is held in the UP position under this high pressure!

Question 3

When you place the Gear Handle in the DOWN position, how is Gear Extension achieved?

Answer 3

1. Placing Gear Handle in DOWN position turns the Hydraulic Fuel Pump ON, shifting the SHUTTLE VALVE, and sending hydraulic fluid from the Reservoir down the lines and into the LOW Pressure Hydraulic Chamber
2. In the Low Pressure Hydraulic Chamber, hydraulic fluid is directed down individual lines to the TOP of the Cylinders of the L/R/Nose Gear
3. Along with Gravity, this forces the gear to move DOWN. Hydraulic fluid in the BOTTOM of each gear cylinder is now forced to move back up the lines, thru the High Pressure Chamber, and into the Reservoir
4. There are 3 Down Limit Switches (L/R/Nose). Once all 3 are activated (~600 psi) the SHUTTLE VALVE moves back to neutral, and the Hydraulic Pump turns off

Gear is held in the DOWN position under this pressure!

Question 4

If gear is in the Up Position, and the Emergency Extension Gear Knob is pulled, how is gear extension achieved?

Answer 4

Shuttle Valve does not have to move, High seeks Low in the lines.

1. Pulling the knob opens up the Emerg. Gear Extension VALVE
2. Hydraulic fluid from the High Pressure line will flow freely through the Valve and up into the connected Low Pressure line, making its way up to the Low Pressure Hydraulic Chamber
3. Excess hydraulic fluid is distributed evenly through all Low Pressure lines to the TOPS of the Gear Cylinders
4. Pressure is EQUALIZED throughout the Gear Cylinders, and GRAVITY will force the gear to drop

Question 5

What are the Components of the Electrical System?

Answer 5

Left/Right Alternators
Battery
TIE BUS
BATT BUS
AVI 1
AVI 2
Main BUS
NON-ESS BUS
Diodes

Question 6

L/R Alternators are ___A / ___V, and charge the:

Answer 6

70A/14V
Provide charge the TIE BUS!

• will go offline if over 17V is received
  POH 7-19

Question 7

The Battery is ___A / ___V. Where is it located in the Seminole?

Answer 7

35A/12V

Located in the Nose!

Question 8

The Battery in the Electrical System is kept charged primarily by ___ and acts as what?

Answer 8

The L and R Alternators, and acts as source of stored electrical power to backup the Alternators

Question 9

What does the TIE BUS provide power to?

Answer 9

Main BUS (thru one way diodes)
NON-ESS BUS
AVI 1/2
BATT (thru BATT BUS)

Question 10

What is unique about the connection between the BATT and BATT BUS? What does the BATT BUS run?

Answer 10

It is always providing charge to the BATT even the Batter Master Switch is OFF

Runs the clock, Hobbs meter, and Tach meter

Question 11

What does AVI 1 power?

Answer 11

COM 1/NAV 1
XPDR
Elec. Trim
Audio Panel

Question 12

What does AVI 2 power?

Answer 12

COM 2/NAV 2

Marker Beacons

Question 13

What does the MAIN BUS power?

Answer 13

Everything!

Electricity in the fuel/gear systems/Pitot HT/Strater, etc.

Question 14

What does the NON-ESS BUS power?

Answer 14

Recog lights/STBY lights
Heater
Vent fan
Overhead blower fan

Question 15

What are the components of the Fuel System?

Answer 15

L/R Main Tanks
Selectors/X-Feed lines
Filters
Engine Driven Fuel Pumps
Auxiliary Fuel Pumps
Primers
Carburetors
L/R Engine/Cylinders
Heater/Heater Fuel Pump
Drains

Question 16

What happens in the Fuel System when you activate the Primer(s)?

Answer 16

Fuel is shot into engine cylinders 1, 2, and 4

Manifold Pressure readings are taken from Cylinder 3

Question 17

What are the components of the Vacuum System?

Answer 17

1. Filter
2. Gyroscopic Instrument (Attitude Indicator)
3. Manifold Check Valve
4. Vacuum Gauge
5. Regulator (set to 4.8” - 5.2”)
6. Vacuum Pump (should be 4.8” - 5.2” or else Regulator will assist)

Question 18

What are the components of the Propeller system?

Answer 18

Prob Hub
Spring
Prop Blades
Oil Sump
-intake/return lines

Pilot Valve
[-][To Hub][-][From Hub][-]

Fly Weights
Speeder Spring
Unfeathering Accumulator
- N2/Oil pressure

Question 19

How does the Unfeathering Accumulator work?

Answer 19

1. When propeller goes to Feathered Position, Pilot Valve moves to neutral position, and accumulator is SEALED holding oil under pressure/N2 charge on other side
2. To bring Prop out of feathered position, Prop Lever is moved to FULL FWD position
3. Flying Weights cant in, Speeder Spring pushes Pilot Valve down, oil line to Prop Hub Opens, Accumulator oil now unsealed and moves freely into prop hub to give it a little kick
4. Oil PUMP activates and continues sending oil from sump to prop hub so that Un-Feathering can be achieved.

Question 20

How do Fly Weights work?

Answer 20

Fly weights are connected to a rotating disk via hinges, and held “In and Down” by a Speeder Spring.

As disk rotates, CENTRIFUGAL FORCE makes fly weight want to fly “Out and Up”