Technical Interview 4

Question 1

What sort of equipment would a 2-stroke engine be used for?

Answer 1

For example:

Minibike
Lawnmower

Question 2

How does a carb heat system work?

Answer 2

It consists of a movable flap which draws hot air into the engine intake

The air is drawn from the heat stove, a metal plate around the (very hot) exhaust manifold

Question 3

What systems of your previous flown aircraft were electricly driven?

Note: make sure to be able to answer this question for your previous aircraft type

Answer 3

DA42

Flaps
PFD
MFD
Air Data Computer
AHRS
Pitot heating
Lights
Stall warning
Radios
Audio panel
Autopilot

Question 4

What is electricity?

Answer 4

Electricity is a form of energy produced by the movement of electrons.

Question 5

Is fuel heavier or lighter than water?

Answer 5

Fuel is lighter than water. If fuel is mixed with water, the fuel will float on top of the water.

Question 6

How does a 2-stroke engine work?

Answer 6

A two-stroke engine is an internal combustion engine that completes the process cycle in one revolution of the crankshaft (an up stroke and a down stroke of the piston, compared to twice that number for a four-stroke engine)

Question 7

How does an alternator work?

Answer 7

An alternator is an electromechanical device that converts mechanical energy to electrical energy in the form of alternating current

Question 8

What contaminates fuel?

Answer 8

Water

Question 9

When would you use carb heat in a SEP?

Answer 9

When OAT is between -10 & +30, with high humidity (greater than 40%) and/or visible moisture

Question 10

Explain the Otto cycle

Answer 10

Induction
Inlet valve opens and piston moves down drawing in air mixed with fuel from the carb
Compression
Inlet valve closes and the piston moves up compressing the mixture
Power
The compressed mixture is ignited by a spark and combusts
The piston is forced down by the pressure release
Exhaust
The exhaust valve opens and the piston moves up pushing the exhaust gas out

Question 11

What can you tell regarding the AC or DC power supply of your previous flown aircraft?

Note: make sure to be able to answer this question for your previous aircraft type

Answer 11

The DA42 has a 28v DC electrical system. Power is generated by two 28v engine driven alternators, one per engine, each rated at up to 60 amps. When the alternators are offline (e.g. failed or engines not running) power is provided by a 10 Ah 24v main battery.

A non rechargeable dry battery provides emergency power to the standby attitude indicator and panel flood light.

Question 12

What are the benefit of turbocharged engines?

Answer 12

Fly higher, faster and a better climb rate

Question 13

Tell me about the DA42 and Cirrus electrical systems.

Note: make sure to be able to answer this question for your previous aircraft type

Answer 13

The DA42 has a 28v DC electrical system. Power is generated by two 28v engine driven (by a flat belt) alternators, one per engine, each rated at up 60 amps. When the alternators are off-line (e.g. failed or engines not running) power is provided by a 10 Ah 24v main battery

Question 14

How do you recover from a spin in a small aircraft?

Answer 14

Close throttle, Ailerons neutral, oppose spin with full rudder and nose down.

When out of the spin recover from dive.

Question 15

What colour is avgas?

Answer 15

Blue

Question 16

How does the battery get recharged and how do you know it’s recharging/recharged?

Answer 16

By alternators, if the alternators produce more voltage than needed

The ammeter indicates the charging (+) and discharging (-) of the battery. It consists of a dial, which is marked numerically from -60 to 60 amps.

Question 17

What is the difference between Volts and Amps?

Answer 17

Volts is the measure of “electrical pressure” that causes current flow.

Amps are a unit of electrical current i.e. the number of electrons flowing in a circuit when an electrical force is applied.

Question 18

Why do you need a battery if you have two alternators? What does it power?

Answer 18

A battery provides electricity to the starter motors for starting the engines and can be used as a backup when both alternators fail

Question 19

What is the difference between a generator and an alternator?

Answer 19

An alternator must always operate at a constant speed that is precisely synchronized to the electrical frequency of the power grid.

A DC generator can operate at any speed within mechanical limits, but always outputs direct current.

Question 20

How would you check for, or prevent, water contamination?

Answer 20

• Water drains in fuel tanks
• Fuel heaters
• Atmosphere exclusion