DA42 - Imported cards

Question 1

Describe the gearbox on the DA42.

Answer 1

The gearbox reduces the engine RPM of 3800 to a prop RPM of 2300 via a ratio of 1.69:1.
It uses a separate oil system from the engine.
It has an overload clutch to decouple engine vibration from propeller during normal operations. It decouples the rotating mass of propeller from crankshaft during start & shutdown. This limits impact load to the crankshaft.

Question 2

Can you move the propellers by hand?

Answer 2

No because it is geared! It can damage the gearbox.

Question 3

How is the pitch of the propeller blades controlled?

Answer 3

The ECU controls the pitch of propeller blades automatically through Constant Speed Unit (CSU).
The RPM is based on preprogrammed power lever settings

Question 4

Where is the propeller pitch change mechanism located and how does it work?

Answer 4

The Propeller pitch change mechanism is located in the propeller hub.
It moves a piston that reacts to changes in oil pressure. Movement of piston adjusts the pitch of the propeller blades.
Increasing oil pressure moves the blades towards fine pitch.
It uses oil from gearbox system.

Question 5

What happens with a failure of oil pressure in the CSU?

Answer 5

The propeller will automatically feather because the spring in the propeller pitch change mechanism pushes the piston back and forces oil out; resulting in a higher pitch.

Question 6

What are some characteristics of the unfeathering accumulator?

Answer 6

It holds a mixture of nitrogen & oil at 290 PSI when the engine is running.
It’s used for: Unfeathering; and maintaining RPM as the engine slows down.

Question 7

How does the engine feather?

Answer 7

The feathering of the propeller can only occur above 1300 RPM and is accomplished by shutting down the engine with the appropriate engine master switch.
This opens the governor valve which allows oil to flow back from the propeller thereby allowing the propellers to move into the feathered position.
At the same time the accumulator valve closes and the oil pressure is restored in the accumulator.
The feathered angle is 81°

Question 8

How does the engine unfeather?

Answer 8

To unfeather, the engine mater switch must be set to the ON position.
This opens the electric valve at the pressure accumulator and the stored pressure will move the blades into a low pitch (high RPM) position.
As soon as the propeller starts turning and the gearbox oil operates, the pressure in the accumulator will be restored.

Question 9

Upon a normal engine shut–down, will the propeller feather? Why or why not?

Answer 9

No. The coarse pitch stops prevent the propeller from feathering below 1300RPM.

Question 10

Describe the common rail injection system.

Answer 10

Simply put, it’s a high pressure reservoir of fuel which feeds the injectors
Pressurized to 1800psi which assures optimal vaporization which results in a fine tuned engine, efficient and cleaner burning with more power.

Fuel from tanks passes through a filter
A low pressure fuel pump which supplies fuel to a high pressure fuel pump
High pressure pump supplies fuel to common rail injectors
The ECU interprets the rail pressure from the fuel rail pressure sensor, compares it to a target value, and adjusts rail pressure control valve to reach correct pressure
Injectors supply fuel directly into cylinders
Surplus fuel is returned to the main fuel system through a fuel cooler
At max power, engine burns approx 29 L/hr (7.6 GPH), and return fuel flow is 82 L/hr (22 GPH)

Question 11

Where is the air intake for the engine?

Answer 11

Lower right hand side of the cowling.

Question 12

Where is the alternate air intake for the engine?

Answer 12

Aft of the normal air intake.

Question 13

How the turbocharger regulate how much air compressed?

Answer 13

Through a wastegate: It’s a bypass for exhaust gases located behind the turbine. It’s controlled by the ECU.

The more it’s open, the less exhaust gas flows over the turbine, resulting in less compression. The more it’s closed, the more the turbine spins resulting in more compression of the air from the air intake.

Question 14

How does the ECU control the waste gate?

Answer 14

The ECU controls the wastegate based on a manifold pressure sensor behind the compressor. The sensor allows the correct position of the waste gate to be determined and allows any excess exhaust gases to bypass the turbocharger thereby preventing excessive manifold pressures at low density altitudes.

Question 15

What is the purpose of the intercooler?

Answer 15

Since the air temperature is increased as it’s compressed via the compressor, it needs to be cooled. Cooling the makes it more dense so it provides more power. It also prevents detonation.

Intercooler intake is on the LH side of the engine.

Question 16

How is the engine cooled?

Answer 16

It is liquid cooled using a waterbased with antifreeze additive
Uses a two circuit system for engine cooling; Main circuit to coolant heat exchanger; Second circuit a bypass for cold engine temperatures (below 88°C or 190°F)
Separate circuit for cabin heat exchanger
Coolant level sensor in expansion tank; activates “Coolant Level” caution on PFD

Question 17

Describe the coolant flow.

Answer 17

Coolant flows through passages in crankcase and cylinder heads
Leaves through thermostat valve into the coolant radiator
From radiator on to coolant pump then into the engine

Question 18

How are the engine parameters controlled?

Answer 18

The ECUs Monitor, control and regulates all important parameters of the engine. Most notably: Manifold pressure, Injected fuel quantity & Propeller speed
The ECUs receive input from sensors & compare signals with programmed characteristics
There are 2 ECU’s per engine, A & B: A is used for normal operation, B for backup
Because the ECUs are electronic, electric power is required to run the engines.

Question 19

For normal operations, which ECU controls the engine?

Answer 19

For normal operations, the SWAP switch is set to automatic, and ECU A controls the engine. If an internal error or the loss of a sensor signal occurs, the system automatically switches to the ECU B. If the cause of the problem was a sensor loss, the system switches back to ECU A. If the switch to ECU B does not happen automatically, a manual switch may be necessary.

Question 20

If the ECU swap switch has been set to B, how do you switch it back to ECU A?

Answer 20

Once the switch has been set to ECU B, the ECU B will remain in control even if the ECU SWAP switch is returned to AUTOMATIC. To change back to ECU A, the power lever must be set to idle and the ECU TEST button is pressed until both ECU caution lights on the annunciator panel go off.

Question 21

How are the ECUs powered?

Answer 21

Under normal operation, power is supplied to the ECUs from the alternator.

If both alternators fail, main aircraft battery can provide power for 30 minutes after which, both engines quit!!!

Question 22

Why should the power levers be moved slowly?

Answer 22

It avoids over speeding the propellers.

Question 23

Why would an ECU swap occur automatically?

Answer 23

Each ECU monitors its condition and calculate its “health level” continuously. If the health of one ECU is not 100%, the system switches to the other ECU automatically. An Annunciation appears on the PFD.
Any abnormality is sent to an “event log” which maintenance can view with a diagnostic tool

Question 24

How is the ECU health level calculated?

Answer 24

Health level drops if a sensor is lost. Resulting health levels vary based on importance of sensor, eg: crankshaft more important than gearbox oil temp.

Question 25

What happens when the Engine master switch is switched to ON?

Answer 25

``` It provides power for: Engine Engine pre heat system (glow plugs) Unfeathering accumulator Enables starter to be engaged Connects respective alternator to the excitation batteries ```

Question 26

How does the engine lubrication system work?

Answer 26

The bottom of the crankcase makes up the sump for oil system. The engine oil pump takes oil from sump, through a filter and oil thermostat to a cooler. The cooler is bypassed when temp is colder than 80°C. The oil from the cooler (or bypassed thermostat valve) returns to the engine Oil separator: vents blowby gases and any remaining oil mist overboard Tank: oil filter housing; also houses oil pressure sensor Engine nacelle drains: 1 from oil separator, one from engine coolant expansion tank

Question 27

Where is the oil cooler located?

Answer 27

Top rear of engine nacelle

Question 28

How does the alternate air for the engines work?

Answer 28

It serves both engines simultaneously. Only one lever for both engines. It allows air to be drawn in from the engine compartment instead of the normal air intake. Lever is located under the instrument panel to the right of the center console.

Question 29

Describe the propeller

Answer 29

constant speed feathering pitch controlled auto by ECU to change blade pitch gearbox oil is pumped into propeller hub regulated by electric operated value (governor), controlled by the ECU

Question 30

Propeller oil pressure and RPM

Answer 30

Increase oil pressure, decreased pitch, higher RPM | Decrease oil pressure, increased pitch, lower RPM

Question 31

Briefly describe the fuel system on the DA42.

Answer 31

There are 4 fuel tanks totaling 76.4 usable gallons of JET A. 2 main tanks with 25 usable gallons each 2 aux tanks with 13.2 usable gallons each The main tanks are made of aluminum and are composed of 3 chambers joined by rubber hoses. The aux tanks are made of aluminum with baffles on the inside to prevent rapid fluid movement.

Question 32

Describe the main fuel tanks and their components.

Answer 32

The main tanks are made of aluminum and are composed of 3 chambers joined by rubber hoses. The fuel quantity probes are in the inner and outer chambers, not middle. The outer chamber has the tank filler, tank vent and check valve. The inner chamber has the fuel temperature sensor, low level fuel switch, and the fuel supply/return connections With the aux tanks installed, the outer high level fuel switch is used to stop aux fuel pump when main is full. The inner switch not currently used, according to maintenance manual.

Question 33

How do the low level fuel sensors work?

Answer 33

They are float based. The floats will drop with decreasing fuel. At 34USG, the float operates a micro switch which activates the low fuel indication in the cockpit.

Question 34

Why should the engines not be shut off by moving the fuel selector to off?

Answer 34

Shutting down the engine with the selector valve can cause damage to the high pressure fuel pump.

Question 35

With the fuel selector in the on position, what is the flow of the fuel?

Answer 35

Fuel is drawn from tank, into the engine, returned through the fuel cooler to the engine tank.

Question 36

With the fuel selector in the x–feed position, what is the flow of the fuel?

Answer 36

Moving the fuel selector to the xfeed position disables flow to and from the associated tank. The engine pump takes fuel from opposite tank. The returned fuel is supplied back to the tank from which it was taken. The fuel will flow through the cooler on the side from which the fuel was taken.

Question 37

If the RH engine has failed. How do you get fuel from the right tank?

Answer 37

With the RH engine failed, set the left fuel selector set to xfeed.

Question 38

Why is a fuel cooler necessary on this aircraft?

Answer 38

A biproduct of compressing something is it gets hotter. Because the fuel is compressed to a high pressure, it also gets heated. The excess fuel that is not used in the common rail fuel injection system needs to be cooled before it goes back into the fuel tank. If it doesn't, the fuel could get too hot and turn into vapor causing vapor lock.

Question 39

How do you use the fuel from the aux tanks?

Answer 39

Turn on the aux transfer pumps. These transfer fuel to the main tanks via the main fuel return line after the fuel cooler. The fuel passes through the fuel filter, then the aux fuel pump, then a pressure check valve. The pumps shut off when the fuel level too low, or the main tank is full.

Question 40

How fast do the aux fuel transfer pumps transfer fuel?

Answer 40

1 gal per minute

Question 41

How do you know when the aux tanks have finished transferring?

Answer 41

Caution Annunciation on the PFD. If the auxiliary tank is empty: ‘L/R Aux Fuel E’ Transfer pump must be turned off now. This will take about 13 minutes.

Question 42

Briefly describe the ice protection system on the DA42.

Answer 42

``` It's a ‘Weeping wing’ system certified for known icing that distributes a thin film of deicing fluid over the: Wing Horizontal/Vertical Stabilizers Propellers Canopy ```

Question 43

What are some of the characteristics of the de–ice fluid?

Answer 43

It is glycol based with additives. Approved fuids are: AL5 (DTD 406B) Aeroshell Compound 07 Note: Use of nonapproved fluids can damage the system and provide inadequate protection.

Question 44

Does the nose baggage area maximum weight change depending on the de–ice tank level?

Answer 44

No, max baggage area weight in the nose is 66lbs independent of deicing fluid level.

Question 45

How does the de–icing fluid get from the tank to the airframe and propellers?

Answer 45

There are 2 main pumps which feed the deicing fluid to 2 filters, then on to the 3 proportioning units. The 3 proportioning units regulate the flow via capillaries to the porous panels and the propeller slinger rings.

Question 46

How many proportioning units are there? Where are they located?

Answer 46

There are 3 proportioning units: 2 In each engine nacelle. 1 In the upper vertical tail (forward of the front spar).

Question 47

What are the porous panels? Where are they located?

Answer 47

The porous panels weep fluid at a low rate through fine holes. They are located on the leading edge of the: Outer wings Vertical tail Horizontal tail

Question 48

How do the propeller slinger rings work?

Answer 48

They spray fluid into slinger ring mounted on propeller's spinner back plate. From there, fluid is distributed through 3 nozzles by the centrifugal force of the spinning plate out onto the propeller.

Question 49

How does the de–icing fluid get onto the windshield?

Answer 49

There are 2 pumps with valves installed in nose compartment. Only one pump is active and it pumps fluid into the spraybar. The switch in the cockpit allows pump selection.

Question 50

What are the different modes of operation of the de–ice system?

Answer 50

``` The different modes are: Off Normal High Max ``` Normal and High are selected using the toggle switch. Max is selected by pressing the max button op the deicing panel.

Question 51

Describe the normal mode of operation.

Answer 51

``` It is used prior to ice accumulation. During normal mode, both pumps run simultaneously. They cycle: On: 30s Off: 90s ``` The max duration in normal mode is approximately 2.5 hrs based on a full tank.

Question 52

Describe the high mode of operation.

Answer 52

It is used when ice has already accumulated. During the high mode, the selected pump runs continuously. The max duration in high mode is approximately 1.0 hrs based on a full tank.

Question 53

Describe the max mode of operation.

Answer 53

It is used in severe icing conditions. During the max mode, both pumps run continuously for 2 minutes every time the max button is pressed. The max duration in max mode is approximately 30 minutes based on a full tank.

Question 54

What does the pump switch do?

Answer 54

It allows you to toggle between pump 1 or 2 in high mode.

Question 55

What does the windshield push button do?

Answer 55

It activates the selected windshield pump for 5 seconds.

Question 56

If the main de–icing switch is off and the windshield push button is pressed, will fluid spray out of the spray–bar?

Answer 56

Yes, it will work even if main switch is off.

Question 57

How do you purge air from the de–icing system?

Answer 57

Press and hold windshield button.

Question 58

What main bus is the de–icing system connected to? What do you do if that bus fails?

Answer 58

It is connected to the LH main bus. If the LH main bus fails, flip the alternate switch. That connects the system to RH main bus. Note: Only high mode on pump #2 is available with the alternate switch on.

Question 59

How do you test the de–ice system?

Answer 59

Press the AnnunTest test button. This activates a “DEIC PRES LO” caution after 2 minutes.

Question 60

Define 'Absolute Ceiling'.

Answer 60

With both engines at max power, no further climb is possible.

Question 61

Define 'Service Ceiling'.

Answer 61

With both engines at max power, a climb rate of 100fpm can be maintained.

Question 62

Define 'Single Engine Absolute Ceiling'.

Answer 62

With one engine feathered, no further climb is possible.

Question 63

Define 'Single Engine Service Ceiling'.

Answer 63

With one engine feather, a climb rate of 50fpm can be maintained.

Question 64

Define 'Critical Engine'.

Answer 64

The engine whose failure would most adversely effect the performance and handling characteristics of the aircraft.

Question 65

Define 'Sideslip Condition'.

Answer 65

The sideslip condition is where the adverse yaw and roll created by an inoperative engine is compensated by use of the rudder while the aircraft wings are kept level with reference to the horizon. This will enable the pilot to maintain heading, however it will produce much drag as the relative wind will be hitting the side of the plane. This will cause a significant degradation in performance and an increase in Vmc.

Question 66

Define 'Zero Sideslip Condition'.

Answer 66

This is the answer to maintaining aircraft heading while minimizing drag. It involves using a horizontal component of lift to assist overcoming the turning moment brought by the operative engine. This is done by banking the aircraft 25degrees into the operative engine. This reduces the amount of rudder required and aligns the aircraft to the relative wind. The amount of rudder required is indicated by splitting the inclinometer ball in half towards the operating engine.

Question 67

What makes a critical engine critical?

Answer 67

Pfactor Accelerated slipstream Sprialing slipstream Torque

Question 68

Explain why P–factor contributes to the engine being critical.

Answer 68

This is caused by the down blades of a propeller having a greater angle of attack then the up blades when an aircraft is flying at an angle to the relative wind (as in climbing or slow flight). This causes more thrust on the down going side of the propeller which is on the right side. Therefore, the right engine on a conventional twin will have a trust line further from the center of the aircraft than the left engine. Hence, loosing the left engine would be more critical then losing the right.

Question 69

Explain why accelerated slipstream contributes to the engine being critical.

Answer 69

P factor causes the induced slipstream (accelerated slipstream) to be further outboard on the right wing and inboard on the left. Thus, loosing the left engine would cause the remaining induced slipstream (on the right wing) to be further outboard than would be the case if you lost the right engine. This would cause a greater rolling tendency towards the dead engine.

Question 70

Explain why spiraling slipstream contributes to the engine being critical.

Answer 70

The corkscrew vortex of air induced by the propellers acting on the aircraft vertical stabilizer causes the aircraft to yaw to the left (this is normally trimmed out in airframe design). This effect counters the adverse yaw of a right engine failure but compounds that of a left one.

Question 71

Explain why torque contributes to the engine being critical.

Answer 71

For every action there is an equal but opposite reaction. A propeller spinning to the right will induce a reaction in the aircraft to the left. Once again this effect counters the adverse yaw of a right engine failure but compounds that of a left one.

Question 72

What are the criteria for Vmc?

Answer 72

``` Maximum take off power Critical engine inoperative Inoperative engine windmilling 5 degrees of bank into the operative engine Most adverse legal weight Most adverse legal C of G Gear up Flaps takeoff position Cowl flaps open Sea Level Conditions Out of ground effect ```

Question 73

What happens to Vmc as altitude increases?

Answer 73

It decreases.

Question 74

What happens to the stall speed as altitude increases?

Answer 74

It stays the same.

Question 75

What is the danger of doing a Vmc demo at a high density altitude?

Answer 75

A point may be reached when Vmc and stall speed are equal, this is known as coffin corner because a spin may be induced if the aircraft yaws (as in a Vmc demo) and stalls as the same time. You never spin a twin.

Question 76

Recover from a spin

Answer 76

Power pull back Ailerons neutral Rudder full opposite Elevator pitch down

Question 77

Steep Turns

Answer 77

``` Clearing turns HDG / AlT Slow below Va 120 Kias 55% power Bank 45 deg Add 5% Passing 30 deg, add backpressure 20 deg start rollout Roll out, opposite aileron opposite rudder Passing 30 deg, reduce 5%, reduce backpressure ```

Question 78

What is the elevator friction dampner and why need

Answer 78

designed to prevent flutter in event of trim cable failing

Question 79

Nose gear switches

Answer 79

two downlock switches | gear up switch

Question 80

What 3 things cause gear warning horn to sound

Answer 80

engine below 25% and gear up Flaps ldg and gear up gear up while on gound

Question 81

What is the purpose of a hydraulic accumulator

Answer 81

Charged to 1150 PSI and helps maintain constant pressure and helps pump not have to run so long and dampens pressure changes

Question 82

Describe brake system

Answer 82

Four brake cylinders, in series per pedal | brake resevoirs on copilot side

Question 83

Which tanks have fuel guages

Answer 83

main has fuel sensor in outboard to stop aux pump when full inner chamber detects low fuel and fuel temp sensor aux tank has sensor for empty

Question 84

Where is the coolant level sensor

Answer 84

Expansion tank of radiator

Question 85

What five things occur when eng master on

Answer 85

``` ECUs get power Connect starter relays to battery bus activate glow plugs Connect altinator to excitation battery release gearbox oil from the unfeathering accumulator ```

Question 86

How to detect fire

Answer 86

detection sensor next to turbocharger, activates when over 250 degrees

Question 87

Describe voltage and power sources

Answer 87

``` 28v system 2 60 amp alternators 1 main 24v battery 2 12v excitation batteries for alt series 24v 2 12v ECU batteries series 24v ``` 30 mins runtime with full loss of power

Question 88

G1000 cooling fans

Answer 88

one in rear rack for GIA cooling one under glareshield to remove heat one behind PFD for cooling one behind MFD for cooling

Question 89

required equipment day VFR

Answer 89

``` A altimeter T tach O oil temp M man press A airspeed T temp guage O oil press F fuel guage L land gear pos A Anti collison M mag comp E Elt S seatbelts ```

Question 90

required equipment night VFR

Answer 90

``` F Fuses F Flashlight L Landing lights A Anti collison P Position S Source of power ```

Question 91

Required equipment IFR

Answer 91

``` G gen or alternator R Radio/nav for flight A Attitude ind B Ball A Alt enc xpdr C Clock A Altimeter R Rate of turn D directional gyro D Database gps ```

Question 92

How to handle inop equipment

Answer 92

Since no MEL, Have to use KOEL. If not required in KOEL, or for VFR/IFR flight, or AD, then placard inop, deactivate or remove, sign logbook

Question 93

Where is the aerodynamic balance located and what is it's purpose?

Answer 93

It is located on the outboard bottom of the aileron. It's purpose is to aid in raising of the aileron during a turn.

Question 94

How are the flaps constructed?

Answer 94

Using the GFRP / and CFRP sandwich method. Outer end of the inboard flap has a tongue that engages in a slot in the inner end of the outboard flap.

Question 95

Why are the flaps connected?

Answer 95

It's a fail safe method that prevents a slip flap condition; where one flap is down, and the other is not.

Question 96

How many motors operate the flaps?

Answer 96

Only one motor moves the push rods for all the flaps.

Question 97

What is the purpose of the variable elector stop?

Answer 97

It's used to help stop the pilot from pitching the plane up too much on a goaround. Pitching up too much on a goaround could stall the plane, scrape the tail, or render the plane uncontrollable (especially with one engine).

Question 98

What type(s) of elevator trim exist on the DA42?

Answer 98

There is a mechanical and an electrical trim. The mechanical trim uses a cable from the trim wheel to the actuating level at the rear of the elevator. The electrical trim uses a servo underneath the copilots that connects to the trim wheel via a chain gear.

Question 99

What happens to the trim if the autopilot fails?

Answer 99

Since the electrical trim uses the autopilot servo, if the autopilot fails, you will loose electrical trim functionality.

Question 100

How many actuating levers are on the elevator trim? Describe the functionality.

Answer 100

There are 2 actuators for the elevator trim. When looking at the plane from the rear: The left actuator connects to a long flexible cable that adjusted by the pilot using the control wheel. The right actuator has a friction dampener that prevents fluttering in case of mechanical failure of the trim cable.

Question 101

Describe how the rudder works.

Answer 101

When either pilot steps on a rudder petal, it's pulls the control cable connected to the rudder via a system of cables and pulleys.

Question 102

Is it possible to break the rudder using the rudder petals?

Answer 102

No, the cables would break before the rudder.