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Engine Starting

Starting is divided into two general categories:

  • Ground starting, and
  • Air starting.

Ground starting is achieved through the use of electrical power provided by either the aircraft batteries or from an external power source. Air starts are achieved by unfeathering the propeller and windmilling. Note: The starter function through the START buttons is inhibited after liftoff.

Ground starting is further divided into two categories:

  • Normal mode starts, and
  • Manual mode starts.

Ground Starts - Normal Mode

The usual starting procedure for the Conquest is in normal mode with the fuel computers on. This procedure simplifies the starting process for the pilot as the entire process is controlled by the fuel computers requiring minimal supervision of the entire start cycle by the pilot.

Before attempting a normal mode start it is important to ensure that the propellers are 'on the start locks'. This means that the propeller blades are in the ‘fine pitch’ position to reduce the loads on the starter motor during the propeller acceleration period of the start cycle.

On Locks Off Locks

If the propellers are not ‘on the locks’ prior to engine start simply:

  • Place the battery switches to the ON position,
  • Retard the affected engine power lever to the REVERSE range, and
  • Hold the UNFEATHER pump switch to the Left or Right position as appropriate and observe the propeller blades moving toward the 'fine pitch position'. A definite 'click' will be heard once the start locks engage.
  • Once the start locks are engaged release the UNFEATHER pump switch and move the power lever to the FLIGHT IDLE position.
  • Turn the battery switches OFF again if required.

Prior to the first flight of the day, or any flights in which an Air start is planned a High Power Monitor Check should be conducted. This procedure is conducted to ensure that the fuel computers are working correctly in relation to both power lever and condition lever movement with the engines not running.

It is advisable that a High Power Monitor Check also be conducted:

  • after any engine control system maintenance, or
  • any indication of engine malfunction during previous flights.

To Conduct a High Power Monitor Check:

  • Turn the battery switches ONand ensure that the guarded fuel computer switches are ON and their associated warning lights are OFF,
  • Position the Power levers to GRND IDLE,
  • Position the Condition levers to TAKEOFF CLIMB and LANDING, then
  • Reposition the power levers forward of the FLIGHT IDLE detent and observe the FUEL COMP LIGHTS illuminate.
  • Reposition the Condition levers to START TAXI,and
  • Individually switch the guarded fuel computer switches OFF and then ON. This should extinguish the corresponding FUEL COMP OFF lights on the annunciator panel.

Guarded Fuel Computerswitches mounted on the left hand switch panel. L FUEL COMP OFF light Illuminated on annunciator panel

After completion of the relative pre start checks a normal mode engine start can now be conducted. Note: Prior to any start ensure that the approved FLIGHT.ORG Air pre start checklist is complied with. An abbreviated start procedure is shown below:

Abbreviated Pre start checklist:

  • Ensure the Pressurisation source selector switch is OFF,
  • Battery switches are ON,
  • Generator switches are OFF,
  • Place the left hand boost pump switch to AUX,
  • Gyro inverter and all anti-icing switches are OFF,
  • Torque Temp limiting switches are in the AUTO position.

The start cycle:

Press the Left START button whilst guarding the left STOP button and holding the left Condition lever should a hot or hung start ensue. Check rotation of the left hand propeller and note illumination of the LEFT ENG START light (if fitted) and increasing left engine RPM indication.

At 10% engine RPM note:

  • Illumination of the left ignition light located forward of the switch panel beside the pilots left knee.
  • Left Fuel flow indication and a corresponding rise in left engine EGT as the combustion process begins.
  • As the combustion temperatures increase the pilot must monitor the rate of temperature rise to abort the start process should an abnormally fast rate of rise occur. This could possibly lead to a HOT start causing serious engine damage.

10% - 60 % engine RPM:

  • The rate of temperature rise will be quite fast up to approximately 500° C where it will begin to slow down and stabilise at 695° C where the start temperature will be regulated by the electronic fuel computers until 60% engine RPM.

Normal mode stabilised start above 60% RPM

  • At 60% engine RPM the computer controlled 60% switch will turn off the starter motor function of the starter generator and allow the engine to accelerate on its own to the governed RPM of approximately 70% - 75% engine RPM.
  • A noticeable drop in EGT should be observed at this point where the temperature should stabilise between 400°C - 500°C (approximately).

Once the left engine has stabilised after start:

  • Left generator switch can be turned ON to charge the battery assisting with the right hand engine start,

Note: It is advisable to allow the generator amperage to fall below 100 amps before beginning the right engine start procedure.

  • Left boost pump switch can be positioned to MAIN,
  • Pressurisation source selector positioned to LEFT.
  • Repeat the normal mode start process for the right hand engine.

NTS Check

Another procedure that should be conducted at the first start of the day is the NTS check. This procedure is conducted during the start cycle by holding the UNFEATHER switch to the corresponding Left or Right position prior to pressing the engine START button. This will cause the NTS Check light to illuminate.


Left hand NTS CHECK light illuminated

Holding the UNFEATHER switch in the corresponding left or right position will effect the NTS check during the start cycle causing the NTS CHECK light to go out after engine rotation is initiated. The NTS check will be completed with illumination of the NTS CHECK light again at approximately 30% engine RPM (usually between 20% - 25% RPM).

Ground Starts - Manual Mode

When the electronic fuel computers are unserviceable, or during training, the Conquest engines may be started in manual mode with the fuel computers off. This procedure requires the pilot to undertake the functions of the fuel computers during the start cycle as well as the usual supervision of the entire start cycle. This means that manual mode starts are much busier for the pilot and requires a lot more diligence with the engine monitoring process to ensure that no limitations are exceeded. Before attempting a manual mode start it is important to ensure that the propellers are ‘on the start locks’ to reduce propeller rotational loads during the start cycle.

The manual mode start is not that much different to a normal mode start, but requires the pilot to activate the manual mode start switches located on the left hand vertical switch panel mounted next to the pilots left arm rest. These switches are manually activated by the pilot at 10% and 60% engine RPM.

Guarded START MANUAL switches mounted on the left hand switch panel. L FUEL COMP OFF light Illuminated on annunciator panel during Man. Mode start.

The start cycle:

  • Press the Left START button whilst guarding the left STOP button and holding the left Condition lever should a hot or hung start ensue.
  • Check rotation of the left hand propeller and note illumination of the LEFT ENG START light (if fitted) and increasing left engine RPM indication.

At 10% engine RPM manually activate the 10% START MANUAL switch (push switch up) and note:

  • Illumination of the left ignition light located forward of the switch panel beside the pilots left knee.
  • Left Fuel flow indication and a corresponding rise in left engine EGT as the combustion process begins.
  • As the combustion temperatures increase the pilot must monitor the rate of temperature rise to abort the start process should an abnormally fast rate of rise occur. This could possibly lead to a HOT start causing serious engine damage.

10% - 60 % engine RPM:

  • The rate of temperature rise will be quite fast up to approximately 500° C where it will begin to slow down and stabilise at 695° C where the start temperature will be regulated by the electronic fuel computers until 60% engine RPM.

Manual mode stabilised start above 60% RPM

  • At 60% engine RPM manually activate the 60% START MANUAL switch (push switch down) which will turn off the starter motor function of the starter generator and allow the engine to accelerate on its own to the governed RPM of 75% ±10% engine RPM.
  • A noticeable drop in EGT should be observed at this point where the temperature should stabilise between 400°C - 500°C (approximately).

Once the left engine has stabilised after start:

  • Left generator switch can be turned ON to charge the battery assisting with the right hand engine start, Note: It is advisable to allow the generator amperage to fall below 100 amps before beginning the right engine start procedure.
  • Left boost pump switch can be positioned to MAIN,
  • Pressurisation source selector positioned to LEFT.
  • Repeat the Manual mode start process for the right hand engine.

As can be seen from the Manual mode Start procedure the pilot is basically substituting the automatic functions of the electronic fuel computer switches at the 10% and 60% phases of the start cycle.

It does become a busy process though as the usual monitoring process must be carried out whilst monitoring the entire start cycle which usually takes no more than 35 secs.

Emergency engine shutdowns

Should an abnormality occur during the start cycle, i.e. hot or hung start, the pilot will need to effect emergency shutdown procedures prior to any engine limitations being exceeded. The emergency shutdown procedure requires that the pilot moves the condition lever into the EMER SHUTOFF position, and, press the engine STOP button for the affected engine.

Stop Button. Left condition lever in the cutoff position.

Moving the Condition levers rearward manually shuts off the fuel at the fuel control unit effecting an engine shutdown, whilst pressing the engine STOP buttons will electronically shut the engines down and reset the fuel computers for subsequent engine starts.

Engine clearing procedures

Following an aborted start, an engine clearing procedure must be performed before attempting another start procedure. To clear the engine, it must be motored without fuel and ignition to remove any unburnt fuel and combustion gases from the engine. Note: Natural draining of the fuel will be accomplished if the engine remains static for at least 3 minutes. Before beginning an engine clearing procedure ensure that the fuel and ignition are off by pressing the engine STOP button and checking that the IGNITION OVERRIDE switch is off. Also check that the propeller is clear and is on the start locks.

Begin the engine clearing procedure by holding the STARTER MOTOR switch in the respective Left or Right position as required. Monitor the engine RPM to 15% then release the STARTER MOTOR switch. Repeat the procedure if necessary.Note: Do not exceed starter duty cycle limitations and do not attempt a restart with EGT above 200° C.


Guarded STARTER MOTOR switches mounted on the left hand switch panel.

After Start checks

  • Following a successful start of both engines there are several subsequent checks that may be carried out including the:
  • Normal mode over speed governor check,
  • Manual mode fuel control check, and the
  • Manual mode over speed governor check.

These checks are not normally carried out by aircrew at FLIGHT.ORG Air and will not be discussed in these course notes.

Ground Operation of the engines

Once the appropriate preflight checks are completed the pilot must release the propeller start locks in order to commence taxying. To release these locks the shear loads must be removed in the propeller hub in order for centrifugal forces to move the locking pins against spring pressure and release the blades from the locked blade position. This shear load is relieved by moving the power levers into the reverse range prior to taxi. Release of the propeller locks can be identified by monitoring the BETA light for the appropriate engine and observing it go out and come back on again with a corresponding rise in torque, EGT and fuel flow indicating that reverse thrust is being achieved.

Once the propellers have come off the start locks return the power levers to the ground idle position. The aeroplane can now be taxied once both propeller start locks have been released. Note: It is almost impossible to taxi the aeroplane successfully if both propeller start locks are not released properly.

Taxying

The aeroplane can be taxied with the condition lever in any position between START, TAXI and TAKEOFF, CLIMB AND LANDING. START, TAXI is the usual position for ground operations as it provides the best conditions for operating the ground heating and cooling modes and it is quieter at 75% RPM for ground personnel.

Taxi speeds are controlled by movement of the power levers both forward of the flight idle detent and into reverse range if required plus pilot manipulation of the aircraft brakes. During ground operations the power levers control the propeller blade pitch angles to increase thrust for taxying.Note: Below 80% RPM EGT reads compensated EGT and must not exceed 770° C.

Flight Operation (Normal mode)

When lined up and ready for takeoff, the condition levers need to be moved forward of the START, TAXI position and will drop down off this detent into the CRUISE position. Prior to moving the condition levers forward of this rearward CRUISE position the engine RPM should read approximately 90% RPM. Note: It is good airmanship to allow the engine to stabilise at 90% RPM prior to further forward movement of the condition levers.

In the TAKEOFF, CLIMB AND LANDING position engine RPM should stabilise at approximately 96% RPM. The under speed governor is now reset to approximately 96% RPM and in Normal mode is controlled by the electronic fuel computers.

Once the engine Rpm passes through 80% the following will also occur:

  • The fuel enrichment valve will close,
  • Primary nozzles only solenoid will close,
  • The fuel computers Single Red Line (SRL) logic will be reset and the EGT guage will indicate Calculated not Compensated EGT and Max. EGT will now be 450° C not 770°C
  • Flow limiting system is engaged on the bleed air system.

With the condition levers in the TAKEOFF, CLIMB AND LANDING position, movement of the power lever forward of the FLIGHT IDLE detent will now cause the power lever to assume control of the fuel to the engine and engine RPM will now be controlled by the condition levers. As the power levers are advanced the fuel computers command the propeller governor to decrease the blade angle and increase the engine RPM to 100% where it is governed by the propeller governor. The pilot must monitor engine limits as the power levers are advanced for takeoff with torque normally being the limiting factor in typical OAT conditions.

It is the pilots responsibility to ensure that torque or EGT limits are never exceeded. Note: Never assume that the Torque Temp. Limiting system (TTL’s) will maintain the engine within maximum engine parameters. The Torque Temp. Limiting system capability will be overridden once the pilot moves the power lever 1 lever width past the point that initial Torque Temp. limiting occurs.

Once the Conquest has climbed to altitude the engines can be configured for cruising flight. The TPE331 engines are designed to be able to run at 100% RPM continuously, however it is usual practice for the pilot to reduce the RPM to 96%, by retarding the condition levers, for passenger comfort. Note: Engine operation below 96% RPM is not permissible whilst airborne.

Once the condition levers have been retarded and the adjusted for 96% RPM the power levers may be adjusted to attain the desired power setting for cruise flight. Adjust the power levers until the desired EGT has been attained (usually just below 450° Celcius), then usual pilot monitoring of all engine instruments should be accomplished.

If an engine should need to be feathered in flight for reasons other than an emergency, the power lever should be retarded toward flight idle and the EGT should be allowed to stabilise. This will reduce the risk of thermal shock in the engine. To feather the engine the Condition lever should be moved into the EMER SHUTOFF position followed by pushing the F/W SHUTOFF button on the annunciator panel.

Condition lever in the EMER SHUTOFF pos. F/W SHUTOFF button center of annunciator panel


Propeller feathering system

It is imperative during all engine shut downs, be they intentional or not, that the appropriate checklists are followed in order to maximise pilot safety and minimise engine damage.

If an Air start should need to be accomplished this task may be conducted in both Normal and Manual mode operations. During an airstart, the starter motor is not functional as it is disengaged by the left hand landing gear squat switch after takeoff. The starter motor function is replaced by the unfeathering pump and is activated by pressing the associated START switch.

Before conducting an airstart ensure that all checklist items are completed and that the following limitations are observed:

  • EGT below 200° C,
  • Airspeed below 200 kts IAS, and
  • Aircraft below 20 000 ft.

For a normal mode airstart ensure that the FUEL COMP OFF light is extinguished, set the power lever at AIR START and the condition lever at START TAXI.


Left hand power and condition levers in airstart position

Momentarily press the associated START switch and visually check for propeller rotation. At 10% RPM check for fuel flow and that the ignition light comes on followed by a corresponding increase in EGT. Monitor the start cycle whilst guarding the STOP switch and the condition lever ready to abort the start in case an abnormal start cycle is observed. At 60 % RPM the unfeathering pump will be shutdown and the ignition system turned off. Move the condition lever to the TAKE OFF, CLIMB AND LANDING POSITION and allow the engine to stabilise before selecting cruise power on both the condition lever and power lever to reduce thermal stress. Should the airstart be unsuccessful be sure to follow the ‘If Air start Attempt Fails’ checklist.

During Normal operations descent is controlled by retarding the power levers toward the FLIGHT IDLE position with the condition levers remaining in the CRUISE position. The power levers should not be moved rearward of the FLIGHT IDLE stop whilst airborne.

Prior to landing the condition levers should be moved in to the TAKEOFF, CLIMB AND LANDING position. This will maximise drag and aid in the effectiveness of reverse thrust should it be selected during the landing roll. If one engine is operating in Manual mode, ensure that the second engine is also operated in manual mode during the landing phase, as reverse thrust is unavailable in manual mode thus ensuring that symmetrical thrust/drag will be produced at all times.

After touchdown the power levers may be moved rearward of the FLIGHT IDLE detent to produce the required amount of reverse thrust. The pilot has complete control of the propeller blade angle with the power levers whilst the electronic underspeed governor will schedule the fuel into the engine to ensure that there is enough power to balance the propeller load generated. Reverse thrust must not be used above 90 kts IAS and to reduce propeller blade erosion, terminate the use of reverse thrust below 40 kts IAS. For the remainder of the ground operation the condition levers can be moved into the START TAXI position for normal ground operations.

Flight Operation (Manual mode)

During flight in Manual mode the power lever will control the fuel flow through the mechanically operated fuel valve on the Fuel Control Unit. Since there is no mechanical connection from the condition lever to the propeller governor, the pilot has no control over the engine RPM. During all manual mode operations the engine RPM is mechanically preset at 100% RPM. Fuel scheduling during for all power lever positions is less during manual mode operations requiring greater movement of the power levers for the same power settings. RPM changes will also be slower so advancement of the power levers during manual mode should be done cautiously.

There are nine basic differences between normal mode and manual mode operations. These are:

  • Reverse thrust is unavailable in Manual mode.
  • Torque, Temp. limiting is unavailable during Manual mode.
  • Manual fuel enrichment is required through use of the START switches during Manual mode.
  • Automatic START function is unavailable during Manual mode, i.e. manual selection of the 10% and 60% start switches required.
  • EGT is ‘compensated’ not ‘calculated’ therefore Max. EGT is no longer based on a Single Red Line and must be calculated by either table 2-5 in the flight manual, or from the OAT guage method, or by setting fuel flow/torque against a normal mode engine.
  • Engine RPM is governed at only 100% RPM in Manual mode.
  • Engine power is less and response to power lever movement is more sluggish during Manual mode.
  • Synchrophasing is unavailable during Manual mode operations.
  • Bleed air ground operation is unavailable during Manual mode.

    To maintain a constant Torque setting during climb in manual mode requires progressive power lever movement. A higher power setting will be required during descents due to the lower fuel flow scheduling during manual mode operations. Note: Retarding the power levers to FLIGHT IDLE in manual mode just before touchdown may result in higher than normal rates of descent.

    BETA lights may illuminate at a higher power setting due to the lower fuel scheduling in manual mode. If the BETA lights illuminate during manual mode during a descent or during the landing phase of flight, forward movement of the power levers should extinguish them.

    After touchdown in manual mode, the power levers may be moved into GRND IDLE with a much higher drag force being produced than in normal mode. Propeller pitch control is available as in normal mode, but there is no underspeed governor control causing the engine to ‘bog down’ if reverse thrust is attempted. Maximum aerodynamic drag is achieved at flat propeller pitch with the power levers set at GRND IDLE.

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    Starting Engines


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