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ASU-600 Series Model No. Breakdown

ASU-600-270-SC P

Above example is a 270 PPM unit powered by Scania Tier 4 Final Diesel engine, Trailer mounted unit

Air Start Unit 600 Series

Products

100 – 100 PPM 150 – 150 PPM 180 – 180 PPM 200 – 200 PPM 270 – 270 PPM 300 – 300 PPM 400 – 400 PPM

CU = Cummins DU = Deutz DD = Detroit Diesel SC = Scania

P = Portable, Trailer Mount S = Skid unit / Truck Mount

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I - Description

1. General Unit Description (See Figures 1 & 2) A. The ASU-600 Series Continuous Jet Start Unit is a completely enclosed self-contained truck or trailer

mounted module. The module features a steel channel base and frame, sheet metal enclosure, hinged doors, instrument panel, hose storage compartment, and removable roof. The panels and doors are formed sheet metal lined with acoustical foam of high absorptive quality. The four doors provide ample access to all components for ease of routine maintenance. SCP designates a trailer-mounted unit. The unit is equipped with drum type brakes actuated by a lever mounted at the front of the unit near the tow bar. SCS designates a skid-mounted module. The module is designed to be mounted on any suitable truck chassis. The unit is capable of providing a continuous supply of air per its rating and is suitable for starting jet aircraft engines. The major components are as follows: Heavy duty industrial diesel engine, “dry screw” rotary compressor, delivery air bypass valve, compressor oil heat exchanger, engine radiator, compressor discharge silencer. The illuminated instrument panel permits selection of “Standby”, “Air Pacs”, "Hangar", or “Jet Start” modes. In addition, a unit display indicates compressor discharge pressure and temperature readings. A warning light for engine, compressor, and system faults is provided. The unit incorporates a “Demand Type” throttle system. This system controls engine speed so that compressor airflow matches that required by the aircraft to maintain the selected air start pressure. In this manner, minimum airflow is bypassed (wasted) resulting in optimum fuel consumption. Options available on the ASU-600 Series Jet Start Unit [SCANIA T4F] are listed below:

1 Engine Block Heater

2 Low Fuel and DEF Warning

3 Low Fuel and DEF Warning with Ramp Down to Idle or Shutdown

4 Warning Beacons

5 Sound Attenuation Kit

6 Third Discharge Air Outlet

7 Engine Start Counter

8 Tow-bar Actuated Brake Kit

9 Shut-off Valve Lockout Kit

10 Other options are also available to meet specific customer needs

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1 Doors

2 Parking Brake

3 Running Gear

4 Tow-bar

5 Hose Bin

JET START UNIT FIGURE 1

Note: Standard unit shown. Refer to Chapter 4 for actual configuration.

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1 Radiator fill 8 Fuel Filter / Water Separator

2 Engine Alternator 9 Regulator Assembly

3 Fuel Fill Port 10 Bypass Air Valve

4 Pressure Relief Valve 11 Instrument Panel

5 Engine / Compressor coupler access 12 Shutoff / Bleed Valve Assembly

6 Fuel tank 13 DEF Fill Port and Tank

7 Engine Starter 14 Tier 4 Final Evaporator / SCR Module

JET START UNIT

FIGURE 2 (SOME PANELS & DOORS REMOVED FOR CLARITY)

Note: Standard unit shown. Refer to Chapter 4 for actual configuration.

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2. Major Component Description For the purposes of orientation and to familiarize operators and maintenance personnel with the location of components, the radiator is considered to be at the front of the unit. The compressor is at the rear. Right and left are determined by standing at the rear end facing the unit.

A. Engine System (See Figure 3)

The unit is powered by a 4-cycle Scania Diesel in-line 6 cylinder turbocharged engine with Scania Electronic Control System. The engine is equipped with a 24 VDC automotive type electrical and battery charging system. The engine incorporates integral Oil and Fuel filtration systems. The fuel pre-filter, water separator, and fuel heater are standard on every engine. The components shown below are received standard from the manufacturer. (For a complete list of components, see Chapter 5 of Manual).

1 24 v DC Alternator

2 Engine Control Unit

3 Fuel Filters and Water Separator

4 Oil Filters

DIESEL ENGINE FIGURE 3

Note: Only Diesel Motor shown. See below for Tier 4 Final After-treatment components.

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(1) Engine Control Unit (ECU) The Scania Electronic Control System manages critical engine functions to provide optimum fuel economy and emissions control. The system is comprised of an electronic control module, SCR Control Module, Extra High Pressure fuel injection system (XPI) and various engine sensors. The ECM receives digital/analog electronic input from sensors on the engine and uses the data received to control engine operation. In addition to providing data for efficient fuel combustion, the sensors monitoring engine functions provide data to the ECM for engine protection from failure or damage caused by conditions such as high engine temperature or low oil pressure. The ECM computes fuel timing and fuel quantity based upon pre-determined calibration maps in its memory. Fuel is delivered to the cylinders by cam driven, solenoid operated electronic fuel injectors. Fuel is mechanically pressurized and electronically metered to ensure precise fuel delivery. Its control logic achieves fuel efficiency and improved operating economy. The ECM incorporates a diagnostic connector providing industry standard serial communications links with a portable data reader or PC equipped with decoding software for accessing and interpreting display codes. The ECU as a whole is also responsible for the basic engine functions, such as rated speed and power, fuel injection timing, engine governing, torque shaping, cold start logic, transient fuel delivery, diagnostics, and engine protection.

(2) eXtra-high Presure Injection (XPI)

High injection pressures are required for minimizing exhaust emmissions. The XPI system also contributes to effectiveness and efficiency of fuel consumption. XPI allows for a small amount of fuel to be injected into the combustion chamber slightly before the main injection to reduce noise and prepare the chamber for lower emissions. A small injection after the main injection can optimize aftertreatment temperatures.

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(3) Exhaust Emission Control System (EEC3)

The EEC is responsible for controlling the injection of Diesel Exhaust Fluid (DEF) into the Exhaust System based on the emission levels.

1 EEC3 (Exhaust Emission Control) 5 Electrically Heated Hoses for Reductant

2 Coolant Valve 6 Reductant Pump

3 Exhaust Temperature Sensor 7 Reductant Doser

4 Level & Temperature Sensor in Tank 8 NOx Sensor

EEC COMPONENTS FIGURE 4

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(4) Selective Catalytic Reduction (SCR) System: Function and Working Principle

SCR SYSTEM FIGURE 5

SCR catalyst

Dosing module

Hydrolysis catalyst or

evaporator

Temperature sensor

NOx sensor

Exhaust in from turbo

Exhaust out to silencer or tail pipe

DEF Tank Reductant

Pump Assembly

EEC

Module

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(4.1) Evaporator

Urea injection point, the spray is covered with a plate

Urea mixing chamber (Vaporize the urea solution and mixing)

The length in the labyrinth is also tuned to be a part out the noise reduction

Reduce the low frequency (engine) noise

Dosing unit

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(4.2) DEF Pump

The reductant pump reports pump speed to EEC3. The reductant pump is heated by the engine's coolant at low ambient temperatures.

1 Reductant Intake

2 Reductant Outlet

3 Reductant Pre-filter

4 Expansion Sleeve

5 Overflow Valve

6 Port-to-Pump Chamber

7 Check Valve

The illustration shows a section through the valve block viewed from below.

Reductant is sucked through the intake (1) and pre filter (3) and then through a port (6) to the pump chamber, where reductant pressure is built up.

If the reductant pressure exceeds 13 bar in the pump, the overflow valve (5) and check valve (7) open, reducing the reductant pressure in the pump.

If the reductant freezes at low ambient temperatures in the pump when it is non-operational, which takes place at approx. 12 °F (-11°C), there is an expansion sleeve (4) for the valve block, which is a cavity filled with a soft material which can be compressed.

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(4.3) DEF Doser

1 Electrical Connector

2 DEF Inlet

3 DEF Outlet

4 Metering Nozzle

5 Ventilation

The dosing amount is commanded by the EEC

The dosing unit also incorporates pressure and temperature sensors as inputs back to the EEC.

The dosing unit has a fixed orifice between the pressure and return sides for cooling circulation.

The dosing unit is electrically heated for cold start operation.

(4.4) NOx Sensor

There is a NOx sensor in the system. It is used to measure the content of nitrogen oxide compounds in the exhaust gases after exhaust gas after-treatment. This sensor reports to EEC3, which notifies EMS. The sensor is electrically heated by EEC3. The NOx sensor is located on the SCR catalytic converter's exhaust outlet.

The sensor is electrically heated, which is controlled by the EEC.

The NOx sensor reports to the EEC over a dedicated CAN bus.

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(4.5) Exhaust Temperature Sensor

The exhaust temperature sensor detects the temperature of the exhaust gases before the SCR catalytic converter. The sensor informs the EEC of the exhaust gas temperature. The EEC uses, for example, the exhaust temperature to determine how much reductant should be injected into the exhaust gases in order to obtain the required emission level.

The temperature sensor is located before the catalyst.

When the exhaust temperature reaches 400°F (205°C) the EEC will start injecting DEF into the exhaust.

The catalyst starts functioning above 482°F (250°C)

The optimal function for the catalyst is 572°F (300°C) to 930°F (500°C)

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(4.6) Working Principle

NORMAL START SCR FUNCTIONS FIGURE 6

START (See Figure 6):

The EEC3 control unit monitors the values and functions of all sensors

The engine is started

The reductant pump (11) starts and builds up the reductant pressure to 130-145 PSI (9–10 bar)

When the temperature sensor (9) indicates that the temperature of the exhaust gases has reached 392-482 °F (200–250°C), the EEC3 control unit activates the reductant doser (12), which starts injecting reductant to the hydrolysis catalytic converter (6). The dose is determined by the engine control unit EMS on the basis of the combustion control for the engine

The SCR catalytic converter's (8) reduction process starts

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COLD START SCR FUNCTIONS FIGURE 7

COLD START (BELOW 12.2 °F / -11°C) (See Figure 7):

The EEC3 control unit monitors the values and functions of all sensors

The engine is started

The EEC3 control unit opens the coolant valve (3) so that the coolant can heat the reductant tank (1) and reductant pump (11). The EEC3 control unit also activates electrical heating of the reductant hoses (2 and 4) and the electric heating in the reductant doser (12)

The EEC3 control unit registers, via temperature sensors in the reductant tank (1) and the reductant doser (12), when the reductant is at a temperature above -11°C, at which point the reductant pump (11) starts

When the temperature sensor (9) indicates that the temperature of the exhaust gases has reached 200–250°C, the EEC3 control unit activates the reductant doser (12), which starts injecting reductant to the hydrolysis catalytic converter (6). The dose is determined by the engine control unit on the basis of the combustion control in the engine which is currently being operated by the engine control unit

The SCR catalytic converter's (8) reduction process starts

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SHUTDOWN SCR FUNCTIONS FIGURE 8

SHUTDOWN (See Figure 8):

When the engine is switched off, the reductant pump continues for a specific period (maximum 1 minute) to supply the reductant doser with reductant

However, reductant is not injected into the exhaust but is returned to the reductant tank and has the purpose of cooling the reductant doser

Otherwise it may be damaged by the heat from the exhaust

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(5) Engine Protection, Sensors, and Possible Failures To ensure best possible engine and emission performance at all time, each and every one of the sensors on the engine is monitored with some type of diagnose. Most of the sensors have one or two main purposes. All of them are however used in multiple functions to ensure things as engine reliability, engine running and tampering resistance. No sensor failure is under any circumstances allowed to lead to an engine breakdown. Neither is any sensor failure or tampering allowed to lead to significant increased emissions without the engine derating. Refer to the Scania Documentation in Chapter 5 for further information. 5.1 Catalyst temperature sensor

The sensor is necessary to ensure proper DEF-dosing for all speeds and loads and also activates catalyst protection when necessary. The catalyst temperature sensor has three function modes: normal function, not working and stuck or drifting. An electrical control determines the status of the sensor. Minimum temperature for the catalyst to work properly is 200°C, therefore no DEF-injection is allowed below this temperature. At approximately 600°C the catalyst is destroyed and there could be a possibility for Vanadium to leak from the catalyst. To protect the catalyst from any risk of damage the engine has been calibrated to normally operate at maximum 500°C. If the temperature for some reason would rise to 550°C the engine output will be derated for engine protection. When the temperature drops below 550°C full power is automatically available again.

5.2 DEF injector pressure The DEF-injector pressure sensor is necessary to uphold the right injection pressure, find fault in the system and to detect attempt of tampering. During normal function the pressure is hold above 9 bars. Minimum pressure for DEF-dosing is 9 bars. If the pressure drops below this limit, no injection is allowed. Pressures lower than 9 bars indicate a leak in the system and the injection is turned off.

5.3 NOx sensor The NOx sensor, delivered by Continental, is necessary for the NOx control system to work at its optimal. It is also used by the NOx monitoring system, the function that supervisees fault or tampering that lead to higher NOx levels.

5.4 DEF injector temperature sensor The DEF-injector temperature sensor is included in the system to allow a quick cold start procedure and to work as an injector protection. When the temperature reading is below -8°C the deicing process is initiated. It is also used to monitor the maximum temperature and if too high a derate is activated.

5.5 DEF tank temp sensor The DEF-tank temperature sensor is included in the system to detect frozen DEF and allow a quick cold start procedure. The same sensor control as for the DEF-injector temperature sensor is applied. If an electrical fault on the sensor is detected, the deicing mode for the SCR system is always initiated at start for 10 min.

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5.6 Coolant water temperature sensor (See figure 9) The coolant water temperature is necessary for the engine to operate at optimal temperature and to protect it from damage due to overheating. It is also necessary to allow a good cold start. If the temperature is below 23 °F [-5 °C], the engine runs in “cold start mode”. This mode is calibrated specifically to prevent white smoke and engine miss firing. NOx emission is not affected since the DEF-dosage has been calibrated for these circumstances [However, a block heater is recommended below 14 °F (-10 °C)]. A low coolant level condition is identified on the instrument panel by warning messages on the unit display and electronic engine gauge and the unit status light turning red.

COOLANT LEVEL SENSOR

FIGURE 9 Note: Generic Engine model shown. Refer to Chapter 4 for actual configuration.

NOTE:

These safety devices are bypassed in Jet Start mode to prevent damage to the aircraft (engine). However, if a fault light illuminates on the unit’s instrument panel, repair the

fault as soon as that jet engine start is completed. CONTINUED ATTEMPTS TO RUN THE UNIT WITHOUT REPAIRING IT CAN CAUSE

SEVERE DAMAGE TO THE UNIT AND THIS WILL VOID THE WARRANTY.

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5.7 Boost temperature sensor The boost temperature sensor is necessary to monitor that the engine is not running to hot. If the temperature rises above 90 °C torque and power will be reduced to protect the engine from damage. The sensor has no effect on emissions.

5.8 Boost pressure sensor

The boost pressure sensor is normally used in algorithms calculating the airflow and for calibrations affected by it. If the sensor breaks the value will be approximated from other sensors. The sensor has no effect on emissions.

5.9 Ambient intake pressure sensor

Ambient intake pressure is used to estimate the altitude and to protect the turbo charger from over revving. At 900 mbar boost pressure and fuel amount gradually starts to reduce for engine protection. At 700 mbar timing is set earlier for the engine running and NOx could be slightly affected, this pressure corresponds to an altitude of 5500 feet.

5.10 Ambient intake temperature sensor

The ambient intake temperature sensor is included in the system to allow a quick cold start procedure and is used for the deicing process of the SCR system.

5.11 Common rail pressure sensor

Sensor is required to control the injection pressure. This is crucial for engine running and emission control. Fault leading to pressure exceeding 3000 bar will open a relief valve mounted on the rail. With the valve open pressure is set to approximately 1000bar.

5.12 Engine speed sensor

The speed sensor is the most crucial sensor on the engine and is used by most of the calibration maps. If there would be a failure on the sensor engine would immediately shut down.

5.13 DEF tank level sensor

The sensor measure the distance between DEF surface and bottom. A floating body affects the resistance of the level device like a slide rheostat. The different threshold levels are calibrated and activate the low DEF level warning.

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(6) Air Intake Filter (See Figure 10) The air filter is a self-contained, disposable assembly with an integral element. The filter consists of a steel housing with a pleated paper filter media providing an air cleaning efficiency of 99.9% (per S.A.E. J726). A rubber elbow and hump reducer secured by a band clamp connect the filter to the engine. A restriction indicator and switch is located on the intake pipe. A high engine air intake condition is indicated by the unit status light turning amber and a warning message on the unit display. The Intake Mass Flow Sensor (1) is used by the engine computer to determine the mass flow and temperature of the air going into the engine for efficient combustion process.

1 Intake Mass Flow Sensor [Scania]

2 Air Intake Tube

3 Restriction Indicator and Switch

4 Air Filter Assembly

AIR INTAKE FILTER FIGURE 10

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(7) Exhaust (Gas) System (See Figure 11) The exhaust (gas) system consists of the Tier 4 Final exhaust components supplied by the engine manufacturer and plumbing assemblies. The Evaporator (1) serves as a noise reduction device and the SCR (2) incorporates a spark arresting function. Exhaust gases are treated per Tier 4 Final regulations in this system and then discharged to the atmosphere through a vertical outlet pipe fitted with a rain cap.

1 T4F Evaporator Module

2 T4F SCR Module

3 Turbo Exhaust Connection and Clamp

4 Exhaust Flexible Bellows

5 T4F NOx Sensor

6 Exhaust Pipe 1

7 Exhaust Pipe 2

8 End Tail-pipe

EXHAUST (GAS) SYSTEM FIGURE 11

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(8) Exhaust (DEF) System (See Figure 12) The exhaust (DEF) system consists of the Tier 4 Final DEF components supplied by the engine manufacturer. This system is responsible for storing, heating, pumping, and controlling the DEF. It also houses the Exhaust Emissions Control (EEC3) system for Tier 4 Final after-treatment. The (hot) coolant from the engine is routed to the DEF tank to maintain usable temperature for the DEF.

1 DEF Tank

2 DEF Fill

3 EEC Exhaust Emissions Control System

4 Coolant Connection

5 DEF Line Connection

EXHAUST (DEF) SYSTEM FIGURE 12

Note: Generic DEF Tank model shown. Refer to Chapter 4 for actual configuration.

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(9) Engine Cooling System (See Figure 13) The Engine Cooling System consists of the Jacket Water and Charge Air cooling apparatus. The top tank of the Radiator also houses the coolant level sensor supplied byt the engine manufacturer and installed by TLD during assembly. Refer to the sections regarding engine sensors for more information.

1 Radiator / CAC Assembly

2 RAD / CAC Fan

3 Coolant Level Sensor (Scania)

ENGINE COOLING SYSTEM FIGURE 13

Note: Generic DEF Tank model shown. Refer to Chapter 4 for actual configuration.

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B. Compressor System (See Figure 14) An air-cooled, dry rotary screw compressor, manufactured by Aerzener Maschinenfabrik, Gmbh, Aerzen, Germany, produces the high pressure discharge air required for starting aircraft jet engines. The precisely machined rotors eliminate the need for sealing agents or coatings that may erode or fail due to variable expansion of the rotors inside the housing. Timing gears and air cooling to reduce thermal expansion prevent contact between the rotors, housing, and end plates to maintain high compressor efficiency throughout its life span. An integral gearbox increases input shaft rpm delivered by the engine to the highest efficient rotor operating speed in order to achieve maximum compressor performance. Lubricating oil is circulated through a fan cooled compressor oil heat exchanger mounted on the side of the air compressor. The compressor oil heat exchanger fan is compressor driven. The compressor is protected from damage resulting from low oil pressure or high oil temperature during operation by a safety circuit that causes the engine to shutdown should these conditions occur. This safety circuit is overridden when the unit is placed in jet start mode in order to protect the aircraft engines. There is also a safety circuit which prevents switching to operating modes other than idle if there is a high compressor air filter intake restriction

SCREW COMPRESSOR FIGURE 14

1 Air Inlet Filter Assembly

2 Restriction Indicator and Switch

3 Air Discharge Port

4 Cooling Fan

5 Compressor Oil Heat Exchanger

6 Oil Breather

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(1) Compressor Protective Devices (a) Oil Pressure Switch (See Figure 15)

The low oil pressure switch will shut the unit down in the event that the compressor oil pressure falls below 15 psi. A low compressor oil pressure condition is identified by a fault message on the unit display and the unit status light turning red.

(b) Oil Temperature Switch (See Figure 15)

The compressor high oil temperature switch will shut the unit down in the event that the compressor lubricating oil temperature rises above 215oF (101.7oC). A high compressor oil temperature condition is identified by a fault message on the unit display and the unit status light turning red.

OIL PRESSURE AND TEMPERATURE SWITCHS FIGURE 15

1 Port Access

2 Oil Pressure Switch

3 Oil Temperature Switch

4 Oil Filter

NOTE:

These safety devices are bypassed in Jet Start Mode to prevent damage to the aircraft (engine)

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(c) Discharge Temperature Sensor (See Figure 16) The compressor high discharge temperature sensor will shut the unit down in the event that the compressor discharge temperature rises above 480°F. A high compressor discharge temperature condition is identified by a fault message on the unit display and the unit status light turning red. The minimum engine speed will increase to improve compressor cooling in the event that the compressor discharge temperature rises above 450°F.

1 Discharge Temperature Sensor

DISCHARGE TEMPERATURE SENSOR FIGURE 16

Note: Dual Discharge Outlet configuration shown. Refer to Chapter 4 for actual configuration.

NOTE:

The high temperature shutoff is bypassed in jet start mode to prevent damage to the aircraft.

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(d) Black Box Recorder (See Figure 17) The Black Box Recorder is installed on Air start units to continuosly monitor the compressor discharge pressure and operating mode and store data into internal flash memory for future analysis. The Black Box Pressure Recorder is a part of the jet start proteection circuit of the air start units. If the black box pressure recorder is disconnected by way of removing the power source or the pressure source, it will not allow the unit to operate in Jet Start, Hangar, or Air Pac modes.

1 Black Box Recorder [BBR]

CONTROL BOX FIGURE 17

Note: Standard configuration shown. Refer to Chapter 4 for actual configuration.

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C. Delivered Air System (See Figure 18) Whenever the engine is running, air is drawn into the compressor through the air filter assembly installed on the compressor inlet. The air filter cleans the supply air and dampens inlet noise. The air compressor is equipped with mating helically grooved rotors that operate in constant mesh to provide seamless compression of intake air. The rotor set is comprised of a lobed male rotor and a fluted female rotor that capture the air stream drawn into the compressor through the suction inlet and compresses its volume in the interlobe space between the male and female rotors. As the rotors mesh, the air is compressed between the rotors and is drawn toward the discharge outlet where it is released into the delivery line. The dense, high pressure volume of air released by the compressor enters the discharge silencer; the silencer dampens noise from the compressor discharge. Compressed air leaves the silencer and enters the air delivery manifold where it is either partially or entirely bypassed to the atmosphere by the bypass valve or delivered to the aircraft through the shut-off/bleed valve. The compressor outlet port supplies a pressure signal through a sensing line to the inlet of the electronic pressure regulator valve. Signal air is filtered through an in-line filter/water separator. The regulator valve provides adjustable (0-30 psig) signal pressure to the bypass valve actuating piston. The vent solenoid valve relieves air from the bypass valve actuating piston when de-energized. The regulator controls the position of the bypass valve, which regulates delivered air pressure and flow to the aircraft. (1) Air Pacs Mode

With the unit running at idle, selecting “air pacs” energizes the air delivery control solenoid (L5) through the normally closed air delivery pressure switch (S9). Also energized is the signal pressure regulator (V34) which pressurizes the pneumatic cylinder of the bypass valve. With shutoff valve(s) (V36) and (V42) closed, air will be diverted through the bypass valve (V1). Opening the shutoff valves (V36) or (V42) will deliver air to the aircraft at the pressure established by the regulator valve (V34). Delivered air pressure above 43 psi opens the air delivery pressure safety switch (S9) and de-energizes the air delivery control solenoid (L5). Delivered air flow is bypassed until air pressure drops below 32 psi. The signal pressure regulator provides an adjustable signal pressure of 0-30 psig to the air delivery control solenoid valve. In the energized position the air delivery control solenoid valve provides this signal air pressure to the bypass valve actuating piston; when de-energized the air delivery control solenoid removes the pressure from the actuating piston, allowing the delivered air to bypass. In either the “air pacs,” 'hangar," or “standby” mode, a compressor or engine fault will result in unit shutdown, the unit status light turning red, and a fault message on the unit display. The palm button emergency stop switch (S23) may be used for emergency unit shut down.

(2) Hangar Mode With the unit running at idle, selecting “Hangar” energizes the air delivery control solenoid (L5) through the normally closed air delivery pressure switch (S9). Also energized is the signal pressure regulator (V34) which pressurizes the pneumatic cylinder of the bypass valve. With shutoff valve(s) (V36) and (V42) closed, air will be diverted through the bypass valve (V1). Opening the shutoff valves (V36) or (V42) will deliver air to the aircraft at the pressure

NOTE:

Air Pacs pressure may be adjusted per customer preference. Pro

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established by the regulator valve (V34). Delivered air pressure above 43 psi opens the air delivery pressure safety switch (S9) and de-energizes the air delivery control solenoid (L5). Delivered air flow is bypassed until air pressure drops below 40 psi. The signal pressure regualtor provides an adjustable signal pressure of 0-30 psig to the air delivery control solenoid valve. In the energized position the air delivery control solenoid valve provides this signal air pressure to the bypass valve actuating piston; when de-energized the air delivery control solenoid removes the pressure from the actuating piston, allowing the delivered air to bypass. In either the “air pacs,” 'hangar," or “standby” mode, a compressor or engine fault will result in unit shutdown, the unit status light turning red, and a fault message on the unt display. The palm button emergency stop switch (S23) may be used for emergency unit shut down.

(3) Jet Start Mode With the unit running at idle, selecting “jet start” energizes the air delivery control solenoid (L5) through the normally closed air delivery pressure switch (S9). Also energized is the signal pressure regulator (V34) which pressurizes the pneumatic cylinder of the bypass valve. With shutoff valve(s) (V36) and (V42) closed, air will be diverted through the bypass valve (V1). Opening the shutoff valves (V36) or (V42) will deliver air to the aircraft at the pressure established by the regulator valve (V34). Delivered air pressure above 43 psi opens air delivery pressure safety switch (S9) and de-energizes air delivery control solenoid (L5). Delivered air flow is bypassed until air pressure drops below 40 psi. The air pacs regulator provides an adjustable signal pressure of 0-30 psig to the air delivery control solenoid valve. In the energized position the air delivery control solenoid valve provides this signal air pressure to the bypass valve actuating piston; when de-energized the air delivery control solenoid removes the pressure from the actuating piston, alowing the delivered air to bypass. The unit shut down system is disabled in the “jet start” mode to avoid hazard to the aircraft engine(s). An engine or compressor fault condition will not shut down the unit. The emergency stop switch (S23) is not disabled in "jet start." When a fault condition occurs in the “jet start” mode, the unit will continue running while the unit status light turne red and a fault message is shown on the unit display to alert the equipment operator of the fault condition.

WARNING:

Hangar mode should not be used for starting aircraft engines. The unit safeties are not disabled in hangar mode; an engine or compressor fault will shut the unit down, possibly resulting in

catastrophic failure of the aircraft engine.

NOTE:

Hangar mode may be deleted from some units or may have different pressure settings depending on customer preference.

WARNING:

DO NOT LEAVE UNIT RUNNING IN JET START MODE UNATTENDED AS ALL THE PROTECTIONS ARE DISABLED.

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1 Discharge Silencer

2 Pressure Relief Valve

3 Air Delivery Pipe

4 Air Bypass Valve

5 Regulator Assembly

6 Shut-off / bleed Valve Assembly

DELIVERED AIR SYSTEM FIGURE 18

Note: Dual Discharge Outlet configuration shown. Refer to Chapter 4 for actual configuration.

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D. Control System (1) System Overview The control system for the unit is based on a Programmable Logic Controller (PLC) that is housed in the control box. The PLC interfaces with the ECM, the unit sensors, and the user interface. The PLC provides instructions to the engine over the J1939 data link with the ECM. The delivered air system is controlled by a set of outputs to the regulator and valves.

(2) Delivered Air Pressure Control The pressure of the air that is delivered to the aircraft is regulated by the bypass valve assembly (V1). The bypass valve cylinder is pressurized in jet start, hangar, and air pacs modes. This pressure holds the trim valve shut until the delivered air pressure is sufficient to open it, and then provides variable back pressure in the delivered air manifold to hold the delivered air pressure at the target pressure. The air delivery control solenoid valve (L5) is a normally open valve that closes when energized. When the L5 valve is open, the bypass valve cylinder is not pressurized. When it is closed, the cylinder can pressurize. The L5 valve is powered by the PLC (via the air delivery pressure switch) when the unit is in jet start, hangar, or air pacs modes. The signal pressure regulator (V34) provides signal air at variable pressure to the bypass valve cylinder. The pressure of this air determines the pressure of the air in the delivered air manifold. The signal pressure regulator output is controlled by a 1-9 V DC signal; output pressure is linearly proportional to the voltage signal. The PLC outputs a PWM signal that is converted into a voltage signals by the PWM -> 0-10 VDC converter (E10.) This signal then controls the signal pressure regulator. The output of the PLC is based on current operating mode and barometric pressure. a. Calibration

The PWM output of the PLC is based on the current operating mode and a lookup table in the software that provides PWM output for a given delivered air pressure set-point. This table is populated by the PLC program's calibration functions. In the 'Calibrate Pr-Reg' Menu of the unit display can be found 'Quick Auto-Cal' and 'Full Auto-Cal.' The full auto-cal will calibrate the PWM output for all possible delivered air pressures, including those for altitudes other than the current altitude. The quick auto-cal will calibrate the PWM output for only those delivered air pressures and altitudes which have been used by the unit in question before. Calibration will only be necessary if a control component has been replaced. If calibration is needed, the unit should be placed in 'idle' with the discharge valves closed. Once the desired calibrate function has been selected, the unit will run through the calibration cycle with the unit display indicating the progress of the calibration cycle. Once the calibration cycle has been complete, the unit should go through a performance check, and will then be ready for normal operations. There is an 'auto-cal' function which runs in the background of the PLC program continuously. This function continuously compensates for any drift that may have occurred as the unit and components wear or ambient conditions change.

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(3) Trim Height Sensor (See Figure 19) Because the compressor is a positive displacement or “constant mass flow” source, a portion or all of the air flow will at times need to be bypassed to the atmosphere. This depends on what the flow capacity required by a particular aircraft is and whether the internal aircraft ports are open to accept air flow. The engine speed determines how much air is created, while the current operating mode and setting of the signal pressure regulator will control how much air is bypassed and how much is delivered to the aircraft. Engine speed is controlled by the unit PLC based on input from the trim height sensor (R18) and the delivered air pressure sensor (S16). Depending on the selected mode; “jet start,” "hangar," or “air pacs,” the signal pressure regulator (V34) will provide a signal pressure to the bypass valve (V1) actuator piston. This signal pressurizes the bypass valve cylinder, providing the force to hold the trim valve closed if delivered air pressure is low, while letting the trim valve open and air to bypass if the pressure begins to rise. The trim height sensor (R18) monitors the height of the trim in the bypass valve (V1.) The trim valve opens as the trim moves up to allow more air to bypass and closes as the trim moves down, restricting the bypass air. As the trim valve opens and the sensed height increases, an error signal is generated in the PLC that too much air being created, and is bypassing. The PLC then causes the engine to decelerate until the trim drops or the minimum engine speed is reached. If the trim valve closes completely, an error signal is generated in the PLC that too little air is being created. The PLC then causes the engine to accelerate until the trim has lifted and the bypass valve is very slightly open, which is the nominal operating condition. As the backpressure against the bypass valve is fixed for a given operating mode, variations in delivered air pressure are caused by variations in the compressor flow from the aircraft demand. The delivered air pressure sensor (S16) monitors the pressure of the air being delivered to the aircraft. As the pressure deviates from the set-point for the given operating mode, an error signal is generated by the PLC. If the pressure is too high, the PLC signals the engine to decelerate; if the pressure it too low, the PLC signals the engine to accelerate. When the unit shut-off/bleed valves are closed or the aircraft valves are closed, the pressure in the unit delivered air piping will increase and the bypass valve will open. Based on the signals from the trim height sensor and the delivered air pressure sensor, the PLC will signal the engine to decelerate until the minimum engine speed is reached. When the valves are opened and the aircraft begins taking air the bypass valve will close and the delivered air pressure will drop. Based on the signals from the trim height sensor and the delivered air pressure sensor, the PLC will signal the engine to accelerate until the required flow is reached; i.e. the pressure is at its set-point and the bypass valve is slightly open. If the demand from the aircraft is sufficient to require the full output of the unit, the bypass valve will not open and the acceleration will stop when the engine speed reaches its maximum. The error signals from the trim height and delivered air pressure both pass through gain functions before being combined into the Proportional-Integral-Derivative function that the PLC uses to determine how rapidly to accelerate or decelerate. This allows the unit to react rapidly to significant variations in trim height and pressure, but more slowly to minor variations, thereby preventing overshoot and engine hunting. a. Sensor Drift Compensation

When the unit is powered on, the PLC logs the output of the trim height sensor and the delivered air pressure sensor. If these are outputs are not zero, the control system then zeroes the outputs by making the initial sensor reading the offset. In this way minor variations in the sensors are compensate for.

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If the sensors drift, the offset will increase. If the offset drifts past a certain threshold, a warning message will appear on the unit display, alerting the user to the need to replace or calibrate the offending sensor.

1 Trim Height Sensor

2 Delivered Air Pressure Sensor

TRIM HEIGHT SENSOR FIGURE 19

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(4) Miscellaneous Functions a. Unit Display

The unit display normally indicates the unit status, operating mode, fuel level, delivered air pressure, and delivered air temperature. Depending on the options included with the unit, other information may be available by scrolling up and down the display.

b. Warnings and Faults

The control system incorporates the unit safeties that protect the engine and compressor from damage. These safeties include: 1. Engine high coolant temperature 2. Engine high oil temperature 3. Engine low oil pressure 4. Low Coolant Level 5. Compressor Low Oil Pressure 6. Compressor High Oil Temperature 7. Compressor High Discharge Air Temperature 8. Low fuel level (option) These safeties will shut down or roll back the unit if they occur unless the unit is in 'jet start' mode; in 'jet start' mode, all safeties display a warning message and trigger the unit status light to go to red. There are warnings that do not cause the unit to ramp down or shut down, but will cause the unit display to show a warning message and may prevent the unit from switching out of 'standby' mode. These include: 1. Engine air filter inlet clogged 2. Compressor air filter inlet clogged 3. Black Box Recorder fault

c. Warmup and Cooldown

If the engine oil is cold when the engine is started the unit will go into 'warmup' mode. In this mode, the mode selector switch is disabled. The unit will accelerate to a fast-idle speed in order to build heat more quickly. The unit display will indicate that the unit is in 'warmup' mode, showing the engine oil temperature that must be reached to come out of 'warmup' mode and the current engine oil temperature. The unit status light will switch amber during the warmup. Once the engine oil temperature reaches the target temperature the unit will come out of warmup and go to whatever mode is currently selected. When the engine stop button is depressed the unit enters the cooldown cycle. To prevent damage to the compressor the unit has to idle for 3 minutes before shutting down. If the unit has not been in 'standby' mode for at least three minutes when the engine stop button is pressed, the countdown to automatic engine stop will begin and be shown on the unit display. Once the countdown has expired, the engine will stop automatically. During the cooldown cycle the engine start/stop pushbutton will flash and the unit status light will switch to amber. The mode selector switch will not function during the cooldown, but it may be stopped at any time by pressing the engine start/stop button again.

d. Automatic Power Down

If the unit power is left on for 30 minutes after the engine is stopped it will automatically be turned off. This can be temporarily disabled for maintenance purposes in the unit display menu by navigating to 'Settings,' 'Maintenance.'

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(5) Menu Navigation The unit display normally displays the information necessary for unit operation along with any information that pertains to the options of the unit. The unit display also contains a menu system that can be used to look up more detailed data, test certain safeties, and change some settings. This menu system can be accessed by pressing the 'scroll up,' 'scroll down,' 'select.' and 'escape' pushbuttons simultaneously.

Maintenance Menu

Unit Information

AIR PRESS-ACT

AIR PRESS-SP

AIR PRESS-OFFSET

AIR PRESS-MAX-SP

BAROMETRIC PRESS

PRESS REG PWM-SP

TRIM HEIGHT

TRIM HEIGHT OFFSET

Software

PLC Software

Display Software

Calibration

Quick Auto-Cal

Full Auto-Cal

Testing

Low Fuel Level

High Air Temp

Settings

Unit Model Options

Sensors

Low Fuel

E-Stop Counter

Eng Start Counter

JS Overrun Counter

Beacon

Maintenance

Auto Power Off

Records

Fault History

Warning History

E-Stop Count

Eng-Start Count

Eng-Hourmeter

JS Overrun Count

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E. Aircraft Protection Devices (See Figure 20) The delivered air pressure switch (S9) protects the aircraft and unit compressor from pressures in excess of 43 psig. When actuated, it de-energizes the air delivery control solenoid valve (L5), which will exhaust pressure from the bypass valve actuating cylinder. Air will then be vented to the atmosphere. In addition to the pressure switch, the aircraft and compressor are protected from over pressure by a relief valve located in the air delivery manifold. This valve is set at 46 psig and is capable of venting the entire supply of delivered air. The shut-off/bleed valves provide delivered air through the hoses and aircraft coupler when the valves are in the open position. Flow is shut off to the aircraft when the valve handle is in the closed position. This position also allows for venting the supply hose through the bleed valve so that the hoses may be de-pressurized before disconnecting them from the aircraft.

1 Pressure Relief Valve

2 Pressure Switch

3 Air Delivery Control Solenoid Valve (L5)

4 Shut-off / Bleed Valve Assembly

AIRCRAFT PROTECTION DEVICES FIGURE 20

Note: Dual Discharge Outlet configuration shown. Refer to Chapter 4 for actual configuration.

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F. Control Box (See Figure 21) The control box houses the programmable logic controller that controls the unit operations, the engine diagnostic connector, and unit fuses. The door of the control box contains the instrument panel. The programmable logic controller (PLC) controls the unit, interfacing with the ECM, the unit sensors, and the instrument panel. It regulates operating speed and pressure, and monitors the unit safeties.

1 Programmable Logic Controller [PLC]

2 Engine Diagnostic Connector

3 Unit Fuses

CONTROL BOX FIGURE 21

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G. Instrument Panel (See Figure 22) The instrument panel provides mounting facilities for the engine and compressor controls. The following instruments and controls are mounted on the instrument panel assembly.

1 Panel Lights 7 Engine Start/Stop Pushbutton

2 Electronic Engine Gage 8 Emergency Stop

3 Unit Display 19 ‘SELECT’ Pushbutton

4 Unit Status Light 10 ‘ESCAPE’ Pushbutton

5 Selector Switch 11 ‘SCROLL-UP’ Pushbutton

6 Power On/Off Pushbutton 12 ‘SCROLL-DOWN’ Pushbutton

INSTRUMENT PANEL ASSEMBLY FIGURE 22

Note: Standard Panel configuration shown. Refer to Chapter 4 for Actual configuration.

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1) Panel Lights: Illuminate instrument panel to aid in low-light operation. Constantly on when unit power is on.

2) Electronic Engine Gage: The electronic engine gage displays engine operating parameters and fault messages on an LCD display for easy reading. Major parameters that the Electronic Engine gage displays are:

A Engine RPM F Engine Oil Pressure

B Engine Power Load G Engine Operating Voltage

C Engine Torque Load H Engine Hours Run

D Engine Coolant Temperature I Engine Fuel Economy

E Engine Manifold Temperature J Engine Fault Codes

3) Unit Display:

The unit display indicates unit operating parameters and status messages on an LCD display. Some major parameters that the Unit Display shows are:

A Fuel Level D Delivered Air Temperature

B DEF Level E Unit Operating Mode

C Delivered Air Pressure F Unit Status

The unit display may display additional information based on version and options. The unit display acts as the user interface for accessing some options and settings and displaying unit history

4) Unit Status Light:

Multi-colored LED indicator displays green for 'ready,' amber for 'warning,' and red for 'fault.'

5) Selector Switch: A four position rotary switch that enables the operator to select either: Standby || Air Pacs || Hangar || Jet Start modes

6) Power On/Off Pushbutton: Hold to turn unit power on Press again to turn unit power off

7) Engine Start/Stop Pushbutton: Hold to start engine Press again to start shutdown cycle

8) Emergency Stop Switch: Immediately shuts down unit

9) Select Pushbutton: For navigating Unit Display menus

10) Escape Pushbutton: For navigating Unit Display menus

11) Scroll-Up Pushbutton: For navigating Unit Display menus

12) Scroll-Down Pushbutton: For navigating Unit Display menus

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