PrattWhit DIF Book 1

7/28/2019 PrattWhit DIF Book 1

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PW Diff.PW Diff.For Training Purposes Only

MDMDMD---111111

P & W ENGINE 4462P & W ENGINE 4462

DIFFERENCESDIFFERENCESATAATAss 26, 36, 3026, 36, 30


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TABLE OF CONTENTS

SUBJECT PAGE

FIRE PROTECTION. 5

PNEUMATICS........... 27

ICE AND RAIN ......... 55


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THIS PAGE INTENTIONALLY LEFT BLANK


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MD-11FIRE PROTECTION

PRATT & WHITNEY 4462

DIFFERENCES


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PW 4462 ENGINE


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FIRE DETECTION LOOP INSTALLATIONS

The Engine Fire Detection System causes fire

warnings in the Flight Compartment if a fire oroverheat condition occurs. Each engine has a dual-

element Fire Detector Assembly installed at important

locations.

The two (2) elements (Loop A and B) of each fire

detector assembly can independently cause a fire

warning. This makes sure the system continues to

operate if one element becomes damaged.

A Fire Detection Control Unit, for each engine,

monitors the fire detector assemblies. If a fire occurs,

the control unit sends the signals that cause the FIRE

WARNING indications in the flight compartment.

The Fire Detection Control Units also monitor their

related fire detector assemblies for failures. If a failure

occurs, the Fire Detection Control Unit causes an

alert message to come into view on the Engine and

Alert Display.

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FIRE DETECTION LOOP INSTALLATIONS


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THRUST REVERSER COWL (LEFT SIDE)

The Fire Detectors are installed so the most critical

fire zones are monitored for Overheat and Fire. TheFire Detectors are installed at the lower section of the

Thrust Reverser Cowl inner structure:

1. To detect Engine Fires from flammable fluids thatleak on hot surfaces

2. During some engine operation, it can detect an

overheat condition from blown bleed air ducts.

The elements monitor the left lower areas to include:

1. The Intermediate Case Group

2. The Main. Gearbox Group

3. To the Diffuser and Combustion Group.

The two (2) Responders (loop A and B) are installed

vertically at the forward section of the cowl assembly.

It extends horizontally to the rear and a short section

vertically.

The routing of the fire detector wire assembly goes

vertically around the forward inner section. It ends at

the top of the cowl door to an electrical disconnect

point.

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THRUST REVERSER COWL (LEFT SIDE)


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FIRE DETECTOR INSTALLED (LEFT SIDE)

The Fire Detector is installed at the lower, left section

of the Thrust Reverser Cowl Door.

The Responders are attached to a flat piece of metal

with four (4) bolts, washers and nuts.

The stainless-steel support tube is permanently

attached to the flat piece of metal.

The detector tubes are attached to the support tube

by the clamp assemblies. The clamp assemblies arepermanently attached to the support tube.

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FIRE DETECTOR INSTALLED (LEFT SIDE)


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THRUST REVERSER COWL (RIGHT SIDE)

The Fire Detectors are installed so the most critical

fire zones are monitored for Overheat and Fire. TheFire Detectors are installed at the lower section of the

Thrust Reverser Cowl inner structure:

1. To detect Engine Fires from flammable fluids thatleak on hot surfaces,

2. During some engine operation, it can detect an

overheat condition from blown bleed air ducts.

The elements monitor the right lower areas to include:1. The Intermediate Case Group

2. The main Gearbox Group

3. To the Diffuser and Combustion Group.

The two (2) Responders (loop A and B) are installedat the forward section of the cowl assembly

horizontally. It extends to the rear makes a curve,

horizontally and a short section vertically.

The routing of the fire detector wire assembly goesvertically around the forward inner section. It ends at

the top of the cowl door to an electrical disconnect

point.

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THRUST REVERSER COWL (RIGHT SIDE)


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RIGHT THRUST REVERSER DOOR (OPEN)


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PYLON FIRE DETECTORS (ENGINES 1 AND 3)

The top fire detector is installed at the bottom section

of the wing pylon for the number 1 and 3 engines.The top fire detector assembly is put in that position:

1. To detect a fire/overheat condition in the top

section of the core compartment2. And to detect a torch type fire.

NOTE: Torch-type fires are cause by a burn-

through of the combustion case.

This torch-type flame would hit the burn-through

barrier and move in all directions. The elements must

send the Fire Alarm signal before the fire can go into

the pylon area.

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PYLON FIRE DETECTORS (ENGINES 1 AND 3)


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PYLON FIRE DETECTORS (ENGINE NUMBER 2)

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FIRE AGENT- DISCHARGE LINE

The engine discharge line stops at five (6) discharge

nozzles in each engine compartment. Four (4)discharge nozzles are located in the lower section of

the pylon above the engine. A flex hose is connected

to a tube from the center of the pylon dischargenozzle line. This line is installed for the agentdischarge at the accessory gearbox fire area.

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FIRE AGENT DISCHARGE LINE


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MD-11

PNEUMATICS

PRATT & WHITNEY 4462

DIFFERENCES


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PNEUMATIC SYSTEM DIAGRAM

The pneumatic system supplies bleed air from the

aircraft engines or the auxiliary power unit for theoperation of aircraft systems. The air comes from the

8th and/or 15th stages of the engine compressors.

Each engine usually supplies air only to its relatedsystems. For example, number one engine suppliesthe air for the number one air conditioning pack and

left wing anti-ice. The number three engine supplies

the air for number three air conditioning pack and

right wing anti-ice.

Two isolation valves, in the pneumatic manifolds,

make it possible for one air source to supply all the

aircraft pneumatic systems. This lets you use air from

the auxiliary power unit or a ground air supply topressurize different systems. If an engine relatedmalfunction occurs, you could close its air supply and

use a different engine to continue systems operation.

The isolation valves are also important for engine

starts. During a start, the valves open and send air

from the air source to the applicable engine starter.

The pneumatic system is automatic in its operation.

Electronic systems controllers operate the different

valves in the system. The valves control the air flows,the air pressures, and the air temperatures throughthe system. A manual mode of operation is also

available from the flight compartment.

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PNEUMATIC SYSTEM COMPONENT LOCATION

(ENGINES 1 AND 3)The primary pneumatic-system components installed

on the wing engine are:

1. Precooler

2. Fan Air Valve3. Pressure Regulator Valve4. Left side Low-Stage Check Valve

5. Right side Low-Stage Check Valve

6. High-Stage Valve

7. Anti-ice Valve.

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PNEUMATIC SYSTEM COMPONENTS LOCATION

(ENGINES 1 AND 3)


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(ENGINE NUMBER 2)The primary engine components in the number 2

engine pneumatic system are identical to the wingengine pneumatic components. The engine

pneumatic components are:

1. The pre-cooler2. The fan-air valve

3. The pressure regulator valve

4. The left low-stage check valve

5. The right low-stage check valve

6. The high-stage valve7. The anti-ice valve.

Due to the location and installation, the number 2

engine pneumatic manifold is different than the wingengine pneumatic manifolds.

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(ENGINE NUMBER 2)


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ENGINE 1 AND 3 (LEFT SIDE)

PNEUMATIC SYSTEM COMPONENT INSTALLATION

This shows the pneumatic components installed on the

engine left side;

1. This left low-stage check valve2. The high-stage valve

3. The pressure regulator valve

4. The fan-air valve.

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ENGINE 1 OR 3 (LEFT SIDE)


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LOW-STAGE CHECK VALVES

During engine operation, two (2) each low-stage

check valves (LSCV) open to supply engine bleed airfrom the 8th stage manifold. Low stage engine bleed

air is then directed to the pressure regulator valve to

supply a source of pneumatic air supply.

The LSCV prevents reverse flow of the pneumatic air-

supply pressure when it has greater pressure then

the low-stage bleed air supply.

The LSCV has two (2) flappers that are connected atthe middle of the LSCV by a hinge. When greater

pressure or reverse air enters the outlet side of the

LSCV, it moves the flappers closed. This procedure

isolates the 8th stage engine duct and the 8th stageengine ports.

The LSCV is installed between the 8th stage duct and

the duct that goes to the pressure regulator valve.

One (1) valve is found on the upper right side of the

engine core. The other LSCV is found on the upperleft side of the engine.

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LOW-STAGE CHECK VALVES


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LOW-STAGE CHECK VALVE (ENGINE LEFT SIDE)

LEFT SIDE LOW-STAGE CHECK VALVE LOCATION

This shows the low-stage check valve installed in the

8th. stage manifold on the left side of the engine.

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LOW-STAGE CHECK VALVE (ENGINE LEFT SIDE)


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COMPRESSOR CASE GROUP (CENTER RIGHT SIDE)

RIGHT SIDE LOW-STAGE CHECK VALVE

INSTALLATION

This shows the low-stage check valve installed on the

upper right side of the engine.

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COMPRESSOR CASE GROUP (CENTER RIGHT SIDE)


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HIGH STAGE VALVE

15th stage bleed air, supplies the pneumatic system

with a source of high stage bleed air supply. Duringengine operation the high stage valve (HSV) controls

the quantity of 15th. stage bleed air used for

pneumatic supply. When necessary high stage air isused when low-stage (8th. stage) air pressure is toolow for pneumatic system supply. When low-stage air

is used for pneumatic system supply and does not

have the necessary temperature or pressure. Some

high stage air will be used to help the low-stage air

pneumatic system supply.

The HSV also functions as a check valve, and closes

to prevent reverse air pressure flow. This function

isolates the 15th. stage manifold.

The HSV is located on the left side of the engine. It is

installed between the 15th. stage manifold and the

duct that goes to the pressure regulator valve.

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HIGH STAGE VAVLE


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HIGH-STAGE VALVE (ENGINE LEFT SIDE)

HIGH-STAGE VALVE LOCATION

This shows the high-stage valve installed between

the 15th stage manifold and the duct that goes to the

pressure regulator valve.

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HIGH-STAGE VALVE (ENGINE LEFT SIDE)


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PNEUMATIC PRESSURE REGULATOR VALVE

When necessary, the pressure regulator valve (PRV)

modulates to adjust the pneumatic system outputpressure. The PRV uses low-stage pneumatic supply

(8th stage engine bleed air) and/or high-stage

pneumatic supply (15th stage engine bleed air) as thesource of pneumatic supply system.

The PRV also functions as a check valve (it closes to

prevent reverse air flow). This function isolates the

low and high stages of engine bleed air sources.

The PRV is found on the upper left side of the engine.

It is installed between the intersect duct and the pylon

interface duct.

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(ENGINE LEFT SIDE)PNEUMATIC LOCATION PRESSURE REGULATOR

VALVE

This shows the pneumatic pressure regulator valve

installed between the intersect duct and the pyloninterface duct.

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(ENGINE LEFT SIDE)


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FAN-AIR VALVE SIDE VIEW (ENGINE LEFT SIDE)

FAN-AIR VALVE SIDE VIEW

This is a side view of the fan-air valve (FAV) that

shows the spring-loaded open butterfly actuator. The

FAV is found on the upper left side of the engine nearthe pylon.

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FAN-AIR VALVE SIDE VIEW (ENGINE LEFT SIDE)


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FAN-AIR VALVE TOP VIEW (ENGINE LEFT SIDE)

FAN-AIR VALVE INSTALLATION

This shows a top view of the fan-air valve (FAV)

installed on inlet side of the FAV duct. The FAV is

found on the upper left side of the engine near thepylon.

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FAN-AIR VALVE TOP VIEW (ENGINE LEFT SIDE)


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MD-11

ICE AND RAIN

PRATT & WHITNEY 4462DIFFERENCES


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ENGINE ANTI-ICE

The engine anti-ice system uses engine bleed air

from the high pressure compressor to prevent ice onthe engine inlet cowl. An anti-ice control valve on

each engine controls the airflow to its inlet cowl.

When the valve opens, the air flows through amanifold into the cowl assembly. This hot airincreases the temperature in the inlet cowl, and

prevents ice.

An Anti-ice Control Panel in the flight compartment

contains the engine anti-ice control switches.Disagree lights on each switch tell you if a valve does

not open or close with relation to its switch position.

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ENGINE ANTI-ICE


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The pneumatic system supplies bleed air from the

aircraft engines or the auxiliary power unit for theoperation of aircraft systems. The air comes from the

8th and/or 15th stages of the engine compressors.

Each engine usually supplies air only to its relatedsystems. For example, number one engine suppliesthe air for the number one air conditioning pack and

left wing anti-ice. The number three engine supplies

the air for number three air conditioning pack and

right wing anti-ice.

Two isolation valves, in the pneumatic manifolds,

make it possible for one air source to supply all the

aircraft pneumatic systems. This lets you use air from

the auxiliary power unit or a ground air supply to

pressurize different systems. If an engine relatedmalfunction occurs, you could close its air supply and

use a different engine to continue systems operation.

The isolation valves are also important for engine

starts. During a start, the valves open and send air

from the air source to the applicable engine starter.

The pneumatic system is automatic in its operation.

Electronic systems controllers operate the different

valves in the system. The valves control the air flows,

the air pressures, and the air temperatures throughthe system. A manual mode of operation is also

available from the flight compartment.

8th 15th

Ground Idle

140o

F (60o

C)


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ENIGNE 1 OR 3 (LEFT SIDE)


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ANTI-ICE VALVE AND PRESSURE INDICATION

The anti-ice valve regulates the airflow to the inlet

cowl. The anti-ice pressure switch monitors the anti-ice valve operation. The anti-ice pressure switch and

anti-ice valve are both installed on the right side of

the fan cowl.

The anti-ice pressure switch senses pneumatic

pressure on the downstream side of the anti-ice

valve. If a disagree condition occurs (over-pressure or

under-pressure), the anti-ice pressure switch sends

information to the flight deck about valve position anddisagree fault logic.

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ANTI-ICE VALVE AND PRESSURE INDICATION


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ENGINE ANTI-ICE VALVE

The anti-ice valve is located on the lower right side of

the fan cowl. The valve regulates the pressure sent tothe inlet cowl at high engine power. At low engine

power, the valve will be full open due to low engine

bleed air pressure.

The anti-ice pressure sensor (adjacent to anti-ice

valve) receives pneumatic air from the downstream

side of the anti-ice valve. It monitors anti-ice valve

position and pressure sent to the inlet cowl.

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ENGINE ANTI-ICE VALVE

INLET COWL ANTI ICE SWIRL TUBE


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INLET COWL ANTI-ICE SWIRL TUBE

Fifteenth stage pneumatic air is sent through the anti-

ice duct to the swirl tube. The swirl tube has a singlecalibrated opening that increases the movement of

the air into the inlet cowl. High airflow and increased

movement of the hot air into the inlet cowl correctlyheats the outer skin and prevents ice. The pneumaticair is then sent past the D-duct bulkhead through air

discharge holes to the overboard exit duct.

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INLET COWL ANTI ICE SWIRL TUBE


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INLET COWL ANTI-ICE SWIRL TUBE

INLET COWL ANTI ICE EXIT DUCT (WING ENGINE)


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INLET COWL ANTI-ICE EXIT DUCT (WING ENGINE)

After the pneumatic air is used to heat the forward

edge of the inlet cowl, the air is sent overboardthrough an exit duct. This duct is installed on the

bottom of the inlet cowl at the 6 o'clock position. The

exit duct prevents over-pressure of the inlet cowl.

During flight, the shape and location of the exit duct

causes a low pressure area outside of the exit duct.

The airflow over the engine cowl causes a suction

that helps pull the air out of the exit duct.

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INLET COWL ANTI ICE EXIT DUCT (WING ENGINE)


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INLET COWL ANTI-ICE EXIT DUCT (WING ENGINE)

ENGINE ANTI ICE VALVE CROSS SECTION


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ENGINE ANTI-ICE VALVE CROSS SECTION

The engine anti-ice valve is controlled by its electrical

solenoid and is operated by engine pneumatic air.

OPEN

A torsion spring and pneumatic pressure keep thevalve in the open position when the solenoid is de-

energized.

CLOSED

The solenoid must be energized to close the anti-ice

valve. When the pneumatic pressure under the

actuator diaphragm is greater than the spring force,

the piston moves. The movement of the piston closes

the valve.

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ENGINE ANTI ICE VALVE CROSS SECTION


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ENGINE ANTI-ICE VALVE CROSS SECTION

ANTI ICE VALVE


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ANTI-ICE VALVE

To manually lock the anti-ice valve:

1. Loosen the lock screw in the center of the position

indicator

2. Use wrench on hex head to open (clockwise) orclose (counterclockwise). The force required toturn the valve shaft is less than 75 inch pounds.

Tension springs lock the position indicator in the

open or closed position

3. Tighten the lock screw in the center of the position

indicator.

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ANTI ICE VALVE


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ANTI- ICE VALVE

ENGINE NUMBER 2 (RIGHT SIDE)


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Air is sent through ducts from the engine pneumatic

manifold to an anti-ice valve. The anti-ice valve isinstalled at the five o'clock position on the fan case

(same as engines 1 and 3).

Routing of the ducts downstream of the anti-ice valveis different on the number two engine.

The ducts on the numbers 1 and 3 engines go

forward to the inlet cowl at the four o'clock position.

The ducts on the number 2 engine 90 up to the twoo'clock position. They then go forward through the

inlet adapter to the inlet forward lip.

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ENGINE NUMBER 2 ANTI-ICE DUCT


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ENGINE NUMBER 2 ANTI-ICE DUCT

HORIZONTAL STABILIZER


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The tail section of the aircraft includes the number 2

engine. Access to the number 2 engine is through theaircraft tailcone.

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NUMBER 2 ENGINE INLET COWL ANTI-ICE AIR FLOW


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NUMBER 2 ENGINE INLET COWL ANTI ICE AIR FLOW

The pneumatic air enters the inlet cowl area through

a single duct. The air is sent into the D-duct and flowsinto a passage between the inner and outer skin. The

air heats the outer skin and flows overboard through

an anti-ice exit duct located at the seven o'clock

position on the inlet duct.

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NUMBER 2 ENGINE INLET COWL ANTI-ICE AIR FLOW


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NUMBER 2 ENGINE INLET COWL ANTI ICE AIR FLOW

INLET COWL ANTI-ICE EXIT DUCT (ENGINE NUMBER 2)


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INLET COWL ANTI ICE EXIT DUCT (ENGINE NUMBER 2)

After the pneumatic air is used to heat the forward

edge of the inlet cowl, the air is sent overboardthrough an exit duct. This duct is installed on the left

side of the number 2 inlet cowl at the 7 o'clock

position.

During flight, the shape and location of the exit duct

causes a low pressure area outside of the exit duct.

The airflow over the engine cowl causes a suction

that helps pull the air out of the exit duct.

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INLET COWL ANTI-ICE EXIT DUCT (ENGINE NUMBER2)


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INLET COWL ANTI ICE EXIT DUCT (ENGINE NUMBER2)

COWL DUCT THERMAL SWITCH (ENGINE NUMBER 2)


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( )

The cowl duct thermal switch sends a signal to the

flight deck if a pneumatic manifold failure occurs. Thisswitch is installed adjacent to the anti-ice duct on the

number 2 banjo spar.

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COWL DUCT THERMAL SWITCH (ENGINE NUMBER 2)


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( )

ENGINE NUMBER 2 INLET DUCT


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The anti-ice duct on the number 2 engine inlet

assembly is at the 2:30 position. The duct delivers thehot air to the inlet cowl. A shroud around the duct

prevents damage to the structural components if a

duct failure occurs.

If the anti-ice duct fails, a thermal leak detector on the

number 2 banjo spar alerts the flight crew about the

fault.

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ENGINE NUMBER 2 INLET DUCT


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ENGINE 2 COWL ANTI-ICE SCHEMATIC


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The Engine 2 Anti-ice Valve is powered by the 28

VDC 2 Bus. When the Engine 2 Anti-ice switch is set,power is removed from the Anti-ice Valve. The valve

will open and send a position signal back through the

Anti-ice Panel (AIP).

On the engine a Nose Cowl Pressure Switch is used

to monitor Anti-ice air pressure. With anti-ice on a

pressure of less than 70 PSI will turn on the DISAG

(disagree) light. If the anti-ice Is off, a pressure of

more than 85 PSI will turn on the DISAG light.

The Environmental System Controller (ESC) receives

a disagree signal and sends disagree information to

the Display Electronic Units. Engine 2 has a leak

detector. The leak detector sends a ENG-2 ANTI-ICEDUCT FAIL signal to the ESC.

Engine 2 also has a Heated Drain Hose. The Heated

Drain Hose is not used on engine 1 or 3.

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ENGINE 2 COWL ANTI-ICE SCHEMATIC


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WATER DRAIN SYSTEM (ENGINE NUMBER 2)


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Due to the engine number 2 inlet length and

installation, it is important to make sure that waterdoes not collect in the inlet. If water collects and

freezes, the ingested ice can cause engine damage.

There is a water drain system installed in the enginenumber 2 inlet. The drain system helps remove water

from the inlet cowl. The water is sent overboard

through a drain hose that has an internal 28VDC

heater. This heated drain makes sure that water or

ice does not collect and cause damage to the engine.

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WATER DRAIN SYSTEM (ENGINE NUMBER 2)


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INLET COWL


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The Ice Detector is installed on the inlet cowl of

engines number 1 an 3. The Ice Detector Probe andSensing Elements extend into the airflow at the 8:00

position of the inlet cowl.

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INLET COWL


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ENGINE NUMBER 1 ACCESS PANELS


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Access panel number 411 AL may be used for

inspection, removal, and replacement of the IceDetector Probe (engine 1 and 3).

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ENGINE 1 ACCESS PANELS


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INLET COWL ICE DETECTOR (ENGINES 1 AND 3)


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The Ice Detector will detect ice formation on the

sensing element. This element is installed in thepatch of the airflow that enters the inlet cowl. The Ice

Detector is an electrical unit and sends inputs to the

Ice Detection Processor.

The electrical wires from the ice detector to the aft

bulkhead of the inlet cowl are found in the inlet cowl

structure. The inlet cowl has access panels to permit

inspection and maintenance of the ice detector, and

electrical wires and connections.

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INLET COWL ICE DETECTOR (ENGINE 1 AND 3)


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ICE DETECTION SENSOR (ENGINES 1 AND 3)


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ICE DETECTOR INSTALLATION


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The Ice Detector assembly is installed on the engine

inlet at the 4 o'clock position. The air that enters theengine, flows directly over the sensing element.

When ice collects to .020 of an inch, the Ice Detector

will send the signals to the flight compartment.

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ICE DETECTOR INSTALLATION (ENGINES)


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DUAL PRIMARY ICE DETECTION SYSTEM

BLOCK DIAGRAM


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BLOCK DIAGRAMThere are two separate Ice Detection systems on the

MD-11 aircraft. The two systems must operate forprimary ice detection. The three main components in

each system are:

1. Ice detection probe2. Ice detection controller

3. Environmental System Controller (ESC).

The Ice Detector probe is in the engine inlet cowl

(numbers 1 and 3 only). Dirt. oil, or other foreignmaterial does not affect this unit. When there is no

ice, the probe sensor tube vibrates at 40 KHZ.

The ice detector controller is the main processor in

the ice detection system. The controller receivessignals from the ice detector probe and sends

information to the ESC about:

1. Ice detected /no ice detected

2. Ice detector probe condition and faults3. Ice detector controller condition and faults.

When ice conditions occur, the ICE alert shows on

the EAD. Also, the ice detector controller sends an

input to the probe heater. The heater operates for 5seconds to melt the ice built-up on the sensor tube.

This is enough heat to melt light to moderate ice

build-up.

The ESC sends the ice information to the Display

Electronic Unit (DEU). There are four alerts thatappear on the DEU for the Ice Detection system:

1. ICE (Level 2)

2. NO ICE DETECTED (Level 1)3. ICE DET (detector) SINGLE (Level 1)

4. ICE DETECTOR FAIL (Level 1)

A built-in test function in the ice detector controller

monitors the condition of the system andcomponents. All faults found in the system go to the

Central Fault Display System.

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DUAL PRIMARY ICE DETECTION SYSTEM BLOCK DIAGRAM


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ICE DETECTOR CONTROLLER


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There are two Ice Detector Controllers on the MD-11

aircraft. There is one Controller for each Ice Detectionsystem. The two Controllers are in the forward edge

of the wing (one on the left wing and one on the right

wing) and inboard of the engine pylon.

The Ice Detector Controller has all of the electrical

hardware to operate the Ice Detection system. This

unit also has built-in test functions. The Controller

sends drive signals to the ice detector probe, and the

probe vibrates at a specific frequency. The Controllerreceives feedback signals from the probe and

monitors conditions.

In ice conditions, the Controller sends an ICE alert to

the flight deck. The flight crew must manually turn onthe anti-ice systems. The ICE alert goes out when all

anti-ice switches (wing, tail, and engines 1, 2, and 3)

are on. A NO ICE DETECTED alert comes on when

ice is no longer present. The NO ICE DETECTED

alert goes off when the flight crew turns the anti-iceswitches off.

A fault in one of the Ice Detector Controllers shows

on the Engine and Alert Display (EAD) as an ICE

DET (Detector) SINGLE. A fault in each of the twoControllers shows on the EAD as ICE DETECTOR

FAIL. The faults go to the Central Fault Display

System.

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ICE DETECTOR CONTROLLER


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COWL ICE DETECTION SCHEMATIC


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ENG 1 ICE DETECTION PROCESSOR is powered

by 115 VAC from AC Generator Bus 1. ENG 3 ICEDETECTION PROCESSOR is powered by 115 VAC

from AC Generator Bus 3.

Internal circuits send 115 VAC to heat the (ENG 1and ENG 3) ICE DETECTION SENSORS. The

OSCILLATOR MONITOR circuit sends a signal to:

1. The drive coil

2. The 39.87 KHZ detector circuit.

The detector circuit compares the signal from the

drive coil and the feedback coil. The output of the

detector circuit goes to a 60 second (SEC) delay

circuit and to the heater control circuit. The output ofthe 60 second (SEC) DELAY (on BRK) circuit will

send a low to the Environmental Systems Controller

(ESC). The ESC then sends an Engine 1/3 ICE signal

(through XMTR A and XMTR B) to the Display

Electronic Units (DEUs), for the air crews attention.

The OSCILLATOR MONITOR circuit sends a

SENSOR FAULT signal to the ESC when an ICE

DETECTION SENSOR fails. The INTERNAL FAULT

MONITOR circuits send a CONTROLLER FAULTsignal when the ICE DETECTION PROCESSOR

fails.

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COWL ICE DETECTION SCHEMATIC


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Date post:	03-Apr-2018
Category:	Documents
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PrattWhit DIF Book 1

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