(b)
After preservation process is complete, drain oil from control unit. Replace all caps and plugs previously removed.

(c)
Whenpackagingunit for shipping, ensure all shipping plugs and caps are secure. Place unit in moisture and vapor proof container or plastic bag and seal. Pack sealed unit in a shipping carton or case.

4. Removal of Fuel Control Unit
(a)
Ensurefirewallshutoffvalve is in OFF position.

(b)
Removeenginecowling. (Refer to 71-10-00.)

(c)
Refer to Pratt and Whitney MaintenanceManual p/n 3034342, Chapter 73, for Removal of Fuel ControlUnit.

5. Installationof Fuel Control Unit
NOTE: Refer to Pratt and Whitney Maintenance Manual p/n 3034342, Chapter 73, for Installation of Fuel Control Unit.
6. Fuel Control Unit Checks and Adjustments
NOTE: Refer to Pratt and Whitney Maintenance Manual p/n 3034342, Chapter 73, for Fuel Control Unit Checks and Adjustments.
EFFECTIVITY:
040999  73-20-00 PAGE

73-20-00 Jan 10/90
PIPER AIRCRAFT
PA-42-720(Advanced Trainer)
MAINTENANCEMANUAL

A. Indicating
1. Descriptionand Operation
inthe PA-42-720 by Ragen Data Systems.The system containsa turbine type transmitter, located in high pressure fuelline betweenfuel control unitand fuel nozzlesof each engine. These transmitterssupplyelectrical pulses(in relation to fuel flowvolume)to signal conditioners(locatedbehindannunciator)which provideoutput signals to drive fuel flow gauge and totalizers.
The fuel flow indicating system installed is manufactured
The fuel pressureindicatingsystemcontainsa fuel pressure transmitterin low pressure fuel line betweenenginedrivenfuel pump and fuel oil heater. The transmitter uses an electrical arrangementtodetect changes in fuel pressure, andrelays these changesto fuel pressure indicatoron instrument panel.
2. Fuel Flow IndicatingSystem
(a) Removalof Fuel Flow Transmitter
(1.) Remove screwswhichholdmagneticshield assembly halvesoverfuelflow transmitter.
(2.) Remove electricalconnectorfrom fuel flow transmitter.
(3.) Disconnectfuellines attached tofuel flow transmitterand remove transmitter.
(4.) Cap all open fuellines to preventcontamination.

(b) Installationof Fuel Flow Transmitter
(1.) Attach magnetic shield halves to fuel flow transmitter.
CAUTION:  ENSUREARROWONSHIELD-HALFLINES UP WITH FLOWDIRECTION ARROWON TRANSMITTER.
(2.) Removeprotectivecapsfromfuel lines. Connect fuel lines to flow transmitter,ensuring flow arrow on transmitter is pointing in proper direction of fuel flow. (3.) Install electricalconnectorto transmitter.
(c) Removalof Signal Conditioner
(1.) Disconnect electricalconnectorsfrom signal conditioner.
(2.) Removescrewsholdingsignalconditionerto back of electrical shelf(behindannunciator

panel).

(3.) Removesignalconditioner.
(d)
Installationof Signal Conditioner

(e)
Removalof Fuel PressureTransmitter

(1.) Attach signalconditionerto bracket on back of eledtrical shelf with attachinghardware. (2.) Connect electrical connectorsto signal conditioner.
(1.) Remove electricalconnectorfrom transmitter.
(2.) Disconnect fuellinesattachedto transmitter and remove transmitter.
(3.) Cap all open fuellines to preventcontamination.

EFFECTIVITY:
040-999  73-30-00 Page1
73-10-00
Jan 10/90

PIPER AIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCE MANUAL

A. Indicating(continued)
2. Fuel Flow Indicating System (continued)
(f)
Installationof Fuel Pressure Transmitter

(1.) Remove protectivecaps. Connect fuel lines to inlet and outlet on transmitter. (2.) Attach electricalconnectorto transmitter.

(g)
Removalof Fuel Pressure Indicator

(1.) Ensure battery master switch is OFF.
(2.) Rotate clamp actuating screw counterclockwise instrument

to loosen clamp securing in panel. (3.) Withdraw instrumentfrom panel. Disconnect attachinglines and electrical wires.
(h)
Installationof Fuel Pressure Indicator

(1.) Connect lines and electrical wiring.
(2.) Insert instrument into appropriate openingin Instrument panel.
(3.) Rotate clamp actuating screw clockwise andtighten clamp around instrument case.

(i)
Test and Adjustment of Fuel Pressure Transmitterand Gauge

(1.) Connect Barfield Pressure Tester set with calibrated test gauge to fuel transmitter using appropriateAN fittings and pressure line. (Set must be capable of providing and monitoringstaticpressuresfrom 0-50 psi using engine oil.)
(2.) Turn aircraft master switch ON. (3.) With fittings loosenedandvalvetowardsline, turn handleclockwise until air is bled from line (evident by dripping oil at fitting). Retighten fitting. (4.) Turn valve toward reservoir; turnhandle counterclockwise.
　
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