(11.) Replace torque gauge if it is out of tolerance at any point during calibration.
(12.)Whencalibration is completed, turn valve knob perpendicular to line and disconnect tester.
(13.)Attach torque pressure line to transmitter.
EFFECTIVITY:
040-999 77-10-00 PAGE 1
77-10-00Jan10/90
PIPERAIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCEMANUAL
A. Power (continued)
1. Torque Pressure IndicatingSystem (continued)
Valve Knob Test Gauge TorquePressureTester
TorqueSystemCalibration Figure501
CHART1 TORQUESYSTEMCALIBRATIONDATA
PSIG FT.-LBS. TOLERANCE
13.08 400 + 30 ft-lbs.
16.36 500 ± 20 ft-lbs.
26.17 800 + 30 ft-lbs.
32.71 1000 ± 30 ft-lbs.
39.25 1200 ± 30 ft-lbs.
45.79 1400 + 30 ft-lbs.
52.33 1600 + 30 ft-lbs.
58.87 1800 + 30 ft-lbs.
62.15 1900 ± 20 ft-lbs.
65.42 2000 + 30 ft-lbs.
71.96
2200 ± 30 ft-lbs.
72.94
2230 ± 20 ft-lbs.
EFFECTIVITY:
040-999
Jan 10/9077-10-00
PIPERAIRCRAFT PA-42-720(Advanced Trainer)
MAINTENANCEMANUAL
A. Power(continued)
2. Tachometer-Generators (PropellerandGasGenerator)
Thepropeller(Np)and gas generator(Ng)tachometer-generatorsproducean electric current whichis proportional to gas generatorand propeller speed.The electric currentis monitored bytachometerindicatorsmountedin the instrument panelwhichindicatepropellerandgasgeneratorspeed.Thegasgeneratortachometer-generator onthebacksideoftheaccessory
is mounted gearboxandrotatescounterclockwise. tachometer onthe right sideof
Thepropeller is mounted thereductiongearboxcaseandrotatesclockwise.
(a) Removalof Generator
(1.) Disconnecttheelectricalconnectorfromthegeneratorunit.
(2.) Removethe four mountingnutsat the base ofthegenerator.
CAUTION: IMMEDIATELYAFTERREMOVINGGENERATORUNIT, COVER THETACH GENERATORMOUNTINGPADTO PREVENT FOREIGNMATERIALFROM ENTERINGTHE ENGINE.
(3.) Pulltheunitstraightoutandawayfromthemountinglugs.
(b) InstallationofGenerator
(1.) Place a new gasket on the mounting pad. (2.) Lubricatethe generatorunit shaft splineswith MolybdenumDisulfide,TypeG, paste form lubricant(MIL-G-21164). (3.) With the electrical socketpointingdown,slidethegeneratorinto place over the mounting studs. (4.) Securethe unit in place with the four mountingnutsandtorqueto 65 to 85 inch-pounds.
EFFECTIVITY: 040-999
77-10-00 Jan10/90
PIPER AIRCRAFT
PA-42-720(AdvancedTralner)
MAINTENANCE MANUAL
A. Temperature
1. InterTurbine SensingSystem(ITT)Temperature
(a) Descriptionand Operation
The interturbine temperature(T5) sensing system provides the pilot with an indicationof the
engine operating temperatureoccurringin the zone between the compressor turbine and the
first stage power turbine stator vane ring.
The system consists of a bus-bar and probe assembly,a wiring harness, externally mounted
terminalblock, a trim harness incorporatinga T1 thermocouple probe and preset variable
resistor,andan instrument indicator mounted in the instrument panel.
The T1 trim thermocouple consists of chromel/alumel steel tube,
leads encased in a stainless havinga variable, preset,chromel resistor at the forward end. This unit has been set by the manufacturerin accordance to trim data, in terms of temperature change,that is recorded on the engine data plate. No attempt should be made to adjust the unit once installed and not defective. However, if replaced, it must be adjusted to procedures outlinedin the Pratt and WhitneyMaintenanceManual, p/n 3034342, Chapter 77.
NOTE: Refer to Pratt and Whitney Maintenance Manual,p/n 3034342, Chapter 77 for greater detail on the Interturbine Temperature
Sensing System.
(b) ResistanceCheck of Engine InterTurbine System
Temperature
This check should be performed using a Barfield 2312-G, Temperature Indicating System Test Set, available from Barfield Instrument Corporation, Miami,Florida.
NOTE:If several probes are broken or damaged, the loop resistancewould not necessarilyfall outside the allowable tolerance. However, erroneoustemperature indicationscould occur due to reduced sampling. To check for presence of defective probes or harness lead, it is necessaryto remove the engine power section assembly. (Refer to Pratt & Whitney Maintenance Manual, p/n 3034342, Chapter 72.)
(1.) Remove aircraftexternalleads and T1 trim thermocouple leads from terminal on gas generatorcase. (2.) Connect test set to alumel and chromelterminalson gas generator caseterminalblock (Figure 601) and measure loop resistance of T5 system. Resistance shouldbe between
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