EFFECTIVITY:
04-999
36-10-00 Jan10/90

A. Distribution (continued)
PIPER AIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCEMANUAL

1.Engine Bleed Air Ports

2. Bleed Air Shutoff Valve 
3. Ground BypassValve 
Showing Disconneted Bleed LinesView Showing Disconnected Bleed Lines 
7. Nitrogen Bottle 
6. Nitrogen SupplyRegulator 5. Manual Shutoff (Test Only) 4. Pressure Gauge (Test Only) View Showing N2 Connection —9.BleedAir Lines  ECU 12. Pressure Cap -SupplyLines  I  Sta. 57.00 
8.  Intercooler  11. Check 

Proof Pressure and Leakage Test Setup 
Figure 501 (Sheet 1 of 2) 
EFFECTIVITY: 
040-999 
Jan 10/90 36-10-00 

PIPERAIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCEMANUAL

A. Distribution(continued)
ENGINELEFT SIDE

Pressure LEFTSIDE-FORWARDFUSELAGE
Proof Pressure and Leakage Test Setup
Figure501 (Sheet2 of 2)

EFFECTIVITY: 040-999
36-10-00JPAGE9
36-10-00Jan 10/90

PIPER AIRCRAFT PA-42-720 (Advanced Trainer) MAINTENANCE MANUAL 
CHAPTER 37 
LIST OF EFFECTIVE PAGES 
CHAPTER SECTION  PAGE  DATE  CHAPTER SECTION  PAGE  DATE 
37-EFFECTIVITY 37-CONTENTS 37-00-00 37-10-00 37-10-00 37-10-00  1 1 1 1 2 3  Jan 10/90 Jan 10/90 Jan 10/90 Jan 10/90 Jan 10/90 Jan 10/90 

LIST OF EFFECTIVE PAGESan 10/90
SUBJECT
Descriptionand Operation FaultIsolation
Distribution VacuumSystemTest VacuumRegulatorAdjustment
PIPER AIRCRAFT 
PA-42-720(Advanced Trainer) 
MAINTENANCEMANUAL 
CHAPTER 37- VACUUM 
TABLE OF CONTENTS 
CHAPTER  PAGE 
37-00-00 
1 
1 
37-10-00 
1 
2 
3 

EFFECTIVITY: 040-999
CONTENTSan 10/90
PIPER AIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCE MANUAL

VacuumSystem
A Descriptionand Operation
Thegyro-vacuumsystemfunctionsbybleedairbeingforcedthroughaventuridevicecalledan ejector. Astheprimarybleedairflowisforcedthroughtheejector,adecreasein pressuredevelopsproviding thesecondaryflow.Thesecondaryflowactsasthesourceof airtothesystem.(Shownin Figure1)
The inletfor secondaryflow is locatedbehindthe instrumentpanel. Attachedtothe inlet,a filtercleans
air downto 0.3 micronparticleswith a 99%efficiency.
Thevacuumis controlledon the vacuumsideof the instrumentsbya vacuumregulatorandcheck
valve. Theregulatormaintainsvacuumbetween4.5and 5.2 inchmercury,relativeto cabinpressure.
Onthe vacuumsideof the regulator,a checkvalveisbuilt intothe line,preventingreverseflow to gyro
instruments.
Thevacuumsystemoperatesthepilotsturnandbankindicator.A suctiongauge,locatedonthelower
leftofthepilot'sinstrumentpanel,indicatesnegativepressureinthevacuumsystem.
CHART 1

FAULT ISOLATION (VACUUM SYSTEM) 
Fault  Cause  Remedy 
SuctionGauge-pressure drop. (PressureGauge-mayincrease.)Pilot'sturn andbankbecomes inaccurate.  Blockedbleedair nozzleto Ejectorfails. CheckValvefailsclosed. VacuumRegulatorfails openorclosed,orthe inletfilteriscloggedor blocked.  RemoveEjectorandblow out nozzle. ReplaceCheckValve. ReplaceRegulatorand/ or cleanInletFilter. 
Tubingfrom Ejectorto vacuumregulatorfailed openorclosed.  RepairorreplaceTubing. 
Specificvacuuminstruments tumble.  Thetubingto thespecific instrumentsfailedopen or closed.  Replaceor repairtubing. 

EFFECTIVITY:

37-00-00Jan
10/90
PIPER AIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCE MANUAL

A.  Distribution
Figure 1 gives a schematic descriptionof how the vacuum system is arranged in the aircraft.
Pilot's Turn and Bank Indicator
Engine EngineBleed
Inlet Filter  BleedSuction

Bleed Air Directional Gyro
Check and

Pressure Gauge  GyroHorizonShutoff
Valve VacuumRegulator
(4.2to 5.2 in. Hg Intercooler
Bleed Air
Overtemp-
erature
Switch
(N.O.)
Pressure -
Switch
(N.O.)
15+ 1 PSI

Door Seal Valve (N.C.)
Solenoid Valve (N.C.)
Deice Boots

A.  VacuumLineto Cabin Pressure Control System
B.  To Bleed Air and Cabin Pressure System
Vacuum System Schematic Figure1

EFFECTIVITY:
040-999
37-10-00 PAGE
Jan10/901
PIPERAIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCEMANUAL

A. Distribution
1. Vacuum System Test (Figure 501)
(a)
　
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