Tronair 52 1 Series Installation and operating instructions

OPERATION & SERVICE MANUAL
For Spare Parts, Operations & Service Manuals or Service Needs
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Tronair, Inc. Phone: [phone] | 800-426-6301
1 Air Cargo Pkwy East Web: www.tronair.com
Swanton, OH 43558 Email: [email protected]
52X1 Series
5211, 5221, 5231, 5241
Hydraulic Power Units
02/2023 Rev. 05

REVISION DATE TEXT AFFECTED
01 09/2016 Original release
02 12/2017 Modified 9.2 Electric Motor
03 11/2019 Added 9.14.10 Hand Pump (Option M-7)
04 08/2021 Added section 5.14 Infrequent HPU Use and updated 9.0 Maintenance
05 02/2022 Major revision

Models: 5211, 5221, 5231, 5241
Hydraulic Power Unit
02/2023 | Rev. 05
TABLE OF CONTENTS PAGE
1.0 PRODUCT INFORMATION ..............................................................................................................................................1
1.1 DESCRIPTION....................................................................................................................................................1
1.2 MODEL & SERIAL NUMBER..............................................................................................................................1
1.3 MANUFACTURER..............................................................................................................................................1
1.4 FUNCTION..........................................................................................................................................................1
1.5 REQUIREMENTS...............................................................................................................................................1
2.0 SAFETY INFORMATION..................................................................................................................................................1
2.1 USAGE AND SAFETY INFORMATION..............................................................................................................1
2.2 EXPLANATION OF WARNING & DANGER SIGNS...........................................................................................1
2.3 COMPONENT SAFETY FEATURES..................................................................................................................2
2.4 FUNCTIONAL SAFETY FEATURES ..................................................................................................................2
2.5 PERSONAL PROTECTION EQUIPMENT..........................................................................................................2
2.6 SAFETY GUIDELINES .......................................................................................................................................2
2.7 GENERAL COMMENTS.....................................................................................................................................2
3.0 PREPARATION PRIOR TO FIRST USE ..........................................................................................................................2
3.1 GENERAL...........................................................................................................................................................2
3.2 SERVICING RESERVOIR ..................................................................................................................................2
3.3 CONNECTING ELECTRICAL LEADS................................................................................................................2
4.0 TRAINING.........................................................................................................................................................................3
4.1 TRAINING REQUIREMENTS.............................................................................................................................3
4.2 TRAINING PROGRAM .......................................................................................................................................3
4.3 OPERATOR TRAINING......................................................................................................................................3
5.0 OPERATION.....................................................................................................................................................................3
5.1 OPERATING PARAMETERS .............................................................................................................................3
5.2 NUMERICAL VALUES........................................................................................................................................3
5.2.1 Fluid....................................................................................................................................................................3
5.2.2 Physical...............................................................................................................................................................4
5.2.3 Motor Driven Hydraulic Pump .............................................................................................................................4
5.2.4 Electric Motor......................................................................................................................................................4
5.2.5 Filters..................................................................................................................................................................5
5.2.6 Hand Pump (Option M).......................................................................................................................................5
5.3 LOCATION & LAYOUT OF CONTROLS ............................................................................................................6
5.3.1 Front Panel Controls...........................................................................................................................................6
5.3.2 Electrical Control Panel.......................................................................................................................................7
5.3.3 Hydraulic Control Panel ......................................................................................................................................8
5.3.4 Rear Panel Controls............................................................................................................................................9
5.3.5 Hydraulic Pump Controls ..................................................................................................................................10
5.3.6 Hand Pump Controls (Option M).......................................................................................................................11
5.3.7 Split System Controls (Option C) ......................................................................................................................12
5.3.8 Split System Crossover Check Controls (Option D)..........................................................................................13
5.3.9 Return Back-Pressure with Sight Gauge (Option T)..........................................................................................14
5.4 START UP PROCEDURES..............................................................................................................................15
5.4.1 Procedure for First Time or Different Electrical Supply ONLY...........................................................................15
5.4.2 Initial Start Up of the HPU.................................................................................................................................15
5.5 PRELIMINARY ADJUSTMENTS FOR OPERATION........................................................................................16
5.5.1 Flow Control Adjustment...................................................................................................................................16
5.5.2 Pressure Control Adjustment ............................................................................................................................16
5.5.3 Reservoir Selector Valve Operation..................................................................................................................16
5.5.4 Bypass Valve Operation....................................................................................................................................17
5.6 BLEEDING AIR FROM SYSTEM......................................................................................................................17
5.6.1 To Easily Purge the Unit of Air..........................................................................................................................17
5.7 SPLIT SYSTEM OPERATION (Option C).........................................................................................................17
5.7.1 To Operate the Split System.............................................................................................................................17
5.8 SPLIT SYSTEM CROSSOVER CHECK (Option D)..........................................................................................18
5.9 HAND PUMP OPERATION (Option M).............................................................................................................18
5.9.1 To Operate the Hand Pump..............................................................................................................................18
5.10 RETURN BACK-PRESSURE WITH SIGHT GAUGE (Option T).......................................................................19
5.11 SAMPLE VALVE...............................................................................................................................................19
5.12 EMERGENCY SHUT DOWN PROCEDURE....................................................................................................19
5.13 DESCRIPTION OF ALARM SYSTEMS ............................................................................................................19
5.13.1 High Fluid Temperature Indicator (Option S) ....................................................................................................19
5.13.2 Voltage/Phase Monitor Indicator (Options G  J)..............................................................................................19
5.13.3 High and Low Reservoir Level Indicator (Option L)...........................................................................................19
5.13.4 Clogged Filter Indicator Light (Option R)...........................................................................................................20

Models: 5211, 5221, 5231, 5241
Hydraulic Power Unit
02/2023 | Rev. 05
5.14 INFREQUENT HPU USE..................................................................................................................................20
5.14.1 Infrequent HPU Use Start Up Procedure ..........................................................................................................20
6.0 PACKAGING AND STORAGE.......................................................................................................................................21
6.1 PACKAGING REQUIREMENTS.......................................................................................................................21
6.2 HANDLING .......................................................................................................................................................21
6.3 PACKAGING PROTECTION ............................................................................................................................21
6.4 LABELING OF PACKAGING ............................................................................................................................21
6.5 STORAGE COMPATIBILITY ............................................................................................................................21
6.6 STORAGE ENVIRONMENT.............................................................................................................................21
6.7 STORAGE SPACE AND HANDLING FACILITIES ...........................................................................................21
7.0 TRANSPORTATION.......................................................................................................................................................21
8.0 TROUBLE SHOOTING...................................................................................................................................................22
8.1 HPU WILL NOT START....................................................................................................................................22
8.2 NO FLOW .........................................................................................................................................................22
8.3 REDUCED FLOW.............................................................................................................................................23
8.4 NO PRESSURE or REDUCED PRESSURE ....................................................................................................23
8.5 FLUID OVERHEATS.........................................................................................................................................23
8.6 HAND PUMP (Option M) IS NOT PUMPING FLUID.........................................................................................23
9.0 MAINTENANCE..............................................................................................................................................................24
9.1 GENERAL.........................................................................................................................................................24
9.2 ELECTRIC MOTOR..........................................................................................................................................24
9.3 MOTOR DRIVEN HYDRAULIC PUMP.............................................................................................................25
9.3.1 Motor Driven Hydraulic Pump Replacement Kits List........................................................................................25
9.4 HYDRAULIC FLUID..........................................................................................................................................26
9.5 FILTERS ...........................................................................................................................................................26
9.5.1 Pressure Filter...................................................................................................................................................27
9.5.2 Return Filter ......................................................................................................................................................28
9.5.3 Hand Pump (Option M) Filter ............................................................................................................................29
9.5.4 Desiccant Air Filter............................................................................................................................................30
9.6 HYDRAULIC HOSES........................................................................................................................................31
9.7 INSTRUMENT PANEL......................................................................................................................................32
9.7.1 Electric Panel....................................................................................................................................................33
9.7.2 Hydraulic Panel.................................................................................................................................................34
9.7.3 Control Block/Flowmeter...................................................................................................................................35
9.7.3.a System Pressure Relief Valve...........................................................................................................................36
9.7.3.b Check Valve......................................................................................................................................................37
9.7.3.c Bypass Valve ....................................................................................................................................................38
9.7.4 Flow Control......................................................................................................................................................39
9.7.5 Pressure Control...............................................................................................................................................40
9.8 RESERVOIR ASSEMBLY.................................................................................................................................41
9.9 RETURN MANIFOLD ASSEMBLY ...................................................................................................................43
9.9.1 Return System Pressure Relief Valve...............................................................................................................45
9.10 PRESSURE FILTER ASSEMBLY (Single System)...........................................................................................46
9.11 ELECTRICAL COMPONENTS .........................................................................................................................47
9.11.1 Electrical Components With 100 ft. Input Cord Option......................................................................................49
9.12 HEAT EXCHANGER ASSEMBLY.....................................................................................................................53
9.13 EXTERNAL COMPONENTS.............................................................................................................................54
9.14 ADDITIONAL FEATURES ................................................................................................................................55
9.14.1 25 ft (7.6 m) Hoses (Option A) ..........................................................................................................................55
9.14.2 50 ft (15.2 m) Hoses (Option B) ........................................................................................................................55
9.14.3 Split System (Option C).....................................................................................................................................56
9.14.4 Crossover Check (Option D).............................................................................................................................57
9.14.5 Hour Meter (Options E and F)...........................................................................................................................58
9.14.6 Voltage/Phase Monitor (Options G J).............................................................................................................59
9.14.7 Pyrometer (Option K)........................................................................................................................................60
9.14.8 Electric Reservoir Level (Option L)....................................................................................................................61
9.14.9 Hand Pump (Option M).....................................................................................................................................62
9.14.10 Hand Pump (Option M-7)..................................................................................................................................64
9.14.11 Towing Trailer (Option N)..................................................................................................................................66
9.14.12 Calibration Port (Option Q)................................................................................................................................67
9.14.13 Electric Filter Clogging Indicator (Option R)......................................................................................................68
9.14.14 Electric Over-Temperature (Option S)...............................................................................................................69
9.14.15 Return Sight Gauge (Option U).........................................................................................................................70
9.14.16 Drip Pan (Option 4)...........................................................................................................................................71
9.15 REPLACEMENT LABELS PARTS LISTS.........................................................................................................72
9.15.1 Base Unit ..........................................................................................................................................................72
9.15.2 Fluid Labels.......................................................................................................................................................72
9.15.3 Filter Element Kit Labels...................................................................................................................................72

Models: 5211, 5221, 5231, 5241
Hydraulic Power Unit
02/2023 | Rev. 05
9.15.4 Split System (Option C) and Crossover Check (Option D) Labels ....................................................................73
9.15.5 Pyrometer (Option K) Label ..............................................................................................................................73
9.15.6 Hand Pump (Option M) Labels..........................................................................................................................73
9.15.7 Calibration Port (Option Q) Labels....................................................................................................................73
9.15.8 Back-Pressure Valve with Sight Glass (Option T) Label...................................................................................73
10.0 PROVISION OF SPARES...............................................................................................................................................74
10.1 SOURCE OF SPARE PARTS...........................................................................................................................74
10.2 RECOMMENDED SPARE PARTS LISTS ........................................................................................................74
10.2.1 Spare Electrical Parts........................................................................................................................................74
10.2.2 Spare Parts.......................................................................................................................................................74
11.0 CALIBRATION OF INSTRUMENTATION ......................................................................................................................75
11.1 SOURCE OF CALIBRATION............................................................................................................................75
12.0 IN SERVICE SUPPORT..................................................................................................................................................75
13.0 GUARANTEES/LIMITATION OF LIABILITY..................................................................................................................75
14.0 APPENDICES.................................................................................................................................................................75

Models: 5211, 5221, 5231, 5241
Hydraulic Power Unit
02/2023 | Rev. 05 Page | 1
This product can not be modified without the written approval of Tronair, Inc. Any modifications done without written approval
voids all warranties and releases Tronair, Inc., it suppliers, distributors, employees, or financial institutions from any liability
from consequences that may occur. Only Tronair OEM replacement parts shall be used.
1.0 PRODUCT INFORMATION
1.1 DESCRIPTION
Hydraulic Power Unit
Model NumberFluid Type
5211.......................MIL-PRF-5606
5221.......................MIL-PRF-83282
5231.......................Aviation Phosphate Ester, Type IV and V
5241.......................MIL-PRF-87257
1.2 MODEL & SERIAL NUMBER
Reference nameplate on unit
1.3 MANUFACTURER
TRONAIR, Inc. Telephone: [phone] or 800-426-6301
1 Air Cargo Pkwy East Fax: [phone]
Swanton, Ohio 43558 USA E-mail: [email protected]
1.4 FUNCTION
The Hydraulic Power Unit (HPU) provides a source of clean, pressurized hydraulic fluid for performing required
aircraft maintenance. An electric motor drives a pressure compensated piston pump. Filters are provided on the
pressure and return systems. A bypass (dump) valve allows starting and stopping of the unit under a no-load, safe
condition. The unit may use either the aircraft or on-board HPU reservoir. Cooling is provided for continuous
operation.
1.5 REQUIREMENTS
Adequate electrical power must be provided for proper functioning of the HPU. See the unit nameplate for proper
voltage and frequency. See the Operation & Service Manual for proper sizing of electrical supply and protection
equipment in the facility.
2.0 SAFETY INFORMATION
2.1 USAGE AND SAFETY INFORMATION
The HPU provides pressurized hydraulic fluid for performing aircraft maintenance.
To ensure safe operations please read the following statements and understand their meaning. Also refer to your
equipment manufacturer’s manual for other important safety information. This manual contains safety precautions
which are explained below. Please read carefully.
WARNING! —Warning is used to indicate the presence of a hazard that can cause severe personal injury,
death, or substantial property damage if the warning notice is ignored.
CAUTION! —Caution is used to indicate the presence of a hazard that will or can cause minor personal injury
or property damage if the caution notice is ignored.
2.2 EXPLANATION OF WARNING & DANGER SIGNS
Accidental Starts! Before servicing the HPU or equipment, always disconnect electrical power supply to prevent
accidental starting.
Rotating Parts! Keep hands, feet, hair, and clothing away from all moving parts to prevent injury. Never operate
the HPU with covers, shrouds, or guards removed.
Electrical Shock! Never touch electrical wires or components while the HPU is attached to the power source.
They can be sources of electrical shock. DO NOT operate HPU with cabinet panels removed.
Pressurized Fluid! Before servicing the HPU or equipment, always open the bypass valve to relieve any residual
pressure in the hydraulic system.

Models: 5211, 5221, 5231, 5241
Hydraulic Power Unit
02/2023 | Rev. 05 Page | 2
2.3 COMPONENT SAFETY FEATURES
Pump/Motor coupling guard Control circuit fuses
Sheet metal panels Motor overload protection
Pressure and return system relief valves
2.4 FUNCTIONAL SAFETY FEATURES
Emergency shut off switch Calibration port shut off valve
Floor lock Fluid sample shut off valve
2.5 PERSONAL PROTECTION EQUIPMENT
Safety glasses must be worn when operating the HPU
Additional equipment recommended by the fluid manufacturer (gloves, etc.).
2.6 SAFETY GUIDELINES
Operator must be properly trained prior to operating the HPU
HPU power switch must be in "Off" position when connecting or disconnecting hoses to the aircraft.
Bypass valve must be in the "Open" position when starting or stopping the HPU
Electrical power must be disconnected from the HPU and the bypass valve must be in the "Open" position
before servicing the HPU. (Reference Operation & Service Manual for details on servicing the HPU)
2.7 GENERAL COMMENTS
The HPU is intended to be operated by personnel trained in the proper use in conjunction with the aircraft
maintenance manual.
The HPU must be used in accordance with the Operation & Service Manual and the intended aircraft.
3.0 PREPARATION PRIOR TO FIRST USE
3.1 GENERAL
Prior to operating the HPU, the user should become familiar with this Operation & Service Manual.
3.2 SERVICING RESERVOIR
Fill the reservoir with the correct fluid (see label next to reservoir fill for correct type of fluid) until fluid level is above
the minimum fluid level mark but below the maximum fluid level. See 5.3.1 Front Panel Controls for reservoir fill
location.
NOTE: Leave the Reservoir Selector Valve in the Aircraft Reservoir position (as shipped) until the
Hydraulic Power Unit reservoir has been filled.
3.3 CONNECTING ELECTRICAL LEADS
Electrical Shock! Never touch electrical wires or components while electrical power is attached. Only qualified
electricians should connect the electrical leads.
Install plug onto the electrical cord. If motor rotation is not correct, change any two of the three leads at the plug.
Reference 11.0 Electrical Power and Protection Requirements for power requirements and fuse sizes. (See 5.4
Start up Procedures before starting HPU.)
WARNING!
Balanced three phase voltage must be available to prevent overheating and damage to the motor.
Voltage unbalanced between phases occurs when the voltages differ from one another.
Some reasons for imbalance are:
1. Unequal loading of each phase
2. Poor connections in the supply
3. Single phase condition caused by blown fuses or bad connections
If these conditions occur in the incoming power system, a protective devise, such as a voltage monitor,
should be installed on the machine to prevent motor damage.

Models: 5211, 5221, 5231, 5241
Hydraulic Power Unit
02/2023 | Rev. 05 Page | 3
4.0 TRAINING
4.1 TRAINING REQUIREMENTS
The employer of the operator is responsible for providing a training program sufficient for the safe operation of the
HPU.
4.2 TRAINING PROGRAM
The employer provided operator training program should cover safety procedures concerning use of the HPU in
and around the intended aircraft at the intended aircraft servicing location.
4.3 OPERATOR TRAINING
The operator training should provide the required training for safe operation of the HPU.
NOTE: Maintenance and Trouble Shooting are to be performed by a skilled and trained technician.
5.0 OPERATION
5.1 OPERATING PARAMETERS
The user shall use the HPU in accordance with the aircraft manufacturer's instructions
The user shall operate the HPU in accordance with the Operation & Service Manual
The employer of the operator shall provide all necessary training
The electrical power supply for the HPU must include a fused disconnect using Type J or Type R fuses or
equivalent magnetic type circuit breakers designed for protecting an electrical motor. This necessary
equipment is for protection of the HPU, power cord, and customer-supplied plug and receptacle. Reference the
Table below:
ELECTRICAL POWER AND PROTECTION REQUIREMENTS
60 Hz Applications
Voltage
208
230
380
460
575
Full Load Amps
44.2
40
24.2
20
16
Locked Rotor Amps
257
232
133
116
92.5
Recommended Fuse Size
60
50
30
25
20
Maximum Fuse Size
70
60
35
30
25
50 Hz Applications
Voltage
200
220
380
415
440
Full Load Amps
48
41
23.7
23
22
Locked Rotor Amps
257
229
133
116
116
Recommended Fuse Size
60
50
30
30
30
Maximum Fuse Size
70
60
35
35
35
5.2 NUMERICAL VALUES
5.2.1 Fluid
Model NumberFluid Type
5211.......................MIL-PRF-5606
5221.......................MIL-PRF-83282
5231.......................Aviation Phosphate Ester, Type IV and V
5241.......................MIL-PRF-87257

Models: 5211, 5221, 5231, 5241
Hydraulic Power Unit
02/2023 | Rev. 05 Page | 4
5.2.2 Physical
Weight (Dry)......................1,200 lbs (544 kg)
Width.................................51 in (129.5 cm)
Height................................48.75 in (124 cm)
Depth.................................55 in (140 cm)
Power Cord.......................50 ft (15.24 m) long
Pressure Hoses.................15 ft (4.57 m)........................Standard Length
25 ft (7.62 m)........................Optional Length
50 ft (15.24 m)......................Optional Length
-8 (½ in, 12.7 mm)................Working Diameter
Return Hoses....................15 ft (4.57 m)........................Standard Length
25 ft (7.62 m)........................Optional Length
50 ft (15.24 m)......................Optional Length
-12 (¾ in, 19.1 mm)..............Working Diameter
Hand Pump Hose..............15 ft (4.57 m)........................Standard Length
-4 (¼ in, 6.4 mm)..................Working Diameter
5.2.3 Motor Driven Hydraulic Pump
A pressure compensated, adjustable maximum volume piston pump.
Maximum flow at 60 Hz...................................................10 gpm (37.8 lpm)
Maximum flow at 50 Hz...................................................8.3 gpm (31.4 lpm)
Maximum operating pressure at 50 Hz and 60 Hz ..........3,000 psi (207 bar)
System pressure relief valve setting................................3,250 psi (224 bar)
Performance Curve for 50 Hz and 60 Hz
5.2.4 Electric Motor
A 15 horsepower, TEFC electric motor is the prime mover for the HPU. This is attached to the hydraulic pump
using a pump/motor adapter and a spider/coupling rotating interface.
MOTOR POWER REQUIREMENTS
60 Hz Applications
50 Hz Applications
Voltage
Full Load Amps
Voltage
Full Load Amps
208
44.2
200
48.0
230
40.0
220
41.0
380
24.2
380
23.7
460
20.0
415
23.0
575
16.0
440
22.0
0
500
1000
1500
2000
2500
3000
3500
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0
FLOW (GPM)
PRESSURE (PSI)
0
30
60
90
120
150
180
210
240
0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0
FLOW (LPM)
PRESSURE (BAR)
OPERATING RANGE
50Hz
60Hz
PERFORMANCE CURVE-52 SERIES HYDRAULIC

Models: 5211, 5221, 5231, 5241
Hydraulic Power Unit
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5.2.5 Filters
Pressure...................................2 micron rating, non-bypass high collapse microglass type. Non-cleanable element
Return ......................................5 micron rating, 15 psi (1.03 bar) bypass microglass type. Non-cleanable element
Hand Pump (Option M) ............2 micron rating, non-bypass microglass type. Non-cleanable element
Air/Desiccant............................3 micron filter, silica gel desiccant type. Non-cleanable element
5.2.6 Hand Pump (Option M)
Two stage hand pump, low pressure stage 0500 psi (034.47 bar) and 5005,000 psi (34.47344.74 bar) high
pressure stage. Pump automatically changes stage internally based on system pressure.
Low Pressure Stage.................Piston Diameter.................... 1½ in (38.1 mm)
Working Pressure................. 0500 psi (034.47 bar)
Displacement/Stroke ............2.1 in3 (34.4 cm3)
Force/100 psi (6.89 bar).......12.0 lbs/100 psi (7.74 N/bar)
High Pressure Stage................Piston Diameter.................... ⅝in (15.88 mm)
Working Pressure................. 5005000 psi (34.47344.74)
Displacement/Stroke ............0.4 in3 (6.55 cm3)
Force/100 psi (6.89 bar).......2.2 lbs/100 psi (1.42 N/bar)
Pressure Relief Setting.............5,250 psi (362.0 bar)

Models: 5211, 5221, 5231, 5241
Hydraulic Power Unit
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5.3 LOCATION & LAYOUT OF CONTROLS
5.3.1 Front Panel Controls
Electrical Control Panel
See Section 5.3.2
Hydraulic Control Panel
See Section 5.3.3
Bypass Valve
For loading and unloading the motor driven hydraulic pump
Flowmeter
Displays the flow from the motor driven hydraulic pump
Pump Control Access
See Figure 5.3.5 - Hydraulic Pump Controls
Reservoir Selector
For selecting between using the aircraft reservoir or the HPU reservoir
Sight Gauge
Visual indicator displays the fluid level in the reservoir
Reservoir Fill Access
Locking cap for servicing the HPU reservoir
Desiccant Filter
Access to the reservoir air filter/desiccant filter
Hand Pump (Option M)
Access for hand pump and relief screw, handle stored inside
Floor Lock
Locking/unlocking, foot actuated and released floor lock

Models: 5211, 5221, 5231, 5241
Hydraulic Power Unit
02/2023 | Rev. 05 Page | 7
5.3.2 Electrical Control Panel
Emergency Stop
Removes power to all electrical devices, must turn to reset
Stop Switch
Turns off the electric motors driving the hydraulic pump and cooling fan
Start Switch
Turns on the electric motors driving the hydraulic pump and cooling fan
HPU Power "On" Indicator Light
Light is illuminated when the electric motors driving the hydraulic pump and cooling
fan are on
High Fluid Temperature Indicator
Light (Option S)
Light is illuminated when the return fluid temperature reaches 160F (71C) or
above. The HPU will shut down when light is illuminated. The HPU can be re-started
when the fluid has cooled and the indicator light is off
High Reservoir Fluid Level
Indicator Light (Option L)
Light is illuminated when the fluid level in the reservoir is above the normal operating
range. The HPU will shut down until the fluid level is restored to a normal operating
level
Low Reservoir Fluid Level
Indicator Light (Option L)
Light is illuminated when the fluid level in the reservoir is below the normal operating
range. The HPU will shut down until the fluid level is restored to a normal operating
level
Voltage/Phase Monitor Indicator
Light (Options G  J)
Light is illuminated if any of the following conditions occur
- Voltage imbalance between L1, L2, L3, greater than 5%
- Loss of voltage from L1, L2, L3
- Over voltage from L1, L2, L3, greater than 5%
- Change in phase orientation between L1, L2, L3. The HPU will shut down until
the electrical problem is corrected
Clogged Pressure Filter Indicator
Light (Option R)
Light is illuminated when the pressure filter element requires changing. The HPU will
not shut down when illuminated. Pressing the illuminated button will reset the light

Models: 5211, 5221, 5231, 5241
Hydraulic Power Unit
02/2023 | Rev. 05 Page | 8
5.3.3 Hydraulic Control Panel
System Pressure Gauge
Displays the system pressure on an analog fluid dampened gauge
Pyrometer (Option K)
Displays the fluid temperature in the return system on an analog gauge. A warning
indicator preset to 170F (77C) warns of high operating temperature
Pressure Gauge Calibration Port
(Option Q)
Allows for calibration of the system pressure gauge up to the operating pressure of
HPU. Calibration port shut off valve must be used in conjunction with the calibration
port
Calibration Port Shut Off Valve
(Part of Calibration Port Option Q)
Used to shut off pressure to the calibration port. This valve should only be opened
when the external standard gage is attached. (See Operation & Service Manual for
proper procedure)

Models: 5211, 5221, 5231, 5241
Hydraulic Power Unit
02/2023 | Rev. 05 Page | 9
5.3.4 Rear Panel Controls
* Fluid Pressure System
The source of pressurized fluid from the HPU that flows to the aircraft pressure
system through the pressure hose
* Fluid Return System
Fluid returning to the HPU from the aircraft that flows through the return hoses
Pressure Fluid Filter
Filters the pressurized fluid before it flows to the aircraft pressure system
Pressurized Fluid Sample Port
A sample valve is provided to obtain a fluid sample for analysis.
Hand Pump Pressure Filter
(Option M)
Filters the pressurized fluid before it flows to the aircraft system
Hose Racks
Location for storing the pressure, return and optional hand pump hoses when not in
use
Power Cord Hanger
Location for storing the power cord when not in use
Split System (Optional) consists of two (2) each of these items.

Models: 5211, 5221, 5231, 5241
Hydraulic Power Unit
02/2023 | Rev. 05 Page | 10
5.3.5 Hydraulic Pump Controls
The hydraulic pump flow control and pressure control are located on the front panel.
Flow Control
This control is used to set the maximum flow required from the HPU
Pressure Control
The pressure control is used to set the system pressure of the HPU during operation

Models: 5211, 5221, 5231, 5241
Hydraulic Power Unit
02/2023 | Rev. 05 Page | 11
5.3.6 Hand Pump Controls (Option M)
Reference 5.9 Hand Pump Operation
Pump Handle
Located inside the front access door is the hand pump handle used for opening and
closing the hand pump relief screw and stroking the hand pump arm
Hand Pump Relief Screw
Accessed through the front panel opening, this screw allows opening and closing of
the hand pump hydraulic circuit using the hand pump handle
Hand Pump Arm
The handle is used to access the hand pump arm used for up and down motion to
produce hydraulic flow and pressure
Hand Pump Pressure Gauge
Displays the hand pump system pressure on analog fluid dampened gauge

Models: 5211, 5221, 5231, 5241
Hydraulic Power Unit
02/2023 | Rev. 05 Page | 12
5.3.7 Split System Controls (Option C)
Reference 5.7 Split System Operation
Pressure Manifold
Houses the pressure valves
Fluid Pressure Ball Valve
Used to turn on and off the flow to separate aircraft systems. Always use in either
fully open or fully closed position; never use in a partially open position
Fluid Pressure Hose
Connects HPU to aircraft pressure systems
Fluid Return Hose
Connects HPU to aircraft return systems
Fluid Return Ball Valve
Used to turn on and off the flow from separate aircraft systems. Always use in either
fully open or fully closed position; never use in a partially open position
WARNING!
NEVER open or close split system valves without shutting off the Hydraulic Power Unit. Damage to the
aircraft system or reservoir may result if either return line valve is closed while the machine is running.

Models: 5211, 5221, 5231, 5241
Hydraulic Power Unit
02/2023 | Rev. 05 Page | 13
5.3.8 Split System Crossover Check Controls (Option D)
Reference 5.8 Split System Crossover Check Operation
Pressure Gauge
Displays the pressure in each aircraft system
Hose Assembly
Connects HPU to aircraft pressure system
Ball Valve
Turns on and off the fluid for taking contamination samples
Crossover Check Manifold
Houses the valves and gauges
Cartridge Needle Valve
Used to turn on and off the flow to the separate aircraft pressure systems. Always
use in either fully open or fully closed position; never use in a partially open position
Check Valve
Prevents cross flow from System 2 pressure line to System 1 pressure line
WARNING!
NEVER open or close split system valves without shutting off the Hydraulic Power Unit. Damage to the
aircraft system or reservoir may result if either return line valve is closed while the machine is running.

Models: 5211, 5221, 5231, 5241
Hydraulic Power Unit
02/2023 | Rev. 05 Page | 14
5.3.9 Return Back-Pressure with Sight Gauge (Option T)
This option is only available on 5231 models
Reference 5.10 Return Back-Pressure with Sight Gauge Operation
Return Sight Gauge
Allows viewing of fluid returned through the reservoir connection line (third hose)
Return Line Pressure Gauge
(Panel Mounted)
Indicates the pressure in the main return hose (back-pressure). The panel gauge is
positioned for ease of operation
Hydraulic Panel (Option T)
Added for the back-pressure Option (Option T). It varies slightly from the standard
panel
Return System Ball Valve
The return system ball valve has been added for normal operation when combined
with a Split System Option (Options C or D). The ball valve is not used when the
back-pressure feature is being utilized and must remain open while the machine
is running
Return Line Pressure Gauge
(Manifold Mounted)
Indicates the pressure in the main return hose (back-pressure) The manifold
mounted gauge is positioned for ease of valve adjustment
Back-Pressure Valve
Adjustable check valve, used for creating back-pressure in the main return line
Bypass Valve
Allows fluid to bypass the back-pressure valve
Fluid Return Hose
Connects HPU to aircraft return systems
Reservoir Connection Return Line
Connects HPU to aircraft reservoir overflow line
WARNING!
Never close the return system ball valve while the machine is operating. Damage to the aircraft system or
reservoir may result.

Models: 5211, 5221, 5231, 5241
Hydraulic Power Unit
02/2023 | Rev. 05 Page | 15
5.4 START UP PROCEDURES
5.4.1 Procedure for First Time or Different Electrical Supply ONLY
Phase Monitor (Options G J Only): Check that the phase monitor light on the instrument panel is not illuminated.
If the light is illuminated, change any two of the three input leads at the plug. Once the phase monitor light is not
illuminated with power attached, check for proper motor rotation.
To check rotation (with or without Phase Monitor):
a. Close the fluid pressure ball valve(s) at the rear of the
HPU. Reference 5.3.4 Rear Panel Controls for location of
ball valve.
b. Open the bypass valve on the instrument panel fully counter-
clockwise.
c. Set the flow control to maximum flow (fully counter-clockwise).
d. Place the reservoir selector valve in HPU Reservoir position.
e. Remove the pump/motor coupling guard
Reference Pump/Motor Coupling Access figure.
Rotating Parts! Keep hands, feet, hair, and clothing away from all moving
parts to prevent injury. Never operate the HPU with covers, shrouds, or
guards removed.
Electrical Shock! Never touch electrical wires or components while the HPU is attached to the power source.
They can be sources of electrical shock. Do not operate HPU with cabinet panels removed.
f. Verify that the unit has been prepared for use by connecting electrical leads and servicing the reservoir
(Reference section 3.0 Preparation Prior to First Us.)
g. Keeping hands clear of the pump/motor coupling area, momentarily press the start button and immediately
press the stop button
h. Observe direction of rotation of the pump/motor coupling. When the Operator is facing the front panel, the
pump/motor coupling should be rotating in a clockwise direction
i. If the pump/motor coupling is rotating in a counter-clockwise direction, change any two of the three leads at the
plug. Observe direction of rotation to verify that pump/motor is rotating in a clockwise direction
j. Replace the pump/motor coupling guard
5.4.2 Initial Start Up of the HPU
a. Unit must be prepared per section 3.0 Preparation Prior to First Use and section 5.4.1 First Time or Different
Electrical Supply ONLY before starting the HPU
b. Operator must be familiar with this manual and be properly trained prior to starting the HPU
c. Close the fluid pressure ball valve(s) at the rear of the HPU. Reference 5.3.4 for location of ball valve.
d. Open the bypass valve on the instrument panel fully counter-clockwise
e. Set the flow control to maximum flow (fully counter-clockwise)
f. Place the reservoir selector valve in HPU Reservoir position
g. Press the start switch; the flowmeter should show full flow immediately. If no flow displays on the flow meter,
press the stop switch immediately and reference 9.2 No Flow in Trouble Shooting section
h. Adjust the flow down to approximately 6 gpm (22.71 lpm)
i. Close the bypass valve, adjust the pressure control until 3,000 psi (206.84 bar) is displayed on the pressure
gauge. (If no pressure displays on the system pressure gauge after adjusting the pressure control, reference
Trouble Shooting 8.4 No Pressure or Reduced Pressure)
j. Open the bypass valve; press the stop switch
NOTE: Maintenance and Trouble Shooting are to be performed by a skilled and trained technician.
Pump/Motor Coupling Access