AirComm Corporation Bell 412 Air Conditioner Instructions for Continued Airworthiness User Manual

AIR CONDITIONER SERVICE MANUAL 412AC-208M 
 
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CHAPTER 1 
INTRODUCTION 
1. SCOPE 
The scope of this manual encompasses the scheduled and unscheduled maintenance 
procedures for the continued airworthiness of the Air Comm Corporation air conditioning 
system installed in the Bell 412 series helicopter. 
 
2. PURPOSE 
The purpose of this manual is to provide the aircraft mechanic in the field the necessary 
information to maintain the air conditioning system. 
 
3. ARRANGEMENT 
This...

AIR CONDITIONER SERVICE MANUAL 412AC-208M 
 
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6. ABBREVIATIONS 
InHg:  Inches of Mercury 
Lbs:  Pounds 
Oz:  Ounces 
Psig:  Pounds per Square Inch (guage) 
gr:  Grams  
kg:  Kilograms 
Kg/Cm: Kilograms per Centimeter 
ml:  Milliliters 
mm:  Millimeters 
Nm                  Newton-meters 
 
7. PRECAUTIONS 
The following precautions are found throughout this manual, and will vary depending on 
the seriousness of the Hazard or Condition: 
 
a. WARNING: May be a maintenance procedure,...

AIR CONDITIONER SERVICE MANUAL 412AC-208M 
 
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11. DISTRIBUTION 
This  document  is  to  be  placed  with  the  aircraft  maintenance  records at  the  time  of 
system installation. 
Changes  will  be  made  to  this  document  in  response  to  “Safety  of  Flight”,  and  or  “Non-
safety of Flight” issues. Any changes will result in a revision to this document. Revisions 
shall be noted in the Record of Revisions (page i), and on the List of Revisions (page ii) 
of this manual. 
In...

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Figure 1:  Cockpit A/C Control Panel 
The blower motors are two speed operation (Hi/Lo), and may be operated in conjunction 
with the A/C or Blower modes.  
 
The compressor is mounted on the aft side of the main rotor transmission housing. This 
compressor is driven by two V-belts and three pulleys arranged to reduce the speed 
transmitted by the transmission input quill. 
 
Airflow through the condenser heat exchanger is provided by two...

AIR CONDITIONER SERVICE MANUAL 412AC-208M 
 
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The switch operating pressures are: 
 
Low Pressure Function: 
Cut-out at 28.4 ± 2.8 psi (2.0 ± 0.2 Kg/Cm²) 
Cut-in at 30.0 ± 4.3 psi (2.1 ± 0.3 Kg/Cm²) 
 
High Pressure Function: 
Cut-out at 290 ± 28.4 psi (20.4 ± 2.0 Kg/Cm²) 
Cut-in at 200 ± 42.7 psi (14.0 ± 3.0 Kg/Cm²) 
 
14. DESCRIPTION OF THE AIR CONDITIONER AND ITS INSTALLATION 
This section contains a general overview of a Vapor-cycle air conditioning system and 
how it functions....

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15. Refrigeration Cycle Illustration 
NOTE: This illustration is provided as a reference only and may not match actual  
   installation 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
        High pressure liquid 
        High pressure vapor 
        Low pressure liquid 
        Low pressure vapor 
        Expansion valve        
         By pass line 
 
Figure 2:  Refrigeration Cycle Illustration 
 
 
Receiver-Dryer 
Aft Evaporator 
Forward...

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CHAPTER 2 
AIRWORTHINESS LIMITATION SECTION 
 
 
1. Airworthiness Limitations 
 
The  Airworthiness  limitations  section  is  FAA  approved  and  specifies  inspections  and 
other  maintenance  required  under  Sections  43.16  and  91.403  of  Federal  Aviation 
Regulations unless an alternative program has been FAA approved. 
 
 No airworthiness limitations are associated with this type design change. 
 
 
 
FAA approval: 
       
ACO...

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CHAPTER 3 
 INSPECTIONS   
1. INSPECTION REQUIREMENTS 
 
PERIODIC INSPECTIONS  
          (Hours are aircraft time)  
Item Prior to Cooling Season 
Every 25 Hours of Operation, +/- 3 hrs. 
Every 100 Hours of Operation, +/- 10 hrs. Special Inspection Information  
Evaporator Blower Hi/Lo Operation X  X Check for operation and security.  
Condenser Blower Motor & Fan Assy. X  X Check for operation and security. See Overhaul / Replacement...

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3. INSPECTION PROCEDURES  
 
NOTE 
Refer to “Chapter 4 location and access” to locate all components for inspection. 
 
A. Inspection of the FWD and AFT evaporator blower motors 
 
CAUTION 
Fans are designed to operate with the resistance of the entire ducting system. 
Operation of the evaporator fans with any part of the distribution system removed may 
cause permanent damage to the fan motor. 
 
WARNING 
Fans may take up to 10 seconds to...

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d. Place the A/C mode switch into the Off position and verify that the 
condenser fan is deactivated. 
e. Ensure that the jumper wire is removed from the binary switch. 
 
C. Inspection of compressor drive belt 
a. Remove transmission cowling to gain access to compressor drive 
belt and visually inspect the A/C compressor drive belt for the 
following: 
1. Any signs of excessive wear. 
2. Any signs of glazing. 
3. Any cracks or missing...