AirComm Corporation Airbus AS350 Air Conditioner Instructions for Continued Airworthiness User Manual

							AIR CONDITIONER SERVICE MANUAL AS350-200M-1 
Revision 6 Page 43 
 
d. Refer to Airbus Model AS350 Maintenance Manual for removal of main gearbox 
engine coupling to gain access to the hydraulic pump/compressor drive pulley on 
the main rotor input shaft. Remove drive belt. 
 
Replacement 
 
NOTE 
A  second  belt  should  be  pre-installed  on  the  main rotor  input  shaft 
housing as a spare. 
NOTE 
Flat  belts must  be  installed  so  that  the  direction  of  travel  conforms  to  the 
marking on the belt. 
 
a. Install drive belt on compressor pulley and drive pulley. 
b. Adjust drive belt tension according to adjustment procedure below. 
c. Tighten and torque upper and lower compressor pivot bolt/nut and lower link 
assembly mounting bolt/nut on the compressor mount to torque values in Figure 
7-4. 
 
 
 
 
 
 
Figure 7-4 – Compressor Mount Fasteners Torque Values (Flat & Poly V Belt) 
 
 
  
Torque Nut 160 – 190 in-lbs (18.07 – 21.46 Nm) 
Torque Nut 160 – 190 in-lbs (18.07 – 21.46 Nm)  
Torque Nut 160 – 190 in-lbs (18.07 – 21.46 Nm)  
						

							AIR CONDITIONER SERVICE MANUAL AS350-200M-1 
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12. Adjustment of Compressor Drive Belt 
 
NOTE 
Proper  static  belt  tension (and  alignment  for  Flat belt) is  necessary  to 
insure  proper  belt  life  and  to  avoid  excessive  side  load  on  the M/R  input 
shaft. The belt tension should be reset after several hours of operation for 
a new belt. 
 
a. Ensure compressor mount fasteners are tightened and properly torqued. 
b. Apply appropriate force as per Figures 7-5 or 7-6 depending on belt configuration 
using a tension tester midpoint of belt span between the compressor pulley and 
the drive pulley. 
c. Deviation should be as per Figures 7-5 or 7-6 depending on belt configuration. 
d. Cut safety wire on compressor belt tensioning link and belt tensioning link jam 
nuts, and loosen respective jam nut(s). Adjust belt tensioning link as required. 
e. (Flat belt only – Poly V belt proceed to step i.) Hand turn tail rotor and verify belt 
tracks in the center of the pulley. Premature belt failure will occur if belt rides on 
fence of pulley in service. If belt tracks in the center proceed to step g. 
f. To adjust tracking, loosen AN4H5A Bolt. Adjust 412AC-3016-16 Bolt as follows 
(Figure 7-7): 
a. Turn CW to make belt track more aft on the pulley. 
b. Turn CCW to make belt track more forward on the pulley. 
c. Re-tighten AN4H5A Bolt on mount and tighten NAS509-8 Check Nut. 
Repeat step e. 
g. Run helicopter up to full RPM and engage compressor. Monitor belt untill tracking 
shifts to fence of pulley (this could take several minutes). Belt has stretched and 
needs to be re-tensioned (tracking adjustment may not be necessary). 
h. Re-peat steps e through g. 
i. Tighten and safety wire compressor belt tensioning link and jam nuts. 
 
  
 
Figure 7-5 – Flat Belt Adjustment Value 
 
    
						

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Figure 7-6 – Poly V Belt Adjustment Value 
 
Figure 7-7 – Flat Belt Alignment 
 
13. Removal and Replacement of Compressor Assembly 
(Figure 4-3 & 4-4) 
 
Removal 
 
a. Disconnect  refrigerant  plumbing  from  compressor fittings  once  refrigerant  is 
evacuated. Always use a back-up wrench. 
b. Cut safety wire on compressor belt tensioning link and belt tensioning link jam 
nuts, and loosen respective jam nut(s). 
c. Loosen upper and lower compressor pivot bolts on the compressor mount to 
allow freedom of movement of compressor. 
d. Adjust belt tensioning link to loosen drive belt. Remove belt from compressor 
pulley. 
e. Remove nut and bolt from upper and lower compressor mounts while supporting 
compressor. Remove compressor. 
 
Replacement 
 
Calculating and measuring the lubricant in the new compressor: 
The amount of oil in the replacement compressor needs to be adjusted to 
match  the  amount  of  oil  in  the  old  compressor.  To  properly  calculate  the 
amount  of  oil  required  in  the  replacement  compressor,  it  is  necessary  to 
pour the oil out of the old compressor into a clean container. Drain the oil 
out of the fill plug hole and then pour oil out of the suction and discharge 
ports  while  rotating  the  center  shaft  clockwise.  Measure  the  total  amount 
of  oil  removed  from  the  old  compressor.  Note  that  the  compressor  (new  
						

							AIR CONDITIONER SERVICE MANUAL AS350-200M-1 
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or  old)  retains  .5  oz.  of  unrecoverable  oil  even  after  completely  draining. 
This  total  is  what  is  needed  to  be  in  the  new  compressor.  New 
compressors  come  from  Air  Comm  charged  with  8.0  oz.  of  oil.  This 
should be adjusted according to the amount of oil recovered from the old 
compressor and any other components being replaced. The receiver drier 
should always be replaced when the compressor is replaced or when the 
system  has  been  open  for  an  appreciable  time,  which  accounts  for 
another 1.5 oz. of oil that should be added. 
 
Below is an example of a compressor (and receiver drier) replacement oil 
calculation for illustration: 
 
Evacuating  the  system  recovers  1.5  oz.  of  oil.    Draining  the  old 
compressor  recovered  2.0  oz.  of  oil.  The  new  receiver/drier  requires  an 
additional  1.5  oz.  so  the  total  oil  needed  in  the  replacement  compressor 
for this case is 1.5 + 2.0 + 1.5 = 5.0 oz, plus the .5 oz of unrecoverable oil 
for  a total  of  5.5  oz.  Since  the  new  compressor  comes  with  8.0  oz.  of  oil, 
remove the oil fill plug and pour out 2.5 oz. of oil. 
 
 
a. Position compressor and install  upper  and  lower  nut  and bolt  on  compressor 
mount. Do not tighten. 
b. Install belt on compressor pulley. 
c. Perform belt adjustment according to procedure in paragraph 10. 
d. Tighten and torque mounting bolts to torque values in Figure 7-4.  
e. Replace all O-rings before connecting refrigerant plumbing to compressor fittings 
using a back-up wrench. Torque refrigerant line connections per section 2, p.36. 
f. Service air conditioning system with refrigerant per Chapter 6, p.30. 
 
14. Removal and Replacement of Receiver Drier Bottle  
(Figure 4-11) 
NOTE 
For  the  tail  boom  mounted condenser  option only,  the drier  bottle  is 
accessed through the right side baggage compartment. 
 
Removal 
 
a. Disconnect refrigerant plumbing from receiver drier bottle fittings once refrigerant 
is evacuated. Always use a back-up wrench. 
b. Loosen clamp securing receiver drier bottle. Remove receiver drier. 
 
Replacement 
CAUTION 
Replacement receiver drier bottles  are  capped  to  prevent  moisture 
contamination.    Receiver drier bottles  left  uncapped  and  open  for  more 
than 10 minutes must be discarded and replaced. 
 
a. Install receiver drier bottle and tighten clamp.  
						

							AIR CONDITIONER SERVICE MANUAL AS350-200M-1 
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b. Replace all O-rings before connecting refrigerant plumbing to receiver drier bottle 
fittings  using  a  back-up  wrench.  Torque  refrigerant  line  connections per  section 
2, p.36. 
c. Service air conditioning system with refrigerant per Chapter 6, p.30. 
 
15. Removal and Replacement of Bypass Valve  
(Figure 4-15) 
 
Removal 
 
a. Disconnect refrigerant plumbing from bypass valve once refrigerant is evacuated. 
Always use a back-up wrench. 
b. Disconnect electrical wiring from bypass valve solenoid. 
c. Remove  attaching  hardware  to  mounting  brackets securing  bypass  valve. 
Remove bypass valve. 
 
Replacement 
 
a. Install bypass valve and secure to mounting brackets with attaching hardware. 
b. Replace  all  O-rings  before  connecting  refrigerant  plumbing  to  bypass  valve 
fittings  using  a  back-up  wrench.  Torque  refrigerant  line  connections per  section 
2, p.36. 
c. Connect electrical wiring to bypass valve solenoid. Secure wiring as needed. 
d. Service air conditioning system with refrigerant per Chapter 6, p.30. 
 
16. Removal and Replacement of Binary Switch  
(Figure 4-10) 
 
Removal 
 
a. Access  the  switch  located on  the  refrigerant  line  attaching  to  the  aft  evaporator. 
Note  that  it  is  not  necessary  to  discharge  the  refrigerant  for  this  servicing 
operation. 
b. Disconnect the electrical wiring from the binary switch. 
c. Remove the binary  switch  by  unscrewing it from the Schrader  valve  on the tube 
assembly. 
 
Replacement 
 
a. Install the binary switch. 
b. Connect the electrical wiring to the binary switch. 
 
17. Removal and Replacement of Pressure relief valve  
Removal 
a. Locate  the  pressure  relief  valve  on  the  Y  fitting  adjacent  to  the  receiver-dryer 
bottle below the right side equipment bay.  
b. Evacuate refrigerant from the system.  
						

							AIR CONDITIONER SERVICE MANUAL AS350-200M-1 
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c. Remove the pressure relief valve. 
 
Replacement 
a. Place a small amount of refrigerant oil on the o-ring and install the valve. 
b. Re-charge the system per chapter 6, p.30. 
   
						

							AIR CONDITIONER SERVICE MANUAL AS350-200M-1 
Revision 6 Page 49 
 
CHAPTER 8 
TROUBLESHOOTING 
1. System Troubleshooting 
 
Prior to troubleshooting a defective system, it is advisable to conduct a visual 
inspection for general condition and obvious signs of damage or failure. 
 
The following matrix lists the easiest checks and the most likely problems. 
 
Problem Probable Cause Corrective Action 
System not Cooling 
 
(Evaporator blowers still operating) 
System is low or empty of 
refrigerant 
 
Evacuate the system, determine the 
origin of the refrigerant leak if 
applicable, and re-charge the system 
 Moisture or air in the system Evacuate the system, replace the 
receiver drier, and place the system 
under a vacuum for a minimum of 45 
minutes before recharging the system 
 Compressor If the compressor has failed, it must be 
replaced 
 Compressor drive belt If the compressor drive belt has failed it 
will need to be replaced 
 Bypass valve Check to insure the temperature control 
knob on the A/C control panel in the 
cockpit is in the full cold position, and 
the temperature control circuit breaker 
has not tripped. If the valve remains 
open (by-passing refrigerant) the valve 
will need replacement 
 Condenser blower motor / fan 
assembly. 
Check to insure the condenser blower 
motor/fan assembly are receiving 
power, and the circuit breakers have not 
tripped; if the blowers still do not 
function, they may have failed internally 
and must be replaced 
System not cooling 
 
(Evaporator blowers not operating) 
Air conditioner control circuit 
breaker tripped. 
Reset circuit breaker; if breaker will not 
reset, check for short in circuit 
 Forward or Aft evaporator blower 
circuit breaker tripped. 
Reset circuit breaker; if breaker will not 
reset, check for short in circuit. 
 
   
						

							AIR CONDITIONER SERVICE MANUAL AS350-200M-1 
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Problem Probable Cause Corrective Action 
System not cooling 
(Evaporator blowers not operating) 
Forward and aft evaporator blower 
motor(s) 
Check for power to the motor(s), 
and for the free movement of the 
blower wheel; if the motor shaft 
does not turn smoothly the motor 
must be replaced 
Loss of cooling limited to one 
evaporator 
Expansion valve malfunction If cooling is lost in only one of the 
evaporators, and the blowers 
continue to function, it is most 
likely a blockage at the expansion 
valve orifice, this is most often 
caused by dirt in the system 
forming a blockage as the 
refrigerant passes through the 
valve; evacuating the system and 
changing the receiver drier should 
cure this problem; if the above 
actions do not resolve the problem, 
the evaporator assembly must be 
replaced 
External moisture (Condensate) in 
the area of forward / aft evaporator 
Leak in evaporator, or evaporator 
drainage system 
If water is noted in the area near 
the evaporators, this is normally 
caused by a loose, cracked, 
plugged, or disconnected drain line 
NOTE 
The drain line consists of a tube 
which extends from the lower 
surface of the evaporators through 
the outer contour of the helicopter 
(Contact Air Comm Corporation Service Department for current pricing and availability of 
replacement components and parts) 
  
						

							AIR CONDITIONER SERVICE MANUAL AS350-200M-1 
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Figure 8-1 – Electrical Schematic, Side Baggage Mounted Condenser (Tail Boom Condenser Option identical except for additional condenser blower.) 
 
 
  
  
						

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Revision 6 Page 52 
Figure 8-2 – Electrical Schematic, Relay Panel