S 212-036

 (6)  
Remove the system precooler cooling air valves and examine them for signs of volcanic ash (Ref 36-12-04/401).

 S 212-037

 (7)  
Remove the wing isolation valves and examine them for signs of volcanic ash (Ref 36-11-07/401).

 S 212-038

 (8)  
Remove the APU check valves and examine them for signs of volcanic ash (Ref 36-11-08/401).

 S 212-039

 (9)  
Remove the APU bleed air (shutoff) valves and examine them for signs of volcanic ash (Ref 36-11-09/410).

 (10)
 Examine the ground air connectors for signs of volcanic ash.

 S 212-040
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 S 212-041
 (11)
 Examine the air-driven pump pneumatic screens (if installed) for signs of volcanic ash.

 S 212-042

 (12)
 Remove the pressure regulating valves and examine them for signs of volcanic ash (Ref 36-11-19/401).

 S 212-043

 (13)
 Do a pneumatic system operation check of the duct pressure
 transmitters (Ref 36-12-01/401).

 H. Examine the External Light Lenses
 S 212-044
 (1)  Examine the external light lenses for abrasions. If the lenses are frosted of damaged, they must be replaced when it is possible.
 I. Examine the Fuel System
 S 212-045
 (1)  
Get fuel samples from each fuel tank sump and examine them for signs of volcanic ash (Ref 12-11-03/301).

 S 212-046

 (2)  
Get fuel samples from each surge tank sump (if there is fuel in the surge tanks) and examine them for signs of volcanic ash (Ref 12-11-03/301).

 S 212-047

 (3)  
Examine each surge tank internally for signs of volcanic ash (Ref 28-11-03/401).

 J. Examine the Oxygen System
 NOTE: Do these steps only if there are signs of volcanic ash
____
 contamination in the control cabin and passengers cabin.

 S 212-049
 (1)  Examine the oxygen system as follows:
 (a)  
Examine the oxygen mask/regulator storage boxes for signs of volcanic ash.

 (b)  
Examine the flow control units for signs of volcanic ash.

 (c)  
Examine the oxygen masks of the portable oxygen cylinders for signs of volcanic ash.

 (d)  
Examine the passenger and crew oxygen masks for signs of volcanic ash.

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 K. Examine the Auxiliary Power Unit (APU)
 S 212-053
 (1) Examine the APU inlet and exhaust ducts for signs of volcanic ash.
 NOTE: If there are no signs of volcanic ash, the procedure to
____ examine the APU is completed. The remaining APU steps are not necessary.
 S 212-054
 (2)  
Do an inspection of the APU compressor and turbine sections with a borescope for signs of volcanic ash (Ref 49-21-00/601).

 S 022-055

 (3)  
Remove the magnetic chip detector of the APU oil sump to be examined (Ref 49-27-04/601).

 S 212-076

 (4)  
Examine the magnetic chip detector of the oil sump. Look for metallic particles and signs of volcanic ash (Ref 49-27-04/601).

 S 212-056

 (5)  
Remove the APU oil filters and look for signs of volcanic ash (Ref 49-27-03/401).

 S 212-078

 (6)  
Remove the APU air filters and look for signs of volcanic ash (Ref 49-52-03/401).

 S 212-077

 (7)  
Remove the APU fuel filters and look for signs of volcanic ash (Ref 49-31-02/401).

 S 212-057

 (8)  
Disconnect the discharge pressure lines of the APU compressor and examine them for signs of volcanic ash (Ref 49-53-01/401).
　
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