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AP101B-7200-15
Pneumatic System
PART 1
CHAPTER 5—PNEUMATIC SYSTEM
Contents
Para
DESCRIPTION
General ... ... ... ... ... ... ... 1
Pneumatic
System ... ... ... ... ... 2
DESCRIPTION
General
1. The pneumatic system has three compressors to operate the brakes,
radiator shutters and supercharger gear changeover. Pumps fitted to
both inboard engines supply the vacuum system, which powers the flight
instruments (Chapter 7). An emergency air bottle system is fitted to the
hydraulic system (Chapter 4).
Pneumatic System
2. Three two stage compressors are on No. 2, 3 and 4 engines driven
by the main wheel case. With 1200RPM set, compressor output should
be able to charge the system’s 400 cu ins to 300PSI in four minutes.
The compressor output is fed to two oil and water traps on the rear face
of the No. 3 engine bulkhead in the port wheel well. The output then
passes to a regulating valve, which regulates the pressure to a nominal
450PSI, by opening a relief valve to atmosphere at 480PSI.
3.
Pressure Maintaining Valve.
A Pressure Maintaining Valve (PMV)
in the supply line from the air bottle only allows pressure to be supplied
to the radiator shutters and superchargers if the pressure in the air bottle
exceeds 130PSI. This is to ensure sufficient pressure for the brakes, which
operate at 125PSI. It is necessary therefore to check on the pneumatic
pressure gauge that the pressure is sufficient before high gear is engaged
or radiator override switches are operated.
UNCONTROLLED DOCUMENT - NOT FOR USE IN FLIGHT OR TO BE PRINTED
UNCONTROLLED DOCUMENT - NOT FOR USE IN FLIGHT OR TO BE PRINTED