## (b) Damper Control 

The air dampers can be kept open by means of an olive on the control cables. The dampers are normally held closed by springs which prevent the dampers from opening under the pressure of air from the scoops. 

## (c) Manometers 

The air pressure in the two ballonets and the gas pressure in the envelope are read on three manometers, located on the flight panel. Each manometer is equipped with a three-position valve•. 

When this valve is turned on the position marked "Check" the manometers should read zero. If necessary, the reading can be brought back to zero by means of an adjusting dial. This check should be made before every take-off. 

v7hile in flight the valve should be turned on the position marked "static." 

A mechanical manometer on the instrument panel reads the gas pressure and is used as a check .on tl).e liquid manometer. 

