Discharge Valves and Ground Automatic Relief Valves

Discharge Valves and Ground Automatic Relief Valves

Before installation the valve faces and seating surfaces of discharge valves should be cleaned with a soft lint-free cloth. High pressure air blasts should not be used on discharge valves of the diaphragm-controlled type as damage may be caused to the diaphragms.

To ensure that the joint between discharge valves and appropriate adaptors on the pressure bulkhead or fuselage skin is pressure tight, new mounting gaskets or 0-rings should be fitted. Where specified, mounting surfaces should be lightly smeared with the appropriate lubricant as specified in the relevant Aircraft Maintenance Manual.

Pipelines and valve unions should be checked to ensure that they are in correct alignment. Plug and socket connections to electrically actuated discharge valves should be secure.

If ditching cocks are fitted, the ditching control run in the aircraft should be checked before making the connections and locking the cocks to the appropriate discharge valve. Some discharge valves may be closed for ditching purposes by a directly mounted hand control wheel. In such cases the opening and closing of a valve should be checked by rotating the wheel through the requisite number of turns.

After installation of a discharge valve, functioning tests should be carried out to prove the correct connection of pressure sensing pipelines and, where appropriate, the connection of electrical cables to valve actuators. Details of the tests applicable to particular aircraft installations should be obtained from the relevant Aircraft Maintenance Manual.