Brief Introduction [Propeller Pump Housing]
In the C-130B/E/H aircraft fitted with UTC 54H60 propellers, the pump housing assembly is the lower part of the propeller control assembly. (See figure below) It contains atmospheric and pressurized sumps that have a combined capacity of 7 quarts of fluid (operational propeller). The atmospheric sump holds 1 quart of oil and contains the gear driven main scavenge pump, the auxiliary electrically driven scavenge pump, and the sump relief valve. The sump relief valve maintains pressurized sump pressure at 15 to 20 psi above atmospheric sump pressure
The rotating propeller contains 16 quarts of oil while the prop shaft/control cavity and the valve housing assembly plumbing holds two to three quarts of oil. The total system capacity is approximately 26 quarts.
Located in the pressurized sump are three gear-type positive displacement pressure pumps. The main pump and a standby pump are driven by propeller rotation through a gear train. An auxiliary pump is electrically driven. In normal operation the main and standby pressure pumps and a main scavenge pump are used. The main scavenge pump returns oil from the atmospheric sump to the pressurized sump. The auxiliary pressure pump and auxiliary scavenge pump are used in feathering, un-feathering, and static ground checkout operations.
Both the main and auxiliary pressure pumps have one-way, spring-loaded, ball check valves on the outlet side of the pumps to prevent reverse flow through the pumps in case of individual pump failure. A filter assembly, located on the top side of the valve housing, contains the main and standby filters.
The main filter filters oil from the main and auxiliary pressure pumps. The standby filter filters oil from the standby pressure pump. In case of a clogged filter, pressure is relieved by a filter bypass valve. A high pressure relief valve, which is located downstream of the main filter, is used to bypass system pressure exceeding 1000 to 1375 psid.
The standby pressure pump, which has twice the capacity of the main pressure pump, performs two functions. When large blade angle movements are required, a standby pump check valve allows the standby pump to aid the main pressure pump. The check valve opens at 10 to 15 psid. If the main pump fails, the standby pressure pump maintains pressure output.
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