GE 7FA.05 - Hydraulic and Lift Oil Supply Manifold; Air Bleed Valves; Accumulators; Cooling and Sealing Air System

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GEK 116862 Inspection and Maintenance Instructions for 7FA.05 Gas Only and Dual Fuel Gas Turbines

If the pump does not operate properly, or if there is evidence of damage, it should be overhauled in

accordance with the instructions in the Operation and Maintenance Manual under the Hydraulic

Supply System.

Before reassembly, make sure that all parts are clean and free from lint or other foreign matter. All

parts must be washed in cleaning fluid, such as Stoddard solvent (or equivalent). All “O” rings and

gaskets should be clean and carefully examined for cuts and other damage. Replace all damaged

parts.

B. Hydraulic and Lift Oil Supply Manifold

Leakage problems on the manifold will generally result from damaged “O” rings between the

components and the manifold plate. Care must be used in reseating a part to the manifold to avoid

pinching or otherwise damaging the seals.

All tubing connections and device connections should also be checked for leakage. The manifold

should be cleaned and wiped down. This will help in detecting any further leakage problems.

C. Air Bleed Valves

The air bleed valves should automatically bleed any air present in the discharge lines as the pump is

started. As soon as the system reaches 35 psig (2.41 bars) and a steady stream of oil is present, the

valve should close.

D. Accumulators

Replace accumulator safety disc annually. To assure that precharge pressure is available and the

accumulators can provide the necessary transient flow and shock absorbing characteristics for the

system, the accumulator precharge pressure should be checked periodically and at a minimum of

once a month.

The precharge of the hydraulic accumulators should be within ± 25 psig (1.72 bars) of that specified

in the Device Summary. This check should be done with the unit at standstill and the hydraulic

pumps off. Operation of the hydraulic pumps, without properly charged accumulators in service, may

result in unnecessary hydraulic hammer and possible system damage.

XVII. COOLING AND SEALING AIR SYSTEM

A. General Notes

Loss of cooling air to various parts of the machine may cause hot wheel spaces, insufficient shell

cooling or reduction in bearing sealing air pressure. Small leaks or restrictions may result in loss of

machine performance or reduction in life of nozzles, buckets and wheels. Large leaks or restrictions

may result in complete machine failure and, in case of sealing air, bearing oil leaks and fire if an

ignition source is present.

B. Piping System

Using the Cooling and Sealing Air Piping Schematic (MLI 0417) as a guide, check that all orifice-

flange-plates are in their respective locations. If not already done, it may be wise to identify the

orifice size on the tab of the plate and locate the tab in the most convenient and accessible location

for viewing when assembled. When union orifices are used verify that the orifice is in position in the

union by the tab protruding thru the hole.