HYDRAULIC SYSTEM LEAK CHECK
The primary and utility hydraulic pumps cannot be leak checked by external hydraulic power.
b. Check for leaks.
(1) If hydraulic fluid is leaking from drilled passageway/port on inboard side of primary hydraulic manifold
about one inch below dirty filter indicators, replace indicator packings.
(2) If hydraulic fluid is leaking from drilled passageway/port forward of utility hydraulic manifold about one inch
below dirty filter indicators, replace indicator packings.
Hydraulic system operates at 3000 psi. Do not perform any maintenance on system until hydraulic
pressure is removed from helicopter.
c. Remove pressure from hydraulic system.
7.2.4. Hydraulic Fluid Sampling.
If a hydraulic sample has a high level of either water or particulate contamination, the AOAP
laboratory will request that another sample be taken from the aircraft primary or utility hydraulic
systems. If this occurs, follow the guidance of the AOAP laboratory. If the second sample is
contaminated, follow the procedures below (as required).
a. Contaminated AGPU Resample.
(1) If failure is due to excessive water content, complete the following:
(a) If hydraulic purifier is available, purify AGPU using procedures provided with purifier.
(b) If purifier is not available, drain and flush AGPU and its hoses and refill with clean hydraulic fluid in
accordance with TM 55-1730-229-12, paragraph 3-9.
(2) If failure is due to excessive particulate contamination, complete the following:
(a) Drain AGPU and its hoses.
(b) Replace both low pressure and high pressure filter elements and refill with clean hydraulic fluid in
accordance with TM 55-1730-229-12, paragraph 4-94 and paragraph 3-9, respectively.
(3) After corrective action, resample AGPU in accordance with initial sampling procedures in paragraph 8.b.,
with exception that fluid is only required to be recirculated for five (5) minutes.
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