Piper Navajo PA-31 Service Manual page 376

PIPER NAVAJO SERVICE MANUAL
NOTE
If possible run pump at rated speed while gradually increasing the
pressure up to rated pressure by the end of a thirty minute period.
6-160. INSTALLATION OF HYDRAULIC PUMP.
a.
Place a new gasket on the base of the housing.
b. Install pump on the housing.
NOTE
When installing pump keep the drain fitting facing to the lower
right, in the downward position.
c.
Line shaft up with the gear inside of the housing.
d. Install flat washers, lock washers and nuts on the base of the pump and tighten.
e. Install the two hydraulic hoses and prime the pump before completing the hookup to the
fire wall fittings in accordance with Paragraph 6-161.
f.
Install and time magnetos.
g. Check to be sure that system reservoir contains the required amount of clean fluid.
h. Change system fluid filters, in accordance with Paragraph 6-152.
6-161. PRIMING HYDRAULIC PUMP. The following instructions for priming the hydraulic pump assures
that the pump will not be operated in a dry condition and shall be followed whenever a pump is serviced or
replaced.
a. Remove the hydraulic suction and pressure lines from the fire wall fittings.
b. Install caps on suction and pressure fitting at the fire wall to prevent the loss of fluid prior to the
hookup of the hydraulic lines.
c.
Holding both lines at a level higher than the pump, pour hydraulic fluid, MIL-H-5606, into the
lines.
d. Remove one cap at a time from the fire wall fittings and connect the appropriate line to the
fitting, trying not to spill any of the hydraulic fluid previously put into the lines.
e. After the engine has been operated, check the hookups for leaks.
6-162. HYDRAULIC SYSTEM FAILURE. The emergency use of the hand pump to extend the gears
indicates the engine driven pumps were operating without sufficient fluid. This condition causes additional
wear on the engine driven pumps. Therefore, the filter elements must be removed and check even if pump
failure is not apparent and/or the primary cause of the problem.
a.
Remove the filter elements and check for metal particles.
b. If no metal particles are evident proceed with the following:
1. Replace filter element per Paragraph 6-152.
2. Replenish fluid as noted in Section II.
c.
If metal particles are evident in either filter proceed with the following:
1. Inspect, replace or repair both hydraulic pumps. (Refer to Paragraphs 6-154 to 6-160.)
2. Prime pumps in accordance with Paragraph 6-161. Do not connect the pumps to the rest of
the hydraulic system until the system has been flushed.
3. Proceed to flush the system in accordance with Paragraph 6-4.
Reissued: 10/12/79
HYDRAULIC SYSTEM
2D22