Hydraulic System Failure; High Altitude Gear Operation; Power Pack Test Harness Schematic - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
Figure 6-29. Power Pack Test Harness Schematic
6-158. 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 6-148.
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 6-152 to 6-156.)
2. Prime pumps in accordance with Paragraph 6-157. 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 64.
6-159. HIGH ALTITUDE GEAR OPERATION. Should it be necessary to operate the landing gear above
15,000 feet, the landing gear selector may return to its neutral position before the gear door closing cycle is
complete. If this occurs, manual override of the time delay cycle must be used to close the gear doors.
During gear extension, if the selector returns to neutral at the same time the gears are locked down,
and before the gear doors have had time to close, again select the gear down position and hold the handle
down for an additional 3 to 4 seconds. This allows completion of the door closing cycle.
During gear retraction, if the selector returns to neutral and the gear unsafe light remains lit, again
select the gear up position and hold the handle up for 4 seconds after the gear unsafe light extinguishes. Be
sure that the light has extinguished before exceeding the maximum gear extended speed.
Reissued: 9/23/80
HYDRAULIC SYSTEM
2D10