Checking Time Delay Valve; Checking Handle Release To Neutral - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
6-10. CHECKING TIME DELAY VALVE.
a. Connect the hydraulic test unit in accordance with Paragraph 6-8.
b. With test unit operating and airplane master switch ON, move the landing gear selector handle to
the down position. Note the delay of the handle returning to the neutral position.
NOTE
The time delay between moving the selector handle to the down
position (master switch must be ON) and the automatic releasing
of the selector handle to neutral should be (refer to Table VI-I or
VI-II) at room temperature. Colder temperature will cause a longer
delay.
c. If the time delay fails specification given in preceding "Note" ascertain that valve is not air
locked. Bleed air out by holding selector down for 30 seconds, then make three or four rapid movements to
neutral and back to down.
d.
There is no adjustment of the time delay valve. If it is defective, refer to Paragraph 6-22 or 6-57
for disassembly and repair of the power pack.
e. Disconnect hydraulic test unit in accordance with Paragraph 6-17.
6-11. CHECKING HANDLE RELEASE TO NEUTRAL
a. Place airplane on jacks. (Refer to Jacking, Section II.)
b. Connect hydraulic test unit in accordance with Paragraph 6-8.
c. Cycle the landing gear through two complete cycles in accordance with Paragraph 6-9, ending
with the gear down and locked, and the doors closed.
d. Set the hydraulic test unit bypass valve full open.
e. Place the landing gear selector handle in the full down position.
f. Very slowly close the bypass valve until the handle trips back to neutral. Read the gauge at the
point of handle trip. This pressure should be (refer to Table VI-I or VI-ll). Be sure to allow for time delay
valve to open.
NOTE
One release valve serves to release the handle from both the gear
down and gear up positions. If the handle return springs are
adjusted correctly, the release valve should release the handle from
both positions at the same pressure. The preceding procedure
checks the release pressure from the gear down position, and the
following procedure checks the release pressure from the gear up
position. This is performed only to assure satisfactory operation of
other equipment relative to handle release operations.
g.
Set hydraulic test unit bypass valve full open.
h. Place landing gear selector handle in the full up position.
i. Very slowly close the bypass valve until the handle trips back to neutral. Read the gauge at the
point of handle trip. This pressure should be as indicated in Table V-I or V-Ii. Be sure to allow for time
delay valve to open.
j. Refer to Paragraph 6-46 or 6-87 for handle release adjustment.
k. Ascertain that the landing gear selector handle is in the down neutral position, and that the
landing gear is down and locked.
1. Disconnect test unit in accordance with Paragraph 6-17 and remove airplane from jacks.
Reissued: 9/23/80 HYDRAULIC SYSTEM
2A20