Operating Pressures Table; Ground Procedure; 100 Hour Inspections; Removal Of Boots - Piper Navajo Chieftain PA-31-350 Service Manual

TABLE XIV-VI. OPERATING PRESSURES
Recommended Operating Pressure Test Pressure
PSIG in PSIG
MIN. MAX.
18 16 20
14-73. GROUND PROCEDURE. After the test pressure range is established, connect an external source of
air providing this pressure to the test plug. When the air supply is turned on, the check valves in the lines from
the pneumatic pumps close automatically. The deicer system should be within one psig of the recommended
operating pressure with each inflation cycle.
If deicers do not reach the operating pressure, check the inflation time to ascertain that the solenoid valves
are open the specified length of time, (six seconds). If this is not the cause of trouble or if the boots deflate
slowly, the lines or valves may be plugged. Then the lines should be disconnected and blown clear.
Check the timing of the system through several complete cycles. Wing boots ON six seconds, then OFF,
empennage boots ON six seconds, then OFF. The wing and empennage boots operate in sequence, with a com-
bined total time of twelve seconds. If cycle time is off the specified time, determine and correct the diffi-
culty. On airplanes with serial numbers 31-7652124 and up wing and tail boots are inflated simultaneously for
six seconds.
Inflation must be rapid to provide efficient deicing. Deflation should be completed before the next infla-
tion cycle of the boots.
14-74. 100 HOUR INSPECTION. At each 100 hour inspection of the airplane, inspect and operate the deicer
boots. Make checks as follows:
a. Carefully inspect the deicers for evidence of damage or deterioration and repair or replace damaged
boots.
b. Resurface boots which show signs of considerable wear or deterioration.
c. Inspect all hose connections which form a part of the pneumatic deicing system. Replace deteriorated
sections of non-kink hose.
d. Check the operation of the boots and the operating pressure of the system as outlined in paragraph 14-
64 and Table XIV-VI.
e. If new or replacement boots have been installed, check the tube inflation to make sure that the air con-
nection stems have been properly connected.
f. Disconnect all drain lines in the system and check for proper drainage.
g. Check the on-off control switch for freedom of action. Check associated electric wiring.
h. Clean or replace the air flters.
NOTE
This operation may be omitted if the boots were installed on the
airplane subsequent to the last previous 100 hour check.
14-75. REMOVAL OF BOOTS. The exact location of wing stall strips, as determined by the factory, is very
critical to the airplanes stall characteristics. Therefore, prior to removing deicer boots, determine exact
location of stall strips. Fabricate a template or determine exact vertical and horizontal location measurements
from a hard point on wing surface.
The removal of deicer boots should be done in a well ventilated area to avoid difficulty from the fumes of
the solvents. Materials required to remove the boots are: Turco 388 or Kelite 21 to remove dried cement, and
MEK (Menthylethylketone) in squirt can.
Revised: 3/31/94 ACCESSORIES AND UTILITIES
4G3
NAVAJO CHIEFTAIN SERVICE MANUAL