Air Conditioning System-Air Flow Checks; Sealing Of Ducts Diagram - Piper Navajo Chieftain PA-31-350 Service Manual

14-131. AIR CONDITIONING SYSTEM-AIR FLOW CHECKS. The followinginformation is intended to
point out areas in the air flow portion of the system that may cause air flow inefficiencies. Air flows should be
measured with a flow meter No. 460, purchased from:
Dwyer Instruments. Inc.
P.O. Box 618 Marietta. Georgia 30061
Phone No. 404-427-9406
a. The air flows at the individual outlets should fall at or above the velocities shown in Table XIV-XIV.
For purposes of identification the outlets are numbered left to right, forward to aft, starting with the pilots
outlet (No. 1) as shown in Figure 14-43.
b. Table XIV-XIV shows the air velocities for the corresponding outlet number. Air flows should be
measured with the rear outlets, main cabin and pilots doors closed, and remaining outlets open. A simple way
to check the outlet is to record the outlet number on a sheet of paper, and record the air flows at each outlet.
working from the cockpit and moving aft. Check your recorded flows against Table XIV-XIV.
c. When checking air flows, hold the probe from the flow meter perpendicular to and in the center of the
outlet. Refer to Figure 14-44.
B 125
CHECK FOR TAPE ON BACK SIDE OF DUCTS
DUCT
NAVAJO CHIEFTAIN SERVICE MANUAL
BLOWER
Figure 14-45. Sealing of Ducts
d.
Should the air flow at the various outlets be less than the limits given in Table XIV-XIV. the plenum
chambers at the evaporator boxes and individual air outlet boxes must be checked for air leaks. Air should
enter the air ducts only through the air grille at the bottom of the evaporators, and not through open holes in
the ducting and evaporators.
Also. air should not be re-circulated within the evaporator boxes.
e.
Seal all holes up to .187 of an inch in diameter. and any relief comers of the detail parts with General
Electric RTV 106 (Piper Code 9 1 041 ) sealant. Seal all other holes, voids and joints of the ducts with 3M Pressure
Sensitive Tape No. 69EGS (Piper Code 189 741).
NOTE
Insure that pressure sensitive tape is installed on the forward and
back sides of the duct seams. (Refer to Figure 14-45.)
Reissued: 9/23/80
4H19
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