Table of Contents
Advertisement
MODEL 182 & T182 SERIES SERVICE MANUAL
ed by the electrical system.
A static pressure alter-
NOTE
nate source valve may be installed in the static sys-
tem for use when the external static source is mal-
If leakage rate exceeds the maximum allowable,
functioning.
This valve also permits draining
first tighten all connections, then repeat leak-
condensate from the static lines.
Refer to Pilots
age test.
If leakage rate still exceeds the maxi-
Operating Handbook for flight operation using alter-
mum allowable, use following procedure.
nate static source pressure.
The encoding altimeter
supplies an altimeter reading to the optional 300 or
i.
Disconnect static pressure lines from airspeed
400 transponder for signal transmission.
The stand-
indicator and vertical speed indicator.
Use suitable
by altimeter is connected to the static system by a
fittings to connect lines together so altimeter is the
tube to the vertical speed indicator.
The static tube
only instrument still connected into static pressure
installation will vary when an alternate static source
system.
is installed.
j.
Repeat leakage test to check whether static pres-
sure system or the bypassed instruments are cause of
15-12.
MAINTENANCE.
Proper maintenance of
leakage.
If instruments are at fault, they must be
pitot and static system is essential for proper opera-
repaired by an "appropriately rated repair station"
tion of altimeter, vertical speed and airspeed indi-
or replaced.
If static pressure system is at fault,
cators.
Leaks, moisture and obstructions in pitot
use following procedure to locate leakage.
system will result in false airspeed indications,
k. Attach a source of positive pressure to static
while static system malfunctions will affect readings
source opening.
Figure 15-4 shows one method of
of all three instruments.
Under instrument flight
obtaining positive pressure.
conditions, these instrument errors could be hazar-
dous.
Cleanliness and security are the principal
rules for system maintenance.
The pitot tube and
static ports MUST be kept clean and unobstructed.
Do not apply positive pressure with airspeed
indicator or vertical speed indicator connect-
15-13.
STATIC PRESSURE SYSTEM INSPECTION
ed to static pressure system.
AND LEAKAGE TEST.
The following procedure
outlines inspection and testing of static pressure
1. Slowly apply positive pressure until altimeter
system, assuming altimeter has been tested and in-
indicates a 500-foot decrease in altitude and main-
spected in accordance with current Federal Aviation
tain this altimeter indication while checking for leaks.
Regulations.
Coat line connections and static source flange with
a.
Ensure static system is free from entrapped
LEAK-TEC or a solution of mild soap and water,
moisture and restrictions.
watching for bubbles to locate leaks.
b.
Ensure no alterations or deformations of air-
m.
Tighten leaking connections.
Repair or replace
frame surface have been made which would affect
parts found defective.
the relationship between air pressure in static pres-
n.
Reconnect airspeed and vertical speed indicators
sure system and true ambient static air pressure for
into static pressure system and repeat leakage test
any flight configuration.
per steps "c" thru "h".
c.
Seal one static source port with pressure sensi-
tive tape.
This seal must be air tight.
15-14.
PITOT SYSTEM INSPECTION AND LEAKAGE
d.
Close static pressure alternate source valve,
TEST.
To check pitot system for leaks, place a piece
if installed.
of tape over small hole in lower aft end of pitot tube,
e.
Attach a source of suction to the remaining static
fasten a piece of rubber or plastic tubing over pitot
pressure source opening.
Figure 15-5 shows one
tube, close opposite end of tubing and slowly roll up
method of obtaining suction.
tube until airspeed indicator registers in cruise range.
f.
Slowly apply suction until altimeter indicates a
Secure tube and after a few minutes recheck airspeed
1000-foot increase in altitude.
indicator.
Any leakage will have reduced the pres-
pressure is reduced gradually.
Otherwise instru-
When applying or releasing suction, do not
ment may be damaged.
If test reveals a leak in sys-
exceed range of vertical speed indicator or
tem, check all connections for tightness.
airspeed indicator.
15-15.
BLOWING OUT LINES. Although the pitot
g.
Cut off suction source to maintain a "closed"
system is designed to drain down to pitot tube open-
system for one minute.
Leakage shall not exceed
ing, condensation may collect at other points in sys-
100 feet of altitude loss as indicated on altimeter.
tem
and produce a partial obstruction.
To clear the
h.
If leakage rate is within tolerance, slowly re-
line, disconnect it at airspeed indicator.
Using low
lease suction source and remove tape from static
pressure air, blow from indicator end of line toward
port.
the pitot tube.
15-5
Advertisement
Table of Contents
Troubleshooting
