THRUSH AIRCRAFT, INC – MODEL S2R-R1340
AIRCRAFT MAINTENANCE MANUAL
Effective: 01/01/08
8-3
connected through a tee to a single tube
that runs forward along the left side of
the fuselage to the cockpit.
A. Ensure the static system is free from
entrapped moisture and restrictions.
B. Ensure that no alterations or
deformations to the static lines have
occurred.
Maintenance
C. Attach a source of vacuum to one of
the static port openings and seal the
opposite one with tape.
Flight instruments utilizing pitot-static
pressure are highly sensitive to pressure
variations. Therefore, all tubing and line
connections must be absolutely airtight
to prevent erratic indications. A
moisture trap for the pitot system is
installed below where the pitot line
comes out of the wing root. A moisture
trap for the static system is in the aft
fuselage on the left side in the vicinity of
the static ports. Moisture traps should
be inspected and moisture drained
periodically and whenever flight
instruments operate erratically. If, after
draining, any of the pitot-static
instruments are still inoperative or
operate erratically, clear the pitot and
static lines of any remaining restrictions
with dry, low-pressure compressed air.
Disconnect the pitot and static lines from
the altimeter and airspeed indicator and
cap the static line at the altimeter.
Applying two to four psi air pressure to
the pitot and static lines may purge
them. If not, the entire line will have to
be inspected to find the blockage.
Always cap instrument inlets when lines
are removed.
D. Adjust the altimeter to sea level or an
even thousand foot reading. Slowly
apply suction until altimeter indicates
a 1000-foot increase in altitude.
When applying or releasing
vacuum, do so slowly so as
not to exceed the range of the
airspeed indicator or vertical
speed indicator.
CAUTION
E. Cut off the vacuum source by closing
a valve in the vacuum line between
the source and the static port.
Maintain this closed system for one
minute. Leakage shall not exceed a
100 foot loss of altitude as indicated
on altimeter.
F. If leakage rate is within tolerance,
slowly release vacuum source.
* NOTE *
If leakage rate exceeds the
maximum allowable, first tighten
all connections then repeat the
leakage test. If leakage rate still
exceeds the maximum allowable,
use the following procedure:
CAUTION
Do not introduce pressurized
air into the pitot or static lines
if they are attached to the
flight instruments.
1. Disconnect static pressure line
from the airspeed indicator to
altimeter. If a vertical speed
indicator is installed, remove the
static hose from it and cap it.
Cap tee at airspeed indicator so
that the altimeter is the only
instrument still connected to the
static pressure system.
Inspection and Leakage Test
The following procedure outlines
inspection and testing of the static
pressure system after it has been
opened up. The altimeter calibration
must not be out-of-date.
