THRUSH AIRCRAFT, INC – MODEL S2R-R1340
AIRCRAFT MAINTENANCE MANUAL
Effective: 01/01/08
8-5
2. Repeat the leakage test to check
whether the static pressure
system or the altimeter is the
cause of leakage. If the
altimeter is at fault, it must be
repaired by an appropriately
rated repair station or replaced.
3. If the leakage test is passed with
the altimeter in the system,
repeat it with the airspeed
indicator hooked to the static
system and the static line to the
altimeter capped. If the leakage
test is passed again and a
vertical speed indicator is
installed, repeat the leakage test
with only the vertical speed
indicator in the system.
4. If
any
instrument is repaired or
replaced, repeat the leakage test
to ensure the problem is solved.
5. If none of the instruments is at
fault, remove the static line from
them and cap the static lines and
instrument inlet ports. attach a
source of positive pressure to a
static port opening and close off
the other with tape.
Do not apply positive
pressure with the airspeed
indicator, altimeter or
vertical speed indicator
connected to the static
system.
6. Slowly apply 2 to 3 psi of positive
pressure to the static system
while checking for leaks. Coat
line connections, caps and static
ports opening with a solution of
mild soap and water, watching
for bubbles to locate leaks.
7. Tighten leaking connections.
Repair or replace any parts
found defective.
8. Reconnect
the
flight instruments
to the static pressure system and
repeat leakage test per steps C.
through F.
ALTIMETER
The altimeter is equipped with three
concentrically arranged pointers with a
range of 0 to 20,000 feet. One
revolution of the long hand indicates a
thousand foot altitude change in 20-foot
increments. One revolution of the
shortest hand indicates an altitude
change of ten thousand feet, while the
triangular “bug” indicates 100,000 feet
with one revolution, but is limited to
20,000 feet. Moveable barometric
scales, visible through small windows on
either side of the main dial, indicate the
barometric pressure in inches of Hg and
millibars. An adjusting knob provides a
means of adjusting the barometric scale
to known sea level barometric pressure
at the airplane’s location. Barometric
pressure is sensed through the
instrument static system.
AIRSPEED INDICATOR
The airspeed indicator registers
airspeed in miles-per-hour and/or knots.
The indicator is operated by the
pressure differential between dynamic
air pressure from the pitot tube and local
barometric pressure sensed through the
static system.
CAUTION
MAGNETIC COMPASS
The magnetic compass is a semi-
floating cylinder encased in a liquid filled
case with expansion provisions to
compensate for temperature changes.
The compass is mounted on the center
instrument panel and it is equipped with
compensating magnets that are
adjustable from the front of the case.
Covers on the face of the compass
allow access for adjusting the
compensating magnets. The compass
should be swung and compensated at
regular intervals and at any time
equipment installations are made that
could cause compass errors.
