Maintenance; Inspection And Leakage Test - Thrush Aircraft S2RHG-T65 TURBO THRUSH Maintenance Manual

THRUSH AIRCRAFT, INC – MODEL S2RHG-T65 TURBO THRUSH
pressure ports are located on both sides of the aft fuselage where they are connected
through a yoke to a tube that runs forward along the left side of the fuselage to the
instruments.
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. Moisture drains for the system are installed in the lines at
two different locations; the most in-board end of tubing in wing and in the aft fuselage
just aft of the static ports. Drain the pitot-static system periodically and whenever the
system operates erratically. If after draining, and any of the pitot-static instruments are
still inoperative or erratic, clear the pitot-static vent lines of any remaining restrictions
with dry, low-pressure compressed air. Disconnecting the static line at the altimeter and
applying two to four psi air pressure to the static line may purge the lines.
Disconnecting the line from the airspeed indicator and applying two to four psi
pressures to the line may purge the pitot pressure line. Cap instrument inlets before
attempting to clear lines.
Be sure air pressure is directed towards the pitot head and
not toward the instruments when purging the system.
The following procedure outlines inspection and testing of the static pressure system,
assuming the altimeter has been tested and inspected in accordance with current
Federal Aviation Administration Regulations.
A. Ensure the static system is free from entrapped moisture and restrictions.
B. Ensure no alterations or deformations to the static lines have occurred.
C. Attach a source of suction to static pressure source opening.
D. Slowly apply suction until altimeter indicates a 1000-foot increase in altitude.
When applying or releasing suction, do not exceed the range
of the vertical speed indicator or airspeed indicator.
E. Cut off the suction source to maintain a closed system for one minute. Leakage
shall not exceed 100-foot of altitude loss as indicated on altimeter.
F. If leakage rate is within tolerance, slowly release suction source.
If leakage rate exceeds the maximum allowable, first tighten
all connections then repeat the leakage test. If leakage rate
Effective: 9/16/05
AIRCRAFT MAINTENANCE MANUAL

MAINTENANCE

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INSPECTION AND LEAKAGE TEST

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