Piper SENECA II - 10-1 A; General; Gyro Pressure System; Non-Electrical Instruments

PIPER SENECA II SERVICE MANUAL
SECTION X
INSTRUMENTS
10-1. GENERAL.
The instrumentation in the Seneca II is designed to give a quick and actual indication of the attitude,
performance and condition of the airplane. Maintenance, other than described in these sections, shall be
done by the instrument manufacturer or an authorized repair station.
The two types of instruments have been classified in this section as non-electrical and electrical. The first
part of this section will pertain to maintenance and troubleshooting of all the instruments and their
systems which depend on non-electrical sources for their operation. The remaining portion of this
section is directed to maintenance and troubleshooting of all the electrically operated instruments.
10-1a. REPLACEMENT GAUGES
See Piper Service Spares Letter No. 406 when ordering replacements for the original equipment Stewart
Warner and A.C. Spark Plug Co. gauges.
10-2. NON-ELECTRICAL INSTRUMENTS.
10-3. GYRO PRESSURE SYSTEM.
10-4. GENERAL.
The gyro pressure system is a dry pneumatic engine driven pump system that produces sufficient air
pressure which is regulated to operate the attitude and directional gyros. The system consists of two
engine driven pneumatic pumps, pressure regulators, in line filters, manifold assembly, pressure gauge,
and the necessary tubing and hoses. The system operates at a preset pressure which is monitored at the
pressure gauge mounted in the right side of the instrument panel.
10-4a. HOSES AND CLAMPS
a. These items should be examined periodically and inspected carefully whenever maintenance
activities cause hose disconnections.
b. Ends of hoses should be examined for rubber separation and slivers of rubber on inside
diameter of hoses. These slivers can and do become detached. If this happens, the loose particles
will migrate throughout the system and may eventually contribute to a failure.
c. Replace old, hard, cracked or brittle hose. Sections of the inner layers may separate.
d. Ensure hoses are clear and clean by blowing them out with shop air. Remove from aircraft as
required.
CA
UTION: DO NOT WIGGLE HOSE FROM SIDE TO SIDE DURING INSTALLATION.
WIGGLING COULD CAUSE PARTICLES TO BE CUT FROM INNER WALL OF
HOSE WHICH CAN LEAD TO DAMAGE OF OTHER COMPONENTS.
e. Where hose clearance is tight, making it difficult to reinstall it onto a fitting or barb, spray the
fitting or barb with silicone. Let dry, then install hose by pushing it straight on.
CA
UTION: WHEN REPLACING ANY THREADED FITTING, DO NOT USE PIPE DOPE,
THREADLUBE, OR TAPE. USE ONLY SILICONE SPRAY, LETTING IT DRY
BEFORE ASSEMBLY.
f. Hose clamps and fittings should be replaced when broken, damaged or corroded.
01/01/09 X - INSTRUMENTS
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