Piper SEMINOLE PA-44-180, Maintenance Manual

Page: 509 / 881

FIXED OXYGEN SYSTEM.
INSPECTION, MAINTENANCE AND OVERHAUL TIME LIMITS.
Due to the nature of the process used to test compressed gas tanks, servicing and hydrostatic tests must be
conducted by a DOT or manufacturer (Scott Aviation) approved shop. The following material gives
recommended inspection and maintenance information for the various parts of the oxygen systems.
— Note —
Oxygen cylinders are identified by the ICC or DOT identification stamped on the
c y l i n d e r. The standard weight cylinder (ICC or DOT 3AA1800) must be
hydrostatically tested at the end of each 5 year period. Lightweight cylinders (ICC or
DOT 3HT1850) must be tested every 3 years and be replaced after 4380 refills or 24
years, whichever comes first. The month and year of the last test should be stamped
on the cylinder beneath the ICC or DOT identification.
1. Check the outlets for leakage both in the use and non-use condition, and for leakage around an inserted
connector. For leak testing information refer to the appropriate subject in this chapter.
2. Check the high pressure gauge for accuracy by comparing its indicated pressure with that of a gauge of
known accuracy connected to the fill port.
3. Inspect tank for dents, bulges, corrosion, and major strap chafing marks. Should any of these problems
exist. the tank should be removed and hydrostatically tested.
4. An operational check of the regulator can be accomplished as follows: (Refer to Figure 35-3.)
A. Interconnect a sensitive pressure gauge having a range of 0 to 100 psi, with a Scott Aviation 8570-0
plugin. and connect the apparatus to the pilots outlet in the overhead panel. It is recommended that a
hose of 1/2 in. I.D. x 'h in. O.D. and 18 inches long be used.
B. Interconnect a pneumatic flow apparatus having a range of 0-5 liters per min ( I pm.). with a Scott
Aviation 8570-00 plug-in. Use the same hose dimensions as explained in the last step. Connect the
flow apparatus to the co-pilot's outlet.
C. Insert a Scott plug-in in each of the other outlets and pull the oxygen control knob to the on position.
The pressure and flow should be 55 to 80 psi and 3.3 to 5.3 1 pm. respectively, at sea level.
D. There should be no external leakage anywhere on the regulator when it is turned off, and all fittings
leak free.
5. Check airframe log book for last maintenance on oxygen system and perform as required per Chart 3502.
6. Test the oxygen for odor. Pure oxygen is odorless and tasteless. Any system having a significant odor
present in the gas should be purged and the bottle replaced or removed and purged.
7. Any fittings, connectors, and tubes which have imperfect threads, pitted or disfigured cones. or other
damage should be replaced.
— CAUTION —
OXYGEN TUBES MUST NOT BE CLAMPED TO OR SUPPORTED BY
ELECTRICAL WIRE BUNDLES, HYDRAULIC, PNEUMATIC OR OTHER
LINES.
8. Check plumbing for kinking, cracks, gouges, dents, deep scratches, or other damage, and replace as
necessary.
PA - 4 4 - 1 8 0 / 1 8 0 T
AIRPLANE MAINTENANCE MANUAL
3 5 - 11 - 0 1
Page 35-05
Revised: May 15, 1989
2J13
PIPER AIRCRAFT