Piper Navajo PA-31 Service Manual page 587

PIPER NAVAJO SERVICE MANUAL
Cells installed in the airframe cavity may be inspected for possible repairs by reaching
through the fuel
cell access plate and taking a section of cell between the thumb and forefinger. Wipe
the ridge created by
this action with MEK. If fine cracks are evident, the fuel cell is not repairable.
Baffled Fuel Cells: Inspect everv 2 years by conducting the following inspection.
(a) Defuel both main cells. (Refer to Section II.)
(b) Remove the access plates located inboard of the nacelle. Remove both
wing and fuel
cell access plates.
(c) Inspect fuel cell fittings for deterioration of the rubber used, using the
fingernail to
attempt to scrape the rubber off the metal or nipple fitting. If the rubber
has not
deteriorated, the fingernail will glide across the rubber. If a degraded condition
exists
the fingernail will dig into the rubber. Usually the deteriorated rubber
will have
changed from a light yellowish-tan to a dark reddish brown.
(d) Check the tension and knots of the two nylon support cords.
(e) Inspect the interior of the cell for security of baffle and the free operation
of the
flapper valve. Inspect both sides of the baffle.
(f)
Inspect the exterior of the cells to insure the Velcro tape has not parted from
the cell
surface or liner surfaces.
(g) Install all access plates on fuel cells and wings. Fill cells and check for leaks.
4. Fuel Cell Filler Cap: Inspect large o-ring with a 10x magnifine glass for
cuts or cracks.
Replace o-ring if any damage is found. If o-ring is sound, adjust cap per
steps a through d.
(a) Unlock and remove cap from adapter plate.
(b) Tighten ¼-28 self locking nut at base of cap ½ turn (If castle nut is used
in lieu of self
locking nut remove chain assembly, adjust nut
1/2
turn and replace chain assembly).
(c) Lock cap into adapter plate in top of fuel cell.
(d) If cap continues to leak replace cap and return defective cap to manufacturer
for repair.
c. Due to the length of the fuel cell repair procedures, this information will be found
in Paragraph
9-13.
Revised: 10/12/83
FUEL SYSTEM
3A19