Preparation And Application Of Sealer; Wrinkled Deicers; Electrical Check - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
14-50. PREPARATION AND APPLICATION OF SEALER. Deicers loosened due to destruction of
adhesive bond by lubricants do not respond well to recementing. Therefore, removal, cleaning and
reinstallation of the deicers are recommended. Refer to paragraphs 14-46 and 14-49.
a. Clean an area .500 inch wide around the circumference of the deicer down to the bare metal. Use
MEK or Acetone and clean thoroughly.
b. Clean outer .500 inch of all deicer edges and back under deicer about .250 inch on all sides past
loosened areas with MEK or Acetone. For final cleaning, quickly wipe off solvent with a clean, dry, lint-free
cloth to avoid leaving a film.
c. Recement loosened areas of deicers in accordance with paragraph 14-48.
d. Mix the filler, sealer or paint thoroughly and in the proper proportions by weight, as given in the
following steps:
1.
82-075A/B - one part A/one part B.
2. 82-076-1/2 - Twelve parts - 1 /one part - 2.
3. EC-1031/EC-801 - Twelve parts 1031/one hundred part 801.
4. C-19861/C-21871/C-16176 - one part 19861/seven parts
2
1871/two and two thirds parts
16176.
e. Locate masking tape approximately - .125 inch beyond cemented area around deicer to allow
application of filler directly to metal. Apply one even brush coat of 82-075A B filler (or EC-801 sealer) over
.125 inch of bare metal, cemented area and about .125 of an inch of deicier. (See Figure 14-19.)
f.
Insure that a fillet of filler completely covers the area between deicer strap and blade. (See Figure 14-
20.) Immediately remove masking tape and allow filler to dry for six hours.
g.
Apply new masking tape approximately .125 of an inch beyond filler to allow application of sealer
directly to metal. Apply one even brush coat of 82-076-1 2sealer(or C19861 C-16176 paint) oer
.125 of an
inch of bare metal. filled area and .250 of an inch of deicer. (See Figure 14-19.)
h.
Insure that sealer completely covers area between deicier strap and blade. (See Figure 14-20.)
Immediately remove masking tape and allow sealer to dry for 24 hours before starting engine.
14-51. WRINKLED DEICERS. (Refer to Figure 14-18.) If edge of deicer is found wrinkled or loose. try
recementing. Use MEK or Toluol to loosen the bond for an additional 1 4 inch beyond the loose or
wrinkled
area. Apply one coat of 1300L cement to the deicer and propeller bonding surfaces and allow to air dry for one
hour. Then apply a second coat of 1300L cement to both the deicer and bonding surface. Allow to dry.
Retackify with MEK or Acetone and press with fingers to work out wrinkles or to secure loose edges.
If
material has stretched and will not cement flat. replace the deicer.
14-52. ELECTRICAL CHECK.
a. Check the electrical resistance of each of the two elements within the deicer. Refer to Schematic.
Figure 14-13. and Resistance Readings. Refer to Table XIV-IV.
b.
Check for intermittent open circuits by tensioning the deicer strap slightly while measuring the
resistance. Also, press lightly on the deicer surface in the area adjacent to the strap retainer. Resistance
must not vary.
c. Identification of the circuits within the element may be confirmed by referring to the resistance values
and schematic diagram in Chapter 11. Proper identification is necessary in order to make the system cycle
properly and to obtain the correct amperage values during system operation. Minimum and maximum ohms
between common ground and either of the other terminals is 4.58 to 5.26.
NOTE
These resistances apply only to deicers that are not connected to
terminal studs.
4F6
ACCESSORIES AND UTILITIES