Deicer Blades Resistance Check; Deicer Blades Replacement; Repair Of Deicer Lead Strap - Piper Navajo Chieftain PA-31-350 Service Manual

14-42. DEICER BLADES.
14-43. RESISTANCE CHECK OF DEICER BLADE. To determine incorrect resistance, short or open at
the brush-to-slip ring contact. disconnect harness at the brush block and use low-range ohmmeter to read
resistance from each deicer circuit lead pin (pins A. B. or C of brush block) to brush block ground pin: it should
read as listed in Table XIV-IV. If this reading is not obtained, disconnect the deicer lead straps or deicer wire
harnesses at the spinner bulkhead or starter ring gear and measure heater resistance individually. If first check
is off limits but second check is satisfactory, trouble is probably in the brush-to-slip ring area. If the second
check is off limits. the de-icer or wire harness concerned is damaged and should be replaced.
14-44. REPLACEMENT.
If tests show the blade deicer to have an open circuit, to be the wrong resistance
or to be visibly damaged beyond repair as outlined in paragraph 14-33 of this section, replace the deicer as
directed in paragraphs 14-47 thru 14-55.
14-45. REPAIR OF DEICER LEADSTRAP.
(Refer to Figure 14-16.) Use B.F. Goodrich Field Repair Kit
No. 77-802 which contains rubber patch material sufficient for several repair jobs. Cements and solvents
specified in these directions are not included in the kit. (The abbreviation "MEK" in further steps stands for
Methylethylketone.) The following steps apply wherever "cementing" is specified in the text:
a. Clean the area to be bonded or patched with MEK or acetone to remove all grease and dirt. It is
vital that surface be clean for good cementing job. After last wipe with cleaner. quickly wipe surface with a
clean dry lint-free cloth to remove solvent film.
b.
Apply one even coat of 1300L cement (Minnesota Mining and Mfg. Co.) to area to be bonded or
patched and allow to dry (approximately one hour above 40 °
F). Apply second even coat of 1300L cement
and allow to dry.
c. Cut the patch (.020 thick rubber to about 1 4 inch large on all sides of the damaged area). The
protective paper is on the side to be cemented. Apply masking tape on the open side to prevent the patch
from curling as cement dries then strip off protective paper and apply 1300L cement in a smooth even coat.
Allow to air dry. After one hour. apply second coat and allow to air dry.
d. With cemented surfaces either dry or with just a trace of "tackiness."apply
light coat of MEK or
Toluol over these surfaces to "re-tackify" and quickly complete the cementing job as directed. Allow one
hour to air dry before peeling off the masking tape or mylar coating on the air side. Rub edges and center
of patch to see that it is holding before releasing for flight. (Approximately 24 hours.)
NOTE
Do not touch cemented surface with dirty or oily fingers.
a.
Remove propeller spinner.
b.
Disconnect prop de-icer terminals from studs on spinner bulkhead.
c.
Remove clip which secures lead to spinner bulkhead.
d. Remove strap which secures lead to propeller hub.
NOTE
Cushion jaws of any pulling tool to prevent damage to de-icer. If
de-icer has failed under warranty and is to be returned. use extreme
care to prevent additional damage to deicer during removal.
Revised: 10/15/82
ACCESSORIES AND UTILITIES
NAVAJO CHIEFTAIN SERVICE MANUAL
4E24