Piper Comanche PA-24 Service Manual page 593

PIPER COMANCHE SERVICE MANUAL
7C48. Ipilioa Sysrcm Maiauaaace.
7C49 .• \lqncto.
CAl11:ION
Ascertain that the primary circuit of both mapetoS is grounded before
WotltiaJ
on the . . . .
7C·50. l!llp«tion Of
Mofneto.
..
Aft.r the lim 25 hour and 50 hour periods. and periodically thereafter. $e conuet auemblies
should be checked. Examin. the pain .. for excessive wear or burninJ. Poin .. which have deep pi .. or
excessivelv burned areas .hould
be
discarded. Examine the cam foUower felt for proper lubrication. If
nec .... ry. pam .. can be cleaned by usin8 any bani fmished paper.
aeon
breaker compartment with dry
cloth.
b. If engine operating troubles develop which appear to be caused by the ignition system.
it
is
adVIsable to check the spark plup and wiri"8 first before workinB on the magnetos.
c. Should the trouble appear definitely associated with the mqnero. the most effective measure is to
insull a replacement magneto whieh is known to be
In satisfactory condition and send the suspected unit to
the overhaul shop for test and
repair.
d. Should this not be possible. a visual inspection may disclose the source of trouble. Remov. the
harness outlet plat. from the m"l"eto. Inspe .. for the p ..... nc. of moisture and fomp matter on the
rubber grommet and h;,h tension outlet side of distributor block. Check heiBht of block contact .prinp
(0.·H2 :nax. from tOP of block tower to spri"l)' Abo check for broken leads or damaBed insulation. If
either is present. remove magneto and replace.
e. Remove the: breaker cover and hamess securing screws and nuts. and
~an[e
cover from magneto
hous1ng. Check conu.c:t assemblies to see chat am follower is securely riveted to itS spring. Examine the
contact points for excessive wear or burning. Figure 7C-9 shows how the a,verqe contact point will look
when surfaces are separated for inspection. Desired contact surfaces have a, dull
gray.
sand-blasted (almost
rough) or frosted appearance. over the area whae electrical contact is made. ThiS means t.har .points are
worn in and mated t.o each other. therebY providing the best possible electrical con act and highest
efficlcncv of performance.
f .\r1inor irregularities or roughness of point surfaces are not harmful (refer to Figure 7C-9 center).
Neither arc small pits or mounds. if not too pronounced. If there is a possibility of pit becoming' deep
enough to penetrat.e pa.d. Figure 7C-9. right.. reject contact assembly.
NOTE
!'oIo attempt. should be made t.o st.one or dress the contact points. If the
points are bad or show excessive wear, the complete conact assembly
.hould be replaced.
2
Hll
POWER PLANT
ISSUED: 8/18/72