Contact Points - Piper PA-24 Comanche Service Manual

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PIPER COMANCHE SERVICE MANUAL
7C48. IpiDoa SY" MaiDcmuc:e.
7C49. Mlpfto.
CAUTION
AscmaiD that the primary circuit of botb maptftOS illfOundcd belore
workinl
Oft
the eftIiDe.
1C·'O. Inspection Of Mapleto.
a. After the fim:
2'
hour and
' 0
hour periods. and periodically thereafter. $e contact uscmblies
should be checked. Examine the pointS for excaaive wear or bunUni. Points which have deep pies or
excessivel~'
bumed areas should be discarded. Examine the cam follower felt for proper lubrication. If
necessary. poines can be cleaned by usin, any hard finished paper. Oan braJc.cr compartment with dry
doth.
b. If eneine operatin, troubles devdop which appear to be caused by the ilnition system. it
is
advisable to check the spark plup and wirine fltSt before workinJ on the rnqnetos.
c. Should the trouble appear ddinitciy ISIOCated with the mapeco. the most effective measure
is
to
install a rCl)l.cemcnt mapeto which
is
known
to
be in satisfactory condition and send the suspected lll'ut to
the overhaw shop for tcst and tCl'aU.
d. Should this not be possible. a visual inspection may disclose the source of trouble. Remove the
harness oudct plate from the magneto. Inspect for the presence of moisNre and foreign matter on the
rubber grommet and hilk tension oudec side of distributor block. Check heitht of block contact springs
{OA·22
:'nIX.
from top of block tower to spring}. Also check for broken leads or damqcd insulation. If
either is ?re5eftt. remove magneto and replace.
e. Remove the braker cover and harness SCC\IriftJ screws and nuu. and separate cover from magneto
housing. Check contact assemblies to sec that cam foUower is securely riveted to ies spring. Examine the
contact points for excessive wftr or burning. Figure 1C·9 shows how the avcrqe contact ?oint
Will
look
when surfaces are SCl'&nted for inspection. Desired contact surfaces have a dull gray. sand-blaSted (almost
rough) or frosted appeanncc. over the area where electrical contact is mlde. Thi. mean. that
~oints
are
worn in and mated to each Other. thereby providinc the best possible electrical contact and highest
efficiency of perfonnance.
f. .\\inor irregularities or roughness of point surfaces -ue not harmful (refer to Figure 7C·9 center).
Neither arc small pits or mound•• if not tOO pronounced. If there is a possibility of pit becoming deep
enough to penetrate pad. Figure 1C-9, right. reject contact assembly.
NOTE
So attempt should be made to stone or dress the eentaee points. If the
points are bad
Ot
show excessive wear. the complete contact assembly
should be replaced.
POWER PLANT
ISSUED: 8/18/72
2 Hl1