Piper COMANCHE PA-24-180 Service Manual page 465

PIPER COMANCHE SERVICE MANUAL
7C-48. Ignidon Sysem Mainennee.
7C-49. Mqlneto.
CAUTION
Ascertin thu the primury circuit of both nmgnetos i grounded before
working on the engine.
7C-50. Inspection Of Mqneto.
a After the first 25 hour and 50 hour periods, and periodically thereafter, re contact assemblies
should be checked. Examine the points for excessive wear or burning. Points which have deep ptrs or
excessivelv burned areas should be discarded. Examine the cam follower felt for proper lubricaion. If
necessary. points can be cleaned by using any hard finished paper. Clean 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 plugs and wiring first before working on the magnetos.
c.
Should the trouble appear definiely associated with the magneto, the most effective measure
is
to
install a replacement magneto which is known to be in satisfactory condition and send the suspected unit co
the overhaul shop for rest and repair.
d. Should this not be possible. a visual inspection may disclose the source of trouble. Remove the
harness oudet plate from the magneto. Inspect for the presence of moisture and foreign matter on the
rubber grommet and high tension outlet side of distributor block. Check height of block contact springs
(0.422 max. from top of block tower to spring). Also check for broken leads or damaged insulation. If
either is present, remove magneto and replace.
e. Remove the breaker cover and harness securing screws and nuts. and separate cover from magneto
housing. Check contact assemblies to see hat cam follower is securely nveted to ts spring. Examine the
contact poins for excessive wear or burning. Figure 7C-9 shows how the average 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 where electncal contact is made. This means that points are
worn in and mated to each other. therebv providing the best possible electrical contact and highest
efficlencv of performance.
f
Minor irregularities or roughness of point surfaces are nor harmful (refer to Figure 7C-9 center).
Neither are small pits or mounds, if nor too pronounced. If there is a possibility of pit becoming deep
enough to penetrate pad, Figure 7C-9. nght, reject contact assembly.
NOTE
No attempt should be made to stone or dress the contact points. If the
points are bad or show excessive wear, the complete contact assembly
should be replaced.
POWER PLANT
ISSUED: 8/18/72
2 H1l