Piper Navajo PA-31 Service Manual page 548

NORMAL POINT
IS
SMOOTH
AND FLAT.
SURFACE HAS DULL GRAY
''SANDBLASTED"
APPEARANCE.
223
PIPER NAVAJO SERVICE MANUAL
MINOR IRREGULARITIES -
SMOOTH ROLLING HILLS
AND DALES WITHOUT ANY
DEEP PITS OR
HIGH
PEAKS. THIS IS A NORMAL
CONDITION OF
POINT
WEAR.
WELL
DEFINED MOUND
EXTENDING NOTICEABLY
ABOVE
SURROUNDING
SURFACE. REJECT POINTS.
Figure 8B-3. Contact Points
a. Check the lead terminals for definite contact with spring contacts in outlets.
b. Remove the harness outlet cover from the magneto and inspect for the presence of
moisture and carbon tracking due to moisture.
c. Check contact springs in distributor block for evidence of spark erosion.
d. Check height of contact springs (0.422 maximum from top of block tower to
spring). (Refer to Figure 8B-2.)
e. With the cover and harness separated from the magneto housing, check contact
assemblies to see that cam follower is securely riveted to its spring.
f. Examine the contact points for excessive wear or burning. Figure 8B-3 shows how
the average contact point will look when surfaces are separated for inspection.
CAUTION
Do not open point contacts more than .0625 of an inch for
examination of contact surfaces. Excessive spreading of the
breaker points will over stress and damage the contact spring.
Desired contact surfaces have a dull gray, sand-blasted (almost rough) or frosted
appearance, over the area where electrical contact is made. This means that points are worn
in and mated to each other, thereby providing the best possible electrical contact and
highest efficiency of performance. Minor irregularities or roughness of point surfaces are not
harmful. (Refer to Figure 8B-3, center.) Neither are small pits or mounds, if not too
pronounced. If there is a possibility of pit becoming deep enough to penetrate pad, (refer to
Figure 8B-3, right), reject contact assembly.
NOTE
No attempt should be made to stone or dress contact points.
Should contact assembly have bad points or show excessive
wear, the complete contact assembly should be replaced.
Reissued: 10/12/79
POWER PLANT
2L2