Cessna 172 Maintenance Manual page 38

treating process after rivet installation causes warping. Assemblies that require heat treatment
in a salt bath must be treated prior to assembly, as the salt cannot be entirely washed out of the
joints.
(2) The use of hollow rivets in joining highly stressed parts is not permitted. To determine if blind
rivets may be substituted, refer to Tables 1 and 2. Selection of the proper rivet and the proper
number of rivets is very important. Rivets must be of the proper length for the total thickness of
the parts being riveted. Ordinarily, from 1-1/2 to 2 times the diameter of the rivet is the correct
amount for the rivet shank to protrude through the material to form the head. For heavy material,
such as plates or fittings, from 2 to 2-1/2 times the rivet diameter may be used. The rivet should
not be excessively loose in the hole, as this condition will cause the rivet to bend over while
being driven, and the shank will not be sufficiently expanded to completely fill the hole. A drill
from 0.002 inch to 0.004 inch larger than the rivet shank should be used for sheet and plate
riveting. Parts should be held firmly together by clamps, screws, or bolts while they are being
drilled or riveted. The bucking bar is to be held against the end of the rivet shank. Exercise care
while accomplishing this operation to prevent unseating the rivet by too much pressure. For the
first few blows, the bucking bar should be held lightly against the rivet shank so it will receive
the impact of the blow through the rivet. The bucking bar must be held square with the rivet
to produce uniform upsets. As few blows as possible should be struck to properly upset rivet.
Blows must be as uniform as possible.
D. Loose Or Working Solid Shank Rivets.
(1) Rivets which appear to be loose shall be checked with a 0.002 inch feeler gauge by inserting the
gauge around the head of the rivet in question. If the feeler gauge can be inserted to the shank
of the rivet, it shall be classified as a loose rivet and it shall be replaced. If the feeler gauge can
be inserted approximately halfway to the shank for less than 30 percent of the circumference
of the rivet head, it shall not be classified as a loose rivet. The feeler gauge shall be used to
check the shear section between the riveted members (such as skin to spar or different sections
of skins) in a similar manner to that used around the rivet head. If the skin around the brazier
head or countersunk rivet can be moved by depressing the skin with finger pressure around the
rivet, the rivet shall be replaced. If a rivet is found which turns by applying a rotating load to the
head of the rivet, it should be replaced.
(2) In areas where exterior paint has been applied to rivet heads, the paint may harden due to aging
processes and show hairline cracks around the edge of the rivet heads. This should not be
used as a basis for determining whether or not the rivet is loose. The hardened paint may crack
at times and collect dirt or exhaust fumes which will appear as discoloration. It is not possible
to detect loose rivets visually. Replacement rivets should be of like size and type. In some
instances, however, it will be necessary to use the next size larger diameter. For general repair
practices, the spacing between the centerlines of adjacent rivet holes shall be four diameters or
greater. In some areas where the spacing between rivets prohibits the use of the next larger
rivets, special repair instructions and procedures shall be followed. Contact Cessna Single
Engine Support.
8. Blind Rivets
A. General.
(1) Blind rivets are intended for use where access is available to only one side of the work.
(2) Replacement of solid rivets with blind rivets should only be accomplished within the guidelines
of Table 1, when the installation of a solid shank rivet is not possible. Blind rivets do not have the
same resistance to corrosion and fatigue as solid shank rivets, and should not be considered a
universal replacement for solid shank rivets.
B. Removal of Blind Rivets.
CAUTION: Do not drill completely through the rivet sleeve. This method of removing
(1) Use a small center drill to provide a guide for a larger drill on top of the rivet stem, and drill away
the tapered portion of the stem to destroy the lock.
(2) Pry the remainder of the locking collar out of the rivet head with a drift punch.
CESSNA AIRCRAFT COMPANY
SINGLE ENGINE
STRUCTURAL REPAIR MANUAL
a rivet will tend to enlarge the hole.
© Cessna Aircraft Company
51-40-00
Page 7
Jun 1/2005