Maintenance Manual LS8
Issued: December 2009
Copyright DG Flugzeugbau GmbH - any copy or publishing prohibited
Manual valid with the up-to-date cover page only
5-4
5.2.2 Instructions
Mass balancing of the elevator
The mass balancing of the elevator (approx. 100 %) is by the heavy pushrod
in the fin. It is prohibited to remove the mass fixed to the top of the pushrod
(washers or turned part).
If a change of the hinge moment of the elevator is suspected, proceed as
follows: Remove the mass from the pushrod.
Determine the new mass with the following
equation:
M=(MR x 0,115)-0,4 <kg>
MR= hinge moment in <kg cm>
Determine the number of washers necessary: Steel
or brass washers inner dia. 8 mm, outer dia. 30
mm.
If it is not possible to install enough washers, a
brass turned part with the correct mass must be
produced according to sketch and installed.
Measuring technique for hinge moments:
Remove surfaces suspend
singly (also each elevator half) at two bearings without any tension or
friction.
Measure load at trailing edge with reference line horizontal with a spring
balance in vertical direction. Measure the local radius from hinge line.
Multiply load and radius to yield hinge moment.
When using identical locations for measuring as used in final production
inspection then trailing edge load only must be checked.
Caution: Repairs are possible only in exceptional cases, because after changes of
local static moment due to repairs, mass balance must be fixed in this region to
yield identical static moment values as in the original condition. As this
requirement from the flutter investigation due to low moment tolerances and little
room may exclude a repair, you should contact DG Flugzeugbau beforehand.
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