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8300-088
AeroCruze 110 Installation Manual
Rev 1
Page 6
© Honeywell International Inc. Do not copy without express permission of Honeywell.
3
MECHANICAL CONSIDERATIONS
The installation information in this section is extremely important and must be clearly
understood by the installer. Improper servo installation or failure to observe and
diagnose installation problems prior to flight can result in extremely serious consequences,
including loss of ability to control the aircraft. If there are any questions on the part of the
installer it is mandatory to resolve these questions prior to flight of the aircraft.
Most modern experimental aircraft use push-pull tubes to drive the primary controls. These
tubes generally have a total travel of 3” or less; therefore, it is best to connect the autopilot
servo to the primary control by the same method. This connection consists of an arm on the
servo connected by a push-pull rod to the primary control. Rod-end bearings are required on
each end of the push-pull rod.
The servo arm must not rotate even near to the point called OVER CENTER, the point at
which the primary aircraft control would lock up. Some aircrafts mechanical primary
control installations will not allow this to occur and do not need the servo stops.
This is a
condition that would result from the servo being back driven when the pilot operates the
controls, or from the servo itself driving the controls to a stop. To protect against this
mechanical stops are supplied with the servos. These stops are drilled so that they can be
mounted at different angles as required (18° intervals).
In addition to the proper use of the stop it is important to know the amount of travel on
the primary control that the servo can handle. With the push rod connected to the
outermost hole (1 ½”) the travel on the primary cannot exceed 2 ½”, the intermediate hole 2
1/16”, and the inner hole 1 5/8”.
It is important to note that at the neutral point of the control the SERVO ARM must be
PERPENDICULAR to the push rod, and that the stop must be mounted so as to limit travel
as near as possible to equal amounts in both directions. In certain factory-designed installations
there may be well-proven exceptions.
There will be installations in which space does not permit the use of the stop. When this is
done the aircraft’s primary control stops must be positive and care must be taken to be sure
that at the neutral point the servo arm is perpendicular to the push rod, and that the travel
limits of the servo arm are not exceeded.
There are installations in which the travel of the push-pull tube exceeds the allowable 2 ½”. For
such installations, the drive can be applied to a bell crank at a radius point that moves the
desired 2 ½” of maximum allowed travel in the outermost hole of the arm.
When there is no way to have a drive point of less than 2 ½” or when the primary control is
cable-driven it is necessary to use the capstan-cable servo drive. When this is done the servo
should be mounted so that the 1/16” diameter cable which wraps around the capstan when
