Table of Contents
Advertisement
1.2.2
GSM 85 and GSM 85A Servo Gearbox
The GSM 85(A) servo gearbox is mounted to the aircraft structure, via a custom mounting bracket, and is
responsible for transferring the output torque of the GSA 8X servo actuator to the mechanical flight-
control surface linkage. The GSM 85(A) houses its internal components within an extruded aluminum
housing, like the GSA 8X. There are multiple variations of the GSM 85(A), all designed to accommodate
various flight-control system interfaces and torque requirements. The slip-clutch settings, type of output
capstan, and the available part numbers are listed in Tables 1-4 and 2-2.
The GSM 85A is similar to the GSM 85, but has additional components to allow use in more harsh
environments. The GSM 85A has been tested in the same environmental conditions as the GSM 85, and
additionally tested for fluid susceptibility, sand and dust, salt spray, and more rigorous icing
requirements. See the Environmental Qualification Form (Garmin part number 005-00231-01 for GSM
85 and 005-00231-06 for GSM 85A) for a list of specific conditions tested.
1.2.3
Operational Description
The GSA 8X servo actuator, when mated with the GSM 85(A) servo gearbox, drives a single flight-
control axis of the airplane, or its associated trim. Once installed into the aircraft, the GSA 8X servo
actuator may be easily removed for maintenance, without removing or de-rigging the GSM 85(A) servo
gearbox. Note that while the GSA 8X is removed, it is recommended to use the Servo Gearbox Protective
Cover (P/N 145-00807-00) to cover the opening of the GSM 85(A). The protective cover is included with
the GSM 85(A) unit, and is designed to prevent foreign objects from falling into the GSM 85(A).
The engagement of the drive clutch in the GSM 85(A) is controlled by a solenoid in the GSA 8X.
A slip-clutch allows the capstan to rotate independently of the GSA 8X whenever sufficient force is
applied to the capstan (see Section 1.4.4). This allows the pilot to override the operation of the GSA 8X
in the event of a malfunction by applying sufficient force to overcome the slip-clutch setting.
1.3
Interface Summary
The GSA 8X interfaces with two GIA Integrated Avionics units through serial communication, on
separate RS-485 ports.
Page 1-2
Revision R
Figure 1-2. GSM 85 Servo Gearbox
GSA 8X/GSM 85(A) Installation Manual
190-00303-72
Advertisement
Table of Contents
