Instruction Manual

G1000 / GFC 700 System Maintenance Manual - 200/B200 Series King Air Page 4-23
190-00915-01 Revision 8
4.9.3 Servo Gearbox Adjustment Fixture Procedure
This test is an alternative to the automated and manual slip clutch test procedures.
Only the GSM 85A servo gearbox slip clutch can be adjusted. The GSM 86 servo gearbox does not have
an adjustable slip clutch; however, the torque value can be measured using this procedure.
IMPORTANT!
This adjustment requires the use of the Garmin servo adjustment fixture,
P/N T10-00110-01. For detailed operating instructions for the fixture, refer to
GSA8X / GSM85(A) Installation Manual, listed in Table 1-3.
It is highly recommended that the following test be performed at temperatures
between 50° F and 120° F.
1. Remove the GSM 85A or GSM 86 servo gearbox as per Section 6.12.
2. Place the GSM 85A or GSM 86 servo gearbox on the slip-clutch adjustment fixture and secure with
the toggle clamps. Install the fixture cable between the capstan under test and the fixture capstan.
Remove the slack in the cable using the tension adjustment knob. Tighten the two wingnuts on
bottom of fixture while holding the top thumbscrews.
3. Attach a socket to a calibrated torque wrench of appropriate range and place on top of the fixture
capstan. Adjust the wrench support fixture so that it contacts the handle in the appropriate location.
4. Connect a 2 Amp, 24 V, DC power supply to the fixture.
5. Place the solenoid switch to "on" and move the direction switch to the clockwise or counter-
clockwise position. Allow the clutch to rotate at least one revolution in each direction (note: the
capstan itself is fixed.)
6. Observe the torque reading for at least two full revolutions in each direction. Ensure the minimum
and maximum torque readings are within the tolerance specified.
7. If the minimum and maximum torque values are within the specified range in Table 4-11, the GSM
slip clutch is acceptable. Reinstall the GSM 85A or GSM 86 servo gearbox per Section 6.12.
8. If the minimum and maximum torque values are not within the specified range in Table 4-11, the
GSM 86 slip clutch cartridge must be replaced or the GSM 85A must be adjusted.
9. For GSM 85A only: If adjustment is required, remove cotter pin and adjust the nut on the capstan as
needed to obtain the torque value listed in Table 4-11, as shown on the torque wrench. Position the
nut to align with holes in the capstan shaft and install a new cotter pin.
10. When finished, remove the fixture cable, and then remove the servo gearbox from the fixture.
11. Install the GSM 85A or GSM 86 servo gearbox per Section 6.12.
Table 4-11, GSM 85A/GSM 86 Slip Clutch Torque Settings
Servo Pitch Trim* Pitch Yaw Roll
GSM 85A 65 ± 8 in-lbs* 32 ±5 in-lbs 90 ±10 in-lbs 135 ±13 in-lbs
GSM 86 66 ± 19 in-lbs* 32 ± 9 in-lbs 90 ±27 in-lbs 135 ±40 in-lbs
*Valid with continuous travel servo gearbox only