Cessna T303 Installation, Service & Parts Manual page 280

Avionic Installations Service/Parts Manual
Step 12. In order to eliminate
gyro roll and
pitch signals generated by a non-ere xed gyro, the
400B autopilot has a GYRO switch located on the rear
of the control head; set the GYRO switch to the OUT
position.
Since the 400B IFCS does not have a gyro
out switch, it will be necessary to took up an outside
vacuum source or operate one of the aircraft engines
to erect the gyro.
NOTES
If an outside vacuum source is used, it should
be calibrated in inches of mercury and the
desired suction range required to erect the
gyro is 4. 6 to 5.4 inches of mercury.
If one of the aircraft's engines is operated to
erect the gyro, the engine should be run at
1000 RPM to provide the desired amount of
vacuum and maintain proper bus voltage.
Step 13. Remove the neutral rigging tool, in-
stalled in Step 1.
Step 14.
Place a piece of tape or a mark on the
very top of the airplane's ELEVATOR TRIM com-
mand wheel so a full revolution of the ELEVATOR
TRIM command wheel may be observed and timed
with a stop watch.
Step 15. With 28. 8 volts dc applied to the elec-
tronics bus, place the AP/ON autopilot (ON/OFF)
switch to the ON position.
Allow the autopilot to
sync out (Autopilot PITCH wheel stops running).
Step 16. Observe and time one complete rotation
of the airplane's ELEVATOR TRIM command wheel
by placing the pitch command wheel in the UP posi-
tion and ensure that you obtain a timing of 22 ± 2
seconds for one complete rotation of the airplane's
ELEVATOR TRIM command wheel. Reverse this
procedure and ensure that you are getting a reading
of 22 ± 2 seconds for one full rotation of the airplane's
ELEVATOR TRIM command wheel in the "NOSE-
DOWN" position.
If the rate of travel for one full
rotation does not agree with the aforementioned
travel time limits, then use the following procedures
to obtain the desired rate of pitch trim tab travel.
a. Gain access to the computer amplifier by
first removing the two left-hand, front cargo tie-
down rings from the aft baggage shelf which starts
at Sta. 238. 00.
Then pull up the carpet to gain access
to the computer amplifier's floorboard access cover
plate and then remove the access cover plate.
b. Using Illustration G as a guide, locate and re-
move the center plug button from the top of the com-
puter amplifier to gain access to R46 on computer
module A6.
REMOVE THIS PLUG BUTTON
TO GAIN ACCESS TO R46
ADJUSTMENT POT.
1.
Computer Amplifier 2. Plug Button
Illustration G.
Electric Trim Adjusting Pot
Figure 7-1. Rigging Procedures for Cessna 400B and 400B IFCS (Types AF-550A & IF-550A) (Sheet 12 of 14)