TM 1-1510-223-10 Change 3          3-49 b.   After  SBY  push-button  switch  has  been held depressed for 5 to 8 seconds verify that: (1)   AP TRIM annunciator - illuminates. (2)   Autopilot disconnect horn - Sounds. (3)   SBY push-button switch - Release. (4)   EADI - FD FAIL and glide slope off flag will be extinguished. 10.   Autopilot - Check as follows: a.   Autopilot trim annunciators - Check extin- guished. b.   TURN knob - Center. c.   ELEV TRIM switch - Check ON. NOTE The control wheel must be held at mid-travel due to ballast in the elevator. The autopilot will dis- connect during elevator trim follow up check due to the heavy nose down force if the control wheel is not off the forward stop. d.   Control wheel - Move to mid-travel. e.   AP  ENGAGE  switch-indicator  (autopilot controller) - Depress to engage autopilot and yaw damper. Check that AP ENGAGE and YD ENGAGE switch indicators on au- topilot controller and remote annunciators on instrument panel are illuminated. 11.   Autopilot overpower check - Check as follows: a.   Rudder pedals - Overpower slowly. b.   Control wheel - Overpower slowly in both directions. WARNING If the autopilot or the yaw damper disengages during the overpower test, the system is consid- ered non-operative and should not be used. The elevator trim system must not be forced beyond the limits which are indicated on the elevator trim indicator. 12.   Elevator trim follow-up - Check as follows: a.   Control wheel - Move to mid-travel. Trim wheel should run nose down after approxi- mately 3 seconds. TRIM DN annunciator (autopilot controller) should illuminate af- ter approximately 6 to 8 seconds, and AP TRIM    annunciator    (instrument    panel) should  illuminate  after  approximately  15 seconds. b.   Control wheel - Move forward of mid-trav- el.  Trim  wheel  should  run  nose  up  after approximately  3  seconds.  TRIM  UP  an- nunciator (autopilot controller) check illu- minated    after    approximately    6    to    8 seconds. AP TRIM annunciators (instru- ment    panel)    check    illuminated    after approximately 15 seconds. 13.   AP & YD/TRIM DISC switch (control wheel) - Depress to first to first level. Check that autopi- lot and yaw damper disengages. AP ENGAGE and YD ENGAGE switch indicators on the au- topilot   controller   and   remote   annunciators above the EADI flash 5 times. 14.   Control wheel - Hold to mid-travel. 15.   AP ENGAGE switch - Re-engage. 16.   Turn knob - Check that elevator control trim wheel follows in each applied direction, then center knob. 17.   Pitch wheel - Check that trim responds to pitch wheel  movements  (UP  TRIM  and  DN  TRIM annunciators may illuminate). 18.   Heading marker - Center and engage HDG. Check that control wheel follows a turn in each direction. 19.   GO AROUND button (left power lever) - De- press. Check that AP disengages and FD com- mands   a   wings   level   7   degrees   nose   up attitude. Check GA annunciator on EADI illu- minates.  Yaw  damper  should  automatically engage and YD ENGAGE switch-annunciator should be illuminated on the autopilot control- ler  and  the  remote  annunciators  above  the EADI should be illuminated. 20.   RUDDER   BOOST/YAW   CONTROL   TEST switch (pedestal extension) - TEST. Check the RUDDER   BOOST   annunciator   above   the EADI’s illuminates, yaw damper disengages, YD ENGAGE switch-indicator on the autopilot controller extinguishes, and the YD ENGAGE remote annunciators above the EADI flash 5 times. WARNING If  the  SBY  annunciator  on  the  flight  director mode selector does not illuminate within 10 sec- onds after the avionics master switch is turned on, the autopilot has failed self-test and is con- sidered inoperative and should not be used. CAUTION Do not force the elevator trim system beyond the limits which are indicated on the ELEVATOR trim tab indicator.