TM 1-1510-223-10 8-6           Change 3 (2)   TURN knob — Center. (3)   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  pitch  wheel  check  due  to  the heavy nose down force if the control wheel is not off the forward stop. (4)   Control wheel — Move to mid-travel. (5)   AP ENGAGE switch-indicator (auto- pilot controller) — Depress to engage autopilot and yaw damper. Check that AP    ENGAGE    and    YD    ENGAGE switch-indicators on autopilot control- ler  and  remote  annunciators  on  in- strument panel are illuminated. d.   Autopilot  overpower  check  —  Check  as follows: (1)   Rudder pedals — Overpower slowly. (2)   Control wheel — Overpower in both directions. WARNING If the autopilot or yaw damper disengages during the  overpower  test,  the  system  is  considered non-operative and should not be used. The ele- vator trim system must not be forced beyond the limits  which  are  indicated  on  the  elevator  trim indicator. e.   Elevator  trim  follow-up  —  Check  as  fol- lows: (1)   Control wheel — Move aft of mid-trav- el. Trim wheel should run nose down after approximately 3 seconds. TRIM DN annunciator (autopilot controller) should illuminate after approximately 6 to 8 seconds, and AP TRIM annun- ciator (instrument panel) should illu- minate after approximately 15 seconds. (2)   Control  wheel  —  Move  forward  of mid-travel.   Trim   wheel   should   run nose  up  after  approximately  3  sec- onds. TRIM UP annunciator (autopilot controller)    should    illuminate    after approximately 6 to 8 seconds, and AP TRIM annunciator (instrument panel) should illuminate after approximately 15 seconds. f.   AP   &   YD/TRIM   DISC   switch   (control wheel) — Depress to first level. Check that autopilot and yaw damper disengage, AP ENGAGE and YD ENGAGE switch-indi- cators on the autopilot controller and re- mote annunciators above the EADIs flash 5 times. g.   Control wheel — Hold to mid-travel. h.   AP ENGAGE SWITCH — RE-ENGAGE. i.   Turn knob — Check that elevator control trim wheel follows in each applied direc- tion, then center. j.   Pitch wheel — Check that trim responds to pitch wheel movements (UP TRIM and DN TRIM annunciators may illuminate). k.   Heading  marker  —  Center  and  engage HDG. Check that control wheel follows a turn in each direction. l.   GO AROUND button (left power lever) — Depress. Check that AP disengages and FD  commands  a  wings  level,  7  degree nose up attitude. Check GA annunciator on EADI illuminates. Yaw damper should automatically  engage  and  YD  ENGAGE switch-annunciator should be illuminated on the autopilot controller and the remote annunciators above the EADIs should be illuminated. m.   RUDDER BOOST/YAW CONTROL TEST switch   (pedestal   extension)   —   TEST. Check the RUDDER BOOST annunciator above the EADIs illuminates, yaw damper disengages, TD ENGAGE switch-indica- tor    on    the    autopilot    controller    extin- guishes,  and  the  YD  ENGAGE  remote annunciators  above  the  EADIs  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.