TM 55-1510-219-10 j. TACAN    channel    number-LOAD    (select Key 2 or 8).  Enter channel. Repeat steps a thru j for all TACAN  stations. HSI INTERFACE TEST NOTE Interface  test  must  be  performed after   alignment   progresses   from state  8  but  prior  to  switching  to NAV. a. AUTO/MAN switch-MAN. b. Couple INS to FD and engage AP. c. Data selector (any position but DSRTK). d. CDU TEST-PRESS and HOLD. MSU and CDU all lamps lit 8's.  RMI all angles are 30  degrees.    Cross  track  deviation  bar  is  1  dot  right, NAV    flags    are    retracted,    WX    radar    NAV    display indicates 1 dot right of course. On   HRI,   a   15   degree   RH   steering   command. Aircraft panel LINK UPDATE/TACAN UPDATE annunciated and INS light illuminated. e. Continue holding TEST  switch from MAN to  AUTO.    RMI  all  angles  are  0.    Cross track   deviation   is   one   dot   left.      A   15 degree left steering command is issued. f. Release TEST switch-Operations return to normal. 19. Electric elevator trim and autopilot/flight director operation-Check as follows: a. Pilot  and  copilot  PITCH  TRIM  switches- Press    to    NOSE    UP    and    NOSE    DN positions,  singularly  and  in  pairs.    Check that trim wheel moves in proper direction and operates only when trim switches are pressed  in  pairs.    Any  deviation  requires that   electric   elevator   trim   be   turned   off and flight conducted using manual trim. b. TRIM  DISC  switch-Press  and  check  that electric  trim  disconnects  and  that  ELEV TRIM light extinguishes. c. Flight   director   (FD)   and   radio   magnetic indicator    (RMI)    warning    flags    masked- Check. NOTE Since  the  pressure  of  airflow  that normally   opposes   movement   of control  surfaces  is  absent  during preflight  check,  it  is  possible  to get   a   hard   over   control   surface deflection if an autopilot command   is   allowed   to   remain active  for  any  appreciable  length of time.  Move turn knob and pitch thumbwheel only enough to check operation, then return them to the center position. d. Select HDG mode-Check. e. Horizontal situation indicator (HSI) heading marker under lubber line-Set. f. Engage autopilot and check controls stiff, and AIL HI TORQUE, HDG, and AP ENG are illuminated-Check. g. Move   HSI   heading   marker   10°   left   and right    and    verify    that    FD    and    control wheels respond in the appropriate direction-Check. h. Press AP/YD disengage switch and verify that  autopilot  disengages  and  that  flight controls are free -Check. i. Engage autopilot-Check. j. Command 5°  trim UP with AP pitch wheel and  verify  that  manual  trim  wheel  moves nose  UP  and  AP  trim  light  indicates  UP trim-Check. k. Press   pitch   trim   switch   nose   down   and verify that autopilot disengages and AUTOPILOT   TRIM   FAIL   and   MASTER WARNING lights illuminate-Check. NOTE The   AP   TRIM   FAIL   annunciator will   extinguish   by   pressing   the AP/YD  disconnect  button  on  the control wheel to the first detent. l. Repeat     steps     i     thru     k     above     using opposite commands. m. Engage autopilot-Check. n. Move HSI heading marker to command a bank on flight director-Check. o. Press GO-AROUND switch and verify that GA annunciator light illuminates, autopilot disengages, and that flight director commands    a    wings    level,    7    nose-up attitude-Check. p. Press TEST switch (pilot's HRI) and verify that attitude display indicates an 8-5