TM 1-1510-218-10 9-7 9-16.  DUCT OVERTEMP CAUTION LIGHT ILLUMINATED. Ensure   the   cabin   floor   outlets   are   open   and unobstructed    and    perform    the    following    steps    in sequence    until    the    light    is    extinguished.        Allow approximately  30  seconds  after  each  adjustment  for the    system    temperature    to    stabilize.        The    over temperature  condition  is  considered  corrected  at  any point during the procedure that the light goes out. 1.   CABIN AIR control – In. 2.   CABIN AIR/TEMP MODE switch – AUTO. 3.   CABIN AIR/TEMP switch – Decrease. 4.   VENT BLOWER switch – HI. 5.   CABIN  AIR/TEMP  MODE  switch  –  MAN COOL. 6.   MANUAL   TEMP   switch   –   DECREASE (hold). 7.   LEFT BLEED AIR VALVE switch – PNEU & ENVIRO OFF. 8.   Light  still  illuminated  (30  seconds)  LEFT BLEED AIR VALVE switch – OPEN. 9.   RIGHT    BLEED    AIR    VALVE    switch    – PNEU & ENVIRO OFF. 10.   Light still illuminated (30 seconds)  RIGHT BLEED AIR VALVE switch – OPEN. NOTE If    the    over    temperature    light    has    not extinguished   after   completing   the   above procedure, the warning system has malfunctioned. 9-17.  ICE VANE FAILURE. Ice  vane  failure  is  indicated  by  a  VANE  FAIL caution light illumination.  If an ice vane fails to operate electrically, perform the following: CAUTION Do    not    operate    vanes    electrically    after manual extension. 1.   Airspeed – 160 KIAS or below. 2.   ICE VANE CONTR circuit breaker – Pull. 3.   ICE VANE – Operate manually. 4.   Airspeed – Resume normal airspeed. 9-18.  ENGINE BLEED AIR SYSTEM MALFUNCTION. a.   BLEED   AIR   FAILURE   Light   Illuminated. Steady    illumination    of    the    warning    light    in    flight indicates  a  possible  ruptured  bleed-air  line  aft  of  the engine firewall.  The light will remain illuminated for the remainder of flight.  Perform the following: NOTE BLEED AIR FAIL annunciators may momentarily illuminate during simultaneous    surface    deice    and    brake deice operation at low N₁ speed. 1.   BRAKE DEICE switch – Off. 2.   TGT    and    TORQUE    –    Monitor    (note readings). 3.   BLEED AIR VALVE switch – OFF. NOTE Brake   deice,   on   the   affected   side,   and rudder   boost   will   not   be   available   with BLEED AIR VALVE switch off. 4.   Cabin pressurization – Check. b.  Excessive  Differential  Pressure.    If  cabin differential pressure exceeds 6.1 psi  C D T1 and  6.5 psi  T2 , perform the following procedure: 1.   Cabin   pressurization   controller   –   Select higher setting. IF CONDITION PERSISTS: 2.   Oxygen    (crew    and    passengers)    –    As required. 3.   LEFT    BLEED    AIR    VALVE    switch    – ENVIRO OFF (light illuminated). IF CONDITION STILL PERSISTS: 4.   RIGHT    BLEED    AIR    VALVE    switch    – ENVIRO OFF (light illuminated). 5.   Descend – As required.