TM 1-1510-224-10 (10) Light   still   illuminated   after   30   seconds:   RIGHT ENVIRO & PNEU BLEED AIR valve switch - ON. NOTE If  the  DUCT  OVERTEMP  annunciator has not extinguished after completing  the  above  procedure,  the warning system has malfunctioned. 9-20.  ENGINE ANTI-ICE FAILURE. Ice   vane   failure   is   indicated   by   the   illumination   of   the amber # 1 or # 2 VANE FAIL caution annunciator lights. If the ice vanes fail to operate, perform the following: (1) ICE VANE POWER SELECT switch - STBY. 2. VANE FAIL annunciator - Check extinguished. 9-21.  ENGINE BLEED AIR SYSTEM MALFUNCTION. a. BL  AIR  FAlL  Annunciator Illuminated.    Steady illumination  of  the  warning  annunciator  in  flight  indicates a   possible   ruptured   bleed   air   line   aft   of   the   engine firewall.    The  annunciator  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) ENVIRO    &    PNEU    BLEED    AIR    valve    switch (affected side) - Off. NOTE Brake  deice  on  the  affected  side  will not  be  available  with  bleed  air  valve switch off. (4) Cabin pressurization - Check. b. Excessive Differential Pressure. If cabin differential    pressure    exceeds    6.5    PSI,    perform    the following: (2) Cabin   altitude   and   rate-of-climb   controller   - Select higher setting. If condition persists: (3) LEFT    ENVIRO    &    PNEU    BLEED    AIR    valve switch - PNEU ONLY (L BL AIR OFF annunciator illuminated). If condition still persists: (3) RIGHT   ENVIRO   &   PNEU   BLEED   AIR   valve switch     - PNEU     ONLY     (R     BL     AIR     OFF annunciator illuminated). If condition still persists: 4. Descend immediately. If unable to descend: 5. Oxygen masks - On and 100%. (6) CABIN PRESS switch - DUMP. (7) ENVIRO  &  PNEU  BLEED  AIR  valve  switches  - ON, if cabin heating is required. 9-22.    LOSS  OF  PRESSURIZATION  (ABOVE  10,000 FEET). If  cabin  pressurization  is  lost  when  operating  above 10,000   feet   or   the   ALT   WARN   warning   annunciator illuminates, perform the following: 1. Crew oxygen masks - On and 100%. 2.   Descend as required. NOTE Proper     EFIS     operation     has     been demonstrated at cabin altitudes of up to 12,500 feet. 9-23.          CABIN     DOOR     CAUTION     ANNUNCIATOR ILLUMINATED. Remain clear of cabin door and perform the following: (1) ENVIRO  &  PNEU  BLEED  AIR   valve  switches  - PNEU ONLY. 2. Descend below 14,000 feet as soon as practicable. 3. Oxygen - As required. 9-24.  PROPELLER FAILURE (OVER 1802 RPM). If an overspeed condition occurs that cannot be con- trolled   with   the   propeller   lever   or   by   reducing   power, perform the following: 1. POWER lever (affected engine) - IDLE. 2. PROP lever -  FEATHER. 3. CONDITION lever - As required. (4) .Engine cleanup - As required. 9-9