TM 1-1510-225-10 9-17 CAUTION Do not attempt to free a frozen trim tab by activating either the electric trim or manual trim controls.  The force required to break the ice will probably exceed the force that can be delivered to the hinge-line by either electric or manual controls.  Over stressing the  trim  tab  cable  circuit  or  the  electric drive unit could damage either or both. c.  Electric  Elevator  Trim  Controls  Frozen  in Flight.      Moisture   entering   or   condensing   in   the elevator  trim  control  clutch  assembly  can  freeze  in flight   locking   the   trim   in   a   cruise   position.      This condition is first noticed when preparing for descent or retrimming   at   altitude.      Flight   in   above   freezing temperatures  will  normally  clear  the  problem  before landing,  however  if  the  elevator  control  is  still  frozen during the approach, control forces must be overcome manually.    Descend  using  power  reduction  to  keep heavy control forces caused by airspeed increases to a  minimum.    If  trim  control  freedom  has  not  been attained prior to landing, consider a no flaps approach and landing to ease control back pressure. 9-36.  ELECTROTHERMAL     PROPELLER     DEICE (AUTO SYSTEM) MALFUNCTION. Abnormal  Reading  on  Deice  Ammeter  (normal operation 18 to 24 amps). ZERO AMPS: 1.  PROP deice switch – Check AUTO. IF AMPS REMAIN AT ZERO: 2.  PROP    deice    switch    –    OFF    (for    30 seconds). 3.  PROP deice switch – AUTO. IF AMPS REMAIN AT ZERO: 4.  Manual  backup  system  –  Initiate.    (Refer to  Electrothermal  Propeller  Deice  Manual System Operation, Paragraph 9-37.) BELOW 18 AMPS: 5.  Operation – Continue. 6.  RPM   –   Increase   (briefly   to   aid   in   ice removal if propeller imbalance occurs). OVER 24 AMPS: 7.  Monitor – Continue operation if the PROP deice circuit breaker switch does not trip. 8.  RPM   –   Increase   (briefly   to   aid   in   ice removal if propeller imbalance occurs). 9.  Loadmeter – Monitor for excessive current drain.    If  the  PROP  AUTO  deice  circuit breaker    switch    trips,    use    the    manual system. 10.   If  the  PROP  AUTO  deice  control  circuit breaker   or   the   left   or   right   prop   deice circuit breaker trips, avoid icing conditions. 9-37.  ELECTROTHERMAL     PROPELLER     DEICE MANUAL SYSTEM OPERATION. 1.  Manual  propeller  deice  switch  –  Hold  in MANUAL     position     for     approximately 90 seconds,  or until ice  is  dislodged  from blades. 2.  Manual    system    current    requirement    – Monitor the aircraft's loadmeters when the manual  deice  switch  is  in  the  MANUAL position.        A    small    needle    deflection (approximately  5%)  indicates  the  system is functioning. Table 9-1.  Ditching PLANNED DITCHING IMMEDIATE DITCHING PILOT PILOT A.  ALERT OCCUPANTS A.  WARN OCCUPANTS B.  ORDER  TO  PREPARE  SURVIVAL  GEAR  FOR AERIAL DROP B.  TRANSMIT DISTRESS MESSAGE C.  TRANSMIT DISTRESS MESSAGE C.  LIFE VEST – CHECK (DO NOT INFLATE) D.  LIFE VEST – CHECK (DO NOT INFLATE) D.  APPROACH – NORMAL