TM  55-1510-221-10 e. INST  AC  Warning  Annunciator  Light  Illu- minated. Illumination of the INST AC warning light indicates  that  26  VAC  power  is  not  available.  All items connected to the 26 VAC bus will be inopera- tive (refer to AC wiring schematic diagram in chap ter  2  for  equipment  effected).  Under  these  condi- tions.  power  must  be  controlled  by  indications  of  the Nt and TGT gages. Perform the following 1. Nt and TGT indications - Check. 2. Other  engine  instruments  -  Monitor. f.   Circuit   Breaker   Tripped.   If  the  circuit breaker is for a nonessential item. do not reset in flight. If the circuit breaker is for an essential item, the circuit breaker may be reset once. If a bus feeder circuit  breaker  (on  the  overhead  circuit  breaker panel)  trips.  a  short  is  indicated.  Do  not  reset  in flight. If a circuit breaker trips. perform as follows: 1. BUS  FEEDER  breaker  tripped  -  Do not  reset. 2. Nonessential circuit - Do not reset. 3 -. Essential  circuit  -  Reset  once. NOTE Circuit  breakers  should  not  be  reset  more than  once  until  the  cause  of  the  circuit malfunction  has  been  determined  and corrected.  Do  not  reset  dual  fed  bus feeder circuit breakers. g. BATTERY CHARGE Light Illuminated. If the BATTERY CHARGE caution light illuminates during normal cruise flight. perform the following: 1. Battery  Volt-Ampmeter  -  Monitor.  If battery current continues to increase, turn  battery  switch  off. 2. Battery switch (landing gear/flap exten- sion only) - ON. 9-23.  EMERGENCY  DESCENT. Emergency  descent  is  a  maximum  effort  in which  damage  to  the  aircraft  must  be  considered secondary to getting the aircraft down. The follow- ing procedure assumes the structural integrity of the aircraft and smooth flight conditions. If structural integrity is in doubt. limit speed as much as possi- ble. reduce rate of descent if necessary, and avoid high  maneuvering  loads.  For  emergency  descent, perform  the  following: NOTE Windshield  defogging  may  be  required. 1. Power lever - IDLE. 2. Propeller lever - HIGH RPM. 3.  Flaps  -  APPROACH. 4.  Gear  -  DN. 5. Airspeed - 180 KIAS maximum. 9-24. LANDING EMERGENCIES. Structural damage may exist after landing with brake, tire, or landing gear malfunc- tions.  Under  no  circumstances  shall  an attempt be made to inspect the aircraft until jacks have been installed. a. Landing Gear Unsafe Indication. Should one or more of the three green landing gear indica- tor lights fail to indicate a safe condition. the follow- ing  steps  should  be  taken  before  proceeding  to extend the gear manually. 1.  Gear  -  DN. 2. Gear lights - Check (three green). 3.  Landing  gear  relay  and  indicator  cir- cuit breaker - Check In. NOTE If   gear   continues   to   indicate   unsafe. attempt to verify position of the landing gear  visually. h. Landing  Gear  Emergency  Extension. Continued  pumping  of  the  handle  after GEAR  DOWN  position  indicator  lights (3)  are  illuminated  could  damage  the drive mechanism. and prevent subsequent gear  retraction. 9-12 Change 1