TM 55-1510-220-10 (1.) Brake de-ice - OFF. (2.) TGT and torque - Monitor (note readings). (3.) Bleed  air valve switch - PNEU & ENVIRO OFF. NOTE Brake   de-ice   on   the   affected   side,   and rudder   boost,   will   not   be   available   with bleed  air  valve  switch  in  PNEU  &  ENVIRO OFF. (4.) Cabin pressurization - Check. b. Excessive Differential Pressure. If cabin differential    pressure    exceeds    6.1    PSI,    perform    the following: (1.) Cabin    altitude  and  rate-of-climb  controller  - Select higher setting. (2.) If    condition    persists:        LEFT    BLEED    AIR VALVE switch - ENVIRO OFF (light illuminated). (3.) If condition still persists:  RIGHT BLEED AIR VALVE switch - ENVIRO OFF (light illuminated). 4. If condition still persists - Descend immediately. (5.) If unable to descend: - CABIN PRESS DUMP switch - CABIN PRESS DUMP. (6.) Bleed   air   valve   switches   -   OPEN,   if   cabin heating is required. 9-13.  LOSS OF PRESSURIZATION (ABOVE 10,000 FEET). If  cabin  pressurization  is  lost  when  operating  above 10,000  feet  or  the  ALT  WARN  warning  annunciator  light illuminates, perform the following: 1.    Crew oxygen masks 100% and on. (2.)    Passenger   oxygen   ON   and   check.      The copilot  should  confirm  that  all  passengers  have  oxygen masks on                  and   are   receiving   supplemental oxygen if required. 9-14.  CABIN DOOR CAUTION LIGHT ILLUMINATED. Remain clear of cabin door and perform the following: (1.) Bleed air valve switches - ENVIRO OFF. 2.    Descend below 14,000 feet as soon as practicable. 3. Oxygen - As required. 9-15.  SINGLE-ENGINE DESCENT/ARRIVAL. NOTE Approximately    85%    N 1 is    required    to maintain pressurization schedule.  Perform the  following  procedure  prior  to  the  final descent for landing. (1.) Cabin controller - Set. (2.) Ice and rain switches - As required. 3. Altimeters - Set. 4. Recognition lights - ON. 5. Arrival briefing - Complete. 9-16.  SINGLE-ENGINE BEFORE LANDING. 1. Propeller lever - As required. NOTE During  approach,  propeller  should  be  set at 1900 RPM to prevent glideslope interference  (ILS  approach),  provide  better power  response  during  approach,  and  to minimize  attitude  change  when  advancing propeller levers for landing. 2. Flaps - APPROACH. 3. Gear - DN. 4. Landing lights - As required. (5.) Yaw damp - OFF. (6.) Brake deice - OFF. 9-8