TM 1-1510-224-10 (3) Accumulation     of     ice     on     the     propeller spinner farther aft than normally observed. b. Since  the  autopilot  may  mask  tactle  cues  that indicate   adverse   changes   in   handling   characteristics, use  of  the  autopilot  is  prohibited  when  any  of  the  visual cues  specified  above  exist,  or  when  unusual  lateral  trim requirements  or  autopilot  trim  warnings  are  encountered while the aircraft is in icing conditions. NOTE All   icing   detection   lights   must   be operative   prior   to   flight   into   icing conditions  at  night.    This  supersedes any   relief   provided   by   the   master minimum   equipment   list   (MMEL)   or equivalent. 5-35.   CROSSWIND LIMITATIONS. WARNING Landing     with     wind     conditions     in excess of the demonstrated crosswind  component  may  result  in damage  to  the  aircraft.    This  should only  be  attempted  during  emergency situations. The maximum demonstrated crosswind component is 20  knots  at  90  degrees.    Landing  the  aircraft  in  a  crab will impose side loads on the landing gear and should be recorded on DA Form 2408-13-1.  Refer to Chapter 8 for crosswind landing techniques. 5-36.   OXYGEN REQUIREMENTS. a. Oxygen  requirements  will  be  in  accordance  with AR95-1. b. Oxygen system data/duration tables are found in Chapter 2. 5-37.  CABIN PRESSURE LIMITS. Maximum cabin differential pressure is 6.5 PSI. 5-38.   CRACKED CABIN WINDOW/WINDSHIELD. If  a  crack  occurs  in  any  side  window  or  windshield, aircraft  operation  is  limited  to  25,000  feet  or  less  and cabin  pressurization  of  4.0  PSI  or  less  as  required  to complete the flight.  The aircraft shall not be flown again until  maintenance  actions  are  conducted  unless  proper authorization  is  obtained  for  a  ferry  flight  to  a  location where a maintenance action can be performed. If  a  crack  develops  in  any  side  window  or  windshield in flight, refer to Chapter 9, Emergency Procedures. Section VIII.  OTHER LIMITATIONS 5-39.   MAXIMUM DESIGN SINK RATE. The maximum design landing sink rate is 500 feet per minute,    with    a    normal    flare    initiated    just    prior    to touchdown. 5-40.   INTENTIONAL ENGINE OUT SPEED. Intentional   inflight   engine   cuts   below   the   safe   one engine  inoperative  speed  (V_sse=115 KIAS   P,   V_sse=120 KIAS Q ) are prohibited. 5-41.   LANDING ON UNPREPARED RUNWAY. CAUTION Except   in   an   emergency,   propellers should    be    moved    out    of    reverse below  40  knots  to  minimize  propeller blade  erosion,  and  during  crosswind to minimize stress imposed on propellers,    engines,    and    airframe. Care must be exercised when reversing    on    runways    with    loose sand  or  dust  on  the  surface.    Flying gravel  will  damage  propeller  blades and    dust    may    impair    the    pilot's forward visibility at low aircraft speeds. The   aircraft   has   demonstrated   landings   on   hard, smooth runways.  Hard braking, i.e., skidding tires while operating  on  other  than  smooth  runways,  can  result  in damage to the landing gear. Operations from unimproved runways (rocks, potholes, mud, deteriorated surfaces)  are  prohibited.    When  landing  on  other  than dry  surfaces,  use  discretionary  propeller  reverse  to  stop the aircraft on the available runway. 5-13