TM 1-1500-204-23-1 Inlet duct runup screens may be left off during taxiing   to   and   from   takeoff   position   when requirements  or  existing  conditions  make  the use   of   screens   impractical.      Since   specific conditions  warranting  removal  of  screens  as specified    above    cannot    be    predetermined, specific   conditions   may   be   determined   by each command as necessary to conduct their operations.        Approval    of    screen    removal should    include    any    additional    precautions necessary to assure safe operation of engines. Use   only   nonmetallic-head   hammers   when required to install parts on engine. c. Safety  Around  Aircraft.      The   following   safety precautions  shall  be  employed  to  ensure  safety  around helicopters on the flightline. Stand    clear    of    plane-of-rotation    of    engine cooling fan during operation. Stand      clear   of   tail   rotor   plane-of-rotation during operation. Main rotor blades tend to droop at decreased speeds,    approach    with    caution,    especially blades with a low plane-of-rotation. WARNING Personnel     shall     exercise     extreme caution when hand-pulling a propeller   to   keep   their   bodies   as clear of the plane-of-propeller- rotation as conditions permit. Ground    crew-members    should    be conscious of the fact that an accidental   start   may   occur   at   any time, and should therefore be alert to jump   clear   in   such   an   event.      A suitable   length   of   canvas   strap   or similar material, without metal fittings, may be placed around propeller   blades   to   facilitate   hand- pulling.      Be   especially   certain   that the   ignition   switch   is   in   the   OFF position  before  turning  propeller  by hand.  Death or injury may otherwise result. d. Parking and Mooring.  The following instructions are   general   in   nature,   and   are   applicable   to   Army aircraft.        For    specific    instructions    on    parking    and mooring    particular    aircraft,    refer    to    the    applicable maintenance    manual.        The    following    are    general precautions for all aircraft. Do not park or moor aircraft closer than wing or   rotor   span,   except   by   authority   of   the commanding officer or his designated representative. NOTE When   aircraft   are   to   be   parked   in rows,   position   aircraft   in   adjacent rows     to     most     effectively     reduce propeller wash during engine operation. When possible, park aircraft in such a location that  transparent  enclosures  are  not  in  direct rays of sun. Install gear locking devices (when applicable). Attach    mooring      ropes    to    aircraft    and ground  fittings  at  an  angle  of  approximately 45 degrees.  Attach mooring ropes and install mooring   devices   as   specified   in   applicable maintenance manual. NOTE Allow sufficient slack in the mooring rope   to   prevent   stress   on   ground fittings,   rope,   mooring   devices,   or aircraft  structure  due  to  tire  or  strut inflation/deflation, or wet rope shrinkage. Place fully charged, 50 pound carbon dioxide type   fire   extinguishers   in   readily   accessible areas where aircraft are parked. When  aircraft  are  to  be  moored  for  storage, they  shall  not  be  parked  less  than  750  feet from    center    of    nearest    taxiway.        Provide adequate clearance for maintenance, servicing, fire lanes and taxiways. All   aircraft   parked   inside   enclosures   will   be grounded at all times. 3-2