TM 1-1520-240-10            5-8-1 SECTION  VIII.  WATER OPERATION LIMITATIONS 5-8-1.  WATER OPERATION LIMITATIONS. 5-8-2.  Night Operation on Water. Night operation on water is permissible provided: a. Both AFCS are operational (ALT Hold and Head- ing Select not required for night operation on water). b. Pilot and copilot radar altimeter systems are op- erational. c. A visible horizon is present at the landing site. d. Two or more highly visible, stationary objects are on the water surface to provide necessary visual cues for landing. 5-8-3.  Sea State Limits. Operation on water is restricted to a maximum of Sea State  2.    Refer  to  table  5-8-1  for  information  on  sea states. 5-8-4.  Operation Time Limit. Operation on water is restricted to 30 minutes total flota- tion time without draining the helicopter. 5-8-5.  Gross Weight Limitations. Maximum gross weight for water operations is as follows: a. Normal operations — 36,000 pounds. b. Emergency rescue missions — 46,000 pounds. 5-8-6.  Taxiing Limitations. Taxiing will not be conducted in water conditions above Sea State 1 or in wind above 6 knots.  Fast taxiing will be conducted in a straight line only and to a maximum speed of 10 knots when the lower nose enclosure is left in the water. 5-8-7.  Landing Limitations. Water landings can be performed within the limitations presented on fig. 5-8-1.  The touchdown speeds present- ed do not reflect indicated airspeed but actual forward velocity  at  touchdown.    Running  landings  will  only  be conducted  onto  calm  water.    The  ramp,  lower  rescue door, and main cabin door shall be closed during water landing.  Water landings are prohibited when fuel in the main tanks is less than 50 percent. 5-8-8.  Rotor Starting and Shutdown Limitations. Rotor starting or shutdown will not be conducted when water conditions exceed Sea State 1 or wind exceeds 6 knots. maximum gross weight for starting and shutdown is 28,550 pounds. Figure  5-8-1.  Water Landing Speed Limitations Up To 46,000 Pounds gross Weight Table  5-8-1.     Description of Sea States SEA STATE SEA DESCRIPTION WIND DESCRIPTION WIND VELOCITY (KNOTS) AVERAGE WAVE HEIGHT (FT) Sea like mirror (calm) Calm Less than 1 0.0 0 Ripples with appearance of scales; no foam crests (smooth) Light Air 1-3 0.05 1 Small wavelets; crests of glassy appearance, not breaking (slight) Light Breeze 4-6 0.2