TM  1-1520-240-10            8-3-1 SECTION  III.  FLIGHT CHARACTERISTICS 8-3-1.  General. The flight characteristics of the helicopter throughout the flight envelope and at all gross weights are good. The flight    characteristics    remain    essentially    the    same throughout the CG and GW range. There is no marked degradation of flying qualities as altitude increases. 8-3-2.  AFCS Off Flight Characteristics. The AFCS is required to provide the helicopter with ade- quate stability. Therefore, the stability of the helicopter will be reduced when operating with AFCS off. With prac- tice, the pilot will know in advance what to expect and should  have  little  trouble  controlling  the  helicopter  as long as established limitations (refer to Chapter 5) and certain techniques are adhered to. In general, the AFCS off flight characteristics are enhanced by spoilers on the forward pylon, strakes on the fuel pods and ramp, and a blunted aft pylon. The AFCS may be turned off at any airspeed and turned back on at or near the turn-off-air- speed. If airspeed at turn-on is different from that at turn- off, a low rate pitch transient accompanied by momentary illumination of the AFCS OFF caution capsules may oc- cur. These symptoms indicate that a DASH error signal existed a turn-on and that the DASH actuator is running at a reduced rate to cancel the error signal. When the cautions are extinguished, the error signal is cancelled, and normal DASH operation has resumed. During this period, when the error signal is being cancelled, the re- maining AFCS features function normally. AFCS off flight will  not  be  difficult  when  the  following  techniques  are used: a.  Maintain airspeed below established limits. b.  Enter all maneuvers smoothly, keep control move- ments coordinated and avoid overcontrol. c.  Consistently  scan  the  turn-and-slip  indicator  to maintain trim flight. d.  React positively but smoothly to divergent move- ments. 8-3-3.  Center Hook Loads. In general, the helicopter possesses excellent flight char- acteristics  when  performing  an  external  load  mission. The  combination  of  power  available,  the  load  carried beneath the CG, and the design of the cargo hook sys- tem make loads of minimum or maximum weight relative- ly easy to carry and handle safely. The type loads carried can usually be broken down into three major groups: low density, high density and aerodynamic. Each type load mentioned displays characteristics all its own and there- fore must be discussed separately. CAUTION Do not lift or rotate the center cargo hook into the cabin area or allow the mid hook to lay on the cargo floor or access door panel during inspection or use. The excessive tension  placed  on  the  triple  emergency release cable housing assembly may par- tially dislodge the housing and engage or activate  the  forward  and  aft  hook  emer- gency   release   mechanism.   This   may cause  an  inadvertent  release  of  loaded forward and aft hook assemblies in flight. CAUTION External loads must not be rigged entirely with  steel  cable  (wire  rope)  slings.  To dampen vibration tendencies, a nylon ver- tical  riser  at  least  6  feet  long  must  be placed between the steel cable sling and the  nylon  loop  or  metal  shackle  which attaches  to  the  cargo  hook.  Nylon  and chain  leg  slings  and  pure  nylon  slings must have at least 6 feet of nylon in each leg. CAUTION When  combination  internal  and  external loads  are  carried  during  the  same  flight and  the  external  load  exceeds  12,000 pounds, position the internal load forward of  the  utility  hatch.  This  procedure  will preclude encountering an excessively aft CG. 8-3-4.  Low Density Loads. When carrying low density loads, airspeed is limited by the amount of clearance which can be maintained be- tween the load and the underside of the helicopter since the load will tend to trail aft as speed is increased. 8-3-5.  High Density Loads. High  density  loads  can  usually  be  flown  at  cruise  air- speed and in some cases up to Vne, depending on the configuration of the load, air turbulence, or accompany- ing vibration.