Severance between crewstations

TM 1-1520-238-10 Change 9 2-48.1 LVDT (17.5% or approximately 1.75 INCHES, except in longitudinal aft where the mistrack must be 22.5% or approximately 2.25 INCHES). The BUCS flight control logic will wash in full authority over a period of approxi- mately one (1) second allowing the pilot to transition to BUCS controlled flight. The BUCS ON and ASE (ASE not applicable for collective) caution/warning lights will illumi- nate. SAS will be OFF in the engaged axis. Force trim will be available in all axes. Attitude/Hover hold will be avail- able in the axes that SAS is available. (b) Severance between crewstations. If a severance occurs between the crewstations the pilot will retain full mechanical control. The pilot should keep flying on the mechanical flight controls. The BUCS FAIL warn- ing light and ASE (ASE not applicable for collective) cau- tion/warning light will illuminate when a mistrack is de- tected between the pilot control LVDT and the CPG control LVDT. The CPG control will not follow control in- puts in the axis that is severed. SAS will be OFF in the en- gaged axis. Force trim feel will not be available to the CPG in the engaged axis. Attitude/Hover hold will be available in the axes that SAS is available. d. Control System Engagement Logic (Copilot crewstation – CPG flying the aircraft). (1) Jams. The CPG will have to decouple the SPAD. BUCS will automatically engage in the affected axis. Breakout values will be approximately 15% higher than the pilot’s values. The CPG can expect the control to displace to full travel when the SPAD releases. The DA- SEC will wash in full authority over a period of approxi- mately three (3) seconds allowing the CPG to center the controls and transition to BUCS controlled flight. The BUCS ON and ASE (ASE not applicable for collective) caution/warning lights will illuminate. SAS and force trim will be OFF in the engaged axis. Attitude/Hover hold will be available in the axes that SAS is available. (2) Severances. (a) Severance aft of the pilot’s control. A severance can occur due to malfunction or battle damage between the pilots’ controls and the actuator. Because the two crewstations are still mechanically linked together, this type of severance will operate the same as in the pilot station. BUCS will automatically engage when both the pi- lot and CPG LVDTs achieve the proper mistrack with re- spect to the RAM LVDT. The DASEC will wash in full au- thority over a period of approximately one (1) second allowing either crewmember to transition to BUCS con- trolled flight. The BUCS ON and ASE (ASE not applicable for collective) caution/warning lights will illuminate. SAS will be OFF in the engaged axis. Force trim will be avail- able in all axes. Attitude/Hover hold will be available in the axes that SAS is available. CAUTION The effect of the CPG assuming control with the BUCS trigger select is to trans- fer control of the aircraft from a flight control that still retains some integrity to that of a non–redundant electronic means of flight control. This shall only be activated if the pilot is incapable of flying the aircraft. NOTE The CPG must create sufficient mistrack. If the CPG repositions the flight control (af- fected axis) to a position that is is less than the appropriate mistrack value and engages the BUCS trigger, engagement will not oc- cur. The CPG may engage the trigger and hold it prior to achieving the mistrack. BUCS engagement will occur when the proper mis- track is reached. (b) Severance between crewstations. If suf- ficient mistrack is detected between the pilot control posi- tion and the CPG control position the BUCS FAIL and ASE (ASE not applicable for collective) caution/warning lights will illuminate. In this instance the pilot still has full mechanical control. The CPG should transfer control of the aircraft to the pilot. If it is necessary for the CPG to fly the aircraft, the BUCS trigger should be engaged and BUCS control will be established after sufficient mistrack between the CPG control position and the RAM position is reached. The DASEC will wash in full authority over a pe- riod of approximately one (1) second allowing the CPG to transition to BUCS controlled flight. SAS will be OFF in the engaged axis. Force trim feel will not be available to the CPG in the engaged axis. e. BUCS–Flight Transfer of Controls. Transfer of controls should only be accomplished if the flying crew- member is incapacitated or in the case of the CPG flying the aircraft and a severance occurs between the crewsta- tions. Table 2–3 lists the procedures for transfer of control between the crewmember in BUCS and the opposite crewmember.