completeaerogeek

I trained as a Flight Engineer on the P-3 many years ago and the P-3 was based on the Electra. Control movement operated cables that then moved selector (control) valves which operated boost packs containing the actuators and these moved the flight controls. The Autopilot (AFCS) could electrically signal the control valves giving a kind of analogue FBW. The boost packs could also be reconfigured in an emergency by pulling the Boost Out handles at the FE's feet. This reconfigured the geometry of the boost pack 'cage' and gave limited manual reversion. Quite ingenious! On mechanical (cables and pulleys) DC-4/6 type aircraft, the cables operated servo tabs which then gave aerodynamic assistance (like a crude power steering system) and made the controls lighter to move. The control movement initiated the tab first and the tab moved in opposite sense to the control surface giving this assistance. Does that help? Cheers