The wing is fitted with leading edge and Fowler flaps. Spoilers are fitted to both the upper and the lower surfaces of the wings. All control surfaces are actuated by dual hydraulically boosted irreversible systems. In the event of dual hydraulic failures, an Emergency Flight Control System (EFCS) permits manual control with greatly increased stick forces and reduced control authority. Unlike many tactical jets which required ground service equipment, the S-3 was equipped with an auxiliary power unit (APU) and capable of unassisted starts. The aircraft's original APU could provide only minimal electric power and pressurized air for both aircraft cooling and for the engines' pneumatic starters. A newer, more powerful APU could provide full electrical service to the aircraft. The APU itself was started from a hydraulic accumulator by pulling a handle in the cockpit. The APU accumulator was fed from the primary hydraulic system, but could also be pumped up manually (with much effort) from the cockpit. All crew members sit on forward-facing, upward-firing Douglas Escapac zero-zero ejection seats. In "group eject" mode, initiating ejection from either of the front seat ejects the entire crew in sequence, with the back seats ejecting 0.5 seconds before the front in order to provide safe separation (this was to prevent the pilots, who were more aware of what was happening outside the aircraft from ejecting without the rest of the crew, or being forced to delay ejection to order the crew to eject in an emergency; ejection from either rear seat would not eject the pilots, who had to initiate their own ejections, to prevent loss of the aircraft if a rear crewmember ejected prematurely. If a pilot ejected prematurely, the plane was lost anyway, and automatic ejection prevented the crew from crashing with a pilot-less aircraft before they were aware of what had happened). The rear seats are capable of self ejection and the ejection sequence includes a pyrotechnic charge that stows the rear keyboard trays out of the occupants' way immediately before ejection. Safe ejection requires the seats to be weighted in pairs and when flying with a single crewman in the back the unoccupied seat is fitted with ballast. At the time it entered the fleet, the S-3 introduced an unprecedented level of systems integration. Previous ASW aircraft like the Lockheed P-3 Orion and S-3's predecessor, the Grumman S-2 Tracker, featured separate instrumentation and controls for each sensor