50% speedbrake? (737)
From Boeing.com:
The mid- to outboard portion of the wing was designed for speed-brakes-up maneuver loads of 2.5 g. Loads in this area can be lowered by reducing the in-flight speed-brake angle. The reduction in the acceptable speed-brake angle depended on airplane utilization by the operators: The angle was reduced by 50 percent for the BBJ; the 737-800 commercial airplane required full use of the speed brakes to the in-flight detent position for emergency descent certification requirements. For 737-800 retrofits, a load alleviation system was developed to reduce the speed-brake angle automatically at heavy weights and high speeds for critical design load conditions. For airplanes in production, a strengthened wing allows for full speed-brake capability to be retained. Figure 10, which shows the net load reduction from changing the toe angle and reducing the speed-brake angle, depicts how structural changes to the wing were minimized.