A Boeing CH-47C Chinook conducts flight testing with external cargo hooks. Modifications to the aircraft consisted of the addition of two hooks, each with a 20,000-lb capacity, forward and aft. The existing center cargo hook was retained. The control system provided for individual and/or simultaneous release of loads from each of the hooks. Testing was done at airspeeds up to 100 knots. From Vertiflite, May/June 1974 (page 21).