Operational History And Experience With Boeing Helicopters

The active participation of today's military helicopters in the Vietnam war has produced an opportunity to evaluate helicopters under the most rigorous and extreme environmental and combat situations. From such activity, the opportunities and restraints of the helicopter in large-scale to mid-intensity warfare are becoming well understood. It is the purpose of this paper to present a brief resume of the experience of Boeing helicopters as related to the Vietnam war. Specifically, the CH-47 Chinook and the CH-46 Sea Knight are discussed. The Chinook is the U. S. Army medium transport helicopter, whose principal mission is to provide airmobility within the battle area for combat loads consisting of troops, weapons, and equipment. Powered by two Lycoming T55-L-7 engines, the CH-47A operates at a weight of 33, 000 pounds. A 10,300-pound payload can be transported at a speed of 110 knots for a mission radius of 100 nautical miles. The Sea Knight is the light assault transport helicopter for the U. S. Marine Corps. Its primary mission is to rapidly disperse combat troops, support equipment, and supplies from amphibious assault ships or established shore bases to advanced combat areas. Powered by two General Electric T58-10 engines, the CH-46D, with a design gross weight of 20,800 pounds, has a 100-nautical-mile-radius mission payload of 4000 pounds and operates at a sea level cruise speed of 142 knots. The chronological development of each helicopter is reviewed with the significant milestones identified. Operational statistics to date including combat hits are presented. With this information as a background, typical problems which have had significant operational or maintenance impacts are discussed in detail along with the corrective actions taken. Several recommqndations are made as a result of the lessons being learned from today's experience. These are presented as guidelines for consideration in product improvement of present inventory as well as for the development of new vertical lift weapons systems.