Here’s a fantastic book for any former Quapaw sailor as well as anyone with an interest in US Navy marine salvage.
The Mighty Q is mentioned in a section about Vietnam salvage operations (excerpt from pages 421-422):
A few months later the waters off the coast of Vietnam were the site of another important search and recovery operation conducted for a very different purpose. As the Air Force C–5A transport #68218 flew outbound from Vietnam on 4 April 1975 with a load of refugees, mostly children, it suffered a rapid and complete decompression that carried away the after pressure door and a major portion of the after cargo ramp. The aircraft returned safely to Tan Son Nhut airport; the door and ramp fell into the South China Sea from 23,400 feet. Because passenger-carrying formed a major part of the mission of the C–5A transport, the Air Force wanted the door and ramp back to determine the cause of the failure.
Seventh Fleet ships Deliver, Abnaki, and Quapaw, under the overall command of Commander Task Force 73, Rear Admiral John D. Johnson, proceeded to the scene at their best speed while the Supervisor of Salvage mobilized a contractor search team. The Air Force Accident Investigation Board undertook the task of determining the probable impact point from the inertial navigation position of the aircraft and a ballistic trajectory analogy.
Lieutenant Commander J.A. Mack, the Seventh Fleet Salvage Officer, was assigned to coordinate the overall operation, while Lieutenant Commander Gerald L. Anderson, commanding officer of Deliver, com- manded the salvage force at the scene. While waiting for the search team to arrive from the United States, 230 dives were made to search the high probability impact area visually. Some pieces of debris located by the divers helped to refine the search areas.
The operation took on unusual urgency because North Vietnamese and Viet Cong forces were very close to delivering the coup de grace to the Republic of Vietnam. By the time the search team arrived, the Army of the Republic of Vietnam could not guarantee the security of shore-based precision navigation stations. Inability to place the navigation stations ashore resulted in an innovation. Deliver and Abnaki moored and became floating bases for the precision navigation equipment while Quapaw carried the side-scan sonar and navigation system receivers. The concept worked well.
Forty-eight hours of searching produced no contacts. Diving operations and refinement of the search position continued. Increasing pressure ashore began to affect the operation during the weekend of 26–27 April. Activity in the mountains north of Vung Tau increased and refugee boats began to appear in the search area. Round-the-clock search operations continued. On Sunday morning two substantial contacts were made and marked. Divers identified the cargo ramp and a major portion of the cargo door a few hundred yards away. Quapaw recovered the ramp first, then just at dark, the door. A search for the remaining section of the door began as soon as the first segment had been secured on board. By 10:30 on the night of Sunday, 27 April, only a few hours after the ramp and door segment had been recovered, Commander Seventh Fleet ordered the operation terminated and the area cleared. The situation ashore had deteriorated too much to continue.
Enough debris had been recovered to permit analysis of the failure.35 The Navy’s ability to recover objects from the ocean had taken on a new dimension with the recovery of free-falling debris from an altitude of several miles. Finding a needle in a haystack was easy compared to this kind of search. This operation and many similar ones were now demon- strating that objects lost in the ocean under almost any conditions could be located by combining the proper technology with the patience and determination to work thoroughly and methodically.