The Final Flight of 'Bureau Number 152711'
After the recovery of the Apollo 13 crew, HS-4 was divided between Vietnam, and training in San Diego., and it was assigned to the training force in San Diego.
On June 4th, 1975, the helicopter departed the Naval Auxiliary Air Field at Imperial Beach, CA, at 1900 hours, enroute to the Helicopter Offshore Training Area to conduct a scheduled night anti-submarine sonar training flight. The flight's pilot-in-command was LT Leo S. Rolek and the copilot was LTJG Charles D. Neville. Twenty minutes later, the crew reported their position and commenced operations with four approaches to sonar hover and four night/low visibility and wind-line rescue patterns with hover trim practice until dusk. After sunset (1953 hours), the crew conducted four more approaches to sonar hovers while practicing dip-to-dip navigation with the pilots alternating approaches. Complying with reporting it every half-hour, the practices proceeded normally until 2133. With the sonar dome lowered down to 100 feet below the water's surface, the hover of the helicopter became unstable. The two sonar operators, AWH3 Brady W. Turner and AWH3 Peter C. Cassidy, sank the sonar dome deeper in the ocean, hoping the stability would improve and, for a brief moment, it worked. But, then the sonar dome began to pull Helo '740' downward to 30 feet above the waterline. The helicopter, being pulled backwards, impacted the water, sinking quickly. The four crewmen all egressed and when picked up by a Coast Guard HH-3F shortly before midnight. They were taken to the Naval Hospital at San Diego. Three of the crewmen was released from the hospital in the days that followed. But the pilot, who suffered from a ruptured spleen from the mishap, died of his injuries over three weeks later.