Critical Malfunction of Diving Equipment

Abstract

Two identically constructed diving devices showed complete and uncontrolled release of breathing air at depth below 30 to 40 m. The failures occurred during separate dives. In one case a fatal accident resulted. Post-mission testing procedures for the diving equipment did not show any technical failure, but a subsequent failure analysis revealed a principal problem. The problem resulted from a minor modification and the use of a protective cover. These changes caused pressure equalization to be hindered and caused a temporary blocking of a bypass valve in the “valve-open” position. The blocking occurred at depths below 30 m. An uncontrolled and sudden complete loss of air supply followed. This malfunction could not be reproduced with the equipment by examination onshore, because it only occurred underwater during a dive and was the result of a sequence of events. Modification of the valve design solved the critical and dangerous problem.