Australian edition "The Australian Financial Review" published Andrew Tillett material "Crew feared ageing Australian submarine would sink in deep sea mishap" ("The crew feared that the aging Australian submarine would sink at great depth as a result of the incident"), which reports on a previously unreported serious incident with the Australian SSG 77 Sheean diesel-electric submarine of the Collins type.
Australian diesel-electric submarine SSG 77 Sheean type Collins in Perth, 0304.2021 (c) Australian Navy
In the last [2021] year, on one of the Australian Collins-type submarines, the service life of which is approaching the limit, before diving to a great depth, an incident occurred related to the intake of seawater inside the durable hull. This caused the crew to fear that the boat (we are talking about SSG 77 Sheean) could sink during the testing of combat training activities off the coast of Western Australia. The ingenuity of the crew members prevented a catastrophe: the submarine made an emergency ascent after the backup system for purging ballast tanks failed the first time.
According to informed sources of the Australian Navy, this incident raised concerns about the weak safety culture of navigation on board the specified submarine, since part of the crew was written off on shore due to psychological trauma. The Australian Ministry of Defense only confirmed that there had been a "minor incident in connection with the intake of seawater" on the submarine, but refused to admit that it could have sunk.
"In accordance with the established procedure, HMAS Sheean made an emergency ascent and returned to its home base under its own power. The submarine was not exposed to any risk of flooding and returned to service within a few days," the official release of the military department says. "Safety is the number one priority for the submarine forces, and this is brought to the attention of all categories of military personnel. The physical and mental health of our people is of paramount importance, and the existing systems ensure security in all its aspects in the short and long term."
Transferred to the fleet in 2001, the Sheean boat left the submarine forces base in Perth on September 21, 2021 and began the transition to a combat training ground off the coast of Western Australia, where it planned to work out course tasks, including navigation safety issues, before entering combat service. According to the report of the Australian Ministry of Defense on the investigation of the incident, which was reviewed by AFR Weekend, at 21.43 of the same day, a message was received about "uncontrolled intake of seawater" into the engine compartment through the bow reserve seawater pump. The pump supplies seawater inside the strong hull of the submarine, being an element of the cooling system; at the same time, it was described as a non-critical unit.
The initial report on the incident sounded like a fire, because water vapor triggered an alarm fire alarm, but the crew figured out that there was no smoke, and began implementing measures to prevent the entry and spread of seawater. Despite the fact that the submarine urgently surfaced to the surface position within three minutes after the first alarm, the actions of the crew in the fight for survivability were "complicated" by the failure of the automatic control system for the fight for unsinkability.
The control system for the actuators for opening and closing the entire valve was isolated from the main electric power system in the morning of the same day when technical work was carried out on the latter. According to the source, the valves should have been installed in the closed position, but they should have been checked before diving. Since the system was isolated, it did not work automatically, although it seems that in this case it was activated locally.
The incident described took place at a depth close to the maximum diving depth (the depth gauge had to count another 10 meters) of submarines of this type. Exact data on the maximum diving depth of Collins-type submarines are not disclosed, but it is known that they can dive more than 180 meters. It is also unclear how much water has managed to enter the solid hull, but a submarine of this type can take on board no more than 15 tons of seawater before it begins to sink. The Dechaineux boat of the same type in 2003, being in an underwater position, almost sank as a result of the rupture of the seawater main, having managed to take 12 tons of water; some 20 seconds were not enough before the fatal outcome.
The report says that a one-time unrestricted intake of seawater through a 111 mm diameter backup line would be the "worst possible outcome", and at the depth at which it operated Sheean, the water would rush into the boat at a speed of 4 tons per second.
A source familiar with the described events stated that the pipeline, the rupture of which took place onSheean was of a smaller diameter, but if "the seawater came from a larger diameter pipeline, we would have lost the boat with all the crew, since everything happened at the working depth."
It is alleged that part of the crew of the submarine [after the accident] was written off on shore due to psychological trauma. Another source stated that it was very unusual in this incident that the emergency control system of the outboard fittings was turned off when the submarine was at the working depth of immersion. Retired Australian Navy Commodore and head of the Collins-class submarine procurement program Paul Greenfield said that "such cases are rare," but the high rate of surfacing of the submarine suggests that the matter has taken a serious turn. "The training program for submariners is such that they know exactly what to do if something like this happens," he added.
On another Waller-type Collins submarine last year, two incidents related to the intake of seawater took place at intervals of several weeks, and to top off all the troubles, a large fire occurred on board due to a short circuit in the electric power system.