1975

Standardization Trials On USS Los Angeles (SSN 688)

By Ken Hart '75

BORING !!! That’s the best word to describe the situation, but that was about to change in a dramatic turn of events. The USS Los Angeles (SSN 688) was at sea conducting standardization trials. Being the first of the class, standardization trials were extensive. Add to that some serious concern about snap roll on the newly designed fast-attack submarine class and extra caution was built into every test.

In this rather lengthy part of the trials, we were evaluating the boat’s performance in a turn and specifically looking at any potential for snap roll. These particular runs involved cruising on a straight course, initially at about 30 to 40 percent test depth, and when in steady state condition, initiate a turn using a specified rudder angle. The first runs were made at a relatively slow speed using small rudder angles. Rudder angles were increased to a hard rudder – full throw of the helm. Then the speed was increased by 1 knot and the rudder angles again started small and increased to a hard rudder.

We continued these runs and by now had been at it for about a week. We were simply making turns at a specified speed and rudder angle so the data could be recorded by the civilian test engineers. You can guess why we were bored.

Having progressed through all the speeds at 1 knot intervals and incremental rudder angles, we had reached the final run in the sequence – a full bell and a hard rudder.

That’s a relatively fast speed, although not flank speed, and a significant amount of rudder – a fairly large control surface. So far, in the fast speed runs, the response of the boat would be to roll to port and pitch downward followed by a distinctive hesitation. After the hesitation, the boat would pull out and level off. The depth excursion would typically range from about 50 to 100 feet. In fact, the final run had been completed, typical of the earlier runs without incident or fanfare.

The civilian test engineers were excited and had completed their strip-chart recordings of data, but they requested one more run at full speed and hard rudder. The Commanding Officer agreed – after all, what’s one more run when we had been doing it all week.

Everything started out the same. The boat reached full speed on a steady course and depth at about 30-40 percent of test depth. The rudder was ordered hard over and, as had always occurred before, the boat rolled to port and pitched down followed by a brief, but clearly recognizable hesitation. Then the unexpected – instead of pulling out – the boat rolled and pitched again in a maneuver that seemed completely independent of the initial roll and pitch.

The result was dramatic and nearly instantaneous. The boat rolled further to port and pitched to steep down angle. In a split second, all hell broke loose. The noise in maneuvering was deafening as alarms of every sort rang out.

Liquid levels in all kinds of sumps, tanks, hotwells, and steam generators were well beyond anything they were designed for and many sounded simultaneous high and low level alarms. Nearly every standby pump in the plant started – accompanied by its alarm. The salinity panel was a mass of flashing red lights and audible alarms. Add to that the propulsion lube oil siren. It would be quite a while later before all the alarms could be silenced or even given any more thought. There was a more pressing issue to deal with. The boat reached a roll of 47 degrees to port and had pitched down at a 55 degree angle. (These measurements, and others, were recorded on the test engineer’s strip chart recorders for later verification.) For the sake of comparison, that roll to port made it about equally easy to stand on the port side bulkheads as the deck and the down angle made it considerably easier to stand on forward bulkheads and nearly impossible to stand on the deck. Because of the high rate of initial speed and the considerable down angle, the boat reached a depth rate of 17 feet per second. Sitting in maneuvering, I can recall the depth gage (the gage had digits on wheels like your car’s odometer) with the units and tens whirling by too fast to read and another hundred feet clicking off about every five seconds.

As you might guess, the boat was rapidly approaching test depth. The Throttleman, now standing on his panel because it easier than standing on the deck, turned to the Engineering Officer of the Watch (EOOW) and requested to answer a back emergency. Without waiting for a response, he proceeded to answer a back emergency. The Throttleman slammed shut the ahead throttle and opened the astern throttle. One quick glance at the depth gage and the EOOW affirmed the action.

The Electrical Operator at the time, who was the most seasoned and experienced member of the watch team, said, “just watch total steam flow.” In the midst of complete chaos, the EOOW reflected later that that was “the best piece of operational advice.” The Throttleman brought astern steam flow – as he stood astride the throttle wheels on his panel – to about 30 percent above the prescribed limit for the current reactor plant configuration.

A large tool box came sliding down the starboard passageway past maneuvering and crashed into the reactor compartment bulkhead. It was followed by the Reactor Technician, who also landed on the same bulkhead. The EOOW recalled thinking that at least it didn’t happen the other way around and remarked that it’s strange the things you remember from an event like this.

The noise of the astern steam flow and now the violent shaking of the boat added to the confusion. The boat shuddered in disagreement to the violent reverse thrust, and slowly, the speed began to drop. But, by now, it was too late. The boat had already passed through test depth.

Somewhat belatedly, the control room rung up the order for back emergency, but it was already being answered.

As the reactor plant progressed through the extreme transient, the reactor power level began to climb. The Throttleman, the Reactor Operator, and everyone in maneuvering was focused on the reactor power meter. Reactor power could not be allowed to reach any limits because a scram (an emergency reactor shutdown) at this point could have been disastrous. Carefully watching the reactor plant gages now, the Throttleman readjusted the throttles to bring steam flow back down and ensure no reactor plant power limits or automatic safety trips were exceeded. Even so, the Reactor Operator stood ready to manually drive in the control rods to reduce reactor power quickly, if necessary, to avoid a scram. The action was coordinated so well that no action to drive rods was needed.

Thorough knowledge of the propulsion plant – including automatic trips and limits and the plant response times to a severe transient – and the ability to overcome the tremendous noise and confusion were key factors during this event. It was an amazing display of teamwork and a clear focus on what was most important that brought them, and the entire ship for that matter, through the excursion.

Ever so slowly it seemed, the boat slowed. The roll to port eased off at first and then the boat leveled out. The descent had been stopped. Once the boat was again level, it was noted to be more than 30 percent below test depth. The boat cautiously returned to normal operating depth and then surfaced to do a quick check for signs of damage. The EOOW recalled it was the first, and only time in his long career, that he saw black water in a steam generator sample. One of the propulsion lube oil pumps had seized, apparently from sand blasting grit that had come out of the box girders and entered the pump vents. But even at that extreme angle and under that severe transient, the propulsion train held together. The EOOW noted that he is still impressed by that and “it gave me a lot of confidence in those ships during the rest of my career.” He eventually went on to command a 688-class fast attack submarine.

What had been a week of shear boredom had, in a split second, become an experience no one on board will ever forget. To this day, I credit the Throttleman, the EOOW, and the entire watch team in maneuvering for their prompt action – without waiting for orders – to saving the ship.

 

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