Tag Archives: Navy

Root Cause Analysis - Incident Investigation

8 Injured by Arresting Cable Failure on Aircraft Carrier

By ThinkReliability Staff

An aircraft carrier is a pretty amazing thing. Essentially, it can launch planes from anywhere. But even though aircraft carriers are huge, they aren’t big enough for planes to take off or land in a normal method. The USS Dwight D. Eisenhower (CVN 69) has about 500′ for landing planes. In order for planes to be able to successfully land in that distance, it is equipped with an arresting wire system, which can stop a 54,000 lb. aircraft travelling 150 miles per hour in only two seconds and a 315′ landing area. This system consists of 4 arresting cables, which are made of wire rope coiled around hemp. These ropes are very thick and heavy and cause a significant risk to personnel safety if they are parted or detached.

This is what happened on March 18, 2016 while attempting to land an E-2C Hawkeye. An arresting cable came unhooked from the port side of the ship and struck a group of sailors on deck. At least 8 were injured, several of whom had to be airlifted off the ship for treatment. We will examine the details of this incident within a Cause Map, a visual form of root cause analysis.

The first step in any problem investigation is to define the problem. We capture the what, when, and where within a problem outline. Additionally, we capture the impacts to the goals. The injuries as well as the potential for death or even more serious injuries are impacts to the safety goal. Flight operations were shut down for two days, impacting both the mission and production/ schedule goal. The potential of the loss of or (serious damage to) the plane is an impact to the property goal. (In a testament to the skill of Navy pilots, the plane returned to Naval Station Norfolk without any crew injuries to the flight crew or significant damage to the plane.) The response and investigation are an impact to the labor goal. It’s also useful to capture the frequency of these types of incidents.   The Virginian-Pilot reports that there have been three arresting-gear related deaths and 12 major injuries since 1980.

The next step in the problem-solving process is to determine the cause-and-effect relationships that led to the impacted goals. Beginning with the safety goal, the injuries to the sailors resulted from being struck by an arresting cable. When a workplace injury results, it’s also important to capture the personal protective equipment (PPE) that may have impacted the magnitude of the injuries. In this case, all affected sailors were wearing appropriate PPE, including heavy-duty helmets, eye and ear protection. This is a cause of the injuries because had they NOT been wearing PPE, the injuries would have certainly been much more severe, or resulted in death.

The arresting cable struck the sailors because it came unhooked from the port side of the ship. The causes for the detachment of the cable have not been conclusively determined; however, a material failure results from a force on the material that is greater than the strength of the material. In this case the force on the arresting cable is from the landing plane. In this case, the pilot reported the plane “hit the cable all at once”, which could have provided more force than is typical. The strength of the cable and connection may have been impacted by age or use. However, arresting cables are designed to “catch” and slow planes at full power and are only used for a specific number of landings before being replaced.

Other impacted goals can be added to the Cause Map where appropriate (additional relationships may result). In this case, the potential damage to the plane resulted from the landing failure, which was caused by the detachment of the arresting cable AND because the arresting cable is needed to safely land a plane on an aircraft carrier.

The last step of the Cause Mapping process is to determine solutions to reduce the risk of the incident recurring. More investigation is needed to ensure that the cable and connection were correctly installed and maintained. If it is determined that there were issues with the connection and cable, the processes that lead to the errors will be improved. However, it is determined that the cable and connection met design criteria and the detachment resulted from the plane landing at an unusual angle, there may be no changes as a result of this investigation.

It seems unusual that an investigation that resulted in 8 injuries would result in no action items. However, solutions are based on achieving an appropriate level of risk. The acceptable level of risk in the military is necessarily higher than it is in most civilian workplaces in order to achieve desired missions. Returning to the frequency from the outline, these types of incidents are extremely rare. The US Navy currently has ten operational aircraft carrier (and an eleventh is on the way). These carriers launch thousands of planes each year yet over the last 36 years, there have been only 3 deaths and twelve major injuries associated with landing gear failures, performing a dangerous task in a dangerous environment. Additionally, in this case, PPE was successful in ensuring that all sailors survived and limiting injury to them.

To view the outline and Cause Map of this event, click on “Download PDF” above.

 

Root Cause Analysis - Incident Investigation

Newly Commissioned USS Milwaukee Breaks Down at Sea

By ThinkReliability Staff

On December 11, 2015, just 20 days after commissioning, the USS Milwaukee completely lost propulsion and had to be towed back to port. This obviously brought up major concerns about the reliability of the ship. Said Senator John McCain (R-Arizona), head of Senate’s Armed Services Committee, “Reporting of a complete loss of propulsion on USS Milwaukee (LCS 5) is deeply alarming, particularly given this ship was commissioned just 20 days ago. U.S. Navy ships are built with redundant systems to enable continued operation in the event of an engineering casualty, which makes this incident very concerning. I expect the Navy to conduct a thorough investigation into the root causes of this failure, hold individuals accountable as appropriate, and keep the Senate Armed Services Committee informed.”

While very little data has been released, we can begin an investigation with the information that is known. The first step of a problem investigation is to define the problem. The “what, when and where” are captured in a problem outline, along with the impacts to the organization’s goals. In this case, the mission goal is impacted due to the complete loss of propulsion of the ship. The schedule/production goal is impacted by the time the ship will spend in the shipyard receiving repairs. (The magnitude and cost of the repairs has not yet been determined.) The property/equipment goal is impacted because metal filings were found throughout both the port and starboard engine systems. Lastly, the labor and time goal is impacted by the need for an investigation and repairs.

The next step of a problem investigation is the analysis. We will perform a visual root cause analysis, or Cause Map. The Cause Map begins with an impacted goal and asking “why” questions to diagram the cause-and-effect relationships that led to the incident. In this case the complete loss of propulsion was caused by the loss of use of the port shaft AND the loss of use of the starboard shaft. The ship has two separate propulsion systems, so in order for the ship to completely lose propulsion, the use of both shafts had to be lost. Because both causes were required, they are joined with an “AND”.

We continue the analysis by continuing to ask “why” questions of each branch. The loss of use of the port shaft occurred when it was locked as a precaution because of an alarm (the exact nature of the alarm was not released). Metal filings were found in the lube oil filter by engineers, though the cause is not known. We will end this line of questioning with a “?” for now, but determining how the metal filings got into the propulsion system will be a primary focus of the investigation. The loss of use of the starboard shaft occurred due to lost lube oil pressure in the combining gear. Metal filings were also found in the starboard lube oil filter. Again, it’s not clear how they got there, but it will be important to determine how the lube oil system of a basically brand new ship was able to obtain a level of contamination that necessitated full system shutdown.

While metal filings in the lube oil system is not a class-wide issue, it’s not the first time this class of ship has had problems. The USS Independence and USS Freedom, the first two ships of the class, suffered galvanic corrosion which caused a crack in the Freedom’s hull. The Freedom also suffered issues with its ship service diesel engines, a corroded cable, and a faulty air compressor.

Once all the causes of the breakdown are determined, engineers will have to determine solutions that will allow the ship to return to full capacity. Additionally, because of the number of problems with the class, the investigation will need to take a good look at the class design and manufacturing practices to see if there are issues that could impact the rest of the class going forward.

To view a one-page downloadable PDF with the beginning investigation, including the problem outline, analysis, and timeline, click “Download PDF” above.

Root Cause Analysis - Incident Investigation

Early Problems with Mark 14 Torpedoes

By Kim Smiley

The problems with Mark 14 torpedoes at the start of World War II are a classic example that illustrates the important of robust testing.  The Mark 14 design included brand new, carefully guarded technology and was developed during a time of economic austerity following the Great Depression.  The desire to minimize costs and to protect the new exploder design led to such a limited test program that not a single live-fire test with a production model was done prior to deploying the Mark 14.

The Mark 14 torpedo design was a step change in torpedo technology. The new Mark VI exploder was a magnetic exploder designed to detonate under a ship where there was little to no armor and where the damage would be greatest.  The new exploder was tested using specially instrumented test torpedoes, but never a standard torpedo. Not particularly shocking given the lack of testing, the torpedoes routinely failed to function as designed once deployed.

The Mark 14 torpedoes tended to run too deep and often failed to detonate near the target. One of the problems was that the live torpedoes were heavier than the test torpedoes so they behaved differently. There were also issues with the torpedo’s depth sensor.  The pressure tap for the sensor was in the rear cone section where the measured pressure was substantially less than the hydrostatic pressure when the torpedo was traveling through the water.  This meant that the depth sensor read too shallow and resulted in the torpedo running at deeper depths than its set point.  Eventually the design of the torpedo was changed to move the depth sensor tap to the mid-body of the torpedo where the readings were more accurate.

The Mark 14 design also had issues with premature explosions.  The magnetic exploder was intended to explode near a ship without actually contacting it.  It used small changes in the magnetic field to identify the location of a target. The magnetic exploder had been designed and tested at higher latitudes and it wasn’t as accurate closer to the equator where the earth’s magnetic field is slightly different.

In desperation, many crews disabled the magnetic exploder on Mark 14 torpedoes even before official orders to do so came in July 1943.  Use of the traditional contact exploder revealed yet another design flaw in the Mark 14 torpedoes.  A significant number of torpedoes failed to explode even during a direct hit on a target.  The conventional contact exploder that was initially used on the Mark 14 torpedo had been designed for earlier, slower torpedoes.  The firing pin sometimes missed the exploder cap in the faster Mark 14 design.

The early technical issues of the Mark 14 torpedoes were eventually fixed and the torpedo went on to play a major role in World War II.  Mark 14 torpedoes were used by the US Navy for nearly 40 years despite the early issues.  But there is no doubt that it would have been far more effective and less painful to identify the technical issues during testing rather than in the field during war time.  There are times when thorough testing may seem too expensive and time consuming, but having to fix a problem later is generally much more difficult.  No one wants to waste effort on unnecessary tests, but a reasonable test program that verifies performance under realistic conditions is almost always worth the investment.

To view a high level Cause Map of the early issues of the Mark 14 torpedoes, click “Download PDF”.

You can also learn more about the torpedoes by clicking here and here.

Root Cause Analysis - Incident Investigation

10,000 Pound Buoy Falls on Workers

By Kim Smiley

On December 10, 2014, a buoy that weighs close to 10,000 pounds fell onto workers at an inactive ship maintenance facility in Pearl Harbor. Two workers were killed and two others sustained injuries. While an object this large is an extreme example of the dangers of dropped objects, worker injuries and deaths from falling objects of all sizes is a significant safety concern. A US census report of fatal occupation injuries states that 245 workers were killed after being struck by falling objects in 2013 alone.

The case of the dropped buoy can be built into a Cause Map, a visual root cause analysis, to better understand what happened. Understanding the details of an accident is necessary to ensure that a wide range of solutions is considered and that any solutions implemented will be effective at preventing future incidents.

The investigation into the falling buoy is still underway so some information is not yet available, but it can easily be incorporated into the Cause Map once it is known. Any causes that need more information or evidence can be noted with a question mark to show that there is still an open question.

Exactly what caused the buoy to drop hasn’t been released yet, but it is known that the safety lines attached to the buoy failed. Both of these issues need to be investigated to ensure that solutions can be implemented to prevent further tragedies.

Additionally, there are open questions about why people were working under the path of the lift. The workers were wearing hard hats, but this is obviously inadequate protection against a 10,000 buoy. The contractors were working to strengthen mooring lines at the time of the accident, but no one should be where they could be crushed if such a large object was dropped, as it was in this case. As stated by Jeff Romeo, the Occupational Safety and Health Administration (OSHA) Honolulu area director, “We’re still looking at the facts to try to determine the exact locations of where these employees were located. If in fact, they were working directly underneath the load, then that would be an alarming situation.”

The OSHA investigation is currently underway and is expected to take four to six months. Additionally, the Navy is launching a Safety Investigation Board to review the accident with findings expected to be released by February. Once the investigation is complete, work processes will need to be reviewed to see what changes need to be made to prevent any future injuries from falling objects.

To view an initial Cause Map of this incident, click on “Download PDF” above.

Root Cause Analysis - Incident Investigation

Extensive Fire on USS George Washington Placed Crew at Risk

By ThinkReliability Staff

When fire broke out in 2008 on aircraft carrier USS George Washington in an unmanned space that was being used to improperly store flammable materials, it took more than 8 hours to find the source of, and extinguish, the fire. In the Navy’s investigation report, Admiral Robert F. Willard, commander of the US Pacific Fleet, stated “It is apparent from this extensive study that there were numerous processes and procedures related to fire prevention and readiness and training that were not properly functioning. The extent of damage could have been reduced had numerous longstanding firefighting and firefighting management deficiencies been corrected.”

The processes and procedures that were implicated in the investigation of the fire can be examined in a Cause Map, or a visual root cause analysis. This process begins by identifying the goals impacted. In this case, the primary goal impacted was the safety goal. Thirty-seven sailors were injured; one was seriously burned. There were no fatalities. In addition, the damage to the ship was estimated at $70 million and left the ship unusable for 3 months.

Beginning with the impacted safety goal, asking ‘Why’ questions allows us to develop the cause-and-effect relationships that led to those impacted goals. In this case, the injuries to sailors resulted from the extensive fire aboard ship. In addition, some of the affected sailors (including the sailor who was seriously burned) did not have adequate protective clothing. Specifically, liners worn underneath firefighting gear were not available in one repair locker because they were being laundered. Both the fire and the inadequate protective gear were causally related to the injuries so they are both included on the Cause Map and joined with ‘and’.

Asking additional ‘why’ questions adds more detail to the Cause Map. When investigating a fire, it’s important to include the factors that resulted in the initiation of the fire (heat, fuel and oxygen) as well as those that allowed the fire to spread. In this case, the ignition (or heat) source was believed to be a cigarette butt. On-scene evidence showed that smoking was occurring in the area, against regulation. The ship was found to have inadequate training regarding the smoking policy and inadequate control over the locations where smoking was occurring, because regular zone inspections were not being held.

The initial fuel source was determined to be refrigerant oil and other flammable materials improperly stored in an unmanned space where the fire began. The oil was not turned in as required by procedure over a concern about the difficulty of retrieving it. Because the oil was never entered into the inventory control system, the storage discrepancy was not noted. The unmanned space in which it was stored was not inspected. Unmanned spaces were not included in zone inspections and the area had not been designed as a tank or void to be identified in the void and tank inspection.

Once a fire breaks out, the speed in which the source is found and extinguished has the most impact on the safety of personnel. In this case, the source of the fire was not found for eight hours.   Not only did the fire begin in an unmanned area, the drawings showing the layout of the ship were inaccurate, because the ship was in the midst of alterations.

Developing the causes the resulted in the impacted goals allows for identification of all the processes and procedures that need to be re-examined to reduce risk of recurrence. In this case, the report identified multiple processes and procedures that were re-evaluated in the wake of the disaster, including those for hazardous material storage, training, inspection and firefighting.

To learn more, click here to read the Navy investigation report. To view a one-page overview of the Outline and Cause Map, please click on “Download PDF” above.

Root Cause Analysis - Incident Investigation

Navy Jet Crashes into Apartment Building

By Kim Smiley

On April 6, 2012, a Navy F-18 jet crashed into an apartment building in Virginia Beach, Virginia. Significant damage was done to the apartment building and the jet was destroyed, but amazingly no one was seriously injured or killed.

This incident can be analyzed by building a Cause Map, an intuitive, visual format for performing a root cause analysis.  The first step when building a Cause Map is to determine how the incident affected the organizational goals.  The impacts to the organizational goals are recorded in the Outline which also documents the background information of the incident.  In this example, the safety goal was obviously impacted since there was potential for serious injuries.  The property goal was also impacted because the jet was destroyed and the apartment building suffered extensive damage.

Once the Outline is complete, “why” questions are asked to determine what factors contributed to the incident.  In this example, there was potential for injuries because a jet hit an apartment building.  This occurred because the jet was flying near the residential area and the jet was unable to complete its attempted take off.  The pilots could have been injured had they not been able to safety eject before the crash and there was potential for people on the ground to be injured since the jet crashed into a residential area. The jet crashed because it experienced a dual engine failure.  The investigation into this crash determined that that both engines failed for two separate, unrelated reasons.

The right engine failed because of a catastrophic failure of the engine compressor when it ingested flammable liquid that was ignited.  The left engine afterburner failed to light. Investigators believe that an electrical component failed, but the damage to the left engine was too severe for a conclusive determination of what exactly occurred.   According to the Navy, this is the first unrelated dual engine failure of a F-18.

The Navy plans to update procedures to incorporate the possibilities of this type of incident.

To view a high level Cause Map of this issue, click on “Download PDF” above.

Root Cause Analysis - Incident Investigation

$3 Bolt Causes $2.2 million in Damages to US Submarine

By ThinkReliability Staff

A $3 bolt was left in the main reduction gear of the USS Georgia after a routine inspection.  The extensive damage caused by the bolt resulted in 3 months in the shipyard for the submarine, causing it to miss deployment.  The propulsion shaft was left to operate for two days after sounds indicated that there was something wrong.  This may have increased the damage to the main reduction gear – damage which cost $2.2 million.

How did the bolt end up in the main reduction gear? Why was the propulsion shaft operated for 2 days after damage was suspected?

We can look at the causes that led to this incident in a Cause Map, a visual root cause analysis that clearly outlines cause-and-effect relationships that result in impacts to an organization’s goal.  The first step to building a Cause Map is to determine how the issue impacts the organization’s overall goals.  Here we can consider the US Navy as the organization.  The customer service goal (with the rest of the country as the “customers”) was impacted because the submarine was unavailable for deployment.  The production/schedule goal was impacted because the submarine was in the shipyard for  three months.  The damage to the main reduction gear is an impact to the property goal, and the repairs are an impact to the labor/time goal.  The total cost resulting from this issue was estimated to be $2.2 million.  Once the impacts to the goals have been determined, we can ask why questions to put together the cause-and-effect relationships that led to these impacts.

The bolt was left behind after a routine, annual inspection.  Because of the great potential for damage when foreign objects remain within equipment, detailed procedures are used for these inspections and include a log of all equipment brought into the area and a protective tent to keep objects from falling in.  Details of what went wrong that resulted in the bolt falling into the main reduction gear were not released, but the inspection was reported to have “inadequate prep and oversight” which likely contributed to the issue.

After the propulsion shaft was turned back on, noise indicated that there was a problem.  However, the shaft was operated for two days in a failed attempt at troubleshooting.  It’s likely that this increased the damage to the main reduction gear.  It is unknown what procedures were – or should have been – in place for troubleshooting, but the actions taken as a result of this incident suggest that proper procedures were not followed once the damage was suspected.

In this case, members of the crew who were found to not have performed their job – possibly by not following proper procedure – were punished in varying ways.  It is likely that the investigation went into great detail about whether procedures were adequate, what steps were not followed, and why, and the results also used to improve procedures for the next inspection.

To view the Outline and Cause Map, please click “Download PDF” above.