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AUGER Lifeboat No. 6
This incident occurred on FPS AUGER, a Tension Leg Platform (TLP) at Garden Banks Block 426 in the Gulf of Mexico, on June 30, 2019 and resulted in the untimely deaths of two personnel and injury to a third person. The incident occurred when Lifeboat 6 released from the fall cables during recovery after a routine launch and perceived U.S. Coast Guard requirements.
Our condolences go to the families of the two men that lost their lives during this incident.
The USCG formal investigation has been completed, endorsed by the District Commander, Coast Guard District Eight and was released by USCG Headquarters on December 16, 2021, but Commandant actions are still pending. A bookmarked copy of the Report of Investigation (ROI) is available here.
The Coast Guard publicized the release of the ROI via Maritime Commons blog post and requested "any feedback regarding the recommendations in the report" to be provided no later than February 1, 2022. See the Recommendations tab above for the safety and administrative recommendation made in the report. See also the District Commander's endorsement at the beginning of the report for recommended actions in relation to the recommendations.
Use the tabs on this page (above) to view the following information related to Safety Alert 03-20 that was released while the investigation was in process to promulgate pertinent information and safety concerns, as well as additional information available since the release of the Report of Investigation:
1) Introduction (this tab);
2) Executive Summary (as presented in the Report of Investigation;
3) Graphical representation of the sequence of the lifeboat retrieval and accident;
4) Event and maintenance timelines related to the accident;
5) U.S. Coast Guard Safety Alert 03-20 and the related recommendations;
6) Presentation and Videos detailing observations related to Safety Alert 03-20 and the Report of Investigation;
7) Graphical depictions and accompanying explanation detailing observations related to control cable findings promulgated via Safety Alert 03-20 and detailed in the Report of Investigation; and
8) Safety and administrative recommendations from the Report of Investigation (with recommendation references hyperlinked or included for ready reference).
9) USCG Testing of Schat-Harding LHR 3.5M2 Release Mechanism, Enclosure (2) to the Report of Investigation.
Executive Summary (from the Report of Investigation)
For more details see the full Report of Investigation.
On Sunday, June 30, 2019, at approximately 10:00 a.m., the aft hook on Shell AUGER’s1 Lifeboat No. 6 inadvertently opened as the lifeboat was being winched into the davit following a quarterly launch and retrieval drill. The lifeboat, still hanging from the forward hook, swung in a pendulum motion away from the facility. A few seconds later, the forward hook separated from the lifeboat and opened, and the lifeboat fell approximately 80 feet, landing inverted in the water. The two persons still onboard the lifeboat when it fell were fatally injured. One person, who was exiting the lifeboat when it released, fell into the water and was injured. The lifeboat was a total loss.
Lifeboat No. 6 was a 33-man 24-foot enclosed, dual-fall lifeboat manufactured by Watercraft America2 in 1984 and refurbished in 2012. Lifeboat No. 6 was outfitted with a Schat-Harding3 SeaCure LHR3.5M2 release mechanism.
Image 1 (left): AUGER Lifeboat No. 6 prior to the casualty (Photo credit: Palfinger Marine; taken May 2019).
Image 2 (right): AUGER Lifeboat No. 6 aft hook and lifting ring (Credit: Palfinger Marine; taken June 2014).
The release mechanism was comprised of two hooks, a hook release unit (located inside the lifeboat adjacent to the helm), a hydrostat unit, and three control (push-pull) cables (see Image 3). One control cable connected the hook release unit to the aft hook, the second control cable connected the release unit to the forward hook, and the third control cable connected the release unit to the hydrostat unit
Image 3: Graphic of Watercraft EL-24 outfitted with Schat-Harding LHR3.5M2 release mechanism (Credit: Shell Offshore).
The hook control cables are heavy duty low friction cables with threaded end fittings and four inches of travel at the end rods (see Image 4). Each cable has an outer conduit and an inner member. The conduit is comprised of three layers: a green plastic cover; steel reinforcement; and a white polyethylene liner. The conduit provides a protected path for the steel inner member. With the ends of the conduit fixed at each terminal point (provided it is not fully compromised), the conduit also controls the travel length of the inner member. The inner member transmits linear motion from the hook release unit to the locking shafts located within the hooks via the end rods.
Image 4: Control cable components (Credit: Cablecraft, modified by the USCG).
Generally, the system works in the following manner: When closing or resetting a hook, an operator positioned at the release unit pulls up on the safety lock and pushes forward on the control handle, locking it into place. Consequently, the end rod on the hook end extends. This extension causes the hook’s locking shaft to move to the closed or locked position. When opening the hook, the opposite actions and forces apply.
During the course of the investigation, the Coast Guard, Shell, and Palfinger Marine (the original equipment manufacturer or “OEM”) identified a previously unknown vulnerability in the system: if all three layers of the conduit of a hook control cable separate or break, during a reset the locking shaft may not return to the fully closed position. Rather, the locking shaft may come to rest at an “almost open” position (see Image 5). In such a position, the hooks can support the weight of the boat and its occupants during retrieval. However, an additional load can cause the locking shaft to rotate to the open position, releasing the hook.
Image 5: Hook cutaway views of LHR3.5M2 hook in closed, open and almost open positions. Locking shaft depicted in yellow. (Credit: USCG (hook component data provided by DNV-GL)).
On the morning of June 30, 2019, Lifeboat No. 6 was launched and initially retrieved without incident. However, unknown to the launch crew and boat crew, but documented in an OEM service report completed on or about June 6, 2019, a section of the aft hook control cable conduit was corroded and damaged, although not fully separated.
Image 6: Photograph of damage to Lifeboat No. 6 aft control cable dated (Credit: Palfinger Marine; taken June 6, 2019).
On the day of the casualty, the crew cycled the hooks (open to closed position) two times while in the water. If a cable conduit is already damaged, the act of cycling exposes the conduit layers to additional stresses, including compression and tension (stretching). It is probable4 that during the second cycling event, the conduit, already weakened and damaged, separated during the closing action (see Image 7). As a result, when the system was reset, the locking shaft on the aft hook did not return to the fully closed position, but rather, came to rest at an “almost open” position. In this position, the hook could support the weight of the lifeboat and its occupants as the lifeboat was hoisted from the water to the davit. However, at the davit, additional forces applied to the hook and the lifeboat, as a result of the winch pulling the boat against the bumpers, caused the locking shaft to rotate from the “almost open” to the open position. Under load, the aft hook was free to open and release from the lift ring (a ring attached to the end of the fall cable (wire rope); often called the “D” ring). The forward hook, not designed to bear the entire load of the lifeboat or operate outside of specified angles, was unable to sustain the weight of the lifeboat, separated from the hull and eventually opened.
Image 7: Photograph of aft control cable after casualty. Photograph documents separation of three layers
of the conduit: the green plastic cover; a steel wire; and a white polyethylene liner. Credit: DNV-GL.
The investigation team determined that the initiating event for this casualty occurred when the locking shaft on the aft hook moved from the “almost open” to the open position, which in turn caused the aft hook to open under load and release from the lift ring. Subsequent to the initiating event, the forward hook, bearing the entire load of the lifeboat, separated from the hull and opened. The lifeboat fell approximately 80 feet, with two persons still onboard, and landed inverted in the water.
The primary causal factor that directly contributed to the casualty was the complete separation of the aft hook control cable conduit surrounding the inner member.
Other causal factors include:
1) the operator and/or OEM’s failure to replace the aft hook control cable after it was identified as damaged;
2) the operator and/or OEM’s act of allowing Lifeboat No. 6 to stay in service after the aft hook control cable was identified as damaged;
3) the operator’s, OEM’s, and regulators’ lack of knowledge that a compromised hook control cable could allow a locking shaft to stop at a position short of fully closed after reset;
4) the operators and OEM’s lack of effective communications related to roles and responsibilities; and
5) operator’s and OEM’s focus on function-based inspections vice condition-based inspections, as related to the control cables.
Contributing factors include the lack of systems, policies or regulations in existence to ensure that control cables are properly monitored and changed out in accordance with the OEM’s recommendations and/or best industry practices.
1 Shell AUGER is a floating OCS facility (FOF) of the tension leg design located in the Gulf of Mexico. It is operated by Shell Offshore.
2 The Watercraft America brand is now owned by Palfinger Marine.
3 The Schat-Harding brand is also now owned by Palfinger Marine.
4 In this investigation, Coast Guard investigators use the terms “probable,” and “possible” to communicate confidence in certain conclusions. When investigators use the term “probable” it means that after assessing all evidence, they believe the likelihood of the conclusion being true is more likely than not (51% or more). When investigators use the term “possible,” it means that after assessing all the evidence, they believe that the conclusion is feasible but cannot be declared probable.
Retrieval and Hook Opening Sequence
The following graphics (from page 9 of the Report of Investigation) summarize the sequence around the lifeboat accident and provide a graphical representation of the retrieval and aft hook opening events described in sections 4.1.16 through 4.1.31 of the report.
Timelines Related to the Investigation
The event timeline below details the sequence of events from the meeting for the training evolution through the casualty and recovery of personnel and securing of the lifeboat by an OSV that responded to the accident. Click here for a pdf of the event timeline.
The maintenance timeline below lists the refurbishment and release gear replacement (2012) and service provider maintenance events documented for Lifeboat 6 up to the day of the casualty. See the Report of Investigation for more details about the boat prior to refurbishment. Click here for a pdf of the maintenance timeline.
Safety Alert Overview
Safety Alert 03-20 was published on February 5, 2020, after observations and testing revealed that a damaged/compromised hook control cable could fail in a manner that would allow a hook to open, essentially defeating the safety features that are incorporated into the design of a lifeboat release gear system. Prior failures with these types of control cables were assumed to be 1) a seized cable or 2) a severed cable. Shell Offshore, Inc. and USCG investigation team members observed that another failure mode was possible, as summarized in the safety alert:
"During post-incident laboratory testing the Coast Guard observed that if a control cable, similar to that shown in the image above, is damaged all the way through the outer layers, leaving the traveling inner member exposed, forces applied directly on the separated outer layers can cause the traveling inner member to pull on each of its ends. As the separated outer layers pull apart, the cable’s end rod at the hook can move, which in turn can rotate the locking shaft inside the hook. If the locking shaft rotates enough, the hook can release, even without an operator touching the release handle or overriding the interlocks. The Coast Guard has no indication that a damaged control cable alone can cause a hook to release or open on-load. However, the Coast Guard believes that damaged control cables pose a significant safety risk and should be replaced before attempting to launch a boat that incorporates control cables into the on-load release capability of a hook release system."
Based on the observations related to release mechanism control cables, the USCG strongly recommends the following in Safety Alert 03-20:
The safety alert also noted that:
Presentation and Videos
Safety Alert 03-20 and the observations from CG-testing were presented during the September 30, 2020 National Offshore Safety Advisory Committee (NOSAC) meeting (video teleconference). The presentation and individual videos (mp4 format) are available below. Note that the presentation is a large file size (30mb), as the videos are embedded within the presentation, but can also be downloaded separately. Microsoft PowerPoint® or a compatible viewer will be needed to view the presentation.
Discussion of Observations and Findings related to the Control Cables
Please note that testing was conducted on Schat-Harding LHR-series release gear. As such, the descriptions of components and operation relate to that make and series of release gear. Other manufacturer's release gear designs, functions and component terminology could vary, but the control cable is the area of focus in these findings and could pose a similar vulnerability in other designs.
Generally, the system works in the following manner:
When closing or resetting a hook, an operator positioned at the release unit pulls up on the safety lock and pushes forward on the control handle, locking it into place. Consequently, the end rod on the hook extends. This extension causes the hook's locking shaft to rotate to the closed or locked position. When opening the hook, the opposite actions and forces apply.
A previously unknown vulnerability in the system was identified during the course of the investigation that was referenced in Safety Alert 03-20 and discussed in greater detail in the Report of Investigation: if all three layers of the conduit of a hook cable separate or break during a reset, the locking shaft may not return to the fully-closed position. Rather, the locking shaft may come to rest at an "almost-open" position (see the various positions on the following graphics). In such a position, the hooks can support the weight of the boat and its occupants during retrieval. However, testing has revealed that an additional load can cause the locking shaft to rotate to the open position, releasing the hook.
Please see the presentations and videos tab above to review videos that show the control cable issues that are discussed and portrayed below.
Release Mechanism Arrangement
A typical dual-fall/hook release mechanism is comprised of two hooks, a hook release unit (located inside the lifeboat adjacent to the helm), a hydrostat unit, and three control (push-pull) cables. One control cable connects the hook release unit to the aft hook, the second control cable connects the release unit to the forward hook, and the third control cable connects the release unit to the hydrostat unit.
This graphic shows the positions of the control cable and the hook when the release unit handle is in the closed, or reset, position.
This graphic depicts the actions of the control cable and the hook when the release unit handle is moved into the open, or released, position.
Closed/Reset Position with
compromised cover and steel layers
With the conduit cover and steel reinforcement compromised but the liner still intact, the system continues to function. In this condition, the liner is subjected to compression and tension forces that correspond to the open and close motions of the release handle that is transmitted through the control cable.
Closed/Reset Position with
separated conduit (broken liner)
The conduit tends to separate after the liner breaks. This separation causes the conduit to lengthen and results in the inner member moving the locking shaft arm toward the open position. During testing, it was observed that the:
Effects of Increasing Load with
a separated conduit
Testing confirmed that the locking shaft can be in a partially-closed position that will support the weight of the boat and occupants, but can rotate to the open position with an increasing load/additional weight (such as the additional load that can be imparted to the hooks as a boat is pulled against the davit bumpers).
Close/Reset Position with
separated conduit after additional cycling
Additional cycling (opening and closing) of the release handle during testing showed that the cable conduit would separate before any rotation was transferred to the locking shaft. This condition leaves the hook in an open position that will not support any weight.
Recommendations from the USCG Report of Investigation (ROI)
The following recommendations were made in the ROI and were subject to feedback after release. The review of the recommendations was also presented to the National Offshore Safety Advisory Committee as a task statement on April 26, 2022 (with a 1-year completion period). Commandant action on the recommendations is pending.
See also the District Commander's endorsement at the beginning of the report (and included below in italicized font for ready reference) for recommended actions in relation to the recommendations in the report.
Please note that hyperlinks are provided throughout this page to U.S. Coast Guard offices, regulations and documents that are referenced in the recommendations and endorsements to aid in review and/or research.
Safety Recommendation 1: Recommend the Coast Guard Commercial Regulations and Standards Directorate (CG-5PS) develop a working group to look at consolidating lifesaving gear regulations under one subchapter.
District Commander's Endorsement: I partially concur with this recommendation. 46 CFR Subchapter W does not currently apply to OCS facilities, but had it been applicable, the prescriptive lifesaving gear regulations housed therein may have addressed the latent unsafe condition with respect to the degraded control cable before it resulted in this fatal marine casualty. The proposed working group should identify a strategy to update the lifesaving equipment regulations applicable to OCS facilities. Possible options include (1) adding more prescriptive maintenance requirements to 33 CFR Subchapter N, using those in 46 CFR Subchapter I-A and in 46 CFR Subchapter W as a model, or (2) amending 33 CFR Subchapter N to make the requirements of 46 CFR Subchapter I-A and/or 46 CFR Subchapter W applicable to OCS facilities.
Safety Recommendation 2: Recommend the [Lifesaving and Fire Safety Division] CG-ENG-4 review procedures related to release mechanism type approval to ensure all components, to include control cables, are thoroughly addressed in type approval submittals and testing.
District Commander's Endorsement: I concur with this recommendation. This investigation revealed that failure of a control cable could result in the uncontrolled release of a lifeboat. Commandant (CG-ENG- 4) should review 46 CFR 160.133 and associated regulations and procedures, and consider any updates that may be necessary regarding control cables or other components of release mechanisms.
Safety Recommendation 3: Recommend that the Office of Commercial Vessel Compliance (CG-CVC) develop regulations requiring thorough annual inspections (including inspection of entire length of cable) and time-based and/or condition-based replacement. Most appropriately, these regulations would apply to all lifeboats. In the absence of rulemaking, the CG-CVC should issue strong recommendations to OEMs and operators that they voluntarily apply the same.
District Commander's Endorsement: I concur with the intent of this recommendation. I recommend that Commandant [Office of Operating and Environmental Standards] (CG-OES) develop standards, applicable to all U.S. vessels and OCS facilities, requiring the annual inspection of the control cables and time-based and/or condition-based replacement. I note that Commandant (CG-INV) issued Safety Alert 03-20 on February 5, 2020, which strongly recommends that lifeboat owners, manufacturers, operators, and service providers implement an inspection regime that allows for cable damage to be identified, and, as necessary, for cables to be replaced in a timely manner.
Safety Recommendation 4: Recommend [that the Lifesaving and Fire Safety Division] CG-ENG-4 develop regulations that require that all approved components are approved as a system or are designed to work together (e.g. specific winches allowed to be used with a particular davit, release mechanisms allowed to be used in a specific boat, etc.).
District Commander's Endorsement: I concur with this recommendation. All approvals should ensure that release mechanisms approved under 46 CFR 160.133 properly interface with the launching appliances approved under 46 CFR 160.115 and 160.132. The replacement of any component should require notification and further review of the system by the OCMI and/or Commandant [Office of Design and Engineering Standards] (CG-ENG).
Safety Recommendation 5: Recommend the [Coast Guard Commercial Regulations and Standards Directorate] CG-5PS develop regulations that require the maintenance requirements in 46 C.F.R. § 109 (or similarly structured requirements) to be applicable to FOFs. NOSAC’s report, due September 9, 2020, can help inform this process.
District Commander's Endorsement: I concur with the intent of this recommendation. 46 CFR Part 109 is not applicable to OCS facilities but the more prescriptive maintenance requirements therein may have addressed the latent unsafe condition with respect to the degraded control cable. As discussed above under Recommendation 1, a working group should identify a strategy to update lifesaving gear regulations applicable to OCS facilities.
Safety Recommendation 6: Recommend [the Coast Guard Commercial Regulations and Standards Directorate] CG-5PS reevaluate the use of lifeboats as rescue boats. During witness testimony it was noted the freeboard was too high to lift an unconscious person into the boat and the doors were not wide enough to allow two persons to lift an unconscious person through.
District Commander's Endorsement: I concur with the intent of this recommendation. In accordance with 46 CFR 108.510(b), OCS facilities constructed before October 1, 1996, such as AUGER, are not currently required to have rescue boats. The working group discussed in Recommendation 1 and 5 should determine if all FOFs, regardless of build date, should be equipped with an approved rescue boat.
Safety Recommendation 7: Recommend the [Coast Guard Commercial Regulations and Standards Directorate] CG-5PS develop regulations ensuring oversight of lifeboat, winch and davit repairs and modifications all vessels and facilities not subject to 46 C.F.R. Subchapter W, Lifesaving Appliances and Arrangements.
District Commander's Endorsement: I concur with the intent of this recommendation. I recommend that Commandant (CG-5PS) consider the development of regulations requiring notification to the cognizant OCMI when an operator intends to conduct repairs or modifications to primary lifesaving equipment on an OCS Facility.
Safety Recommendation 8: Recommend [the Coast Guard Commercial Regulations and Standards Directorate] CG-5PS develop policy that ensures OCMIs and their representatives properly evaluate type approved equipment in regards to repairs and modifications (especially as they relate to serviceability and maintaining equipment in an as-approved condition), and that CG-ENG-4 remains engaged appropriately in these activities as necessary after initial approval.
District Commander's Endorsement: I concur with the intent of this recommendation. I recommend that Coast Guard Force Readiness Command (FORCECOM) also evaluate Marine Inspector training on this topic, taking into account the information in this report, and if necessary develop training to ensure USCG Marine Inspectors are properly equipped to complete oversight activities.
Safety Recommendation 9: Recommend the D8 OCMI (ocs) update current policy on drill and maintenance requirements for regulated facilities operating on the OCS to best reflect current regulatory requirements.
District Commander's Endorsement: I concur with the intent of this recommendation. The D8 OCS OCMI published Policy Letter 01-2020, which clarified emergency evacuation drill requirements but did not address the maintenance requirements in 33 CFR 146.15. As noted in my endorsement of Safety Recommendations 1 and 5, I recommend that Commandant (CG-5PS) consider potential updates to lifesaving gear regulations applicable to OCS facilities, particularly with regard to more prescriptive maintenance requirements. In the meantime, I have directed the D8 OCS OCMI to review current guidance and consider the most appropriate means to ensure compliance with the intent of current regulations.
Safety Recommendation 10: Recommend the [Coast Guard Commercial Regulations and Standards Directorate] CG-5PS, with input and involvement by the OCS NCOE, develop a workgroup to research/revise regulations and policies and engage with other administrations for input into their management of the following for the offshore oil & gas operations:
District Commander's Endorsement: I concur with this recommendation. The group should include the D8 OCS OCMI. In addition, I recommend this work group reach out to the Bureau of Safety and Environmental Enforcement (BSEE) to evaluate if the above activities should also be incorporated in the Safety and Environmental Management System under 30 CFR 250.1915 and 250.1916.
Administrative Recommendation 1: Recommend the D8 OCMI (ocs), after being routed and reviewed by [the Office of Investigations & Casualty Analysis] CG-INV, communicate Findings of Concern to the OEM, recommending:
District Commander's Endorsement: I concur with the intent of this recommendation. The investigation revealed the critical importance of the release cable and the necessity to improve the level of oversight and associated training by OEMs. Additionally, this investigation discovered that lifeboat crew members may be confused by the color scheme utilized to demonstrate with "open/closed" on lifeboat hooks, and that this confusion could lead to additional marine casualties. I recommend that Commandant (CG-ENG) notify OEMs of these Findings of Concern and associated recommendations.
Administrative Recommendation 2: Recommend the D8 OCMI (ocs), after being routed and reviewed by [the Office of Investigations & Casualty Analysis] CG-INV, communicate Findings of Concern to the Operator, recommending:
District Commander's Endorsement: I concur with this recommendation. This investigation revealed that it is paramount that emergency gear be kept in good condition at all times, which may have been achieved by promptly acting upon all OEM recommendations. This investigation concluded that the OEM had made a recommendation to the Operator that the control cable in Lifeboat NO.6 be replaced, and that such replacement was not accomplished.
District Action: The D8 OCS OCMI will draft an appropriate Finding of Concern to communicate recommendations to the Operator, including incorporation of OEM recommendations into their maintenance system, as well as clarification of roles and expectations between the OEM and the Operator.
Administrative Recommendation 3: Recommend [the Office of Investigations & Casualty Analysis] CG-INV issue a finding of concern recommending that operators ensure that persons planning, conducting and overseeing routine lifeboat maintenance have read and are familiar with the applicable lifeboat operations and maintenance manual.
District Commander's Endorsement: I concur with this recommendation. This investigation highlighted the importance that those crew members charged with regular maintenance and inspection duties be thoroughly familiar with the components of lifeboats with which they interact. With the assistance of the D8 OCS OCMI and the OCS NCOE, CG-INV should communicate this importance to vessel and OCS facility operators via a Finding of Concern.
Administrative Recommendation 4: Recommend [the Office of Investigations & Casualty Analysis] CG-INV issue a finding of concern recommending operators, with the assistance of the OEM, train crews to ensure they understand how the hook indicators, when installed, function and convey information regarding the condition of the hook. Operators and OEMs should also communicate to crews the need to verify the status of the hook indicator at least two times during the retrieval process: at the water after the falls are connected and immediately after the lifeboat clears the water.
District Commander's Endorsement: I concur with this recommendation. Commandant (CG-INV) should communicate the importance of ensuring those associated with lifeboat duties on vessels and OCS facilities understand the functions of the lifeboat hook and color position indicators.
Administrative Recommendation 5: [The Office of Investigations & Casualty Analysis] CG-INV and [the Office of Commercial Vessel Compliance] CG-CVC should widely publicize this investigation’s findings related to the hazards posed by compromised control cables to all marine sectors maintaining and operating lifeboats, to include Coast Guard inspectors.
District Commander's Endorsement: I concur with this recommendation and note that some of the findings have already been disseminated via Safety Alert 03-20. Additionally, the information in this Report of Investigation should be utilized when training CG Marine Inspectors.
Administrative Recommendation 6: [The Office of Commercial Vessel Compliance] CG-CVC and [the Lifesaving and Fire Safety Division] CG-ENG-4 should provide additional guidance to inspectors and the regulated community regarding certificates of approval regulated under 46 CFR 2.75-5. This guidance should include clarity on who they are issued to, how they relate to the sale and production of equipment, the significance of their validity period, and what constitutes replacement in kind of equipment no longer holding a valid approval certificate.
District Commander's Endorsement: I concur with this recommendation. In the course of this investigation it was discovered that Lifeboat NO.6 had been sold multiple times. As indicated in this Report of Investigation, especially sections 22.214.171.124.1 and 5.10, there is lack of clarity regarding how to correctly apply certain provisions of 46 CFR 2.75 and 46 CFR 160.135-23. Additional guidance for Marine Inspectors would be useful.
Referenced ROI sections (for ready reference):
Administrative Recommendation 7: Recommend the [Office of Investigations & Casualty Analysis] CG-INV issue a finding of concern that highlights the benefits of using FPDs during lifeboat launches and retrieval drills.
District Commander's Endorsement: I concur with this recommendation. Commandant (CG-CVC) and CG-ENG-4) should review the efficacy of utilizing Fall Protection Devices for training and maintenance evolutions.
Administrative Recommendation 8: Recommend that this investigation be closed.
District Commander's Endorsement: I concur with this recommendation.
USCG Testing of LHR 3.5M2 and Control Cable Failures
The U.S. Coast Guard investigators and members of the OCSNCOE conducted additional testing on January 14, 2020 to determine if theories related to the control cable were plausible and gain additional data. The lifeboat utilized in the tests was the same model and was outfitted with the same release mechanism (hooks and release unit) as the lifeboat that was involved in the casualty. The testing report, listed as Enclosure (2) to the Report of Investigation can be accessed here.
Highlights from the report are listed below. Please see the full report for additional details.
The measurements and tests conducted and detailed in this report were developed with the intent to obtain data for the Schat-Harding LHR 3.5M2 release mechanism related to the following:
Further tests were developed to document what would happen when additional force was applied to the hook with the release system in a compromised state (i.e., locking shaft rotated between the closed and open positions due to a separated polyethylene liner in the control cable).
The results of these experiments show that damage to the conduit and polyethylene liner can result in failure of the cable. With damage present, a combination of the force required to open the locking shaft and the friction force in the cable itself produces a tensile force in the polyethylene liner that can cause it to fail completely. If the failure occurs while cycling the release lever, it can result in the hook locking shaft stopping between the open and closed positions (“B” and “C” positions, respectively, on Figure 34).
With the locking shaft in a partially-closed position immediately following conduit separation, the hook can still support the weight of the lifeboat and the occupants. Additionally, if the locking shaft is in a position that is relatively close to the open position, but still allows the hooks to be locked, the hooks can support the weight of the boat, though an additional load can cause the locking shaft to rotate and allow the hook to open.
However, it must be emphasized that after the initial liner failure and separation, any further cycling of the system will result in the locking shaft remaining in the fully open position. With a failed liner, the cable conduit freely extends, rendering the system unable to rotate the locking shaft to the closed position. This prevents the hooks from locking, rendering them unable to hold any load (see the observations for Experiment 2, Step 15).
The results of the testing show that a compromised control cable can place the locking shaft in a position that could be forced to open with application of an increased load.