CGC Sequoia reduction gear repair

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Contract Opportunity

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Reduction Gear Tech Services USCGC Sequoia (WLB-215)

Lube Oil System Investigation

CGC Sequoia experienced a reduction gear casualty pier side resulting in their Generator pinion failing as well as their PTO shaft breaking in multiple places. The purpose of this scope of work is to inspect the lubrication system to identify if it was a causative factor in the failure of the aft PTO bearing and review potential ways to mitigate future failures with enhanced monitoring systems

1. Background, Problem Statement:
   
   
   
   
   1. Background:
   
   
   
   

USCGC SEQUOIA was conducting pier side light-offs at Port Huron, MI as part of testing following their post-Major Maintenance Availability (MMA) dockside and engine overhauls (BMDE & BSSDG). The cutter was clutched in when the Thruster System power take-off (PTO) shaft sheared at both the bulkhead seal and Vulcan coupling coming from the reduction gear.

SEQUOIA underwent MMA from Jan23 to Sep24. Her only U/W operation since the completion of MMA was the transit to home port. No issues with the subject systems were observed during the extensive MMA sea trials or during the transit to homeport. Since returning home she underwent a routine post-MMA maintenance period aimed at re-baselining equipment not addressed during MMA. Neither the Reduction Gear nor the Thruster Power Generation system the PTO shaft in question connects to were worked on in MMA or in the dockside. However, the bulkhead shaft seal was renewed as part of an MMA work item. Also, IBCTPL conducted a Reduction Gear overhaul on SEQ in 2019.

1. 
   
   
   
   1. Problem Statement:
   
   
   
   

Upon initial investigation following the reduction gear failure, it was apparent that the likely causal factor was a seized aft pinion bearing. This was made apparent by discoloration of the aft bearing races. Misalignment does not appear to be the cause of the bearing seizure but rather wear and/or loss of lubrication. It is believed that the seized bearing is the cause of the superheating of the PTO shaft that ultimately led to the shaft failing in torsion.

An investigation of the reduction gear’s internal lube oil system is needed to confirm or deny that a possible blockage in the lube oil system contributed to the aft bearing failure.

MFR ID 96-DHCMGH-CP

B Class Model Gear Unit Reduction: NSN 3020-XF-C11-6019

Input RPM 900 Output RPM 254

Gear ration 3.541:1

1. Tasking:

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   1. Inspect Reduction Gear Lube Oil System
      
      
      
      
      1. Perform in depth inspection of internal lube oil system of the reduction gear in question.
      
      
      2. Confirm or deny the presence of any blockages or flow restrictions.
      
      
      3. Confirm proper flow throughout entire lube oil system.
      
      
      4. Isolate system supply lubrication to the bearings to confirm or deny adequate lubrication was provided to bearing.
      
      
      5. Maintain any found foreign material for testing/analysis
      
      
      
      
   
   
   
   

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   1. Review current temperature monitoring capabilities
      
      
      
      
      1. Review and assess current temperature monitoring to determine if additional monitoring would aid in preventing a reoccurrence of this failure.
      
      
      2. Provide recommendations and procedures to improve temperature monitoring if needed.
      
      
      
      
   
   
   2. Inspect Bull Gear and other prudent components.
      
      
      
      1. Inspect for visible, via minimally invasive methods e.g. removal inspection covers, for collateral damage and/or contributing factors to the main PTO shaft failure. Objective of this preliminary inspection (prior to major repair efforts) is to obtain any information (before evidence is lost) of value to a “failure analysis team” to help understand or render facts related to failure. In addition, preliminary early findings that would benefit the “repair team” to anticipate and react early to unknown (at this time) required additional repairs and/or new parts required to restore failed MRG to full operation.
      
      
      
      
   
   
   
   

1. Provide written report of findings
   
   
   
   
   1. In office setting, perform additional research/investigations as required. Provide final presentation of data/findings of 3.1, 3.2, 3.3 into a report.
   
   
   2. USCG will be provided an opportunity after receipt of report, to ask questions related to content and then answers provided in a timely manner.
   
   
   
   


2. Delivery

The CTR will travel to and perform work on board CGC Sequoia 2700 Omar St. Port Huron, MI. 48060. Technician should have borescope for inspection and necessary feelerg gauges and tools to support analysis of L/O system

1. PERIOD of Performance

The period of performance for this contract will be up to 7 days on site 8-hour days period during an agreed upon time between 30 APR 25 and 15 MAY25

1. PLACE OF PERFORMANCE & POC’s

The primary place of performance will be on CGC SEQUOIA (WLB 215)

2700 Omar St.Port Huron, MI 48060

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   1. GOVERNMENT FURNISHED RESOURCES
   
   
   
   

Technicians to support chain falling, lifting, interference removal and assistance with L/O analysis.

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   1. Security Requirement
   
   
   
   

Provide name of technician to crew prior to arrival and good contact information.

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   1. Point of Contact:
   
   
   
   

Any cutter site visits will be coordinated through the cutter POC.

Cutter POC: CWO A. Lee Lowery

Engineer Officer

CGC SEQUOIA (WLB 215)

Work Cell: (810) 956-3675

Pers Cell: (808)721-1431

Email:

6.2 Off site coordination: LTJG Christopher Lansing

Work Cell:443-764-4921

Personal Cell: 315-744-2419

Port Engineer on site

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