ABL Rig Inspections Bulletin | April 2025

Power Management, Dynamic Positioning & Controls Inspection

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ABL Rig Inspection Blog Series: 1st Edition

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Welcome to the ABL Rig Inspections Bulletin!

A regular blog series brought to you by ABL’s global rig inspection team. This series will explore the technical challenges, market trends, and key findings that our teams encounter in the field.

Expect a mix of real-world case studies, detailed findings, and practical insights drawn from our global operations.

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Power Management, Dynamic Positioning & Controls Inspection

Situational Context

During a full condition inspection of a 6^th Generation Drillship, part of the work scope required the collaboration between the ABL Dynamic Positioning Team and Rig Inspection Team to conduct a bespoke in-depth survey of the power management, dynamic positioning (DP), and controls systems.

Before mobilisation to the rig, a remote documentation and certification review had been conducted. This highlighted various issues that would need to be followed up on and gave the inspectors an initial insight into the status of the onboard equipment. On mobilisation to the rig, comprehensive visual inspections of all related equipment were carried out, including power generation and distribution, thruster equipment and auxiliaries, dynamic positioning equipment and control systems.

Situational Findings

During the period onboard, the Inspectors identified several critical and major non-conformances that had the potential to lead to unplanned downtime, were associated with safety critical systems or had safety implications.

These included:

• 2 out of the 3 DP System Motion Reference Units (MRU) were overdue for calibration as per Original Equipment Manufacturer (OEM) recommendations
• All 3 gyrocompasses were obsolete, had no historical maintenance records, and OEM performance tests had not been carried out
• Hull valves for the hydroacoustic position referencing (HPR) Systems had their remote operating gear removed, and valve position indicating proximity switches tampered with
• One of the DGNSS position reference systems and its associated HMI screen were found to be powered from different UPSs
• Major maintenance was overdue on 3 of the main engines / turbochargers
• 4 of the thrusters had not been overhauled for over 12 years (>70,000 running hours)
• LV distribution equipment was not being inspected or tested as per OEM recommendations
• Several LV distribution systems and emergency lighting circuits had low insulation faults
• A critical uninterruptible power supply (UPS) had been operating in bypass for an extended period and would therefore not provide battery back-up in an emergency situation
• Defective air conditioning units in switchboard rooms
• Electrical safety equipment overdue for inspection

Discussion

The combined inspection by the ABL DP Team and ABL Rig Inspection Team covered all aspects of power management, generation and distribution, propulsion, dynamic positioning (DP) and control systems. The DP-related non-conformances and several of the maintenance-related non-conformances stated above had not been identified during the 5-yearly or annual DP trials.

Traditionally, during the conduct of DP trials, the focus will be firmly on the DP system on the bridge, with little or no inspections carried out on associated equipment. In addition, due to time constraints, maintenance records are not fully scrutinised on occasion.

This holistic approach enabled the ABL team to identify and highlight critical and major non-conformances which required immediate action or had the potential to cause downtime during operations.   

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Contact Us

Contact ABL to find out how the ABL DP & Rig Inspection Teams can assist with assurance of dynamic positioning, power management, generation & distribution and controls systems: