DSV Bibby Topaz – Case Study & Discussion of Lessons Learned

• Water depth 91m, Weather;– Wind NW– Wind gusting up to 30 – 35 kts– Sig wave height 4.0m

• Vessel set up west of template• 2 x DGPS, 2 x HiPap, 1 x taut

wire online• 3 Generators online, 5 out of 6

thrusters running & selected onto DP

• MOC conducted to enter template via side

• Venting annulus gas prior to barrier testing

Scope of Work

DSV Bibby Topaz – Build 2008

• Propulsion– 2 x Main Propulsion , 2 x Retractable Azimuth, 2 x Tunnel

Thrusters

13 245 & 6

Time Line; 20.13• Dive 047, starboard

bell locked off• Bell located upstream

of template structure• Divers umbilical

length into template –27m from bell

Time Line; 20.49 to 22.09

• Diver 1 & 2 located inside drilling template structure carrying out barrier testing activities

• ROV monitoring

Time Line; 22.09• Alarm for ‘RBUS’

activated• DP amber alert activated• Master & Dive Control

informed• Dive Supervisor

instructed divers to leave structure and locate to bell stage

• Attempts made to reselect thrusters into DP

Vessel Tracking

Vessel Tracking

Vessel heading and approximate position between 22.09.30 and 22.13.00 (30 sec intervals)

Time Line; 22.11

Easterly Direction

• DP Red alert activated• Vessel drifting easterly,

all references & thrusters unavailable to DP

• 4th generator started, thruster 4 running

• Diver 1 & 2 locating onto top of template

Time Line; 22.11 – 22.12 • Diver 2 umbilical

snagged on transponder bucket located on side of structure

• Bellman pulling in diver 1 slack

Easterly Direction

Time Line – 22.12 • Bellman providing slack

to diver 1• Bellman attempting to

provide slack to diver 2• Diver 1 pulled off

template, returning to bell• Loss of comms to diver 2• Momentary loss of

comms to bell

Easterly Direction

Time Line – 22.13 to 22.15• Diver 2 umbilical severed• Diver 1 made way back to bell stage• OPM relocated from Dive Control to Bridge• Mode switch to manual thruster control• Port Taut Wire stowed (wire parted)• Downline and tugger parted

Time Line – 22.17• Vessel position 240m NE of Drilling Template• Vessel being manually driven using fwd and aft azimuths• Chief Officer on thrusters 2 & 3, Master on main propulsion thrusters 5 & 6

240m

• Diver 2 locator beacon identified at template

Time Line; 22.30 – 22.34• ROV back at Drilling Template• Diver 2 located on top of template• DP controllers power recycled• Vessel back on full auto DP

150m

Time Line – 22.38• Diver 1 left stage,

relocated onto template

• Recovery of Diver 2 commenced

Time Line – 22.40• Vessel back at Drilling

Template• Recovery of Diver 2

InvestigationTime Line – 22.46• Diver 2 recovered to

bell, unconscious & breathing

• 23.13 Bell sealed and left bottom

• 23.38 Bell locked on• 24.00 commenced

transit to port

DP Control System Investigation• Determine the fault which caused sudden loss of all analogue and

digital RBUS input / output signals with subsequent loss of DP control; resulting in vessel drift off

• Testing on the system to try to recreate sequence of events & method for provoking RBUS jamming developed

• Test procedure developed for demonstrating fault mechanism

DP Control System Investigation• Components in DPC-3 cabinet exposed to earth faults changed out

as precaution & sent back to Kongsberg Maritime (KM), Norway for factory inspection

• KM supplied equip inspected & modified according to grounding philosophy

• KM disassembled hardware module by module to fully substantiate root cause of the failure

• DP system proving trials conducted• Vessel assurance approved, returned operational (8th Oct)• KM investigation concluded end November• KM Technical Bulletin issued – DP-02/2012

Causal FactorsThe investigation determined RBUS jammed as a result of a rare sequence of events involving the combined effects of faults in one or more RBUS I/O modules in the DPC-3 cabinet (one of 3 cabinets / central processing units containing DP control system hardware). Faults found included; • Loose / intermittent connections of fuse in DPC-3 cabinet• Grounding; current was measured in the bound from the RCU units

to ground. • Inner shield on field cables not connected to instrument earth.• DPC 3 cabinet not earthed to ship hull structure.

Preventative Actions• A permanent solution has been made available as a RBUS I/O

Modules (RMP20X) Firmware Update kit. • The kit consists of a CD and an installation & verification procedure• The watchdog functionality self-test function allowing unit to

recognise jamming fault (and provide diagnostic coverage for other CPU faults).

• Provides module isolation should any of these faults occur & is capable of removing the unit from the network in case of similar malfunction, ensuring that the inbuilt network redundancy can be utilised

HSE Safety Notice• HSE issued Safety Notice - OSD 1-2013• Target suppliers of DP systems, operators of offshore installations,

marine ‘type approval’ bodies, classification societies, verification bodies and marine consultancies

• Notice will focus on Duty Holders Safety Case and the verification of performance and communication architecture of DP systems

• Requirements that if the DP functions are dependent on a dual BUS network the Offshore Installation Duty Holder should ensure that appropriate measures are in place to prevent a single fault causing failure of the dual BUS network.

• If not in place manufacturer / suppliers provide adequate information regarding vulnerability to single point failure

Lessons Learned / Summary TOR• A number of engagement sessions conducted with client base,

industry associations (IMCA, OGP DIWG, MSF) • The objective being to;

− Present the incident and the investigation findings− Importantly to identify, from the lessons learned, where

potential improvements could be made to diving and marine operations and to mitigate the likelihood and consequence of a similar incident was to occur in the future.

• IMCA Safety Notice 02/13 issued 29th Jan

Diving & Marine Safety Enhancement ProjectDiscussed with and endorsed by the HSE• Design of the bell staging to assist the recovery of unconscious

diver• The design of rescue equipment and method of recovery of

unconscious diver back to the bell• The design and provision of diver transponder / locator beacons• The design and provision of thermal protective undersuits• The specification of diver bailout bottles • The assessment and technology of diver re-breather units• Provision of addition life support equipment on the seabed for the

dive team • ROV interface to aid and assist diver recovery

Diving & Marine Safety Enhancement Project• Review of existing dive management system procedures and risk

assessment criteria• DP control system (software and hardware) inspection and

verification regime• DP field entry trials and set up to enable time for driving the vessel

in manual mode • Enhancement of the understanding and familiarity of manual

systems and operation• Bridge Team Management and the management of major

emergencies / command and control• Fully integrated approach to FMEA / FMECA and the schedule and

criteria for FMEA / FMECA review• Competency scheme performance criteria, training, drills and

exercises