Answer
When drafting an official technical report on cylinder liner and piston damage caused by off-spec/bad fuel, the report must establish a clear cause-and-effect chain linking fuel analysis records, engine operational parameters, and observed physical damage. This report is critical for your Technical Superintendent, Flag/Class authorities, insurance adjusters (P&I / Hull & Machinery), and potential legal claims against fuel suppliers.
Structure of the Technical Technical Report1. Vessel & Incident Overview
Basic Details: Vessel Name, IMO Number, Engine Model (e.g., MAN B&W 6S60ME-C), Total Running Hours of damaged units, Date and Geographical Location of incident.
Fuel Details: Bunkering Port, Date of Bunkering, Fuel Grade (e.g., VLSFO 0.50% S), BDN (Bunker Delivery Note) sample numbers, and fuel tank transfer history.
2. Sequence of Events & Operational Log
Timeline: Log of when the suspect fuel was transferred, purified, and supplied to the main engine.
Operating Conditions: Engine load, RPM, fuel inlet temperature/viscosity at the engine inlet, scavenge air temperature, and cylinder lubrication feed rates prior to the failure.
Initial Alarm Indications: Sequence of events leading to detection (e.g., high exhaust temperature alarm, high scavenge space temperature/fire, increased blow-by, auto-tuning / PMI pressure imbalance alarms).
3. Evidence 1: Fuel Laboratory Analysis Results
Include official laboratory test results (e.g., VPS / FOBAS / Veritas Petroleum Services) highlighting off-spec parameters:
Catalytic Fines (Al+Si): High aluminum and silicon content causing severe abrasive wear (cat-fine wear).
Asphaltene / Stability (TSE/TSP): High total sediment, leading to heavy sludge, filter clogging, and injector fouling.
Water Content: High free water/saltwater causing corrosion and localized combustion disruption.
CCAI (Calculated Carbon Aromaticity Index): Poor ignition quality leading to delayed combustion, high peak pressure rise (ΔP/Δθ), and thermal overloading.
Chemical Contaminants: Presence of waste chemicals (e.g., chlorinated hydrocarbons, fatty acids) causing chemical attack on oil film.
4. Evidence 2: Inspection Findings & Damage Assessment
Categorize physical findings per affected cylinder unit:
Piston Assembly Damage:
Piston Crown: Burn marks, thermal erosion, excessive carbon buildup, or micro-cracking due to late burning / poor atomization.
Piston Rings: Broken, collapsed, micro-seized, or stuck rings with loss of tension; presence of heavy abrasive scoring on ring faces.
Piston Skirt: Heavy scuffing, drag marks, and metallic pickup.
Cylinder Liner Damage:
Running Surface: Deep vertical scoring lines, scuffing, clover-leafing, or complete wiping out of the honed wave-cut grooves.
Corrosive / Abrasive Wear: Measurement of liner bore diameters using a internal micrometer to quantify wear rates (mm/1000 hrs) against Class limits.
Scavenge Ports: Carbon blockage, heavy sludge accumulation, and evidence of blow-by past the rings.
Fuel Injection Equipment:
Inspection of fuel injectors (atomizer tips eroded, needle valves seized, severe carbon trumpeting).
5. Root Cause Analysis (RCA)
Synthesize the fuel lab findings with the physical evidence:
Mechanism: E.g., "High concentration of hard abrasive Al+Si particles (>60 ppm) passed through the filtration system, leading to rapid abrasive scuffing of the piston rings and liner surface. This destroyed the cylinder oil lubricating film, resulting in blow-by, localized overheating, thermal cracking of the piston crown, and premature wear."
6. Corrective Actions Taken & Repairs
Immediate Actions: Switching engine fuel source to clean/settled fuel from an unaffected tank, derating engine load, stopping the affected cylinder unit if necessary.
Component Renewals: Details of parts replaced (e.g., replaced Cylinder Liner Unit #3, renewed Piston Assembly, fitted new piston rings, overhauled fuel valves).
Fuel Treatment: De-sludging of settling/service tanks, cleaning fuel purifiers, lowering transfer rates, and adjusting cylinder lubricating oil feed rate (alpha lubrication boost).
7. Financial & Operational Summary
Parts & Spares Used: List of major spare parts consumed with part numbers.
Off-Hire / Downtime: Total hours vessel was off-hire or anchored for emergency repairs.
Consumables: Amount of off-spec fuel remaining onboard requiring offloading/debunkering.
Photographic Evidence: High-resolution, labeled photos of damaged piston crowns, scuffed liner walls, broken rings, and clogged injectors/filters.
Bunker Records: Copy of BDN, Lab Fuel Analysis Reports, and Fuel Transfer Logbook.
Calibration Reports: Liner bore measurement tables (Fore-Aft & Port-Stbd measurements at various stroke depths).
Alarm & Performance Logs: PMI/CoCoS indicator cards, auto-tuning history, and alarm prints for exhaust/scavenge temperatures.