Poor maintenance poses greatest engine threat
Friday, 5th October 2018
A report from The Swedish Club has found that the majority of damage to auxiliary engines takes place – ironically enough – immediately after maintenance work.
The findings of an investigation by The Swedish Club into auxiliary engine damage have shown that the majority of all damage takes place immediately after maintenance work.
A key finding is that 55% of casualties occur within the first 100 hours or so of operation after overhaul. In most cases the damage occurs only a few hours after start-up.
The report, Auxiliary Engine Damage, also finds that container vessels have a significantly higher claims frequency due to the larger number of installed engines on these vessels. In addition, these engines have considerable output, leading to higher repair costs compared with other vessels.
This latest report from The Swedish Club has been created in response to the Club’s members’ concerns over damage to auxiliary engines – a significant segment of machinery claims, both in number and in cost. In fact, the period between 2010 and 2016 saw 192 claims, with an average cost of US$344,615. The Swedish Club senior technical advisor Peter Stålberg explained: “Auxiliary engines run at high revolutions and have a common lubrication system for both cylinder and crank case lubrication. They are not under the same strict regime from the classification society as the main engine, and maintenance is often carried out by the vessel crew."
The most common causes of damage have been:
• Incorrect maintenance and repairs.
• Failure to adhere to repair procedures and use of incorrect tools.
• Crew lacking formal engine- specific training.
• Inexperienced crew and no expert in attendance.
• Failure to detect contamination due to poor lubrication oil management.
• Not following up on results from lubrication oil sampling.
Mr Stålberg said “We see incorrect maintenance and wrongful repair in all too many cases, and poor lubrication management is also a major contributing factor to auxiliary engine breakdowns. With an average repair cost of more than US$345,000, we cannot emphasise enough the principle that prevention is better than cure.”
Of the cases analysed, four major causes of damage presented themselves. Of these, 58 cases involved the connecting rod bolts. These mainly concerned the wrong assembly of bolts and nuts for main bearings, connecting rod studs etc. The improper tightening of bolts was also
a key factor, as was the hydraulic tool/pump not being properly calibrated. Finally, a lack of crew training and adherence to procedures was found to be a significant cause of problems.
The second major cause of damage was the contamination of lube oil with water or soot. Twenty-seven such cases were recorded, resulting from improper lube oil management; lube oil filters degraded over time; the introduction of dirt (often via rags) during maintenance; and damage causing lube oil to leak. Incorrect maintenance and procedures also played a significant part in failures. These included problems such as incorrect valve clearance adjustment; pistons installed incorrectly; the wrong types of plunger being installed; inlet and outlet valves getting mixed up during overhaul; personnel not following the manufacturer’s service letter regarding required modifications; and not installing the correct bearings during crankshaft grinding.
Finally, in 16 cases, overspeed proved a contributing factor to failure. Overspeed trips were not in working condition, reassembly was done incorrectly after governor exchange, fuel linkage was incorrectly assembled and drive systems on the governor worn out. On a small number of casualties, latent defects were the cause of damage. These were: the wrong material in the flywheel; a connecting rod machined incorrectly by the manufacturer; a cracked piston; and fuel injectors cracked at the newbuilding yard. The common factor in these occurrences in most cases is the incorrect assembly of vital engine parts in connection with regular overhaul. In particular, the assembly of connecting rods, bearings and pistons causes severe and costly accidents. The Swedish Club’s findings from this are clear. Non-adherence to procedures, and lack of training and experience, are clearly major problems. For instance, the connecting rod assembly is a critical and highly stressed joint, and must be re-assembled exactly in accordance with manufacturer’s instructions with proper tools. All too often, though, the club reports seeing insufficient understanding of the importance of the procedures.
Equally, according to the report, special hydraulic tools are often used for the engine assembly. These tools must be treated with care and need to be calibrated and carefully checked before use. Ultimately, the manager has the responsibility to ensure that crew are competent to undertake such repairs/ overhaul. The crew should either be trained on the specific management is critical for minimising the risk of engine failures. This is essential when operating the engine on heavy fuel oil (HFO). The lubrication oil must be analysed at regular intervals. Detection of water, soot particles, metal particles, etc. will serve as an early warning for engine problems. Negative results from oil analysis must be investigated and addressed promptly.
The Swedish Club’s report characterises poor lubrication as “the root of all evil,” pointing out that poor lubrication oil management is in many cases the predominating factor for an auxiliary engine breakdown. Auxiliary engines are four- stroke engines and, as such, the engine oil is used for cooling of pistons crowns and lubrication of cylinder liners, bearings, etc. There is an apparent risk that the lube oil will be contaminated with soot and combustion particles, especially if the engine has accumulated some running hours.
Proper lubrication oil management is critical for minimising the risk of engine failures. This is essential when operating the engine on heavy fuel oil (HFO). The lubrication oil must be analysed at regular intervals. Detection of water, soot particles, metal particles, etc. will serve as an early warning for engine problems. Negative results from oil analysis must be investigated and addressed promptly.
While prevention is always better than cure, steps can be taken to mitigate the damage caused by the failure of the auxiliary engine. Most modern auxiliary engine installations can be started and stopped remotely from the engine control room. It is good practice to always be present at the engine when starting it, especially after longer periods of stand-still and after overhaul. During start-up, if anything goes wrong, it usually happens very quickly. If someone is present at the engine there is at least a chance to intervene and shut down the engine manually.
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