Exam Question
(a) Describe what would be the indications of crank case explosion in main engine. (4)
(b) Describe actions to be taken, if there is crank case explosion in main engine. (8)
(c) Describe means of prevention of crank case explosion. (4)
Class 4 (4th Engineer)
MEP
📅 Feb 2024
Reference Answer
### (a) Indications of a Crankcase Explosion in the Main Engine (4 Marks)
A crankcase explosion, whilst rare due to safety measures, is a severe emergency. The indications can range from subtle precursors to overt signs of catastrophic failure. A Class 1 Examiner expects a detailed understanding of both primary and secondary indicators:
* **Loud Bang / Detonation Sound:** The most immediate and unmistakable primary indication is a sudden, very loud explosive noise, often described as a 'detonation' or 'boom', emanating from the crankcase area. This is the sound of the ignition of the oil mist/air mixture.
* **Flame Emission from Relief Valves:** Simultaneously with or immediately after the bang, flames or hot gases will be expelled from the crankcase relief doors (explosion doors). These doors are designed to open rapidly to vent excessive pressure, but in doing so, they can emit ignited oil mist and combustion products.
A crankcase explosion, whilst rare due to safety measures, is a severe emergency. The indications can range from subtle precursors to overt signs of catastrophic failure. A Class 1 Examiner expects a detailed understanding of both primary and secondary indicators:
* **Loud Bang / Detonation Sound:** The most immediate and unmistakable primary indication is a sudden, very loud explosive noise, often described as a 'detonation' or 'boom', emanating from the crankcase area. This is the sound of the ignition of the oil mist/air mixture.
* **Flame Emission from Relief Valves:** Simultaneously with or immediately after the bang, flames or hot gases will be expelled from the crankcase relief doors (explosion doors). These doors are designed to open rapidly to vent excessive pressure, but in doing so, they can emit ignited oil mist and combustion products.
Full answer on MeoMock — surveyor-grade reference answers for 7,000+ written exam questions.
Prepare on Android — MeoMock on Google Play