Following a catastrophic engine failure on a rock truck, the maintenance supervisor initiates a Root Cause Analysis (RCA). The initial investigation reveals a severely clogged oil cooler. Using the '5 Whys' technique, which of the following is the most likely 'Because' statement for the second 'Why' question, assuming the first 'Why' was 'Why did the engine overheat?'

Question: Following a catastrophic engine failure on a rock truck, the maintenance supervisor initiates a Root Cause Analysis (RCA). The initial investigation reveals a severely clogged oil cooler. Using the '5 Whys' technique, which of the following is the most likely 'Because' statement for the second 'Why' question, assuming the first 'Why' was 'Why did the engine overheat?'

Answer options: ✅ Because engine oil flow was restricted by the clogged cooler.

• Because the oil cooler was not cleaned during the last maintenance.
• Because the engine experienced excessive loading conditions.
• Because the oil cooler itself was compromised internally.

Correct answer: Because engine oil flow was restricted by the clogged cooler.

Explanation: If the first why is 'Why did the engine overheat?', and the answer is 'Because the oil cooler was clogged', the next 'Why' would naturally be 'Why was the oil cooler clogged?'. The answer 'Because engine oil flow was restricted by the clogged cooler' further clarifies the immediate impact of the clog, leading towards a deeper root cause.