During operation with N1 < 72%, engine oil pressure range?

During operation with N1 < 72%, engine oil pressure range?

• A. 0-40 psi
• B. 40-80 psi (with N1 < 72%)
• C. 80-110 psi
• D. 40-60 psi

Answer: (B)

Oil pressure tracks how hard the engine is working: as N1 increases, the oil pump tends to push more oil and the pressure rises, up to a limit. When N1 is below 72%, the engine is not demanding maximum pump output, so the lubrication system is expected to operate within a mid-range pressure that’s high enough to keep the bearings sprayed with oil but not so high as to over-pressurize the system. That’s why the 40 to 80 psi band is the correct range. The other options either would leave too little pressure for safe lubrication at this speed, or would indicate abnormally high pressure for a low-N1 condition, or narrow the range to a value that doesn’t reflect the full acceptable band at this operating point.

Oil pressure tracks how hard the engine is working: as N1 increases, the oil pump tends to push more oil and the pressure rises, up to a limit. When N1 is below 72%, the engine is not demanding maximum pump output, so the lubrication system is expected to operate within a mid-range pressure that’s high enough to keep the bearings sprayed with oil but not so high as to over-pressurize the system. That’s why the 40 to 80 psi band is the correct range. The other options either would leave too little pressure for safe lubrication at this speed, or would indicate abnormally high pressure for a low-N1 condition, or narrow the range to a value that doesn’t reflect the full acceptable band at this operating point.