After cold start, the engine must remain at idle until what occurs?

• A. Oil pressure returns to normal range
• B. N1 reaches 50%
• C. EGT reaches target
• D. Fuel flow stabilized

Answer: (A)

After a cold start, getting proper lubrication is the priority. Cold oil is thicker, so the oil pump must build enough pressure to coat bearings and gears. If you raise RPM before oil pressure is back to normal, there’s a risk of insufficient lubrication and potential wear or damage. That’s why you hold the engine at idle until oil pressure returns to the normal range, signaling that lubrication is adequate and it’s safe to increase speed. Other indicators like N1, EGT, or fuel flow don’t directly guarantee safe lubrication during warm-up, so they aren’t the basis for moving off idle.