Narrative:

Shortly after take-off; we noticed a drop in oil pressure on the number 1 engine. We continued to monitor the oil pressure as it continued to drop. We notified ATC and requested a return to ZZZ. When the oil pressure reached its lower limits we proceeded to complete the engine shutdown per the engine shutdown checklist and [requested priority handling] and made an uneventful landing. Maintenance discovered a crimped O ring which appeared to have been in an oil line since the last engine overhaul.

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Original NASA ASRS Text

Title: Citation 550 First Officer reported a loss of oil pressure caused an air turn back and emergency landing.

Narrative: Shortly after take-off; we noticed a drop in oil pressure on the number 1 engine. We continued to monitor the oil pressure as it continued to drop. We notified ATC and requested a return to ZZZ. When the oil pressure reached its lower limits we proceeded to complete the engine shutdown per the engine shutdown checklist and [Requested Priority Handling] and made an uneventful landing. Maintenance discovered a crimped O ring which appeared to have been in an oil line since the last engine overhaul.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.