As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW INFLIGHT - CLIMBING THROUGH APPROXIMATELY FLIGHT LEVEL 180 LEFT HAND ENGINE PRESSURE RATIO N1, N2 AND N3 WERE RAPIDLY DECREASING AND LEFT HAND ENGINE WAS PUTTING OUT SIGNIFICANTLY LESS POWER. RETURNED TO DFW AND LANDED WITHOUT INCIDENT. FOUND FITTING ON P1 LINE BELOW OIL TANK OFF. ATTACHED LINE AND SAFE TIED. SYSTEM GROUND CHECKED NORMAL OPERATION.