B757-200
Maintenance Airframe; Maintenance Powerplant
Maintenance Technician 3
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
Aircraft Aircraft Damaged; Flight Crew Diverted; Flight Crew Landed in Emergency Condition; Flight Crew Overcame Equipment Problem; General Flight Cancelled / Delayed; General Maintenance Action
Aircraft; Procedure
I went out to assist with a engine run for a fellow employee who was changing a scavenge oil transmitter. When I arrived to the [Aircraft] he said he had everything ready and just need to do a engine run to see if the message stayed away. I proceeded to run the engine at idle for 5 minutes and the impending clog light never came on. During the run all engine parameters were completely normal and nothing noteworthy was noticed. I shut down the engine and let him know that no message appeared. My coworker forgot to install the O-rings on the transmitter and inflight the oil quantity went to zero. The plane had to make a diversion into ZZZ1.
During routine engine maintenance; a technician omitted installing O Rings on a scavenge oil transmitter; causing loss of oil quantity and a diversion to a precautionary landing.