A line mechanic reports he thought he saw adequate oil on the sight glass for both engines; but appa...

Narrative:

Weekday evening; when the ATR-42 came in from ZZZ; I checked the oil in both engines. I thought I saw an indication of adequate oil on the sight glass on both engines; but specifically #1 engine. Apparently I mis-read the indication; however; since when the plane attempted takeoff two days later in the morning; the flight crew received a cap warning and low oil pressure on the guage immediately after rotation. They were able to set the plane back down and stop safely in the remaining runway. Immediately after landing; the oil pressure went back up.after the plane returned to the ramp; I could see no oil indication on the sight glass. I added 5 quarts of oil to bring the oil level back up. There were no signs of leaks on the nacelle; the prop; or in the exhaust. The plane flew to ZZZ with no difficulty; but on landing oil was seen on the bottom of the nacelle and a loose fitting was found on the oil/fuel heat exchanger.I will be more cognizant of the necessity for insuring proper reading of the engine oil level sight glass.

Original NASA ASRS Text

Title: A Line Mechanic reports he thought he saw adequate oil on the sight glass for both engines; but apparently mis-read the oil quantity indication for # 1 engine. During Take-off; the ATR-42 Flight Crew received a CAP warning and low oil pressure immediately after rotation.

Narrative: Weekday evening; when the ATR-42 came in from ZZZ; I checked the oil in both engines. I thought I saw an indication of adequate oil on the sight glass on both engines; but specifically #1 engine. Apparently I mis-read the indication; however; since when the plane attempted takeoff two days later in the morning; the Flight Crew received a CAP warning and low oil pressure on the guage immediately after rotation. They were able to set the plane back down and stop safely in the remaining runway. Immediately after landing; the oil pressure went back up.After the plane returned to the ramp; I could see no oil indication on the sight glass. I added 5 quarts of oil to bring the oil level back up. There were no signs of leaks on the Nacelle; the Prop; or in the Exhaust. The plane flew to ZZZ with no difficulty; but on landing oil was seen on the bottom of the Nacelle and a loose fitting was found on the oil/fuel Heat Exchanger.I will be more cognizant of the necessity for insuring proper reading of the engine oil level sight glass.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	861990
Time
Date	200911
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Dawn
Aircraft 1
Make Model Name	ATR 42
Operating Under FAR Part	Part 121
Flight Phase	Parked
Component
Aircraft Component	Lubrication Oil
Person 1
Function	Technician
Qualification	Maintenance Airframe Maintenance Powerplant
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural Published Material / Policy

A line mechanic reports he thought he saw adequate oil on the sight glass for both engines; but apparently mis-read the oil quantity indication for # 1 engine. During take-off; the ATR-42 flight crew received a cap warning and low oil pressure immediately after rotation.