Narrative:

I arrived at the airport 1 hour prior to departure to stock the aircraft and complete a preflight inspection. On inspection, I noted the left as well as the right engine were 1 quart low on oil. I proceeded to add oil to the left engine then the right side. Before oil was added to the right engine, I removed the dipstick and placed it on the right wing near the speed brake. After adding the oil I became distraction by conversation with the aircraft fueler. Thinking I had replaced the dipstick, I secured the oil cover on the nacelle and moved to other things. I had completed a walkaround prior to checking the oil. A final walkaround before boarding the aircraft was apparently not complete enough. I was the first officer on the flight as well as the PF on this leg. Everything was normal on taxi, takeoff, and climb. As we climbed through FL200 a master warning annunciator illuminated. A drop in oil pressure was observed and a precautionary shutdown of the right engine was completed. We declared an emergency and proceeded directly back to cll. Descent and landing were uneventful and we taxied back to our hangar without incident. On inspection it was found that the right dipstick was missing causing a loss of oil pressure at altitude. The cause of this incident was a lack of a thorough final preflight walkaround. On evaluation of the events leading up to this incident, steps have been taken to insure this does not happen again. They are: 1) always complete a final walkaround on the aircraft. 2) doublechk all caps to make sure they are secure. 3) never get in a hurry with preflight of aircraft. 4) stay focused on task at hand. 5) do not let outside environment distract from preflight.

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Original NASA ASRS Text

Title: ENG SHUTDOWN AND RETURN LAND BECAUSE OF LOW OIL PRESSURE. OIL DIPSTICK WAS MISSING.

Narrative: I ARRIVED AT THE ARPT 1 HR PRIOR TO DEP TO STOCK THE ACFT AND COMPLETE A PREFLT INSPECTION. ON INSPECTION, I NOTED THE L AS WELL AS THE R ENG WERE 1 QUART LOW ON OIL. I PROCEEDED TO ADD OIL TO THE L ENG THEN THE R SIDE. BEFORE OIL WAS ADDED TO THE R ENG, I REMOVED THE DIPSTICK AND PLACED IT ON THE R WING NEAR THE SPD BRAKE. AFTER ADDING THE OIL I BECAME DISTR BY CONVERSATION WITH THE ACFT FUELER. THINKING I HAD REPLACED THE DIPSTICK, I SECURED THE OIL COVER ON THE NACELLE AND MOVED TO OTHER THINGS. I HAD COMPLETED A WALKAROUND PRIOR TO CHKING THE OIL. A FINAL WALKAROUND BEFORE BOARDING THE ACFT WAS APPARENTLY NOT COMPLETE ENOUGH. I WAS THE FO ON THE FLT AS WELL AS THE PF ON THIS LEG. EVERYTHING WAS NORMAL ON TAXI, TKOF, AND CLB. AS WE CLBED THROUGH FL200 A MASTER WARNING ANNUNCIATOR ILLUMINATED. A DROP IN OIL PRESSURE WAS OBSERVED AND A PRECAUTIONARY SHUTDOWN OF THE R ENG WAS COMPLETED. WE DECLARED AN EMER AND PROCEEDED DIRECTLY BACK TO CLL. DSCNT AND LNDG WERE UNEVENTFUL AND WE TAXIED BACK TO OUR HANGAR WITHOUT INCIDENT. ON INSPECTION IT WAS FOUND THAT THE R DIPSTICK WAS MISSING CAUSING A LOSS OF OIL PRESSURE AT ALT. THE CAUSE OF THIS INCIDENT WAS A LACK OF A THOROUGH FINAL PREFLT WALKAROUND. ON EVALUATION OF THE EVENTS LEADING UP TO THIS INCIDENT, STEPS HAVE BEEN TAKEN TO INSURE THIS DOES NOT HAPPEN AGAIN. THEY ARE: 1) ALWAYS COMPLETE A FINAL WALKAROUND ON THE ACFT. 2) DOUBLECHK ALL CAPS TO MAKE SURE THEY ARE SECURE. 3) NEVER GET IN A HURRY WITH PREFLT OF ACFT. 4) STAY FOCUSED ON TASK AT HAND. 5) DO NOT LET OUTSIDE ENVIRONMENT DISTRACT FROM PREFLT.

Data retrieved from NASA's ASRS site as of July 2007 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.