Narrative:

During the pre-flight; my trainee added a quart of oil to both the left and right engines. I monitored his adding oil to the left engine; however I did not watch him add the quart to the right engine because I had to run inside to complete some pre-flight paperwork. When I came back out to the aircraft; our cargo was waiting to be loaded and in my haste; I failed to verify that the right engine was secure for flight. After loading up the cargo; we proceeded to the active runway and began our flight. During the climb to 7;000' we monitored our engine gauges as per procedure and everything was within normal operating limits. Upon reaching our cruise altitude of 7;000' MSL; we began to lean out our mixtures as normal. When we attempted to lean the right engine; we noticed that the engine was unable to maintain 26' manifold pressure. I then checked the right engine gauges and noticed the oil pressure around 10-20 psi (40-30 psi below normal) and dropping. I then glanced out to the right engine and saw that the oil door was open and leaking oil. I asked my trainee if he had replaced the oil dipstick and he replied; 'I thought I did.' obviously; he did not and we were now losing oil. Immediately; I made the decision to shutdown and secure the right engine. I contacted approach and reported the shutdown and told them that I wanted to return. They immediately vectored me back and told me to report the airport in- sight. I did and they cleared me for the visual approach. I followed the company's emergency procedures and safely secured the right engine and landed safely. To prevent this from happening again; extra vigilance must be taken to insure the aircraft is ready for flight. As pilot in command; it is my responsibility to complete one last walk-around to verify that all the gas caps; cargo doors; and oil caps are secure. Had I taken the extra minute to do this; this entire situation would have been avoided.

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Original NASA ASRS Text

Title: A PA31 Captain reported returning to departure airport after shutting down the left engine for low oil pressure because his trainee pilot failed to replace and secure the oil dipstick.

Narrative: During the pre-flight; my trainee added a quart of oil to both the left and right engines. I monitored his adding oil to the left engine; however I did not watch him add the quart to the right engine because I had to run inside to complete some pre-flight paperwork. When I came back out to the aircraft; our cargo was waiting to be loaded and in my haste; I failed to verify that the right engine was secure for flight. After loading up the cargo; we proceeded to the active runway and began our flight. During the climb to 7;000' we monitored our engine gauges as per procedure and everything was within normal operating limits. Upon reaching our cruise altitude of 7;000' MSL; we began to lean out our mixtures as normal. When we attempted to lean the right engine; we noticed that the engine was unable to maintain 26' manifold pressure. I then checked the right engine gauges and noticed the oil pressure around 10-20 PSI (40-30 PSI below normal) and dropping. I then glanced out to the right engine and saw that the oil door was open and leaking oil. I asked my trainee if he had replaced the oil dipstick and he replied; 'I thought I did.' Obviously; he did not and we were now losing oil. Immediately; I made the decision to shutdown and secure the right engine. I contacted Approach and reported the shutdown and told them that I wanted to return. They immediately vectored me back and told me to report the airport in- sight. I did and they cleared me for the visual approach. I followed the company's Emergency Procedures and safely secured the right engine and landed safely. To prevent this from happening again; extra vigilance must be taken to insure the aircraft is ready for flight. As pilot in command; it is my responsibility to complete one last walk-around to verify that all the gas caps; cargo doors; and oil caps are secure. Had I taken the extra minute to do this; this entire situation would have been avoided.

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.