Narrative:

On the day of the event I was scheduled as the sic on a 2 leg; one day trip. Upon arrival to the airport I tended to a few management tasks aside from my planned flight. When this was complete I found the logbook for the airplane I was flying that day; grabbed my bags; and went to the ramp to find the airplane. After walking around on the ramp and not finding it I asked our line service. They informed me that it had not been pulled out yet but that it was next. This was at approximately xa:40. I decided to wait for it to be pulled out rather than try to find it in the hangar. It was pulled out at roughly xa:50. This left me feeling pressured for time. During the initial preflight I notice that the battery voltage was lower than normal. So; I called operations on my cell phone to ask for a gpu. It went right to the voice mail so I pressed 0 to get transferred to the after hours cell phone. It rang a couple times and then had a message that the phone was not available. I hung up and tried again with the same results. I then continued with the exterior preflight during which I heard my phone ring. When I pulled it out of my pocket there was no one there. I replaced it and continued the preflight and when I was checking the oil level in the lh engine and was once again interrupted by my phone. This time I was able to answer and it was operations returning my missed call. I informed him of our request for a gpu. When I hung up I continued with the preflight. I can remember looking at the oil level but cannot remember closing the door. I have to assume that I did not get the cap back on (at least fully). The more I think about it I think that I may have left the oil door open when my phone rang and someone else closed it behind me but I can't be sure. During that time; line service was fueling the airplane and may have closed it trying to be helpful. Within 2 minutes of takeoff the lh engine oil pressure annunciator illuminated with a corresponding low oil pressure indication. We reduced the lh engine to idle power as an initial measure to prevent damage. We ran the oil pressure light checklist which called for a precautionary engine shutdown if possible. We notified ATC of our situation and declared an emergency. Continuing the checklist; we verbalized confirmation of the lh thrust lever prior to moving it to cutoff. After the engine shutdown in flight checklist we reviewed the single engine landing checklist. We calculated our wet; single engine landing distance. We discussed our options and agreed that a return to our departure airport was prudent. We decided on delaying until fuel was down to max landing weight. Some of the factors involved in our decision were: 1) weather- the ceiling and visibility were low and we had a little concern for waiting and having the weather get worse. 2) sunrise- if we burned off fuel our approach would be made in daylight. The potential for the weather to go down was compounded by the fact that it would have been easier to see the runway at night. 3) landing distance- while it did not make a huge difference in the numbers; the reduced landing weight would shorten landing distance; improve single engine go around performance and avoid an overweight landing. After that we briefed the passengers on the following items: briefly discuss the problem. Ensure them that the landing would seem like a normal landing. Mention that they may see fire trucks next to the runway. Review the evacuation procedures. We finished up the normal checklists and the approach briefing prior to informing ATC that we were ready for the ILS approach. We made a normal ILS approach to an uneventful landing. My 'take away' from the event: interruption- I can say with some certainty that I fell victim to an interruption. No matter what actually happened with the oil cap I was interrupted and thus distracted during the preflight. I think that as a first step I need to apply our company checklist philosophy tothe preflight. Our standard operating procedures state: checklist continuity- interruptions in a checklist may result in a failure of the crew to verify the completion of necessary tasks. If there is any question as to which items were incomplete or where a checklist was interrupted; the crew will perform the checklist from the beginning. I need to adopt this as a philosophy with all tasks involving critical steps. It would have caused me to go back and start the exterior preflight over due to the interruption. Time pressure-I felt pressured for time for a couple of reasons. 1) my non flight related tasks were taking me away from the tasks at hand. 2) the airplane was late being pulled out from the hangar which caused me to be rushed to complete the preflight. As a personal SOP to combat that- I need to arrange my workload so that I can completely focus on the flight and also recognize the dangers of interruptions and time pressure.

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Original NASA ASRS Text

Title: Learjet 31 First Officer reports interruptions during preflight that resulted in departure with the engine oil cap off or loose. Shortly after takeoff low oil pressure was indicated and the engine shut down; a single engine approach and landing ensued.

Narrative: On the day of the event I was scheduled as the SIC on a 2 leg; one day trip. Upon arrival to the airport I tended to a few management tasks aside from my planned flight. When this was complete I found the logbook for the airplane I was flying that day; grabbed my bags; and went to the ramp to find the airplane. After walking around on the ramp and not finding it I asked our line service. They informed me that it had not been pulled out yet but that it was next. This was at approximately XA:40. I decided to wait for it to be pulled out rather than try to find it in the hangar. It was pulled out at roughly XA:50. This left me feeling pressured for time. During the initial preflight I notice that the battery voltage was lower than normal. So; I called Operations on my cell phone to ask for a GPU. It went right to the voice mail so I pressed 0 to get transferred to the after hours cell phone. It rang a couple times and then had a message that the phone was not available. I hung up and tried again with the same results. I then continued with the exterior preflight during which I heard my phone ring. When I pulled it out of my pocket there was no one there. I replaced it and continued the preflight and when I was checking the oil level in the LH engine and was once again interrupted by my phone. This time I was able to answer and it was Operations returning my missed call. I informed him of our request for a GPU. When I hung up I continued with the preflight. I can remember looking at the oil level but cannot remember closing the door. I have to assume that I did not get the cap back on (at least fully). The more I think about it I think that I may have left the oil door open when my phone rang and someone else closed it behind me but I can't be sure. During that time; line service was fueling the airplane and may have closed it trying to be helpful. Within 2 minutes of takeoff the LH Engine Oil Pressure annunciator illuminated with a corresponding low oil pressure indication. We reduced the LH engine to idle power as an initial measure to prevent damage. We ran the Oil Pressure Light checklist which called for a precautionary engine shutdown if possible. We notified ATC of our situation and declared an emergency. Continuing the checklist; we verbalized confirmation of the LH thrust lever prior to moving it to cutoff. After the engine shutdown in flight checklist we reviewed the single engine landing checklist. We calculated our wet; single engine landing distance. We discussed our options and agreed that a return to our departure airport was prudent. We decided on delaying until fuel was down to max landing weight. Some of the factors involved in our decision were: 1) Weather- The ceiling and visibility were low and we had a little concern for waiting and having the weather get worse. 2) Sunrise- If we burned off fuel our approach would be made in daylight. The potential for the weather to go down was compounded by the fact that it would have been easier to see the runway at night. 3) Landing Distance- While it did not make a huge difference in the numbers; the reduced landing weight would shorten landing distance; improve single engine go around performance and avoid an overweight landing. After that we briefed the passengers on the following items: Briefly discuss the problem. Ensure them that the landing would seem like a normal landing. Mention that they may see fire trucks next to the runway. Review the evacuation procedures. We finished up the normal checklists and the approach briefing prior to informing ATC that we were ready for the ILS approach. We made a normal ILS approach to an uneventful landing. My 'Take Away' from the event: Interruption- I can say with some certainty that I fell victim to an interruption. No matter what actually happened with the oil cap I was interrupted and thus distracted during the preflight. I think that as a first step I need to apply our company checklist philosophy tothe preflight. Our Standard Operating Procedures State: Checklist Continuity- Interruptions in a checklist may result in a failure of the crew to verify the completion of necessary tasks. If there is any question as to which items were incomplete or where a checklist was interrupted; the crew will perform the checklist from the beginning. I need to adopt this as a philosophy with all tasks involving critical steps. It would have caused me to go back and start the exterior preflight over due to the interruption. Time Pressure-I felt pressured for time for a couple of reasons. 1) My non flight related tasks were taking me away from the tasks at hand. 2) The airplane was late being pulled out from the hangar which caused me to be rushed to complete the preflight. As a personal SOP to combat that- I need to arrange my workload so that I can completely focus on the flight and also recognize the dangers of interruptions and time pressure.

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.