Narrative:

This incident happened because of a 'get the job done' mind set. I wanted to make the aircraft available to fly a scheduled mission. The better decision would have been to cancel the flight. In addition, a major contributing factor was lack of clarity of expectations regarding the job of completing the oil filter change. A secondary factor was that the entire oil change was not completed by a single person. Pilot advised me yesterday evening that he had experienced loss of engine oil on his flight from gnoss to imperial on friday morning resulting in an emergency landing at stockton. The loss of oil was due to the oil fill cap not being installed. Here is the history of this incident. I scheduled an oil change with an FBO for thursday morning. I had intended to perform the change under the supervision of an a&I being away from the airport for a day. I told him that the cancellation was a problem, since the aircraft was scheduled for mission flying, and that I would come to the airport to work out a solution. When I arrived, we discussed options. I decided to perform the portion of the oil change that did not require special skills or tools, and to leave the remainder to be completed by a&I when he returned. I warmed the oil in the runup area, taxied to the FBO hangar, and performed the basics: removed both cowling halves, drained the oil, removed the old filter, filled the crankcase with new oil, loosely installed the new filter, and reinstalled the lower cowling half. Owner agreed that a&I would torque the filter, safety wire it, and reinstall the upper cowling half in time for an XA00 departure on friday. I shifted my focus to installation of the VHF DF radio, which we had received back from avionics repaired and with the new training ELT frequency installed. The reinstallation was complicated by short wires. Avionics reinstalled the radio. I do not recall reinstalling the oil fill cap. The last step of the oil fill process is removing the funnel from the fill pipe. The funnel is, of course, oily and needs to be put where it will not create a mess. Doing so may have distraction me. And since I did not reinstall the upper cowling half, I missed an opportunity to notice whether or not the fill cap was installed.

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Original NASA ASRS Text

Title: UNDER SELF-IMPOSED PRESSURE, A ACFT MGR ATTEMPTED TO PERFORM MAINT ON HIS ACFT IN THE HOPES THAT AN A&I WOULD LATER TAKE CARE OF THE UNFINISHED ITEMS. THERE WAS NO COM BTWN THEM. THE MGR SELF-ADMITTED THAT HE FORGOT TO REPLACE THE OIL FILLER CAP. DURING THE MISSION, THE PLT HAD TO MAKE AN EMER LNDG AT SCK.

Narrative: THIS INCIDENT HAPPENED BECAUSE OF A 'GET THE JOB DONE' MIND SET. I WANTED TO MAKE THE ACFT AVAILABLE TO FLY A SCHEDULED MISSION. THE BETTER DECISION WOULD HAVE BEEN TO CANCEL THE FLT. IN ADDITION, A MAJOR CONTRIBUTING FACTOR WAS LACK OF CLARITY OF EXPECTATIONS REGARDING THE JOB OF COMPLETING THE OIL FILTER CHANGE. A SECONDARY FACTOR WAS THAT THE ENTIRE OIL CHANGE WAS NOT COMPLETED BY A SINGLE PERSON. PLT ADVISED ME YESTERDAY EVENING THAT HE HAD EXPERIENCED LOSS OF ENG OIL ON HIS FLT FROM GNOSS TO IMPERIAL ON FRIDAY MORNING RESULTING IN AN EMER LNDG AT STOCKTON. THE LOSS OF OIL WAS DUE TO THE OIL FILL CAP NOT BEING INSTALLED. HERE IS THE HISTORY OF THIS INCIDENT. I SCHEDULED AN OIL CHANGE WITH AN FBO FOR THURSDAY MORNING. I HAD INTENDED TO PERFORM THE CHANGE UNDER THE SUPERVISION OF AN A&I BEING AWAY FROM THE ARPT FOR A DAY. I TOLD HIM THAT THE CANCELLATION WAS A PROB, SINCE THE ACFT WAS SCHEDULED FOR MISSION FLYING, AND THAT I WOULD COME TO THE ARPT TO WORK OUT A SOLUTION. WHEN I ARRIVED, WE DISCUSSED OPTIONS. I DECIDED TO PERFORM THE PORTION OF THE OIL CHANGE THAT DID NOT REQUIRE SPECIAL SKILLS OR TOOLS, AND TO LEAVE THE REMAINDER TO BE COMPLETED BY A&I WHEN HE RETURNED. I WARMED THE OIL IN THE RUNUP AREA, TAXIED TO THE FBO HANGAR, AND PERFORMED THE BASICS: REMOVED BOTH COWLING HALVES, DRAINED THE OIL, REMOVED THE OLD FILTER, FILLED THE CRANKCASE WITH NEW OIL, LOOSELY INSTALLED THE NEW FILTER, AND REINSTALLED THE LOWER COWLING HALF. OWNER AGREED THAT A&I WOULD TORQUE THE FILTER, SAFETY WIRE IT, AND REINSTALL THE UPPER COWLING HALF IN TIME FOR AN XA00 DEP ON FRIDAY. I SHIFTED MY FOCUS TO INSTALLATION OF THE VHF DF RADIO, WHICH WE HAD RECEIVED BACK FROM AVIONICS REPAIRED AND WITH THE NEW TRAINING ELT FREQ INSTALLED. THE REINSTALLATION WAS COMPLICATED BY SHORT WIRES. AVIONICS REINSTALLED THE RADIO. I DO NOT RECALL REINSTALLING THE OIL FILL CAP. THE LAST STEP OF THE OIL FILL PROCESS IS REMOVING THE FUNNEL FROM THE FILL PIPE. THE FUNNEL IS, OF COURSE, OILY AND NEEDS TO BE PUT WHERE IT WILL NOT CREATE A MESS. DOING SO MAY HAVE DISTR ME. AND SINCE I DID NOT REINSTALL THE UPPER COWLING HALF, I MISSED AN OPPORTUNITY TO NOTICE WHETHER OR NOT THE FILL CAP WAS INSTALLED.

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.