Narrative:

At top of climb; low oil pressure engine #2 alarm went off. Crew consulted QRH which called for power reduction to below 75% nh. I as captain; asked first officer if QRH called for use of single engine-checklist. It does not. We called ATC to return to departure airport. After uneventful descent; we were cleared for visual approach. According to normal checklist; crew advanced both condition levers to 'maximum.' crew was unprepared for drag increase on engine #2. We descended below safe approach profile. In attempt to rectify problem; we abandoned approach; and opted for straight-in landing to adjacent military base. At this point we declared an emergency; received landing clearance to ZZZ1 and made uneventful landing. Had the QRH called for feathering propeller and/or referred to using single-engine landing check; the (tired) crew would never have fallen into this (otherwise) obvious trap. Our training had never addressed this scenario; which is a contributing factor.callback conversation with reporter revealed the following information: reporter verified that the oil pressure at the time of the warning was in the range between 40 and 55 psi which triggered the use of only the first few lines on the QRH procedure. He expanded on the shortcomings of the aircraft checklist described in the narrative; pointing out that all subsequent steps of the procedure appeared clearly related solely to a condition in which the oil pressure was below 40 psi. In addition; the reporter had reviewed 'generic' E120 checklists obtained from a large independent training school that; like the company checklists; failed to direct the flight crews to treat the landing phase as a single engine operation; including the directive to feather the propeller on the malfunctioning engine. Finally; the reporter advised that a similar incident happened on the same aircraft at a later date. Maintenance determined the oil cap -- as well as a one way check valve intended to prevent loss of pressure and/or engine oil -- was faulty.

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Original NASA ASRS Text

Title: THE FLT CREW OF AN E120 EXPERIENCE DEGRADED OIL PRESSURE ON THE R (#2) ENGINE. FOLLOWING QRH PROCS; POWER ON THE AFFECTED ENGINE IS REDUCED; BUT THE ENGINE IS NOT SHUT DOWN. THEY ATTEMPT TO RETURN TO THE DEP ARPT; BUT ELECT A DIVERSION TO A CLOSER ARPT UPON ENCOUNTERING UNANTICIPATED DRAG FROM THE R ENGINE.

Narrative: AT TOP OF CLB; LOW OIL PRESSURE ENGINE #2 ALARM WENT OFF. CREW CONSULTED QRH WHICH CALLED FOR POWER REDUCTION TO BELOW 75% NH. I AS CAPT; ASKED FO IF QRH CALLED FOR USE OF SINGLE ENGINE-CHKLIST. IT DOES NOT. WE CALLED ATC TO RETURN TO DEP ARPT. AFTER UNEVENTFUL DESCENT; WE WERE CLRED FOR VISUAL APCH. ACCORDING TO NORMAL CHKLIST; CREW ADVANCED BOTH CONDITION LEVERS TO 'MAXIMUM.' CREW WAS UNPREPARED FOR DRAG INCREASE ON ENG #2. WE DESCENDED BELOW SAFE APCH PROFILE. IN ATTEMPT TO RECTIFY PROB; WE ABANDONED APCH; AND OPTED FOR STRAIGHT-IN LNDG TO ADJACENT MIL BASE. AT THIS POINT WE DECLARED AN EMER; RECEIVED LNDG CLRNC TO ZZZ1 AND MADE UNEVENTFUL LNDG. HAD THE QRH CALLED FOR FEATHERING PROP AND/OR REFERRED TO USING SINGLE-ENGINE LNDG CHK; THE (TIRED) CREW WOULD NEVER HAVE FALLEN INTO THIS (OTHERWISE) OBVIOUS TRAP. OUR TRAINING HAD NEVER ADDRESSED THIS SCENARIO; WHICH IS A CONTRIBUTING FACTOR.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR VERIFIED THAT THE OIL PRESSURE AT THE TIME OF THE WARNING WAS IN THE RANGE BETWEEN 40 AND 55 PSI WHICH TRIGGERED THE USE OF ONLY THE FIRST FEW LINES ON THE QRH PROC. HE EXPANDED ON THE SHORTCOMINGS OF THE ACFT CHKLIST DESCRIBED IN THE NARRATIVE; POINTING OUT THAT ALL SUBSEQUENT STEPS OF THE PROC APPEARED CLRLY RELATED SOLELY TO A CONDITION IN WHICH THE OIL PRESSURE WAS BELOW 40 PSI. IN ADDITION; THE RPTR HAD REVIEWED 'GENERIC' E120 CHKLISTS OBTAINED FROM A LARGE INDEPENDENT TRAINING SCHOOL THAT; LIKE THE COMPANY CHKLISTS; FAILED TO DIRECT THE FLT CREWS TO TREAT THE LNDG PHASE AS A SINGLE ENGINE OPERATION; INCLUDING THE DIRECTIVE TO FEATHER THE PROPELLER ON THE MALFUNCTIONING ENGINE. FINALLY; THE RPTR ADVISED THAT A SIMILAR INCIDENT HAPPENED ON THE SAME ACFT AT A LATER DATE. MAINT DETERMINED THE OIL CAP -- AS WELL AS A ONE WAY CHK VALVE INTENDED TO PREVENT LOSS OF PRESSURE AND/OR ENGINE OIL -- WAS FAULTY.

Data retrieved from NASA's ASRS site as of January 2009 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.