Recurrent flight training today - the scenario was a flight from Charleston SC to Atlanta GA - about 25 minutes after departure got a low oil pressure warning on the number one engine. The warning was not accompanied by oil temperature increase and just about the time I got the checklist out the warning ceased. All seemed well for about five minutes and we got the oil pressure warning again. And like before it stopped between 45 and 60 seconds later. I discussed the issue with the first officer - we considered the possibility that this was simply a oil pressure sensor gone bad and therefore it would be a shame to shut down a good engine when who knows but we may need both engine thrust (or electrical generators, or hydraulic pumps) later. We considered the fact that this aircraft with one engine was more than capable of making a successful approach and landing from our position if we choose to secure engine #1 as a precaution. We also considered the possibility that if we were to run both engines and ignore the intermittent warnings we might configure the instrument approach into Atlanta normally but at the last minute unexpectedly lose engine #1.
In the end we both agreed that it would be best to retain the redundancy of two engines as long as possible while planning for a possible loss of that engine at the worst possible time. The worst possible time to lose an engine would be in the event of a missed approach. Attempting to climb with full flaps at low altitude with maximum power on one engine, though certainly possible, would be challenging for the pilot flying along with the increased task load of securing the engine (challenging for the pilot not flying).
Our compromise decision was to idle the problematic engine, run the Engine Shut Down and Single Engine Procedure checklists (without actually shutting down engine #1) to ensure we could simply select fuel cut-off (and press the fire switches, if necessary) if the engine were to actually fail.
The #1 engine did, in fact, fail on approach - no severe damage or fire so I simply went to fuel cut-off and we procedeed to land.
Like most LOFTs*, this is one of those multiple approach type problems that has no book solution - as the instructor said, ‘good thinking outside the box’ Needless to say, the first officer and I were pleased!
*Line Oriented Flight Training