Singling up to extend range
I can't find a reference on current mishap data bases. There are a bunch of SH-2F accidents/write offs from the 80's that have very little detail over at the flight safety web site. All I can recall is that it was a west coast squadron. HSL-31, 33, 35. One of them.
As we got told in the east coast ... there was a reason that singling up to "extend range" was more or less an emergency procedure when using the T-58-8-F engine. The NATOPS manual had some interesting charts on how far one engine could take you. (If you fly over the open seas in single ship ops that kind of info is very handy to have ..)
The data point from the west coast was flight during the early/mid 80's, crew traveling from south to north California.
One engine taken one off line to extend range/extend reserve due to ... memory foggy I cannot recall details well ... perhaps a change in weather and alternates all of a sudden becoming less than desirable.
As it worked out, the one they were running on acted up. They were unable to restart the one that had been windmilling, which seems to have fouled the ignitor plugs ... something like that.
Ended in tears. IIRC, all souls perished, landing in mountainous terrain that went badly.
My takeaway was: use them both, unless it's an emergency.