TR:
I remember some of the "single up to save gas" advocates. I'd be surprised if that is a common meme in commercial twin operations, as it probably would not pass the smell test for an SOP or Chief Pilot review. I always figured "if I've got two, I want two running!"
Digression.
Sea Story.
Avoid if not interested.
There was a tragic crash that got a change to our Squadron SOP when a bird on the other coast did just that ... ending in tears. This was over 30 years ago.
H-2 on a flight in California, from San Diego to points North (IIRC Alameda, but memory does not serve). Crew had chosen to single up (fly with one T-58 engine secured) once they got to altitude to extend range and fuel reserve. Long story short, trouble with the engine they were using got their attention, unable to restart enigne, the engine running didn't get beter, and it all didn't end well.
In discussions after that accident in our squadron (other coast) some interesting "lore" cropped up that had apparenlty been passed down by word of mouth from some of the old hands. This came down from as far back as when the H-2 (A/B) was a single engined helicopter. (The C/D and F were twins).
Turns out that a lot of the old salts had, particularly whilst deployed at sea, not infrequently singled up to save fuel on some long missions to extend their fuel margin. (I'd been taught that this was only done in an emergency if you ended up at rendezvous when the ship wasn't there. )
"Works fine on one engine at both max range and max conserve airspeed." True, it did. But ... te mishap investigation brought to light a tendency for (memory shady) oil to pool in the engine not running in such a case, due to windmilling and various bits inside the engine turning as a result. The investigaiton attributed that to most likely fouling igniter plugs/ingnition sequence when trying to restart.) But the killer was the one guy whose senior HAC, on a prevoius tour, had singled up (he
never trusted the ship drivers to be where they said they'd be) on most missions. Per his recounting, they had done two separate single engine landings back on the ship when they'd not gotten a restart!
But they kept that story at sea ...
... so as to avoid trouble "back home."
Our CO decided that "the taxpayers bought you guys two engines, you will use them unless and until they quit" and clearly stated that in the revised SOP.
He was a bit perturbed that he'd had to spell it out in writing, as he figured it was common sense. In this case, I guess he had to legislate common sense.
