CFM56 Oil System Pumps

[320.jockey]

Hi folks,

new here with a quick question for the experts, just out of interest.

I can't find an exact explanation in my operations manual of the kind of pumps (oil supply + scavange pumps) used in the engine oil system of the CFM56 (in my case -5A/-5B). My guess is they are engine driven, as that would make a lot of sense and there is no CB for an engine oil pump in the cockpit (as far as I know). But I couldn't find any confirmation there or via google.

Can anyone confirm or clarify?

[tdracer]

Originally Posted by 320.jockey

Hi folks,

new here with a quick question for the experts, just out of interest.

I can't find an exact explanation in my operations manual of the kind of pumps (oil supply + scavange pumps) used in the engine oil system of the CFM56 (in my case -5A/-5B). My guess is they are engine driven, as that would make a lot of sense and there is no CB for an engine oil pump in the cockpit (as far as I know). But I couldn't find any confirmation there or via google.

Can anyone confirm or clarify?

Nothing particularly unique about the CFM. All large turbine engines have an accessory gearbox - nearly always driven from the high speed shaft - that drives oil pumps, electrical generation for the aircraft, hydraulic pumps, a dedicated generator or alternator to power the FADEC, high pressure fuel pump, etc. The engines designed to be pretty much 'stand alone' - they need little to run from the aircraft other than fuel.
I'm unaware of any engine that uses aircraft power to drive an oil pump - you wouldn't want a problem with the aircraft electrical system to cause all the engines to fail.

[320.jockey]

Yup, makes sense. I just found it a bit odd that in the system description it's not stated explicitly, however in the description of all other accessory gearbox components - for example the HP fuel pump - it is. Thanks nevertheless

[Zar_1]

Yup, and IDK if I'm correct, but I guess they use a CVT (transmission) to maintain accessory shaft RPM.

CVT's are super cool, and it's kinda funny how they're used everywhere, from my collegiate Baja ATV's to a freakin' CFM56.