meritflyer
Well-Known Member
The two hoses that are on the underside of the engine cowling, if I remember correclty, are an over flow for oil and what else?It's been a while since I studied 172 systems...
Drain hoses on the bottom of a 172
- Thread starter meritflyer
- Start date
R
Roger, Roger
Guest
Not an oil overflow, but the crankcase breather. It keeps the crankcase from pressurizing due to exhaust gases that blow by the piston rings. Most engines will blow oil out the breather if over-filled. The second one is the battery vent. At least that is the way it is on the newer 172s (I fly R models).
ppragman
FLIPY FLAPS!
:yeahthat:
Crank case breather, and battery breather it seems is most common. I've seen other esoteric hoses and stuff from model to model, but check the POH or ask a mechanic if you don't know.
The 207 is notorious for wasting precious oil. If you fill it to 12qts (the max) it will blow all the oil out until it stabilizes at 10qts or so, then minimum oil is 9qts.
Blip16
Well-Known Member
most aviation engines don't seem to like full oil. the o-320's and o-360's seem to like 7 even though 8 is max
R
Roger, Roger
Guest
We run our 360s on 6 quarts, and they don't blow very much oil out the breather. The only reason most of those engines have such a large sump capacity is certification...I can't remember the specifics, but it has something to do with them needing to be able to run x number of hours with y rate of oil consumption, and still not get below the minimum oil needed to run.
*edit*
33.39 (a)
The lubrication system of the engine must be designed and constructed so that it will function properly in all flight attitudes and atmospheric conditions in which the airplane is expected to operate. In wet sump engines, this requirement must be met when only one-half of the maximum lubricant supply is in the engine.
So they make the sump bigger, so that the engine can meet that requirement with the sump half full.
Part 23 has some additional requirements for dry sump engines.
23.1011 (c)
The usable oil tank capacity may not be less than the product of the endurance of the airplane under critical operating conditions and the maximum oil consumption of the engine under the same conditions, plus a suitable margin to ensure adequate circulation and cooling.
*edit*
33.39 (a)
The lubrication system of the engine must be designed and constructed so that it will function properly in all flight attitudes and atmospheric conditions in which the airplane is expected to operate. In wet sump engines, this requirement must be met when only one-half of the maximum lubricant supply is in the engine.
So they make the sump bigger, so that the engine can meet that requirement with the sump half full.
Part 23 has some additional requirements for dry sump engines.
23.1011 (c)
The usable oil tank capacity may not be less than the product of the endurance of the airplane under critical operating conditions and the maximum oil consumption of the engine under the same conditions, plus a suitable margin to ensure adequate circulation and cooling.
ppragman
FLIPY FLAPS!
The M model 172 we've got with an O-320 seems to like about 6.5 or 7 I agree.
Well there ya go. Thanks a bunch, I've always wanted to know that.