Factors in AERATION and DEAERATION of AIRCRAFT-ENGINE OIL 460209
AERATION of aircraft-engine oil has spasmodically caused trouble with pressure regulation for several years.
A protracted investigation and test program by Wright Aeronautical Corp., though still unfinished, shows by laboratory, test stand, and flight test, that some facts well known for years have been neglected and aeration of oil therefore invited while deaeration has been definitely restrained.
A review of basic facts and known methods indicates that if they were taken into account in design and service operation, we could go a long way in reducing trouble with oil pressure regulation due to entrained air, according to Mr. Weeks.
The engine itself, obviously, is the main source of entrained air, but the scavenge pumps are not solely responsible, the author reports. Oil fed to them from gear trains contains 6-20% very finely divided air.
Entrained air is, he concludes, inherent to engines with integral reduction drive gears, supercharger drives, and multiple accessory drives.
In facing this fact, Mr. Weeks states further, we cannot continue to handicap deaeration with low operating oil temperatures and localized oil flow through tanks as imposed by the conventional hopper.
With these restraints to deaeration removed, he feels that it will probably be found unnecessary to add accessory operating devices to the powerplant oil system in most cases, although several devices or means either have been or can be developed.