A gas turbine engine includes a turbine and a compressor in rotational communication with the turbine via a shaft. The shaft is rotatable about a longitudinal centerline and includes a first axial end and a second axial end opposite the first axial end. The gas turbine engine further includes a first bearing compartment including a first compartment casing detachably mounted axially outside the compressor and the turbine. The first bearing compartment is in contact with the first axial end of the shaft and includes a first bearing which rotatably supports the shaft. The first bearing compartment is self-contained such that an internal lubrication system of the first bearing compartment is fluidally isolated from a remainder of the gas turbine engine outside the first bearing compartment.