Aircraft fuel pump bearing.jpg: Metcar bushings use aviation fuel as a lubricant.
Aircraft fuel pump bearing.jpg: Metcar bushings use aviation fuel as a lubricant.

The Metcar carbon-graphite bushings are used to support both the drive gear shaft and the idler gear shaft and use aviation fuel as the bushing lubricant.

The bushings are self-lubricating and can run dry for short periods without failure or significant wear. According to MCC they are also dimensionally stable, which permits the close bushing to shaft running clearances required in gear pump applications.
 
MCC says the bushings have a low elastic modulus that are pre-stressed in compression. This means they exhibit almost the same coefficient of thermal expansion as the metallic gear pump housing material. This assures the running clearance between the shafts and the bushings will remain the same throughout the operating temperature range of the pump.