M7 Answer Sheet 7.11 Bearings

This set of vocabulary flashcards covers aircraft bearing mechanics, maintenance procedures, lubrication types, and common failure modes as discussed in the M7 lecture notes.

Sealed or shielded bearings

Bearings designed to prevent the ingress of foreign particles, contamination, or FOD, but which cannot normally be re-greased and must be replaced if lubricant is lost.

Axial / Thrust loads

One of the two primary forces acting on a bearing, alongside Radial / Journal loads.

Radial / Journal loads

One of the two primary forces acting on a bearing, alongside Axial / Thrust loads.

Rust-preventative oil

A manufacturer-specified coating used on bearings that are cleaned but not to be installed immediately.

Overpacks

A condition caused by too much grease or lubrication, which causes the bearing to run hot and shortens its service life.

Effective lubrication

A process that reduces friction, abrasion, and heat; prolongs service life; prevents rust/corrosion; and keeps foreign material away from rolling elements.

Tapered roller bearings

The specific type of bearings found in wheels which must be repacked with the correct grease during servicing.

Hydrodynamic lubrication

One of the four types of lubricants used for bearings.

Hydrostatic lubrication

One of the four types of lubricants used for bearings.

Boundary lubrication

One of the four types of lubricants used for bearings.

Solid film lubrication

One of the four types of lubricants used for bearings.

Fatigue

One of the two most common causes of bearing failure, alongside contamination.

Contamination

The main cause of bearing failure, involving abrasive foreign matter like sand, grit, or dirt that causes denting, scratching, and wear.

True Brinelling

Bearing damage caused by excessive impact or static overload beyond the elastic limit of the material.

False Brinelling

A defect caused by vibration while the bearing is stationary, often in combination with poor lubrication and small-amplitude oscillating motion.

Galling

A condition resulting from insufficient lubrication that leads to scoring or tearing of the metal surface and rough, smeared marks on the raceway.