| Subcomponents | Failure Modes | Main Causes |
| Gears | Fretting corrosion | Vibration among gear tooth surfaces |
| Bending fatigue | Excessive Stress on gear tooth | |
| Bearings | Cracking | Inhomogenous cooling |
| Abrasion | Contamination of lubricant oil | |
| Scuffing | The texture of surface is rough | |
| Lubricant Oil | Grain Pollution | Wear debris, Dust |
| Foam | Breathing of housing, Air trapped in oil, Not enough settling time |