Grounding can cause damage to the propeller and tail-end shaft. Potential defects include bending, breakage, twisting, or cracks in the propeller or tail-end shaft. Propeller blades might show distortion, cracks, or even loss of sections, while the propeller cone can be damaged or misaligned. Additional issues may include damage to coupling bolts, liners, or bearings and, in extreme cases, complete detachment or loss of the propeller.

Repairs:

Tail End Shaft:

• Minor surface defects can be machined out, provided the shaft diameter is not reduced by more than 3%. Cracks deeper than 15% of the shaft diameter require the shaft to be replaced. Damaged seals, liners, and bearings should be replaced, and coupling bolts should be renewed. Proper shaft alignment must be checked after repairs.

Propeller:

• Distorted or deformed blades can be straightened by slowly and uniformly heating them to the correct temperature and using weights and levers, followed by slow cooling to prevent internal stresses. Minor edge cracks can be removed by flaring, while larger cracks require drilling, welding, grinding, and polishing. Missing portions of blades can be replaced if necessary.

The crankshaft can sustain damage due to grounding. Common issues include slippage of the crankshaft on the main journal, damage to bearings, and deformation or cracking of the crankshaft itself.

Repairs:

Crankshaft Damage:

• If the crankshaft is irreparably damaged, it must be renewed. Minor damage might allow for machining and rebalancing, but this depends on the extent of the defect.

Crankshaft Slippage:

• For minor slippage (up to 5°), fuel pump and exhaust valve timing can be corrected by hydraulically expanding and rotating the camshaft position. For significant slippage, the crankshaft should be hydraulically jacked back into its original position or replaced if realignment is not feasible. Bearings damaged during the grounding event should also be replaced.