import numpy as np
from scipy.interpolate import griddata

def inpaint_nans_3d(array):
    # Get coordinates of non-nan values
    valid_mask = ~np.isnan(array)
    coords = np.array(np.nonzero(valid_mask)).T
    values = array[valid_mask]
    
    # Get coordinates of nan values
    nan_coords = np.array(np.nonzero(~valid_mask)).T
    
    # Interpolate
    filled_values = griddata(coords, values, nan_coords, method='linear')
    
    # Create output array and fill with interpolated values
    result = array.copy()
    result[~valid_mask] = filled_values
    return result