L - Cracks have only light spalling (little or no FOD potential) or no spalling, and can be filled or non-filled. If non-filled, the cracks have a mean width of ¼ in. (6 mm) or less; filled cracks are of any width, but their filler material is in satisfactory condition.
Porous Friction Courses:
L - Average raveled area around the crack is less than ¼ in. (6 mm) wide.
M - One of the following conditions exists: (1) cracks are moderately spalled (some FOD potential) and can be either filled or non-filled of any width; (2) filled cracks are not spalled or are lightly spalled, but filler is in unsatisfactory condition; (3) non-filled cracks are not spalled or are only lightly spalled, but the mean crack width is greater than 1⁄4 in. (6 mm), or (4) light random cracking exists near the crack or at the corners of intersecting cracks.
Porous Friction Courses:
M - Average raveled area around the crack is between ¼ to 1 in. (6 to 25 mm) wide.
H - Cracks are severely spalled and pieces are loose or missing causing definite FOD potential. Cracks can be either filled or non-filled of any width.
Porous Friction Courses:
H - Average raveled area around the crack is greater than 1 in. (25 mm) wide.