Surface Preparation
If surfaces are to be milled, they generally must be covered with HMA during the same construction window. In some cases, airport operators have allowed operations on runways with partially milled surfaces. However, the milled surface must meet the pavement requirements set forth in 14 CFR Part 139 CERTIFICATION OF AIRPORTS:
- No hole exceeding 3 inches in depth
- No hole with an edge slope in excess of 45°.
- Free of cracks and surface variations that could impair air carrier aircraft steering or that produces loose aggregate or other contaminants.
- Edges between abutting sections must not exceed 3 inches difference in elevation.
- No mud, dirt, sand, loose aggregate, debris, foreign objects, rubber deposits or other contaminants.
- Sufficiently drained and free of depressions to prevent ponding that obscures markings or impairs safe aircraft operations.
- Any chemical solvent used must be removed as soon as possible.
