SubscribeIn 2003 and 2004, the US Federal Aviation Administration (FAA) Airport and Aircraft Safety Research and Development Airport Technology Branch, William J Hughes Technical Center investigated performance expectations and safety concerns relating to airside use of artificial turf.
It was concluded that artificial turf performed as well or better than natural turf.
Although the FAA tests covered a wide range of interest, this paper discusses one particular aspect: resistance of aviation-grade artificial turf (AGAT™) to jet blast and high winds.
Problem Statement
AGAT had been shown to be effective in mitigating a number of airside hazards. However, aerodrome operators expressed concern as to whether an artificial turf (also known as synthetic turf) installation could be dislodged or could cause foreign object debris (FOD) damage by:
- Jet blast from transport category aeroplanes;
- Concentrated air blowers;
- Everyday usage in an aerodrome blast pad;
- Helicopter operations;
- High winds; or
- Accidental abuse.
Artificial Turf
Artificial turf is a synthetic surface made to resemble grass, usually by binding grass-like fibres into a backing and then maintaining them upright with blends of infill material (e.g. sand, aggregate, etc.), as illustrated in Figure 1. Infill material, deposited to a density of 8 lbs / sq ft (39.05 kg / sq m), also performs as anchoring ballast. The edges of the installation are anchored to a turf attachment system.
Figure 1. Aviation-grade artificial turf (AGAT™) cross-section. Note. From Van Dyke (2006).
Air FieldTurf AGAT fibers have a unique honeycomb shape. When subjected to jet blast or high wind, the fibers fold over the top of the infill material to trap it within the honeycomb shape.
FAA Test Methods and Conclusions
Wind Tunnel
Wind tunnel tests simulated maximum jet blast effects of one month's aerodrome traffic mix of aircraft such as Boeing B737, B767, Fokker 100, McDonnell Douglas DC-9 and various turboprops.
Aeroplane Tests
Tests were conducted with static Boeing B757, B777 and B747 aircraft, each cycled at different engine power levels up to 80% thrust, to evaluate infill migration and AGAT surface damage. The aircraft were positioned close to the AGAT installation and the engine exhaust directed:
- Toward the AGAT and its edge;
- At an angle to the AGAT and its edge; and
- Parallel to the AGAT and its edge.
Following the static tests, the B777 and B747 aircraft were taxied parallel to the installation with the outboard engine over the AGAT.
Vehicle Tests
Vehicles, such as the Vammas® snow plow/sweeper/blower, use concentrated air to clean debris or snow from runways and taxiways. Concentrated air was directed toward the AGAT installation at various angles and differing velocities with a multiangle nozzle.
Helicopter Traffic
Although not intended as part of the evaluation, the FAA report notes that "airport operations personnel have witnessed helicopters taxi across the top of the surface at low altitudes with no adverse affects to the artificial turf from the rotorwash."
Conclusions
In all cases, Air FieldTurf AGAT showed no visible infill migration, artificial turf displacement or surface damage.
Anecdotal Data and Conclusions
Air FieldTurf has significant and relevant operational experience with a number of AGAT installations.
Helicopters
The Air FieldTurf AGAT installation at US Marine Corps Air Station Miramar (NKX/KNKX) has been exposed to rotorwash from large helicopters such as the Boeing CH-46 and CH-47 and Sikorsky CH-53 for several years.
The USMC evaluated the effects of jet blast and propwash on AGAT using aircraft such as the Boeing C-17, F/A-18, Lockheed C-5, and Lockheed C-130,
Aerodrome flooding
The Air FieldTurf AGAT installation at Ocean City, New Jersey (26N/K26N) is subject to repeated flooding when high tides and high rainfall rates coincide.
Severe weather
The parent company of Air FieldTurf has installed over 2000 sporting fields worldwide. One such sport field in Florida, United States had been passed over by a confirmed tornado.
Damage to AGAT installation
Prior to the FAA evaluation, a key concern expressed by aerodrome operators was whether or not damaged AGAT could itself be a source of FOD.
FAA tests using heavy vehicles and aircraft showed that damage to AGAT from normal use or moderate abuse is unlikely. However, in 2006, an asphalt contractor dug up one 30 ft (9.1m) edge of the AGAT installation at San Francisco International Airport (SFO/KSFO) and plied it back. No FOD was created and the infill on the undisturbed installation was more than sufficient to anchor the turf until repairs could be performed.
Conclusions
In all cases, Air FieldTurf AGAT showed no visible infill migration or artificial turf displacement.
References
Connelly, T. & Teubert, C. (2006). DOT/FAA/AR-06/23 Airside applications for artificial turf. U.S. Department of Transportation. Retrieved August 27, 2006 from http://www.tc.faa.gov/its/worldpac/techrpt/ar06-23.pdf
Federal Aviation Administration (FAA). (2005a). Advisory Circular AC No: 150/5379-XX Airside applications for artificial turf.
Van Dyke, D. L. (2006, October). Enhancing airside safety with synthetic turf. Paper presented at the Royal Aeronautical Society lecture, Montreal, Canada.
19 February 2007