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BAGRAM AIR FIELD, Afghanistan—Since Jan. 30, airmen who work on the flightline here have seen a new vehicle crossing the runway.
The vehicle, a TrackJet TJ-24 complete with high-capacity vacuum suction system, looks like a water tanker with a vacuum attached to the front.
Since its arrival, the slow-moving TJ-24 driven by contractors has been crisscrossing the flightline removing excessive rubber from the Department of Defenses’ busiest landing strip.
Removing excess rubber from runways dates back to the early 1970's when NASA, the Federal Aviation Administration and the Air Force began conducting runway traction studies.
According to FAA Advisory Circular AC 150/5320-12C, the most persistent contaminant problem is deposit of rubber from tires of landing jet aircraft. Rubber deposits occur at the touchdown areas on runways and can be quite extensive. Heavy rubber deposits can completely cover the pavement surface texture causing loss of aircraft braking capability and directional control, particularly when runways are wet.
To ensure safe operating conditions the FAA enacted friction levels for safe operation of aircraft and mandated individual airports incorporate rubber removal into their maintenance schedules based on the number of takeoffs and landings that each airport experiences.
To meet this requirement, 455th Expeditionary Civil Engineer Squadron engineers, on a semiannual basis, seek out companies with the equipment necessary to remove the excess rubber built up from the more than 16,000 takeoff and landings Bagram sees each month.
In Nov. 2010, a $430,000 contract was awarded to EMTA Electric Engineering Construction Contracting and Trade Inc. headquartered in Turkey to remove rubber from 27,000 square meters of runway.
“Usually we like to do this type of work ourselves or hire local contractors, but this is more technical than normal roadwork,” said Maj. Brock Sissel, 455th ECES Plans and Programs officer. “EMTA had to drive the million-dollar piece of equipment all the way from the manufacturer in Germany."
To put it into perspective the TJ-24 is capable of delivering 36,000 pounds of water-pressure per square inch versus the 3,600psi pressure-washer you purchase at the local hardware store for home use.
When the TJ-24 its crew of six are not removing rubber due to continuing operations they are stripping and repainting of more than 40 aircraft parking spaces.
“The conditions in the winter here bring the possibility of rain and snow which combined with the friction loss from excess rubber could cause a very dangerous landing for an aircraft,” explained Sissel.
Although the exact amount of rubber and paint to be removed is uncertain, the contractors guess it is enough to fill half of a 20 yard dumpster--more than 1,700 gallons of rubber.
“There is a lot of rubber on this airfield,” said Sven Kimmel, a contractor from the Weigel Cooperation who traveled with the TJ-24 crew to oversee the process. “This runway has more rubber built up on it then I have seen in my seven years in this business.”
Although the excess rubber is not the number one safety concern landing here at Bagram, it is one topic that often comes up between pilots after missions.
“Those that fly know the effects of built-up rubber, especially when it is wet,” said Maj. Gregory Craven, 455th Air Expeditionary Wing chief of flight safety. “While there haven’t been any direct mishaps from excessive rubber, there have been numerous pilots, in wet weather conditions, report concerns about being able to stop the aircraft before the end of the runway.”
For instance, an F-15E Strike Eagle, in most cases, touches down around 160 mph and slows to a taxi speed of 29 mph within a few thousand feet, but the larger the aircraft, the greater the distance required to slow down to a safe taxi speed.
“It’s not necessarily the amount of takeoff and landings, it is the type of aircraft taking off and landing here,” said Lt. Col. John Vincent, 455th AEW chief of safety. “A C-17 Globemaster III has 16 wheels and a whole lot of tonnage hitting the runway which leaves a lot of rubber.”
Because of the amount of continued air traffic here the rubber removal process will take several weeks to finish with the slow moving TJ-24.
“This is a reoccurring maintenance item. The entire process is needed and necessary, and not just at Bagram but every flightline for the safety of our pilots and passengers,” Sissel said.
| Date Taken: | 02.03.2011 |
| Date Posted: | 02.03.2011 03:37 |
| Story ID: | 64702 |
| Location: | BAGRAM AIR FIELD, AF |
| Web Views: | 157 |
| Downloads: | 0 |
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