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The average 747 contains 171 miles of wiring and five miles of tubing, and is made up of six million parts-half of them fasteners. The first 747 required 75,000 engineering drawings. Given such complexity, people's failure to appreciate the importance of the huge airliner's wheels is hardly surprising. Yet aircraft wheels are subject to enormous pressures, particularly during landing. A Boeing 747 weighing more than 660,000 pounds touches down at around 124 miles per hour.
During those few landing seconds, the safety of the airliner and all on board depend on the wheels. Consequently, civil aviation authorities around the world insist that each wheel undergoes strict tests at regular intervals to maintain its top condition. Dunlop Aerospace Services (DAS, Coventry, UK), the repair and overhaul business unit of Dunlop Aerospace Braking Systems, a Meggitt group company, tests aircraft wheels. DAS specializes in nondestructive testing (NDT) of aircraft wheels, as well as repair of aircraft brakes, engine accessories and braking systems equipment.
Looking for the latest technology for aircraft wheel inspections, DAS turned to GE Inspection Technologies (Germany) to supply the equipment to test aircraft wheels. DAS and GE Inspection Technologies worked together to develop the WheelScan 5 automatic wheel inspection rig.
"We looked at equipment from a number of alternative suppliers," says Andrew Pawson, wheel cell team leader for DAS. "But WheelScan 5 had clear advantages in a variety of areas." The equipment's versatility was a plus because WheelScan 5 can test the full range of aircraft wheels currently on the market-from those fitted on the smallest aircraft to the wheels used by the new Airbus 380.
Pawson was influential in determining DAS's decision to buy WheelScan 5. Once he knew that it was being developed, he wanted the rig before it had been officially launched. "It's the latest and most advanced equipment on the market in technological terms, and I couldn't see the point of waiting," Pawson says.
"WheelScan 5 has delivered enormous benefits to DAS and to our clients. All of our customers who have come in to see the rig in action have been impressed, as have visitors from the regulatory authorities," Pawson adds.
Pawson says that the inspection tool's ability to store and retrieve data for a specific wheel has excited customers-it holds and recalls up to 100,000 wheel records, without the need for paper printouts. "Our clients now know that we can save their wheel's serial number in the computer. Should they ever wish to retrieve any data on that particular wheel, we can download it immediately and e-mail the results to them," Pawson says. "We can keep data on a specific wheel for years, so if, for example, it develops a crack, we can look back at the history of the wheel and see how the crack came about."
Once gathered, data can be stored digitally for future recall. The retrieval process can be automated so that a single bar code scan recalls the whole test. The operator ID and job references also can be inputted by bar code. This removes the need for manual data entry, the most frequent cause of data error in comparable systems. A key switch can prevent the operator from making adjustments. Automating the process provides a guaranteed inspection for DAS.
Pawson also cites significant time savings as one of the merits of investing in the latest technology. In an industry increasingly required to drive down costs and lead times, this is an asset. WheelScan 5's increased efficiency gives DAS an advantage in terms of winning new customers and retaining old ones.
The new testing equipment is sturdier than the previous equipment used by DAS-it is made of steel rather than aluminum. This is important because some of the wheels tested in Coventry can weigh up to 120 pounds. According to Rupert Anderson, a fitter and tester at DAS, it is easier to use than its predecessor and the operator can quickly program it. The company can set up the WheelScan 5 to test a particular wheel within a couple of seconds rather than the 40 seconds required by the old equipment.
Robin Evans, aerospace segment manager at GE Inspection Technologies, points out that the company sends people to DAS to make changes on site to the machine's hardware or software as required. "This could have caused problems since we were not only trying to meet the Coventry unit's service requirements but also working in a production environment. We had to ensure that operators weren't inconvenienced and that we did not disrupt the unit's output," Evans says.
The equipment's mobility was another key factor in DAS's decision to buy. "Everything in our workshops is now mobile," says Pawson. "It means we can load the equipment on a [truck], draw up alongside an airliner and inspect the wheels. It's not something we do at the moment but I think that's the future because mobile testing and repairs could deliver significant cost-savings to the airline industry in terms of reduced inventory," he adds.
DAS's investment in WheelScan 5 already has paid dividends, according to Pawson. It has helped the company to maintain its competitive edge and to win new business and clients.
The inspection tool has been perfected from DAS input after using the tool for two years. Says Evans of GE Inspection Technologies, "DAS submitted the idea of using steel rollers, while their in-service testing of the machinery played a vital role in ensuring that the product met the needs of customers."
GE Inspection Technologies
• The inspection rig can store and retrieve data for a specific wheel-recalling up to 100,000 wheel records without paper printouts.
• Adding to its durability, the WheelScan 5 is made of steel rather than aluminum.
• The equipment can be set up to test a particular wheel within a couple of seconds vs. 40 seconds required by the company's previous equipment.
• The WheelScan 5 test equipment is mobile and can be loaded on a truck for inspection alongside an airliner.