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/lp/emerald-publishing/automatic-eddy-current-inspection-for-space-shuttle-wheels-HXCrPqpUnG
- Publisher
- Emerald Publishing
- Copyright
- Copyright © Emerald Group Publishing Limited
- ISSN
- 0002-2667
- DOI
- 10.1108/eb037030
- Publisher site
- See Article on Publisher Site
Abstract
comparison to future inspections and for certifications. Following a BFG equipment evaluation to meet the new requirements, a Model AT1 15-6 wheel Automatic Eddy inspection turntable was purchased from Air Treads and combined with a Magnaflux ED-800 eddy current unit Current with a dedicated contour probe, also from Magnaflux. The eddy current signal is recorded on a Gould 220, 2- channel recorder. Inspection for Inspection is performed by placing the wheel on the turntable and starting the machine and recorder. As the Space Shuttle turntable rotates, the eddy current probe arm gradually traverses the length of the wheel until the entire outer Wheels surface has been inspected. T o complete the procedure, the recording of the trace is examined for any indications. by Pat Skow, BFG Chief Plant Metallurgist Space Shuttle specification This system has the capability to easily detect a forging anomoly as small BF GOODRICH has installed and is residual stresses, enhancing the fatigue- as 0.015" deep and 0.030" long. The operating a new system of in-process life of the part. The flange/bead seat/ specification for the Space Shuttle inspection for the manufacture of wheels tubewell areas are ideally suited for this wheel requires that any defect larger for the Space Shuttle. than 0.025" deep by 0.050" long, be operation because of part geometry. detected. This criteria allows a wheel This new process enables BF Goodrich, Because machining and stress rolling of these areas are performed in consecutive with smaller defects to be used in service the designer and manufacturer of wheels and brakes for all NASA Space Shuttles, operations on an NC machining center, with the appropriate inspection intervals to meet the new maintenance and it is undesirable to remove the part from to detect any defect growth, should it occur. design requirement called "fracture the fixture to perform fluorescent pene control." trant inpection (FPI) prior to an Once the eddy current inspection has operation that cold works the machined The "fracture control" design of the been completed and the wheel is surface. determined to be acceptable, the remain new Space Shuttle main landing gear wheels requires the use of higher quality der of the machining operations are Eddy current inspection was selected forgings than previously specified. This completed. The part is then subjected to because it is unaffected by the cold new requirement incorporates eddy working and is able to detect surface FPI before the specific areas of the current inspection of specified areas of and shallow subsurface internal defects wheel are shotpeened and anodized. each wheel during manufacture. The which may have escaped the ultrasonic specified areas include the flange, bead (US) inspection of the raw forging. BF Goodrich Aerospace, seat, and tubewell, following wheel Eddy current is capable of detecting Aircraft Wheels & Brakes, machining and stress rolling. previously open defects, forced closed Waco Street, from surface cold working. PO Box 340, Stress rolling is a mechanical operation Troy OH 45373 in which the machined surface is cold A permanent record of this inspection, Tel: 513 339 3811. worked to induce surface compressive in the form of a trace, was selected for 8 AIRCRAFT ENGINEERING — December 1990
Journal
Aircraft Engineering and Aerospace Technology – Emerald Publishing
Published: Dec 1, 1990