1、 Public Lessons Learned Entry: 3276Lesson Info:a71 Lesson Number: 3276 a71 Submitting Organization: KSC a71 Submitted by: Annette Pitt Subject: Reinforced Carbon-Carbon (RCC) Inspection Processes Abstract: Reinforced carbon-carbon (RCC) is a material that can withstand the high temperatures of reent
2、ry and can be used in areas where greater durability is desired. When RCC is exposed to high temperatures, it oxidizes rapidly, so a coating is required to reduce its exposure to oxygen. Reactions with these coatings can cause subsurface voids in the RCC. To accurately inspect and assess the conditi
3、on of the RCC, a nondestructive evaluation (NDE) is required to see under the outside coatings. Thermography is one method that was utilized for RCC inspections. When using NDE as an inspection process, the criteria and baselines have to be well developed to accurately interpret the results so that
4、indications are understood and an accurate assessment can be made to determine the acceptability of the condition observed. Description of Driving Event: Upon postflight evaluations of RCC materials on the Space Shuttle orbiters, areas of coating were missing, thus exposing subsurface RCC oxidation
5、and voids. These coating issues were referred to as “spaulation.” A tactile method was developed to detect subsurface voids and weak areas in the RCC as a result of oxidation and voids. During the Columbia accident investigation, it was determined that this tactile method was not an efficient method
6、 for detecting subsurface anomalies. Lesson(s) Learned: Although NDE did provide a much better view of the subsurface conditions and should be used for this situation, it is equally important to perform a baseline study to calibrate the results. Voids and anomalies exist on brand new parts, and acce
7、ptance criteria must be developed based on testing. Recommendation(s): Establish NDE requirements for RCC components to detect subsurface flaws and oxidation. Establish a requirement to perform an evaluation to establish a baseline for new parts. During the design stage, establish a method to interp
8、ret NDE results and determine limits. From the standpoint of design for operability, using a clear sealant would help in performing RCC evaluations, and a coating that does not trap gas beneath the coating during re-entry heating would reduce the negative effects on the carbon substrate. Evidence of
9、 Recurrence Control Effectiveness: N/A Documents Related to Lesson: Click here to download OV-105 Panel 14L and 9R Flight Rationale PRT Review Charts Click here to download STS-130 Computed Tomography Results Presentation Mission Directorate(s): a71 Space Operations a71 Exploration Systems Additiona
10、l Key Phrase(s): a71 Engineering Design (Phase C/D). Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-a71 Engineering Design (Phase C/D).Entry Systems a71 Mission Operations and Ground Support Systems. a71 Mission Operations and Ground Support Systems.Ground processing and manifesting Additional Info: a71 Project: Space Shuttle Program Approval Info: a71 Approval Date: 2010-12-02 a71 Approval Name: mbell a71 Approval Organization: HQ Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
