REG NASA-LLIS-3077-2010 Lessons Learned - Design for Operability Door Penetration Thermal Barrier Design.pdf

1、Public Lessons Learned Entry: 3077 Lesson Info: Lesson Number: 3077 Lesson Date: 2010-05-17 Submitting Organization: KSC Submitted by: Annette Pitt Subject: Design for Operability; Door Penetration Thermal Barrier Design Abstract: Door interfaces require a thermal seal that must be flexible and soft

2、 yet handle temperatures as high as 2000 degrees Fahrenheit. Silica-glass-based fabrics are primarily used for this application. Heat cycles on these materials tend to make them stiff and brittle, resulting in parts that are susceptible to damage from both flight and processing operations. New ideas

3、 to address this design requirement need to be explored. For the Space Shuttle Program, configuration changes were made that greatly improved process operability, but the basic design has remained unchanged. From stand-point of flight safety, a single thermal barrier does not supply redundancy, and

4、that risk must be accepted. Description of Driving Event: The original design for Space Shuttle gear doors and external tank (ET) doors used bonded parts that configured to match the full length of one side of the opening. For the main landing gear, a single small area of damage meant that a new 15-

5、foot-long part had to be skived off and a new part needed to be bonded. These main gear door parts were replaced after every flow and were very cumbersome to install. Lesson(s) Learned: The soft goods necessary to seal door interfaces are very susceptible to wear and tear and require a high level of

6、 maintenance. Finding an alternative method to seal door interfaces should be a priority. If this is not feasible, then design changes should be made to ease processing efforts. Recommendation(s): If a replacement material for silica fabric thermal barriers is not discovered, then door edge thermal

7、barriers in high-temperature areas need to be designed for easy replacement. One way to reduce processing time is to segment the thermal barrier so that only the discrepant portion has to be replaced. Using retainers to mechanically hold the thermal barriers in place helps processing by avoiding bon

8、ding procedures and lengthy cure times. High-temperature coatings can help the part last longer. Evidence of Recurrence Control Effectiveness: N/A Documents Related to Lesson: N/A Mission Directorate(s): Space Operations Exploration Systems Additional Key Phrase(s): 1.Ground processing and manifesti

9、ng 1.Entry Systems Additional Info: Project: Space Shuttle Program Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: Approval Date: 2010-08-26 Approval Name: mbell Approval Organization: HQ Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-