1、Lessons Learned Entry: 1876Lesson Info:a71 Lesson Number: 1876a71 Submitting Organization: KSCa71 Submitted by: Gholam Shaykhiana71 POC Name: Glenn Pereza71 POC Email: Glenn.S.Pereznasa.gova71 POC Phone: 321-867-6470Subject: ISS Lessons Learned: Implementing of Fiber Optic Cabling in Spacecraft Abst
2、ract: KSC accepted fiber that was sub par because we did not have a process to properly inspect and verify the quality of work from the manufacturer. The ISS engineers established an inspection system for fiber to combat these issues. Optical fiber transmission uses wavelengths which are above the v
3、isible light spectrum, and thus undetectable to the unaided eye. Typical optical transmission wavelengths are 850 nanometers (nm), 1310 nm, and 1550 nm. These wavelengths were chosen because they best match the transmission properties of available light sources with the transmission qualities of opt
4、ical fiber. The Boeing document MDP 0795 was developed to document the process for properly performing fiber optic inspections.Description of Driving Event: The International Space Station (ISS) Program uses fiber optic cabling extensively in the audio, video, and high rate data subsystems. KSC acce
5、pted fiber that was sub par because we did not have a process to properly inspect and verify the quality of work from the manufacturer.Lesson(s) Learned: Considerations when installing fiber optics in spacecraft: Vibration in the Launch environment can cause cracks and spalls on fiber endfaces to pr
6、opagate. Sharp edges or corners could damage fiber cable jacket. Movement of improperly secured fiber optic harnesses. Contamination on fiber endfaces will migrate more readily in microgravity when demating and mating connectors. Provided by IHSNot for ResaleNo reproduction or networking permitted w
7、ithout license from IHS-,-,-At KSC, we developed expertise in: pre-installation testing, handling, routing and securing, inspection, cleaning and acceptance. Pre-Installation Testing - Fiber endfaces should be inspected post-fabrication to verify proper polishing. - Fiber links should be tested to v
8、erify acceptable optical performance Handling - Care must be taken to prevent damage to fiber optic cable assemblies during the installation process. - Use Caution when handling to avoid violating the minimum bend radius of the fiber. - Fiber optic cables should only be handled and installed by trai
9、ned and certified fiber optic personnel. Routing and Securing - Fiber optic cable assemblies should not be combined in the same wiring bundle as wire or coaxial cable assemblies. - The minimum bend radius shall not be less than 10 times the cable diameter unless specified on the engineering document
10、ation. - For installation, fiber optic cable assemblies shall be tied at least once every 20cm (8 in), or per the engineering documentation. - The minimum bend radius shall not be violated at connector backshells. - Tie downs shall be tight enough to capture the fiber optic cable but shall not defor
11、m the cable outer jacket. The ties shall not pinch, deform, kink, or otherwise stress the cable assembly. - Fiber optic cable assemblies shall not be routed over sharp edges or corners unless appropriate protection is provided.Recommendation(s): It is important that every fiber connector be inspecte
12、d and cleaned prior to mating. An acceptable fiber optic connector endface will be properly polished, clean, and free of scratches, cracks, and spalls. Clean fiber optic components are a requirement for quality connections between fiber optic equipment. One of the most basic and important procedures
13、 for the maintenance of fiber optic systems is to clean the fiber optic equipment. Any contamination in the fiber connection can cause failure of the component or failure of the whole system. Even microscopic dust particles can cause a variety of problems for optical connections. A particle that par
14、tially or completely blocks the core generates strong back reflections, which can cause instability in the laser system. Dust particles trapped between two fiber faces can scratch the glass surfaces. Even if a particle is only situated on the cladding or the edge of the endface, it can cause an air
15、gap or misalignment between the fiber cores which significantly degrades the optical signal. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-When you clean fiber components, always complete the steps in the procedures carefully. The goal is to elimin
16、ate any dust or contamination and to provide a clean environment for the fiber-optic connection. Remember that inspection, cleaning and re-inspection are critical steps which must be done before you make any fiber- optic connection.Evidence of Recurrence Control Effectiveness: The ISS engineers then
17、 began to establish an inspection system for fiber to combat these issues. By performing inspection prior to acceptance, repairs became the responsibility of the provider and not KSC. The Boeing document MDP 0795 was developed to document the process for properly performing fiber optic inspections.D
18、ocuments Related to Lesson: MDP 0795 “INSPECTION OF FIBER OPTIC TERMINALS” Click here to download document. Mission Directorate(s): a71 Space OperationsAdditional Key Phrase(s): N/A Additional Info: a71 Project: ISSApproval Info: a71 Approval Date: 2008-09-23a71 Approval Name: mbella71 Approval Organization: HQProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
