# Presentation: 157399

## 5A AOE-0588 SSQ 21654 Fiber Optic Cable Anomaly - Status

**Boeing - EEE Parts**

**January 13, 2000**

**David Gill**
**(714) 896-6403**

**Notes:**
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This template is intended to provide guidance for preparing to present information to ISSP control panels and control boards pertaining to solutions to problems that may exist in the program.
The format is structured to present:
a clear definition of the problem, 
who/what is impacted by the problem, 
options to resolve the problem, 
how implementing the options will improve the situation, 
and what is expected from the control panel or board.

## Risk Assessment

**Risk Quantification of failure to early ISS fiber optic cables for this post fiber draw processing effects**
- Based on current understanding of root cause(s)
- All shipped cable is suspect of defect
- Model developed uses probability events (failures/15 year life)
- Probability of primary defect(s) that have not been detected
- Primary Defect Probability, Strength, and Optical Loss
- Data from “Bubble” testing being performed in HB
- Probability of Secondary defect
- Data from Strength testing being performed in B-HB
- Life of cable for applied loads
- Original cable qualification assumed no jacketing effects to fiber
- Data from Strength testing being performed in B-HB
- Probability of latent failure on orbit
- Coating Defect Generated
- HF Etch Presence
- Data from HF measured testing being performed in NASA-GSFC
- Probability of system functionality loss

## Risk Assessment Status

- Model correlates test specimens and flight cable
- Similar fiber cable history
- Data from testing will be evaluated by the Fiber Team for consensus of interpretation and define risks to ISS
- Other non-quantifiable risk facts
- Evaluation of failed specimens
- Limited testing of flight links
- Supplier’s positions
**Risk assessment and recommendations to Dorothy Feb 3, 2000**

## B-HB Strength Test Schedule

## Root Cause Status

**Current Potential Root Cause(s)**
- Coating Defect which exposes glass most probably caused by
- Improper carbon and polyimide coating
- Spectran process variations
- Improper polyimide coating combined with high electrical field (ESD)
- Spectran polyimide bubbles caused by process variations
- BICC Cable Jacketing machines generate high electrical fields and lack of moisture controls
- Evidence exists that ESD model produces coating defects large and small.  Some might not be detectable using any currently known non-distructive methods (Small localized damage in combination with low HF vapor pressure or duration)
- Exposed glass becomes etched as a result of FEP jacketing processes
- High temperature extrusion of pellet
- Pellets processed w/o inert gas drying prior to extrusion

## Options and Impact Status

**Testing Lab would not result in 100% confidence**
- No test method exists for secondary defect failure mode (partial etch)
- Primary defect test would impact cost and schedule
- HeNe laser can provide 100% primary defect detection but must have line of sight
- Coverage areas behind backshell or in large bundles would be difficult and would be less than 100%
- OTDR has shown to provide less than 100% primary defect detection
- Coverage washed out near terminations
- Must be shoot from both ends
- Difficult to perform on multi-link segment
- Limited testing of ISS mission critical links could reduce risk and cost/schedule impacts
**Rebuild harnesses**
- No ISS fiber optic cable alternatives available currently (est. 6 month impact to qualify alternative)
- Study is being performed for viable options and risks/trades
- Rebuild fiber optic harnesses would impact cost and schedule
- Major disassembly, rebuild, re-assembly, and regression testing

## ITCE FO Cable Forward Plan

**Place forward requirements PO**
- Monitor processing of new cable
- Urgent requirements on hold waiting cable
**Disposition all 8-98 and later impounded fiber reels as ****“good” **
- Perform lot by lot qualification using strength testing
- Several lots are already known to fail
**Disposition all harnesses impounded that contain 8-98 or later fiber **
- Using the high power HeNe laser protocol for ground test only
- Rebuild with “good” fiber per 8-98 and later reel disposition
**Disposition each installed harness element by element**
- Verify lot code of each fiber link on each harness
- Disposition “use as is” if early cable on harness
- Analyze each harness with 8-98 or later cable links and determine best rework and retest option

## FO Cable Supplier Restart Plan

**PO for 15K feet of SSQ 21654 fiber cable is being processed**
- SEA Currently Has 8K feet that has been laser screened
- BICCGeneral currently has 17K’ of non-jacketed fiber that has been verified for OD and has been laser screened
- Spectran has other users with demands that have re-started their production line for this Flightguide Product (SSQ 21654 fiber optic cable unjacketed and supplied to BICCGeneral for jacketing)
**Team will recommend process inspections and tests of new product as initiate it is being manufactured, assembled, and handled and monitor the first production runs**
**Recommendations are being developed and will be agreed to be team **
- Supplier processing and inspections
- Includes user incoming inspections and testing
- Restart the production line and monitor
- SSQ 21654 Requirement to use high power HeNe laser during acceptance testing to verify fiber cable has no glass etch defects
- Qualify each lot of cable for fiber strength distribution

## Risk Mitigation Plans

**Strategy for on-orbit maintenance**
- Plans are being developed to review from the designer’s standpoint the best maintenance options to recommend to operations
- Analyzing the system functions and how a cable would be detected if failed
- Analyze the installed hardware for repair options
- EVA & IVA installations
- Fusion splicing, single link & cable replacements options
- Overlay techniques if complete cable replacement
- Recommend to program forward plans
**Strategy for alternate cable sources**
- Study currently being performed to analyze available options
- Options considering going away from hermetic coated fiber for those applications where bend radius are not small (99+% of applications)
- Different jacketing options
- Evaluate the effects of termination re-qualifications
- Recommend to program forward plans