REG NASA-LLIS-6116-2011 Lessons Learned - Environment Control and Life Support System (ECLSS) Ground Coolant System (GCS).pdf

1、Public Lessons Learned Entry: 6116 Lesson Info: Lesson Number: 6116 Lesson Date: 2011-6-29 Submitting Organization: KSC Submitted by: Michael Bell Subject: Environment Control and Life Support System (ECLSS) Ground Coolant System (GCS) Abstract: The basic S70-0508 Ground Coolant Unit design (heat lo

2、ad capacity) was oversized and could not handle the wide range of heat loads required when the Space Shuttle Orbiter is powered up. Electrical modifications were designed that almost completely redesigned the circulation unit. The Universal Coolant Transporter System (UCTS) was designed and delivere

3、d. It is important to conduct thorough processes when identifying core requirements for the design, provide a process for continuous improvement recommendations, document work processes, and be persistent in pursuing funding for operationally beneficial design changes. Description of Driving Event:

4、When the Space Shuttle Orbiter is powered up, the avionics and payloads on board develop heat. This heat must be removed, or damage to the equipment occurs. In orbit, cooling is provided by an on-board Refrigerant 21 system chilled by radiators, exposed to space, which are located on the Orbiters pa

5、yload bay doors. When the vehicle is at the pad, the ECLSS Pad GCS removes the heat through an on-board vehicle ground support equipment (GSE) heat exchanger whenever the vehicle needs to be powered up. During launch, the ECLSS Pad GCS chills the vehicles on-board loop low enough to provide a therma

6、l capacitance for cooling until orbit is achieved. The GCS also is required for Orbiter power up at the Orbiter Processing Facilities (OPFs), Vehicle Assembly Building (VAB), the Shuttle Landing Facility (SLF)/ Secondary Landing Site (SLS), and was used at Palmdale. In 1975, Rockwell developed the S

7、70-0508 Ground Coolant Unit. Even with some modifications, the basic S70-0508 design (heat load capacity) was still oversized and could not handle the wide range of heat loads required for launch. In late 1985, the Lockheed Space Operations Contractor (LSOC) investigated S70-0508 problems and recomm

8、ended interim fixes. From 1994-1996, LSOC designed, fabricated, and installed the enhanced new GCSs for the pads. In 1996, electrical modifications were designed that almost completely redesigned the circulation unit. In 2000-2001, United Space Alliance designed and delivered the Universal Coolant T

9、ransporter System (UCTS), which supported the post Columbia Shuttle landing at Dryden Flight Research Center in 2005. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Figure 1: UTCS Supporting the STS-114 See attached ECLSS Ground Coolant Systems Over

10、view Powerpoint presentation for initial S70-0508 modifications, new GCS features, and the complete history of this lesson. Lesson(s) Learned: Continuous improvement enhancements identified include the following: Design to use convoluted metal bellows flex hoses to eliminate the Teflon lined flex ho

11、se moisture permeability issue. An important lesson learned from the UCTS is that corrosion-resistant steel reinforced braided Teflonlined flex hoses are permeable to atmospheric moisture where there is stagnant media and the vapor pressure of allowable moisture for the internal media is less than t

12、he vapor pressure of moisture in ambient air. This was significantly mitigated (but not solved) on the UCTS boom flex hoses using an inline dryer, vapor barrier tape, and modified processes (e.g., boom isolation to reduce amount of moisture transferred from the stagnant boom subsystem to the UCT mod

13、ule). Have a fixed recovery system at the vehicle interface for operational setup time reduction. Change the maximum allowable working pressure from 250 psig to 500 psig. Use R-134a instead of R-124 for the fluid transfer media (primary loop/secondary loop) and use R-404 instead of R-22 for the refr

14、igeration cycle. (R-404 is used in the UCTS.) Found and fixed gaps in post-Shuttle (Pad B) Pressure Vessel processes; the gap inspired an integrated, visual approach to create required work instructions. Recommendation(s): 1. Support thorough thought processes in identifying the core requirements du

15、ring the design stage. 2. Provide a process for recommending continuous improvements for any design. 3. Document work processes. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4. Be persistent in pursuing funding for operationally beneficial design

16、changes Evidence of Recurrence Control Effectiveness: From 1975 to 1986, the S70-0508s had 527 Problem Reports, over five (5) times more than the new GCS for an equivalent time period. No significant support problems were encountered during the operation of GCS GSE for Shuttle support from November

17、13, 1999, to present. A Problem Report count totaling less than 100 for 12 years of service support for the Shuttle program attests to the thorough thought process that went into the core requirements needed during the design stage for this GSE. Documents Related to Lesson: ECLSS Ground Coolant Syst

18、ems Overview presentation Click here to view presentation Mission Directorate(s): Exploration Systems Space Operations Additional Key Phrase(s): Systems Engineering and Analysis.Engineering design and project processes and standards Engineering Design (Phase C/D).Environmental Control and Life Suppo

19、rt Systems Engineering Design (Phase C/D).Launch Systems Mission Operations and Ground Support Systems.Ground support systems Mission Operations and Ground Support Systems.Launch support systems Additional Categories.Ground Equipment Additional Categories.Ground Operations Additional Info: Project: Space Shuttle Program Approval Info: Approval Date: 2011-11-04 Approval Name: mbell Approval Organization: HQ Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-