1、Lessons Learned Entry: 0060Lesson Info:a71 Lesson Number: 0060a71 Lesson Date: 1985-02-20a71 Submitting Organization: KSCa71 Submitted by: David PenningtonSubject: Effective Tagout and Lockout Compliance; Upper Limit Switches Utilized as Operational Stops; Momentary Switches; Wire Rope Spooling Syst
2、em; Access Platform Load Rating; Telescoping Tubes of the OPF Access Platform System; Commonality Between High Bay 1 and High Bay 2 Payload Bay Access Platforms Description of Driving Event: During final closeout operations of the space shuttle orbiter in High Bay 2 of the Orbiter Processing Facilit
3、y (OPF), a payload bay access platform fell from its stowed position, damaging the orbiters left payload bay door and injuring a technician. The platforms hoisting cable was previously weakened when technicians used the platform system while it was tagout/lockout. The weakened cable continued to str
4、etch and break, even though the technicians returned it to its stowed position.Lesson(s) Learned: 1. Use of an inadequate tagout or lockout device may allow improper restoration of a system previously tagged as hazardous.2. Upper limit switches being used as operational stops can not be relied upon
5、to stop the operation during an emergency.3. Momentary switches that stick in the “on“ position may damage equipment and endanger personnel.4. Hoist systems (as used in the OPF) can release excessive lengths of cable from the spool.5. Operations in the orbiter processing facility are limited by acce
6、ss platforms that are limited to loads of 500 pounds or less.6. Telescopic tubes have experienced binding as they were lowered, indicated by a tube descending suddenly to its proper position after becoming free.7. Servicing operations utilizing payload bay access platforms have shown that a common s
7、peed mode for both east and west platforms is undesirable.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Recommendation(s): 1. Design positive lockout devices that will ensure compliance with lockout/tagout directives.2. Install operational stopping
8、 devices that will permit stowing of the platform vertically without the use of the upper limit switch.3. Momentary switches utilized in control systems should have a manual release capability designed in.4. Design the wire rope spooling systems to include stops that will prevent excessive amounts o
9、f wire rope from being released.5. Enhance the hoist system of the OPF access platforms to support heavier loads (up to 1500 pounds).6. Provide a device in the wire rope system that will sense excessive loads and stop the hoist when a safe load is exceeded or the cable is slack.7. Change the High Ba
10、y 1 access platform to operate the same way as High Bay 2, where both east and west platforms have independent speed modes.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Facilitiesa71 Ground Operationsa71 Grou
11、nd Equipmenta71 Hardwarea71 Hazardous/Toxic Waste/Materialsa71 Industrial Operationsa71 Safety & Mission AssuranceAdditional Info: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: a71 Approval Date: 1994-06-02a71 Approval Name: James G. Klinea71 Approval Organization: KSC/HEIa71 Approval Phone Number: 407-867-7614Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
