REG NASA-LLIS-0064-1992 Lessons Learned - Emergency Stop (E-STOP) Switch Cover Inadvertent Disconnection of Flex Hoses Orbiter Tow Tug and Support Truck Emergency Stop.pdf

1、Lessons Learned Entry: 0064Lesson Info:a71 Lesson Number: 0064a71 Lesson Date: 1992-03-12a71 Submitting Organization: KSCa71 Submitted by: David PenningtonSubject: Emergency Stop (E-STOP) Switch Cover; Inadvertent Disconnection of Flex Hoses; Orbiter Tow Tug and Support Truck Emergency Stop Descript

2、ion of Driving Event: After the towing convoy turned off the runway onto the tow way, the cool tractor/trailer suddenly stopped. The observer caused the rig to suddenly stop when his hand inadvertently came in contact with the E-STOP switch cover. This caused the boom to oscillate up and down. The b

3、oom operator lowered the boom to get maximum extension on the two coolant flex hoses attached to the orbiter. The booms oscillation caused the flex hoses to be whipped loose before the orbiter could stop. The flex hoses fell to the ground with freon 14 spewing from them.Lesson(s) Learned: 1. Emergen

4、cy stop switch covers made of soft or pliable material allowing inadvertent actuation of emergency stop switch.2. When the trailing support vehicle inadvertently stops, the tow tug continues allowing the flex hoses to pull free and spew freon 14.3. Lack of integrated emergency stop control switches

5、allowed the tow tug to proceed when the trailing support vehicle initiated an emergency stop.Recommendation(s): 1. Utilize double action switches for emergency stop switches were there is a possibility of inadvertent actuation.2. Add automatic cut off switch activated by a flow sensor, that will sto

6、p the flow of freon Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-during unplanned flex hose separations.3. During tow operations the dead-man switches of both the tow tug and the support truck should be wired together so both trucks will stop toge

7、ther.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): a71 Space Operationsa71 Exploration SystemsAdditional Key Phrase(s): a71 Facilitiesa71 Flight Equipmenta71 Ground Operationsa71 Ground Equipmenta71 Hardwarea71 Launch Processa71 Launch Vehiclea71 TransportationAdditional Info: 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-,-,-