1、Lessons Learned Entry: 1318Lesson Info:a71 Lesson Number: 1318a71 Lesson Date: 2002-11-21a71 Submitting Organization: LARCa71 Submitted by: Chip QuinnSubject: Scaffold Incident Description of Driving Event: An onsite maintenance and operations contractor was tasked to erect scaffolding inside of a w
2、ind tunnel test section so that a heavy gas door seal could be replaced. The test section floor is level until it opens into the tunnel where the floor slopes downward. The portion of tunnel that slopes down from the test section is called the contraction wall. One end of the scaffold had to be plac
3、ed on the down slope. In order to secure the scaffold, three pads were welded onto the test section floor which had a pivoting vertical tube attached to it. The vertical scaffold legs were slid into the tubes. Safety straps were attached to the test section floor because an outrigger section, which
4、extended out over the contraction wall, was installed on the main scaffold.After the completion of work, the onsite maintenance and operations contractor began to take down the scaffold. Four workers were tasked to disassemble the scaffold. Due to the uniqueness of the scaffolding arrangement, the w
5、orkers were told to wait for their supervisor to coordinate the effort. The workers took it upon themselves to disassemble the scaffold. During the disassembly, with the outrigger section still in place, the safety straps were removed. Two employees were on the scaffold when the straps were removed.
6、 As they continued to disassemble the scaffolding, the center of gravity shifted over the outrigger. This caused the scaffolding to topple over since the straps had been removed. Both employees rode the scaffolding to the bottom of the contraction wall. One employee sustained no injuries. The second
7、 employee told his co-workers to call 911. He was taken to a local hospital and released with minor injuries.All employees involved had received training on the assembling and disassembling of scaffolding. The crew lead was one of the employees working on the scaffolding. Under normal conditions, th
8、e crew lead would supervise the work, but the crew supervisor told the crew lead to not begin disassembly until he was present to supervise the work. The crew lead ignored this request and began disassembly. Because the crew lead was actively involved in the take down, he did not see his error Provi
9、ded by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-in removing the straps. He only saw the straps as being in his way of removing scaffolding pieces.Lesson(s) Learned: 1. The take down team should have waited for supervisors assistance as instructed prior to
10、 disassembling the scaffolding.2. Pointing out the high hazard of this task should have been stressed at the start of this undertaking.3. Do not remove the safety straps until the out rigger section has been removed. Explain to workers that the scaffolding could topple over if the straps are removed
11、 prematurely.Recommendation(s): 1. Emphasize the potential for the scaffolding to tip over if the disassembly is not preformed in the proper order.2. Have a knowledgably person (i.e., trained in assembling and disassembling scaffolding) present and in charge but not actively performing the work. Thi
12、s will enable the person in charge to see the “big picture“.3. Provide additional training for employees to avoid future events. Make training specific for the task at hand. Based on the uniqueness of this set up, time should have been devoted to the potential hazards involved in the take down.Evide
13、nce of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71 Sciencea71 Space Operationsa71 Aeronautics ResearchAdditional Key Phrase(s): a71 Human FactorsProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Additional Info: Approval Info: a71 Approval Date: 2003-01-14a71 Approval Name: Leslie J. Johnsona71 Approval Organization: LARCa71 Approval Phone Number: 757-864-9409Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
