1、Lessons Learned Entry: 1316Lesson Info:a71 Lesson Number: 1316a71 Lesson Date: 2002-11-01a71 Submitting Organization: JPLa71 Submitted by: R. Welch/ D. OberhettingerSubject: Mars Exploration Rover (MER) Pyrotechnic Test Damage (2002) Abstract: Pyro pin puller parts were unexpectedly ejected with exp
2、losive force during a test of the Mars Exploration Rover dynamic test model.The lesson makes personnel safety recommendations for pyrotechnic tests, suggests limiting use of refurbished pyro devices, and calls for improved procedures and oversight during their refurbishment. Description of Driving E
3、vent: Parts were unexpectedly ejected with explosive force during a test of the Mars Exploration Rover (MER) dynamic test model (DTM), shown in Figure 1. The MER High Gain Antenna (HGA) pyrotechnic release mechanism was fired in order to assess the shock loading on adjacent Rover components. Two NAS
4、A standard initiators (NSIs) were mounted on the pin puller (Figure 2) that releases the HGA for deployment. When they were fired, the pin impacted the retaining cap of the puller housing, shearing the threads holding the aluminum cap to the aluminum housing (Figure 3). This caused both the pin and
5、cap to be ejected explosively from the back of the mechanism.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-refer to D descriptionDThe device failure was attributed to shearing of the end cap and/or housing threads, also shown in Figure 3. It is pos
6、sible that thread damage occurred in the failed device during its initial firing in an earlier MER pyroshock test and/or during the refurbishment process. This device was refurbished by disassembly and ultrasonic cleaning, and was reassembled without a formal written procedure or mandatory QA inspec
7、tion. The design of the failed pin puller differs from that of the MER flight design, which uses a higher strength aluminum alloy for the housing and a stainless steel end cap.refer to D descriptionDThe ejected cap and pin ricocheted off the Pan Cam Mast Simulator and then gouged the concrete clean
8、room wall. Although only critical test personnel were present in the clean room during this Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-hazardous test and they complied with existing safety procedures, they were narrowly missed by these projectil
9、es. No one was injured, though the Pan Cam Mast Simulator suffered superficial damage. Also, this anomaly released combustion products, which damaged a strip heater on the HGA, requiring replacement of the heater.A failure of this nature during flight operations could lead to significant loss of mis
10、sion objectives.References:1. JPL Problem/Failure Report No. Z76911, July 26, 2002.2. JPL Incident Report, “Mars Exploration Rover (MER) Project Design Test Model (DTM) Rover, Pin Puller Incident,“ Ronald T. Welch, July 2002.Additional Key Words: pyrotechnic shock test, test mishap, test failure, te
11、st hazard, pyro hazard, system safety, occupational safetyLesson(s) Learned: Pyrotechnic events are inherently hazardous and require special precautions to protect personnel, equipment, facilities and the mission. Although this pyrotechnic test setup incorporated standard JPL precautionary measures,
12、 a test failure exposed test personnel, critical hardware, and the facility to an extreme hazard.Recommendation(s): 1. It is always preferred to test pyrotechnic events with the test article remotely located from personnel. If physical isolation is not feasible, impact barriers and configurations ac
13、cepted by Safety should be used to protect test personnel and co-located critical hardware.2. Refurbished pyrotechnic devices should never be used as flight units, and ground test units should not be refurbished more than once.3. Use technically approved procedures, certified technicians, and approp
14、riate oversight during refurbishment of pyrotechnic actuated devices. Refurbished pinpuller assemblies require special attention (beyond visual inspection) to the body and cap thread integrity.Evidence of Recurrence Control Effectiveness: Corrective Action Notice No. Z77329 was closed by JPL on Janu
15、ary 16, 2003. The measures taken to implement Laboratory-wide corrective action on the above recommendations were (1) preparing JPL Assembly and Inspection Data Sheets (AIDS) for these devices that include disassembly, Provided by IHSNot for ResaleNo reproduction or networking permitted without lice
16、nse from IHS-,-,-cleaning, repair, or replacement of suspect parts and reassembly, complete with quality assurance provisions, and (2) updating the JPL standard firing procedures (JPL SOP 409, Rev C) to provide (A) criteria for who may direct, perform, support, or witness the firing operation, (B) r
17、equired barriers for personnel shielding, and (C) maintenance of a list restricting access to specified personnel.Documents Related to Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71 Sciencea71 Space Operationsa71 Aeronautics ResearchAdditional Key Phrase(s): a71 Aerospace Safety Advis
18、ory Panela71 Energetic Materials - Explosive/Propellant/Pyrotechnica71 Explosives Handlinga71 Facilitiesa71 Flight Equipmenta71 Ground Equipmenta71 Ground Operationsa71 Hardwarea71 Industrial Operationsa71 Occupational Healtha71 Personal Protective Equipmenta71 Safety & Mission Assurancea71 Test & V
19、erificationa71 Test Articlea71 Test FacilityAdditional Info: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: a71 Approval Date: 2002-12-09a71 Approval Name: Carol Dumaina71 Approval Organization: JPLa71 Approval Phone Number: 818-354-8242Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
