1、Lessons Learned Entry: 1360Lesson Info:a71 Lesson Number: 1360a71 Lesson Date: 2003-16a71 Submitting Organization: JPLa71 Submitted by: David Oberhettinger/ Carol DumainSubject: Unrestrained Separation Nuts May Damage or Hinder Flight Hardware (2002) Description of Driving Event: In a complex rover
2、separation event after a Mars landing, pyrotechnic devices are used to release the Mars Exploration Rover (MER) Warm Electronics Box (WEB) from the lander basepetal. If the separation does not occur, the rover does not release and cannot escape the lander. The WEB design called for each separation n
3、ut to be free and un-restrained after release, without considering any possible impact damage. The 8 “sep nuts” on each rover were fired successfully during system test. Each was rapidly expelled from the basepetal to strike a rock protection cup located 7 mm beneath the sep nut. refer to D descript
4、ionD In testing of both MER1 and MER2, the impact resulted in severe damage to the pyro cables attached to the bottom of the nuts. The pyro cabling was damaged sufficiently to cause multiple shorts to chassis that could have over-stressed the pyro system electronics. Redesign efforts to apply paddin
5、g to the sep nut backshells were complicated by the configuration of the adjacent hardware. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-References 1. Jet Propulsion Laboratory Problem/Failure Report No. Z78969, January 9, 2003. https:/problemrepo
6、rting.jpl.nasa.gov/cgi-win/VB2FPDDE.exe?T: PFOCPRODPROJECTSWEBALLALL_PVB.INIs32. ”WEB Separation Pyro Cable Protection Redesign Test Results,” JPL document D-25477, February 3, 2003.Additional Key Words: pyro test, ATLO, structural interference, structural modeling, deployment mechanisms, test induc
7、ed damage, system safety Lesson(s) Learned: Unrestrained pyrotechnic separation nuts may cause mission-critical failures by impacting and damaging pyro cabling, or by rebounding to interfere with spacecraft mechanisms.Recommendation(s): 1. Design release mechanisms to retain spent pyrotechnic separa
8、tion nuts.2. Whether the separation nuts are restrained or unrestrained, take measures to ensure that the released nuts cannot impact and damage adjacent hardware/wiring or interfere with spacecraft deployment or separation.Evidence of Recurrence Control Effectiveness: Corrective Action Notice No. Z
9、84191 was opened by JPL on June 28, 2004 to initiate and document appropriate Laboratory-wide corrective action on the above recommendations. The JPL Pyromechanical Devices Users Guide has been updated to cover this design problem and its solution. Also, a plan was prepared on March 2, 2005 for trai
10、ning design engineers using the content in the Guide, the JPL Pyrolab website, and other updated training materials.Documents Related to Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71 Aeronautics Researcha71 Aeronautics Researcha71 Aeronautics ResearchProvided by IHSNot for ResaleNo r
11、eproduction or networking permitted without license from IHS-,-,-Additional Key Phrase(s): a71 Computer-Aided Design/Manufacturing/Engineeringa71 Energetic Materials - Explosive/Propellant/Pyrotechnica71 Flight Equipmenta71 Hardwarea71 Payloadsa71 Safety & Mission Assurancea71 Spacecrafta71 Test & Verificationa71 Test ArticleAdditional Info: Approval Info: a71 Approval Date: 2003-15a71 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-,-,-
