1、 Public Lessons Learned Entry: 6796 Lesson Info: Lesson Number: 6796 Lesson Date: 2012-08-28 Submitting Organization: JPL Submitted by: David Oberhettinger Subject: TRaiNED Deployment Failure Was Traced to Design Flaws and Process Escapes Export Version Abstract: A payload door failed to deploy on a
2、 sounding rocket mission intended to advance the technology for autonomous navigation. In addition to several design flaws, an anomaly investigation board identified several process escapes. Several rigorous mechanical design practices are recommended, along with processes to verify that the specifi
3、ed materials are used, wiring harnesses are not mis-mated, and key knowledge is retained upon personnel rotations. Description of Driving Event: The Terrain-Relative Navigation and Employee Development (TRaiNED) project was a Class D (i.e., low cost, high risk) mission employing a sounding rocket to
4、 capture exoatmospheric and low-altitude imagery. Using the imagery to refine navigation algorithms, the payload developed by the NASA/Caltech Jet Propulsion Laboratory (JPL) for the 41.087 mission (Dr. Martin Heyne, Principal Investigator) was intended to advance the technology for autonomous terra
5、in-relative navigation and hazard detection, providing aerial and surface access to key sites in the solar system. The launch of the 41.087/Heyne Terrier-Improved Orion sounding rocket (Figure 1) from White Sands Missile Range (WSMR) on December 6, 2010 was nominal, but no data was received from the
6、 JPL-furnished cameras located in the exoatmospheric section. The camera field of view was blocked by a blow-off door, which did not release early in the flight as planned. The sounding rocket for the “Heyne“ mission employed a legacy design in which the door (Figure 2) is held in place by tabs and
7、by a single brass screw that is severed in flight by a pyrotechnic guillotine cutter. Rotational acceleration forces then act on the released door, which rotates away from the payload. . Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Figure 1. Heyne
8、 mission sounding rocket just prior to flight at WSMR Figure 2. Close-up of the sounding rocket, with an Exoatmospheric Camera Door clearly visible on the left Review of telemetry records, inspection of the remaining door hardware, and material analysis, established that the blow-off door release (F
9、igure 3) was actuated at the proper time in flight, but the deployment screw was only partially severed by the cutter (Reference (1). A more common industry practice is to use high strength fasteners with an extremely high pre-load, so that the cutter only need weaken the screw to the point that the
10、 tensile load induces failure in the remainder of the material. Figure 3. A detailed diagram of the blow-off door mechanism has been redacted for International Traffic in Arms Regulations (ITAR) compliance. Although the Heyne mission failed to capture camera imagery at 120 km altitude from its exoat
11、mospheric experiment section, the JPL payload did succeed in capturing the requisite descent imagery. References: 1. “41.087/Heyne Terrier-Orion Anomaly Investigation Board Final Report,“ NASA Sounding Rocket Program Office, May 10, 2011. 2. Donald R. Sevilla, e-mail with subject “Re: TRaiNED AIB Fi
12、nal Report - Bolt Cutter Failure,” July 7, 2011. 3. “Mate/Demate, Verify, and Document Connectors One-at-a-Time,“ NASA Lesson Learned No. 1619, NASA Engineering Network, August 8, 2005. Portions of the following text have been redacted, as indicated, for ITAR compliance. “U.S. Persons“ may obtain a
13、copy of the complete lesson learned by contacting the JPL Office of the Chief Engineer (David Oberhettinger at davidonasa.gov). Lesson(s) Learned: In-flight failures are not unexpected on low cost, high risk, projects like the Phaeton projects that provide a learning experience for junior engineers.
14、 Nevertheless, the following TRaiNED lessons learned are applicable to any class of flight project: 1. The anomaly report for the Heyne mission (Reference (1) identified several design flaws. This paragraph, which describes inherent weaknesses with the design of the door assembly for the Heyne missi
15、on, has been redacted for ITAR compliance. 2. The material traceability and control processes for the fabrication and assembly of critical flight hardware were deficient. This paragraph, which explains the flight hardware material traceability and control process deficiencies, has been redacted for
16、ITAR compliance. 3. The wiring harnesses for the two pyrotechnics were indistinguishable and could have been inadvertently swapped. This paragraph, which reports a hardware feature that could result in mis-wiring of pyros, has been redacted for ITAR compliance. 4. Long delays in missions that interr
17、upt the typical mission timelines can be a complicating factor in both pre-launch mission assurance and post-flight collection of information. This paragraph, which discusses the effect of changes in payload team staffing upon proper disassembly of the blow-off door, has been redacted for ITAR compl
18、iance. Recommendation(s): 1. The Heyne design flaws can be addressed by such measures as reverting to the heritage blow-off door design and assessing the suitability of the selected pyrotechnic cutter. However, more rigorous mechanical design practices may prevent such design flaws (Reference (2): o
19、 Avoid identical electrical connectors in close proximity. This paragraph, which recommends a practice to prevent mis-mating, has been redacted for ITAR compliance. o Select reliable electro-mechanical devices. This paragraph, which advocates use of a particular type of part, has been redacted for I
20、TAR compliance. o Adjust microswitches. This paragraph, which proposes a switch adjustment measure, has been redacted for ITAR compliance. o Verify pyrotechnic device functional margin. This paragraph, which suggests performing a Provided by IHSNot for ResaleNo reproduction or networking permitted w
21、ithout license from IHS-,-,-mechanism test, has been redacted for ITAR compliance. o Select screw material, target diameter, and preload. This paragraph, which recommends criteria for developmental testing, has been redacted for ITAR compliance. 2. Implement a process to verify that parts being manu
22、factured for critical payload systems, such as mission success-critical deployment mechanisms, utilize the materials specified on the drawings. Review the adequacy of processes for the control of critical flight hardware during fabrication and assembly. 3. Establish assembly processes that assure th
23、at critical flight wiring harnesses are not mis-mated (see Reference (3), especially on flight projects where there may be frequent changes in the payload team. 4. Flag anticipated changes in payload team personnel during the mission as an additional risk. Implement a process to assure retention of
24、critical payload team knowledge. Plan for launch delays/scrubs by implementing and witnessing appropriate disassembly procedures. Evidence of Recurrence Control Effectiveness: JPL has referenced this lesson learned as additional rationale and guidance supporting Paragraph 6.3.9 (“Managed Margins: Fl
25、ight System Technical Resource Margins - S/C Mechanisms Functional Margins”) in the JPL standard “Design, Verification/Validation and Operations Principles for Flight Systems (Design Principles),” JPL Document D-17868, Rev. 6, October 4, 2012. Documents Related to Lesson: N/A Mission Directorate(s):
26、 Science Additional Key Phrase(s): Engineering Design (Phase C/D).Spacecraft and Spacecraft Instruments Manufacturing and Assembly Safety and Mission Assurance.Quality Additional Categories.Flight Equipment Additional Categories.Spacecraft Additional Categories.Industrial Operations Additional Categ
27、ories.Launch Vehicle Additional Categories.Parts, Materials, & Processes Additional Categories.Hardware Additional Info: Project: Terrain-Relative Navigation and Employee Development (TRaiNED) Year of Occurrence: 2011 Approval Info: Approval Date: 2012-11-28 Approval Name: mbell Approval Organization: HQ Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
