REG NASA-LLIS-0042-1991 Lessons Learned - Sneak Circuitry Down Range Control Area Electrical Ground Connections for Folding Fin Aircraft Rockets (FFAR) Corrosion of Dissimilar Meta.pdf

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1、Lessons Learned Entry: 0042Lesson Info:a71 Lesson Number: 0042a71 Lesson Date: 1991-12-02a71 Submitting Organization: KSCa71 Submitted by: David PenningtonSubject: Sneak Circuitry; Down Range Control Area; Electrical Ground Connections for Folding Fin Aircraft Rockets (FFAR); Corrosion of Dissimilar

2、 Metals Description of Driving Event: The following mishap occurred during preparation of three mighty mouse rockets (2.75“ FFAR) at the NASA Atmospheric Sciences Field Laboratory: The last step before arming the FFAR motors was to replace the activation plug on the payload. With the rocket in posit

3、ion in the launcher tube, the plug used during launcher loading was removed through an access hole in the side of the tube and another plug, attached by a lanyard to a pneumatic withdrawal cylinder, was inserted in the payload. While the worker was performing this lanyard insertion step, the rocket

4、motor ignited and launched. Investigation of the mishap revealed the high probability of a sneak circuit causing the inadvertent firing of the rocket.Lesson(s) Learned: 1. Use of a conductive lanyard to arm payloads having internal power sources may introduce a potential current path for a sneak cir

5、cuit.2. Whenever a potentially “hot“ rocket is on a launch pad, down range clearance must be assured.3. The current design of FFARs does not provide a reliable electrical ground connection between the fins and the nozzle plate.4. Aircraft rocket launcher assemblies may produce a potentially dangerou

6、s galvanic current if dissimilar metals are used in fabrication.Recommendation(s): Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1. Design arming devices to provide electrical isolation from batteries by using a non-conductive lanyard for the withd

7、rawal cylinder.2. Require the down range impact area and air space to be clear of all unauthorized personnel and aircraft during all phases of live testing.3. Analyze grounding circuits and take appropriate action to assure grounds exist - specifically, the grounding of the ignitor circuit.4. Design

8、 launcher assemblies to use materials that are not chemically reactive, or use insulating devices between dissimilar, reactive metals.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): a71 Space Operationsa71 Exploration SystemsAdditional Key Phr

9、ase(s): a71 Energetic Materials - Explosive/Propellant/Pyrotechnica71 Energya71 Flight Equipmenta71 Ground Operationsa71 Ground Equipmenta71 Hardwarea71 Launch Processa71 Launch Vehiclea71 Parts Materials & Processesa71 Payloadsa71 Range Operationsa71 SpacecraftAdditional Info: Provided by IHSNot fo

10、r ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: a71 Approval Date: 1994-06-01a71 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-,-,-