REG NASA-LLIS-0437-1996 Lessons Learned Damaged Capped Inserts (~1976).pdf

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1、Lessons Learned Entry: 0437Lesson Info:a71 Lesson Number: 0437a71 Lesson Date: 1996-07-17a71 Submitting Organization: JPLa71 Submitted by: J.A. RobertsSubject: Damaged Capped Inserts (1976) Abstract: Oversized mounting screws caused apparent damage to capped inserts in a Voyager transponder. When de

2、signing or reworking hardware employing capped inserts, it is critical to verify that correct screw lengths are specified and used.Description of Driving Event: (Relevant Historical Lesson(s) Learned)During a Voyager Radio Frequency Subsystem (RFS) transponder filter capacitor rework, a noise was no

3、ted in the Proof Test Model (PTM) subassembly. On opening the power converter interface module, some of the mounting insert caps were found loose inside and others were partially pushed out from the insert ends. A dimensional check showed the mounting screws used may have an interference fit in leng

4、th. A second possibility exists that longer screws were used at some earlier installation.Fastener inserts used in flight equipment are usually of the capped variety (closed at the bottom) when used in a thru-mounting design. This is done to prevent metallic particles being deposited in the electron

5、ics where they can cause electrical shorting or other problems.See also: In-flight failure, “Receiver 1 Power Converter Failure on Voyager 2“ which was likely caused by this event.Additional Keyword(s): Tolerance StackupReference(s): PFR #40215 Voyager Structure SubsystemProvided by IHSNot for Resal

6、eNo reproduction or networking permitted without license from IHS-,-,-Lesson(s) Learned: Oversized mounting screws can damage capped inserts.Recommendation(s): When designing or reworking hardware employing capped inserts, it is critical to verify that correct screw length is specified and used.Evid

7、ence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): a71 N/AAdditional Key Phrase(s): a71 Hardwarea71 Parts Materials & ProcessesAdditional Info: Approval Info: a71 Approval Date: 1996-03-28a71 Approval Name: Carol Dumaina71 Approval Organization: 125-204a71 Approval Phone Number: 818-354-8242Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-