Attachment letter april 24 2003

This document pretains to SAT-STA-20030324-00039 for Special Temporal Authority on a Satellite Space Stations filing.

IBFS_SATSTA2003032400039_333560

LAW OFFICES WIENER &WRIGHT TEENTH STREET, N.W. HENRY GOLDBERG (202)429-4900 JOSEPHA. GODLES TELECOPIER JONATHAN L. WIENER (202) 429-4912 MICHAEL A. MCCOIN general@z2w2.com I I BRITA D. STRANDBERG - HENRIETTA WRIGHT i i THOMAS G. GKERARDI, P.C. COUNSEL April 24,2003 BY HAND DELIVERY Marlene H. Dortch, Secretary Federal Communications Commission 445 Twelfth Street, S.W. Washington, D.C. 20554 Re: mSat Licensee Corp.: r Suuulement to Request for STA Dear Madam Secretary: As requested by the staff ("PanAmSat"), by its attorneys, The staff failure information. Sincerely, Henry Goldberg Attorney for PanAmSat Licensee Corp. cc: Thomas S. Tycz John Martin Robert Nelson. Karl Kensinger Jennifer Gilsenan

-2- GOLDBERG, GODLES, WIENER & WRIGHT i

TO: Jim Frownfelter CC: KalpakGude Henry Goldberg FROM: Bridget Neville DATE: April 23,2003 RE: SCP Failure Probability idicators The primary spacecraft control processor SCP) on Galaxy IIIR failed on April 21,2001 after 5.4 years in orbit. Cause of the failure was at ibuted to a tin whisker induced short of the odoff relay in the unit power supply. The failur is one of 9 such failures to have occurred across 44 commercial SCPs operational on BSS 60 model satellites. Galaxy IIIR has continued to operate nominally using it’s backup SCP and is e 2ected to continue to operate until the end of its nominal fuel life, February 2005. The failure mechanism for a tin whisker- duced failure of an on-orbit SCP includes several simultaneous conditions: 1) The SCP must contain a pure t 1-plated on/off relay in the unit power supply. 2) There must be a physical stresi n the tin, such as that caused by a surface scratch or an imperfection in the tin pl ting. 3) Conformal coating or other prc ective material on the relay must be absent or have significant voids. 4) The relay case must be ground d to the unit chassis. 5) A tin whisker must grow in thl right direction and become long enough to contact power and ground terr inals on the relay. In an attempt to predict an individua KP’s susceptibility to failure, a detailed review of the failure conditions has been con ucted to determine which, if any, can be correlated to the actual in-orbit failurl statistics. Failure conditions # 1- #4 are principally manufacturing conditions .nd #5 is a function of time in orbit. These conditions are discussed below. I. Relay Correlation Assessment Unit manufacturing records determir the presence and production history of a tin plated relay. One theory is that SCP fi lure susceptibility can be traced to a badly manufactured lot of relays. Table 1 SI- ws the number of SCPs manufactured using relays from different lot codes and thl resulting failure statistics of those SCPs. The relay in the failed SCP on Galaxy IIIR ame from lot 1990-03. The remaining SCP has a relay from lot 1983-16.

11. Production Location Assessment While the data shows that more failures occurred in site 1 produced units than in those from site 2, it clearly shows that units from also suffered failures. Manufacturing location therefore cannot be used as the only indicator of failure risk. Whisker Length Assessment The remaining condition that must failure to occur is the growth of a whisker in the right direction and between power and ground

terminals on the relay (failure condition #: Figure 1 shows that time-in-orbit can be closely correlated with failure statistics and used i a proxy for determining if the tin whisker is present and of a length capable of causing a failur Time in orbit shows a much stronger correlation than production location in assessing susceptib ty of a unit to failure. Similarly, time in orbit can also be used to assess when a unit is no lo er at risk of failure. If the time at which a tin whisker has been shown to reach critical length un r very similar temperature and pressure conditions has passed, then a whisker must not be prc :nt at all. The longer an SCP remains operating past the critical in-orbit time, the lower it’s ch2 :es of failing in the future, regardless of the location in which it was produced or the manufacti ng lot code of it’s relay. figure 1, F Tin Whisker Fdlure Distribution Mevl MeM 5.4 Ymn Distribution Live SCP Population, Normalized Distribution 1 ~ I Failed SCP x Remaining Live SCP I 2 4 6 8 IO 12 Y ~ r Since a Launch At 7.4years of time in orbit, the remainin, ;CP on Galaxy IIIR is well beyond the +lo lifetime defined by a normal distribution analysis in-orbit lifetimes for all failed SCPs, The normal distribution data predicts that 93% of all f ures would have already occurred by a lifetime of 7.4 years. In orbit time is the only parame . which shows a strong correlation to failure probability. The risk of failure of the remi ing SCP on Galaxy IIIR is extremely low and gets even lower with every day it continues to berate. Conclusion All available data indicate that the rer ining SCP on Galaxy IIIR is highly unlikely to fail due to tin whiskers, because, at 7.‘ Fears of age, the Galaxy IIIR SCP already has exceeded the lifetime of the oldest SCI o fail (6.9 years) and the age by which 93% of all failures already would have occurred, !%erisk of failure of the remaining SCP on Galaxy IIIR is extremely low and getti ;lower every day.


Document Created: 2003-09-09 15:32:21
Document Modified: 2003-09-09 15:32:21
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