From: oliver@vf.jsc.nasa.gov
Subject: Re : Atlantis
Organization: NASA Johnson Space Center
Date: 10 Sep 92 14:09:34 -0600

In article <1992Sep7.133449.3330@titan.ksc.nasa.gov>, hollis@titan.ksc.nasa.gov writes:
> 
> HS> Atlantis is the orbiter tentatively picked to get a Russian docking sys
> HS> for missions to Mir.  The system would be installed while Atlantis is a
> HS> Palmdale for its mid-life overhaul, scheduled to start after the Tether
> HS> Satellite mission.  (The overhaul will include the usual set of upgrade
> HS> including better computers and the drag chute, plus extended-duration
> HS> mods, as well.)

The extended duration mods that Atlantis is getting do NOT include plumbing for
the EDO pallet.  All extended or long duration flights that Atlantis will be
making it will do attached to the space station.  Also there is still an 
on-going discussion as to whether it would be best to relocate the current
airlock in the payload bay (about 4 months of work) or to install a Russian
airlock and fly with two airlocks (lots of extra weight but probably much
cheaper to install).

> 
> In actuallity Atlantis is NOT going to Palmdale for a mid-life
> overhaul.  Every 5 or 6 flights each orbiter is now being scheduled
> for an OMDP (Orbiter Maintenance Down Period) during which major
> modifications and structural inspections are scheduled which otherwise
> could not conveniently be completed in normal between flight
> turn-arounds.  In addition some of the more extensive periodic testing
> is also scheduled for this period which otherwise would have resulted in
> turn-around delays.  Columbia was the first orbiter to undergo this
> OMDP (accomplished at Palmdale), followed by Discovery (accomplished
> at KSC).  Endeavor is scheduled for it's first OMDP following it's 5th
> flight.  Subsequent OMDP's will be conducted on all orbiters at like
> intervals of 5-6 flights.
> 
> Just wanted to make that clarification in case someone got the idea
> that Atlantis was having a mid-life crisis... :).
> 
>                                                   Darrell Holloway
> 

The orbiters are scheduled for an OMDP after every 7 flights (plus or minus
one flight), with the exception of OV-105 which will get its first OMDP
following its 12th flight. Many inspections and tests are made each flow and
the amount and kinds vary from flow to flow.  Each requirement is assigned an
interval with which it is to be performed.  The most common intervals are:

     Every Flow    - Includes testing of all Criticality 1 and 1R items.
     Every 2 Flows - Includes a lot of dual systems, system 1 tested on even
                     flows and system 2 on odd flows.
     Every 3 Flows - Primarily stuff that is not used all that much.  Allows
                     testing about once a year.
     Every 5 Flows - Gets stuff tested at least every other year.
     Every OMDP    - Lots of structural inspections, stuff tested in-flight
                     that needs high and low limits checked out, etc.  OMDP's
                     are planned to be about three years apart.

OV-102 had its OMDP following its 11th flight and has the next one scheduled
following its 17th flight (STS-66).  OV-103 will finish its OMDP at the end
of the month, while OV-104 will be going to Palmdale next month to begin its
first OMDP.  Many of the OMDP requirements, with the exception of most of the
structural inspections, will probably be performed on OV-105 following its 5th
or 6th flight.

-- 

Pat Oliver -  	Lockheed Engineering and Sciences Company at NASA JSC
		OLIVER@vf.jsc.nasa.gov
		All standard disclamers apply.
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