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• 25° T O-rings on 51L!
(53° T = lowest previous launch case T)

• 31° T + 5° sky is [underline]only[/underline] LCC

• MSFC runs 24 hr thermal model - gets T at areas in SRB system... but [underline]not[underline] run during countdown

• "compression set" (o-ring doesn't bounce back)

• 51 L pressure check: [underline]no drop[underline]

request: search for internal memos on T operation of 0-rings

* leak port in "same area" as black puff + flame (another trail)

crack in case = another trail

* fax material to/from Thiokol on T concern
O-ring people expressed concern.
Telecom (MSFC, Thiokol, KSC) Thiokol rec. not launch below 53° o-ring. [[margin note]] projected T ≈ 29°

Then