Very nice article. Lots of work obviously went into summarizing and extracting the existing information. No significant errors that I detected but I would add a few clarifying points:

(1) The engine shutdown on STS-51-F that resulted in an abort to orbit was not caused by any performance problem with the engine but was rather was erroneously caused by failing redline sensors (temperature measurements). The ATO action did not result in any loss of mission objectives or any shortening of mission duration.

(2) there were more pre-launch pad shutdowns that indicated in the article.

(3) The final version of the SSME was ground tested up to 111% RPL with the intent to certify the use of 109% for intact (TAL, RTLS, ATO) abort modes. However, vortex flow shedding on components in the main propulsion system plumbing (not the engines themselves) would have lead to low cycle fatigue failures at power levels above 104.5% so the higher power levels were never authorized for use in anything other than a contingency abort (where the failure to use them would have lead to LOCV).

(4) To the end of the program, the engine start sequence incorporated two interesting features to limit acoustic/overpressure problems at the launch pad: the engine starts were staggered by 120 msec, and the liftoff power level was 100% RPL; throttle up to 104.5% was accomplished immediately post liftoff.

(5) The 104.5% power level (vs. 104.0%) was required for the upgraded Block II engines because of the loss of 2-ish seconds of ISP, this was not related to payload (although there was an early plan to use 106% power level for very heavy ISS elements, it was never required and would have incurred other problems - see 3 above).

(6) The lowest throttle down power level was increased to 67% for the same MPS fatigue problems discussed in 3 above. The throttle bucket around Max Q was dynamically calculated based on early performance in first stage and generally resulted in throttle settings in the mid 70% range rather than automatically going to the minimum throttle setting of 67%.



Probably a whole lot more detail than you need