Danny Deger wrote:

"Jim" wrote in message
et...

SSME's are "rated" at a certain thrust. However, the thrust rating has a
minimum, average and maximum. The "rated" thrust is the average. Therfore,
the engines can be run to an amount greater than "rated" thrust. I am not
an engineer or NASA personel, but I have read that during the nominal
acent the engines are throttled from 64% to 104% but can be throttled to
109% of rated thrust if necessary.


You are correct. For 2 engine out aborts, the last engine can be throttled
to 109%.

The engine builders worked for years to get the extra thrust out of the
engines reliably. There were a lot of problems with the engines at
settings over 104%. The reliability is now there up to 109%, although
it is now only reserved for emergencies, not a normal ascent profile.