http://revach.net/article.php?id=4784

Section: Halacha   Category: Tshuvos
Shevet HaKehosi - Fumbling You Way Through Tefilas HaDerech

If a person in on a trip that requires him to say Tefilas HaDerech (or any other bracha for that matter) and doesn't have a siddur and doesn't remember verbatim every word, what should he do?  Can he say the bracha to the best of his memory or can he only make the bracha if he is sure he knows all the words?

The Shevet HaKehosi (2:87) brings the Rambam (Hilchos Krias Shema 1) that anyone who changes a bracha from the way Chazal instituted is not Yotzei and he must repeat it.  However the Kesef Mishneh qualifies this and says that the Rambam is only talking about the Bracha itself with the Shem U'Malchus.  If he says Shem U'Malchus and says the Bracha itself properly, whether there is a bracha in the beginning, end, or both, he is Yotzei even if the rest of the words are not correct as long as it is the same idea as the Bracha that Chazal were misaken.

This doesn't work for Nodeh Licha in Birchas HaMazon where the gemara says that if you don't mention Bris and Torah you are not Yotzei even though it is not part of the bracha itself.  Similarly he says, omitting Mashiv HaRuach also invalidates the bracha (if you didn't say Morid HaTal) since that is specifically required.

Important Note: We bring this tshuvah as a starting point for discussion and not to convey any halacha.  We try to convey the Tshuva to the best of our ability. We admit that our understanding may not be accurate. One should learn the tshuva to verify the accuracy of our interpretation.  Please understand that this Tshuva may not be the final word on this topic. One should consult a Rav before drawing any conclusions.