Q:

Not falling on hands for Tachnun

How come Sepharadim do not "fall on their faces" during Tachanun as Ashkenazim do, if the prayer is called "nefilat apa'im" (literally the falling of the faces)? 
The Shulchan Aruch seems to hold of the practice of literally putting one's face down in O"C 131:1

A:

Rav Yosef Karo, in Beit Yosef (131),
  cites the Zohar, which describes the
  tikkun (improvement, repair) of
  falling upon one's face while reciting
  Tehillim 25:

And this tikkun should be recited with
    great sincerity; then God shows
    compassion to His people and forgives
    their sins.  Happy is the person who
    can entice and serve his MASTER with
    will and sincerity, and woe to the
    person who attempts to entice his
    Master with a distant heart and
    without sincerity… which causes one to
    leave this world before one's time.

Sephardic communities, based upon this
  Zohar, recite Tehillim 25 upon
  concluding Shemoneh Esreh.  The Ben
  Ish Chai (Parashat Ki Tissa 13),
  fearing the Zohar's harsh sentence for
  one who recites this chapter without
  sincere intention, concludes that one
  should recite this chapter WITHOUT
  falling upon one's face.  Despite Rav
  Yosef Karo's ruling, in Shulchan Arukh
  (131:1), that one should fall on one's
  face for Tachanun, Rav Ovadya Yosef
  (Yechavveh Da'at 6:7) concurs with the
  Ben Ish Chai's position and rules that
  Sephardim should refrain from
  performing Nefilat Appayim.

http://vbm-torah.org/archive/tefila/18tefila.htm

A:

http://andalusiaonmymind.wordpress.com/2011/10/06/qabbalah-or-kabbalah-nefilat-apayim-and-authentic-mesorah/

The first source for the custom of not putting one’s head down seems
  to be the Ben Ish Hai (Year 1, Perashat Ki Tisa §13), who says that
  the minhag in his city, Baghdad, was not to put one’s head down at
  all. The reason he gives is that, according to the Zohar, it is
  dangerous to put one’s head down if one is not at a high enough level
  of spiritual refinement and is not able to have the proper intentions
  (kavanot) during Nefilat Apayim. Since the days of the Ben Ish Hai,
  this custom has become prevalent among Sefaradim and most communities
  no longer put their heads down during Tahanun.”

A:

The Rambam (Hilkhot Tefilla 5:13-4)
  describes the different customs
  regarding Nefilat Appayim.  Some, he
  writes, perform a complete
  prostration, while some just do kidda,
  bending down on their knees and
  putting their faces to the floor.  
Apparently, over time, out of fear of violating the biblical and
  rabbinic prohibitions regarding
  prostration, this practice was
  abolished.  Indeed, the Tur (131)
  cites Rav Natrunai Gaon, who writes
  that one who "falls on his face"
  should suspend his head above the
  ground in order not to appear as if he
  is prostrating on the ground.  As we
  mentioned last week, many Sephardic
  Jews do not perform Nefilat Appayim at
  all.

http://vbm-torah.org/archive/tefila/19tefila.htm

