Which vowels were usually not written in Egyptian hieroglyphic writing?

In Egyptian hieroglyphic writing, the system generally avoided the representation of vowels, focusing instead on the consonants of words. Because vowels were omitted from the written script, the hieroglyphic system represents the language's phonology only partially, leaving the exact pronunciation of ancient Egyptian words imperfectly reflected.12

While most vowels were excluded, the system did make use of the semivowels i, y, and w. Consequently, the script functioned primarily as a consonantal system, where logographic signs and phonograms were used to denote sounds and meanings without explicitly recording the vocalic patterns that would have accompanied the consonantal roots in speech.12