While Faingaa failed to join his brother, the hooker Saia, in the Test squad against the British & Irish Lions, he did play well for the Reds against the tourists and was drafted into McKenzie's initial 40-man training squad.
A hamstring injury kept him out of the Reds' 38-9 Super Rugby play-off defeat to the Crusaders two weeks ago and now he has been forced to give up the rest of the season to get his damaged shoulder sorted out. As well as the Rugby Championship he will also miss the November tour to Europe.
Kurtley Beale has also had his season brought to an abrupt end to undergo surgery, but McKenzie has declined the chance to add to his squad at this stage. He is due to trim the number to 30 ahead of the opening game against the All Blacks on 17 August.
"I've been carrying this shoulder injury throughout the last season and I feel that it is not in the best interests of my teammates at the Reds, nor the Wallabies squad to continue to do so," Faingaa posted on his Facebook page.
"I'm immensely disappointed not to be joining my brother, Saia, at the Wallabies camp on Monday. We missed the last tour together and now we are to be split apart again because of my surgery and recovery."