Tuckwell resigned from MACA in October 2012 to work for Ausdrill as its Africa-based CEO.
The West Australian reported yesterday afternoon that non-executive chairman Andrew Edwards thanked Grewar for his efforts over the past year and a half, and welcomed back Tuckwell back to the company.
"Chris is of course very familiar with MACA's clients and operations," he said.
"His recent experience in Africa has added to his already considerable experience."
Tuckwell's notice period with Ausdrill will finish at the end of July.
Ausdrill said it was considering various options regarding the appointment of a suitable successor to Mr Tuckwell and would make a further announcement when a decision was made.
Yesterday MACA shares closed down two cents at $2.14, and have fallen to $2.12 this morning.
Ausdrill is currently trading at 94.5 cents.