Lewis Stevenson's fine form in recent weeks has been rewarded with a starting place in the second row alongside captain Johann Muller. Dan Tuohy is named on the bench as a result.
Pedrie Wannenburg has recovered from the illness which ruled him out of last weekend's trip to Treviso, so he will earn his 50th Ulster cap in front of the Ravenhill faithful.
The South African is joined in the back row by Ferris and Chris Henry, who moves from the blindside to the openside flanker berth.
The half-back and centre partnerships remain unchanged as Brian McLaughlin looks for a settled team ahead of the Heineken Cup quarter-final against Munster on Easter Sunday.
The return of Trimble means Craig Gilroy switches to the left wing and Stefan Terblanche moves to full-back at the expense of Adam D'Arcy.
McLaughlin is delighted to have his Ireland starters back and available for Ulster's run-in, saying: "Whenever Rory, Andrew and Stevie come back into the squad in gives everyone a great fillip. They have such high standards and demand the same from the other players."
Commenting on his decision to promote Stevenson to the starting line-up in place of Tuohy, he explained: "Lewis has been in very good form over the past couple of months. He was very good for us when he came off the bench in Treviso for the final 15 or 20 minutes so he deserves his chance.
"Everyone knows there are places up for grabs in every position and we have great competition throughout the squad. If players get chances they have to take them.
"With Stephen back in and Pedrie fit again, the back row is another area where we are particularly strong. It is harsh on Robbie Diack and Willie Faloon and other players who have been left out."
Wannenburg will make his 50th appearance for the province when he runs out against Aironi on Friday night and McLaughlin was full of praise for the departing back rower.
"It is fantastic for Pedrie to earn his 50th cap. He has been a tremendous servant to Ulster in the two seasons he has been with us," added the Ulster supremo.
"He has shown remarkable consistency last season and this season, despite being unfortunate with injuries in recent times."
Ticket sales for Friday's game have already passed the 8,500 mark but tickets are still available. They can be bought online at www.ulsterrugby.com or by calling the ticket office on 02890493222 (ticketing option). Alternatively, you can pay at the gate on match night.
ULSTER (v Aironi Rugby): Stefan Terblanche; Andrew Trimble, Darren Cave, Paddy Wallace, Craig Gilroy; Ian Humphreys, Ruan Pienaar; Tom Court, Rory Best, John Afoa, Johann Muller (capt), Lewis Stevenson, Stephen Ferris, Chris Henry, Pedrie Wannenburg.
Replacements: Nigel Brady, Paddy McAllister, Adam Macklin, Dan Tuohy, Willie Faloon, Paul Marshall, Ian Whitten, Adam D'Arcy.