* Boeing sees good 787 demand but not raising output
* Boeing to take time to decide on new mid-market jet
* Embraer, Boeing discussing venture in commercial aviation (Adds comments on demand and partnerships)
By Tim Hepher
PARIS, June 15 (Reuters) - Engine problems at Britain's Rolls-Royce have rattled the aviation industry but have not slowed sales of the Boeing 787 Dreamliner, Boeing Co's commercial sales chief said.
The UK engineering company faces problems with parts of the Trent 1000 engine, leading to the grounding of some 787s for repairs, and separately plans to cut 4,600 jobs.
"Does it rattle people? Yes it rattles people. Nobody likes that. Airplanes make money when they are in the air; they don’t make money when they are on the ground," Ihssane Mounir, senior vice president of commercial sales & marketing for Boeing Co, told Reuters in an interview.
"I haven’t seen any slowdown in sales right now. These are growing and teething pains for any product."
Privately, Boeing executives are said to be frustrated about the problems which have left dozens of 787s grounded.
Boeing sees continued 787 demand but it is too early to think about raising output beyond existing plans, Mounir said.
Boeing is expected to complete a plan to raise 787 output to 14 a month from 12 a month by March 2019.
"We are sold out in 2019 right now, and we are doing just fine in 2020 and in the out years. We are taking it one step at a time," Mounir said.
On the larger 777, Mounir said there were still some gaps in production as Boeing steers through a transition between the current-generation 777-300ER and the upgraded 777X.
"There is more work to do....There is a lot of demand for the 777 freighter and we have been pretty active in that marketspace and talking to several customers," he said.
"We have several campaigns and activities for this year."
He downplayed a recent slowdown in demand for the newer 777X which enters service in 2020, as well as the programme's heavy reliance on Gulf orders. Boeing says the 777X will target replacements for the 777, the 747 and Airbus A380.
"We are just entering the period at which airlines would start making their plans for replacements...I would say in 2019 and 2020 is when you would see the 777X sales activity pick up to the tune of what we have been seeing on the 777."
Mounir said Boeing would take the time needed to decide whether to launch a possible new mid-market jet, despite some media suggestions that it is dragging its feet over the move.
"I wouldn’t say the timing is dragging...We are doing our due diligence."
In his first comments on a potential tie-up between Boeing and Brazil's Embraer, Mounir saw potential synergies.
Embraer and Boeing are discussing a venture in commercial aviation including the Brazilian E2 regional jet. Sources say they are edging closer to a deal.
"It is a great strategic fit, there is no question about it. But it is not a must do for us. I watch it from the sidelines and I will be happy either way," Mounir said.
Reporting by Tim Hepher Editing by Geert De Clercq