Norwegian Air has summoned Boeing management to Oslo to explain a slew of technical problems with its 787 Dreamliners after weekend glitches brought further disruption.
The Scandinavian carrier said one of two 787s was grounded due to problems with oxygen supply to the cockpit and technicians were working to fix the problem.
A problem with a valve on the second plane was repaired but only after delaying a flight from Oslo to New York on Sunday.
Technical problems with brakes, hydraulic pumps and power issues have forced Norwegian Air to ground the Boeing jets several times in recent weeks.
"We are going to tell them this situation is far from good enough," company spokeswoman Anne-Sissel Skaanvik told Reuters news agency, referring to plans to call a meeting with Boeing representatives at the airline's Oslo offices later this week.
"We have not had the reliability that we had expected from brand new planes, so something must happen, fast... Clearly Boeing has not had good enough operative quality control."
Boeing said it was disappointed with the problems with the new planes and regretted disruption.
"We are in constant contact with our customer Norwegian," said a Europe-based spokeswoman for Boeing.
"We are disappointed to have issues so early in our 787 operations and are working with Norwegian to address them and return each airplane to service in as timely a manner as possible."
Norwegian has eight 787s on order including three that it ordered directly from Boeing and five that will be leased.