Boeing's troubled 787 aircraft continues to be bogged down by issues, with two Japanese carriers cancelling three Dreamliner flights in the last three days, due to problems with their engines.

ANA Holdings Inc., which operates the world’s biggest fleet of Boeing 787s, canceled a Dreamliner flight on Wednesday from Ube, western Japan, to Tokyo, after an engine failed to start, Bloomberg reported, citing an ANA spokeswoman.

On Monday, ANA canceled a 787 flight from Fukuoka to Tokyo after a sensor near an engine developed a potential problem, the report said. JAL, which operates the second-largest number of Dreamliner aircrafts, also canceled a 787 flight on Tuesday after a Singapore-bound plane developed a problem with the engine's anti-icing system, the report added.

None of the problems were related to the aircraft's lithium-ion batteries that overheated and prompted regulators to ground the Dreamliner worldwide for four months starting on January 16. 

Boeing redesigned the battery system to prevent heat from spreading and causing electrical fires. Both ANA and JAL resumed flying the Dreamliner on June 1.

The U.S. Federal Aviation Administration, or FAA, ordered a temporary cancelation of 787 services, after batteries were found to have been burnt on two of the planes operated by ANA and JAL in January. FAA approved the upgraded battery designs before eight worldwide Dreamliner operators resumed flights in April, May and June.

“I can’t imagine there’s anything out of the ordinary,” Peter Harbison, executive chairman at the Sydney-based CAPA Centre for Aviation, an industry consultant, told Bloomberg. “The positive thing is it’s not a battery system problem. I wouldn’t expect it to affect demand.”

Boeing is aware of the issue and was working with ANA to resolve it as soon as possible, Bloomberg reported, quoting an email from a company spokesperson.