Europe’s Airbus is considering whether to drop Lithium-Ion batteries and switch back to traditional ones on its new A350 as investigators probe Boeing 787 battery problems, several people familiar with the matter said.

The move comes amid a wider rethink in the aerospace industry on whether the powerful but delicate backup energy systems are technically “mature”, they said.

Industry executives, insurers and safety officials told Reuters the technology’s predictability was being questioned at senior levels as investigators struggle to find the cause of incidents that led to the grounding of Boeing’s 787 Dreamliner.

“There is an increasing doubt over the technology,” said a person familiar with industry-wide discussions on the issue. “It may well be the future but for now it is a question of maturity. The information on the two incidents is not reassuring.”

The National Transportation Safety Board, which is examining a fire on a parked 787 at Boston airport a month ago, said on Thursday it had identified where the fire broke out but not the cause and referred to a possibly long investigation ahead.

A spokesman for EADS unit Airbus said the company would evaluate the outcome of the U.S. battery investigation: “Let’s not get ahead of ourselves. There are no conclusions by the NTSB yet and the investigation is still ongoing.”

Airbus has kept all options open, the spokesman added.

France’s Saft, which makes both the new and old generation of batteries for Airbus, did not immediately respond to requests for comment. Its head told Reuters last month that Lithium-Ion would ride out the 787 problems.