CHICAGO, UNITED STATES (REUTERS) - Boeing's grounding of test flights for its new 737 MAX planes could be a short one.

One partner of the joint venture that supplies its engine, Safran, said Thursday it'll take just a few weeks to fix the engine glitch that suspended the flights.

The news comes just days before Boeing was to deliver its first 737 MAX to Malaysian carrier Malindo Air.

The company said it still plans to start deliveries this month. Boeing can't afford a huge delay because experts say that'll cause its inventory to build up.

It had been on course to achieve a rarity among plane manufacturers: delivering a jet on time.

The plane lists for US$110 million (S$155 million) but analysts say discounts could bring that down to around US$50 million.

Teal Group aviation analyst Richard Aboulafia explains just how crucial the 737 MAX is for Boeing's bottom line.

"It's extremely important for a number of reasons. One is it's their best selling aircraft. Second of all, it's one of their biggest sources of profit in the entire corporation. And on top of that, you've got production going from the NG model to the MAX at a point where they're at a record level of output," said Aboulafia.

The Max is the fourth generation of a jetliner that debuted 50 years ago. Boeing needs to get its MAXes off the ground and into the air fast because rival Airbus has had a one-year head start with its competing A320neo jet.