US planemaker Boeing won a fresh boost Tuesday for its crisis-hit MAX aircraft, as investment fund 777 Partners ordered up to 66 of the passenger aircraft worth a combined $8 billion.

The announcement, on the second day of Farnborough airshow, comprises a firm order for 30 medium-haul single-aisle 737 MAX-8-200s plus options to purchase up to 36 more from the same family.

The Miami-based fund operates Flair Airlines in Canada and Bonza Aviation in Australia.

Josh Wander, the fund's managing partner and co-founder, said the MAX-8-200 jets -- configured with more seats than the MAX-8 -- would help ramp up the capacity of both carriers.

Boeing 737 MAX has been picking up orders at the Farnborough Airshow
Boeing 737 MAX has been picking up orders at the Farnborough Airshow AFP / JUSTIN TALLIS

Tuesday's news takes the fund's total Boeing order book to 134 models in the 737 MAX family.

"This new order marks another milestone in the robust growth of our aviation businesses and concurrently, our partnership with Boeing," Wander added in a statement.

The MAX jet, which suffered two deadly crashes in 2018 and 2019, is experiencing a rush of interest at this year's Farnborough, southwest of London.

US airline Delta on Monday announced a deal to buy 100 MAX passenger aircraft worth a combined $13.5 billion.

Japan's ANA has agreed to buy 20 of MAX 8 jets worth $2.4 billion.