Airbus struck a 50-plane deal with veteran low-cost airline investor Bill Franke today, bouncing back from the potential loss of a major customer after IAG placed a lifeline order for Boeing's grounded 737 MAX jet. 

Franke's Indigo Partners signed a memorandum of understanding at the Paris Airshow to buy 32 of the new long-range version of Airbus's A321 jet and to convert 18 existing A320 family jets to the larger model. 

The planes will be allocated to Hungary's Wizz Air, US carrier Frontier Airlines and Chile's JetSMART, in which Indigo Partners owns stakes. 

Industry experts estimate the deal for the 32 aircraft could be valued at around $4.5 billion, based on a slight premium to the A321neo's list price of $129.5m, although most airlines get significant discounts. 

Airbus, which has not disclosed a list price for the A321XLR, launched the plane at the Paris airshow on Monday. 

It is aiming to carve out new routes for airlines with smaller planes and steal a march on Boeing's plans for a potential all new jet for the middle of the market.  

The deal with Franke is a big vote of confidence in the European planemaker, a day after major customer IAG signed a letter of intent to buy 200 of Boeing's 737 MAX jets that have been grounded since March after two deadly crashes. 

Asked about the IAG deal, Franke, who struck the largest ever plane deal by number of aircraft with Airbus in November 2017, called the A321neo the industry's most efficient single-aisle jet. 

Airbus also said today it had reached a preliminary deal to sell 11 A321neos to Taiwan's China Airlines, snatching the renewal of the airline's medium-haul fleet from Boeing. 

The deal signals intensified competition in Asia where Boeing this week predicted 40% of jets would be delivered over the next 20 years. 

Airlines can rarely be persuaded to jump ship to rival suppliers because of the costs of training and parts, but this week's Paris Airshow has witnessed two such announcements as sold-out planemakers mount incursions to continue their growth. 

In a further competitive twist, Boeing announced on Monday it would take over the supply of spare parts for the remaining Airbus A320 fleet at IAG's British Airways. 

Boeing's surprise deal with IAG yesterday enlivened a previously subdued air show, where the talk had been of the possible end of the aerospace cycle, given slowing economies and geopolitical tensions around the world. 

Boeing's 737 MAX crisis and a long-running corruption scandal at Airbus was also being discussed. 

It was not immediately clear how many of the 200 aircraft eyed by IAG would wind up as firm orders and how many would be options, nor how it would affect Airbus's presence at IAG, which placed an order for 14 A321XLR hours before the announcement. 

Six of these are bound for Aer Lingus. 

"It's a great coup, but for now it's a communications coup as it's a letter of intent. We will see what kind of deal lies behind it," a European industry source said. 

Even so, Boeing was expected to try to capitalise quickly on the move and seek further support for the embattled MAX as it offers airlines other big packages at attractive prices. 

Australia's Qantas Airways said today it would order 10 Airbus A321XLR jets and convert a further 26 from existing orders already on the planemaker's books. 

Airbus is also in talks with leasing company GECAS and has been trying to secure eye-catching orders for the A321XLR from JetBlue and American Airlines, though the world's largest carrier does not typically announce deals at air shows. 

Airbus sales chief Christian Scherer said there was some softness in the market but did not see an increase in cancellations. 

He told investors he expected to win more orders for the smaller A220, formerly known as CSeries. 

Both Airbus and Boeing are cushioned by thousands of orders for the single-aisle jets. 

Airbus chief executive Guillaume Faury predicted a pickup in orders after a slow start to 2019. But he voiced concerns about trade tensions and the growing risk of a no-deal Brexit. 

US President Donald Trump said yesterday he would restart trade talks with China, raising the possibility of detente in a costly trade war that has pressured financial markets and provided a tense backdrop to the June 17-23 air show. 

However, in the Middle East, tensions between the US and Iran were heightened after attacks last week on two oil tankers near the strategic Strait of Hormuz shipping lane which Washington has blamed on Tehran.