Guy Norris/Los Angeles MaxKingsley-Jones/London

Boeing has revealed that its 717 twinjet is bettering its performance targets by up to 5%, as the first production example, "P-1", made its maiden flight from Long Beach, California on 24 February.

Boeing's just-released performance details of the baseline 717 reveal it is demonstrating a substantial 5% fuel burn advantage in cruise compared to predicted performance, while climb fuel burn rate is around 3% better than expected. Boeing estimates the average fuel burn benefit is likely to be between 3% and 4.5% for the complete flight, depending on the route length.

The performance gains are largely due to lower than predicted interference drag around the empennage, says Boeing. Performance of the 717's BMW Rolls-Royce BR715 is also better than predicted, it adds, with the engine manufacturer claiming that fuel consumption is bettering estimates by up to 1.5%.

Boeing is studying ways of improving the 717's field performance to increase the number of airports from which it could operate, with the short 1,199m (3,934ft) runway at London City airport a specific target. The studies include the use of an higher 50í flap setting to reduce approach speed and landing length, and greater rudder throw to maintain minimum control speed with one engine out to enable more powerful engines to be used.

The 717 is approaching the halfway point in its 1,700h flight-test programme, with 712 flights and 756h accumulated by late February. "Certification is on target for mid-July and deliveries to Air Tran should begin on 1 September," says Boeing's director of 717 marketing, Rolf Sellge.

Sellge says 717 production will rise from 12 units this year to 32 in 2000 and will stabilise at 60 per year from 2001. Sellge adds that production is sold out until 2001 at the current rates.

Sales of the twinjet have been slow to date with just four customers, Air Tran, TWA, and leasing companies Pembroke and Bavaria, accounting for the 717's 115 orders.

Sellge says the marketing effort is being increased and discussions are underway with several potential customers which could materialise in orders in the second half of this year.

Boeing is marketing the 717 with a sticker price of $31.5 million (1998 value). Industry sources suggest the lessors are pitching for monthly rentals of around $200,000 to $250,000. Bavariahas not yet placed its four 1999delivery slots with airlines.

Source: Flight International