Boeing says it can squeeze another 600 nm of range out of the new 777-200LR by adding three fuel tanks, giving the world’s longest-range commercial airliner the ability to fly in revenue service as far as 10,000 nm. But for all its efforts to break distance records and market the airplane in every corner of the globe, by the start of this month Boeing had yet to attract the kind of attention it really wants–firm orders beyond the pair of sales for five airplanes it had so far accumulated.

Due for U.S. certification by the end of the year, the 777-200LR has undergone a series of design tweaks since its introduction, among the most recent an effort to add Sydney-London–in either direction at any time of the year–to its list of city-pair capabilities.

The results of the various improvements have impressed the engineers. Boeing, of course, hopes airline executives find them equally striking. Australian flag carrier Qantas, in particular, has reportedly shown close interest in the new Triple Seven’s globe-girdling range, as has Air Canada,  which due to a labor dispute with its pilots had to cancel an order it placed in June for fourteen 787s and a mix of eighteen 777-300ERs, 777-200LRs and 777 Freighters. However, Air Canada recently came to terms with its pilots and early this month placed a new order for the same number of airplanes. How many of each type of 777 it plans to take remains unclear.

To fly 10,000 nm with a full load of 300 passengers, the 777-200LR would need a total of six auxiliary fuel tanks, four in front of the lower cargo hold door and two behind it, resulting in the loss of six LD-3 container positions. Today’s published range of 9,420 nm assumes the existence of three auxiliary fuel tanks located behind the wheel well in the lower cargo hold, although the airplane can fly a full passenger load from most cities in the Middle East to Los Angeles with no extra fuel tanks.

Still, “there is more than one airline that would find more auxiliary fuel tanks useful,” 777 program manager Lars Andersen told Aviation International News. He wouldn’t confirm that Qantas has asked specifically for the capability, but asked whether one would need the extra tanks for a Sydney-London route, Andersen said, “You certainly would” to overcome seasonal winds.

“Of course it’s very much dependent on the configuration of the interior of the airplane,” Andersen pointed out. “We have customers looking at all sorts of configurations. You’ll find on ultra-long-range routes that many of the customers are looking at a lower number of seats, and putting a lot more room in the airplane in terms of seat pitch.” So far most of the 200LR’s potential customers want the airplanes to hold about 250 seats, he said.

Andersen wouldn’t name them, but Middle East prospects certainly include 777-300ER operator Emirates, which could use  the 200LR’s range for coveted routes to San Francisco, Los Angeles, Houston and Chicago. During this past summer’s Paris Air Show, Qatar Airways confirmed its plans to order 20 airplanes from Boeing, including some 200LRs. In fact, the 777-200LR demonstrator stopped in Doha during its recent 24-city “Going the Distance” tour, which also included stops in Dubai, Abu Dhabi, Muscat and various cities in Pakistan and India. “We’re hopeful of selling the airplane to most of the airlines in those regions,” said Andersen.

Just last month the Indian government gave state-owned Air India permission to order $8 billion worth of airplanes from Boeing, including eight 777-200LRs. Deliveries could start as early as next year, after launch customer Pakistan International Airlines (PIA) takes the program’s two test articles.

PIA expected the airplanes in January but September’s near-month-long machinist strike at Boeing’s plant in Everett, Washington, will delay deliveries until March, when the airline launches service between Karachi and New York. During the strike, engineers continued to plow through paperwork and submit documentation to airworthiness authorities, but test flying effectively stopped, spoiling plans for refurbishing PIA’s airplanes by the end of the year.

Although by no means happy with the delay, Boeing expects that PIA will find the 777-200LRs worth the wait. “We’ve finished the performance side of the testing on what we were calling the 300ER Enhanced…and we’re really happy with the outcome of those improvements,” said Andersen, referring to airframe tweaks to the larger 777-300ER that will find their way onto the 200LR as well.

One readily apparent change involved the addition of vortex generators to the outboard part of the wing and the installation of smaller generators than originally planned for the inboard section. Tests have shown that the smaller generators–about the size of those on a 737–can keep airflow attached to the 777’s wing just as effectively as the larger devices, allowing less drag and better fuel burn.

Another recently completed study proved the effectiveness of a new air-conditioning cooling system. The 777 uses a system by which ram air travels through an inlet in the fairings below the wing-body connect point, enters a heat exchanger and cools the bleed air coming from the engines, thereby regulating the temperature of the cabin. Behind the inlets Boeing installed computer-controlled louvers that adjust the amount of air intake needed depending on flight conditions. If the system needs less air, the louvers adjust to their ideal position, therefore cutting drag.

All told, the improvements have cut fuel burn by 2.3 percent over original estimates, including about 0.8 percent from various adjustments to the airplane’s 110,000-pound-thrust GE90-110B turbofans. Boeing has also decided to offer a -200LR using 115,000-pound-thrust GE90-115Bs for improved field performance or payload capacity, but it will wait to certify the higher-thrust version until it attracts an order.