A proposed Russian-Chinese helicopter that has been nudging close to the size of the largest U.S. rotorcraft may turn out to be somewhat bigger. In its latest public review of product plans, China's Avicopter suggests that the Advanced Heavy Lifter (AHL) may be eclipsed only by Russia's giant Mil Mi-26.

Meanwhile, Avicopter has slipped the development schedule of a proposed 3.1-metric-ton (6,800-lb.) helicopter, revealed more data about the type and confirmed its designation as the AC332. The manufacturer has also set out its latest advances in rotorcraft onboard systems, including technology of crashworthy fuel tanks. This is a key issue because the Chinese industry is seriously lagging in electromechanical equipment and avionics.

The AHL is still under study, as it has been since 2008, when the Russian and Chinese governments agreed to cooperate on its development. Weight, presumably gross weight, will be 30-40 tons, says Avicopter, which has said the AHL would weigh up to 30 tons. The CH-53E Super Stallion, the largest U.S. helicopter, can fly at 33.3 tons with external loads, while the Mi-26 can take off at 56 tons.

The single-rotor helicopter will have two engines, raising the question of what type may be suitable. Since an unveiling in 2011, the likely Chinese candidate has been the 5,000-kw (6,700-hp.) WJ-10 of Avic Engine's Zhuzhou facilities (Avic Air Power Machinery Research Institute and Avic South Aviation Industry). Comparison with the CH-53E suggests that if the AHL reaches 40 tons, it will need more than 5,000 kw from each engine. Alternatively, the initial version of the type will be lighter.

The AHL will be 31.6 meters (104 ft.) long, not counting the main or tail rotors, the manufacturer said last month at the Aero Electromechanics China conference here organized by Galleon. Other data is unavailable. An official drawing shows 13 airliner-style windows on the left side of the body, the aft of which is shaped for the usual cargo loading door.

In 2009, Avicopter said the AHL would go into service between 2014 and 2019. That now looks highly improbable. One challenge on the Chinese side may be assembling enough people with the right skills, especially given the technical effort demanded by an aircraft of such great and unfamiliar size. A hint that Avicopter expects to be short of resources this decade is in its proposal to fill the market for 4-5-ton helicopters with a revision of a current type that cannot be certified for rich-country markets. Russian Helicopters has said it would expect to develop the dynamic components for the AHL, though its role would surely extend elsewhere.

For the AC332, referred to as the AC3X2 when it was revealed two months ago, Avicopter is aiming to obtain a type certificate in 2018. The previously stated target was December 2016, followed by a production certificate in June 2017. Major timetable slippages before the launch of full-scale development are not uncommon in the Chinese industry, which has a habit of announcing hopes as plans.

Timing is unusually important for Avicopter's projects because the manufacturer, part of state aeronautics group Avic, thinks it has only 3-5 years to establish its position in the early stages of what is expected to be an enormous domestic market. Amid global demand for 1,282 helicopters in the 3-ton class over the next 10 years, Avicopter forecasts that China will need 231.

Although Avicopter has said that AC332 development began at the end of 2012, it is now evident that it was referring to pre-development work. The project will be launched at the end of this year or beginning of next year, Avicopter revealed at the conference here. Timing presumably depends mainly on obtaining approval and funding from Avic's head office. In the meantime, the design is being further refined. A first flight in December 2014, also mentioned when the project was unveiled, looks very unlikely.

The two-engine AC332 will be in the class of the AgustaWestland AW109 Power and Bell 429. Its body will be 1.86 meters wide and 10.87 meters long, not counting the rotors. The tail plane will span 2.86 meters, while the four-blade rotor will have a diameter of 11.2 meters and the tail rotor, 2 meters.

The AC332 was revealed at the China Helicopter Exposition at Tianjin in early September along with the AC312C, a greatly revised version of the Chinese copy of the Eurocopter Dauphin. The development schedule for the AC312C was not stated, and Avicopter did not even mention the upgraded type in its presentation to the conference here. This may mean that it is a good deal further from launch than the AC332, although fast development is an evident reason for the choice of the derivative design in the AC312C's intended market position.

Reviewing other projects, Avicopter says deliveries of the AC313, its updated Aerospatiale Super Frelon, will begin in 2014. A type certificate was issued in 2012. Deliveries of the AC311, a heavily revised Eurocopter Squirrel, began in June, a year after type certification.

The 7.5-ton AC352 will not be certified before the end of 2015, Avicopter says. The aircraft was jointly developed with Eurocopter, which expects to certify its version, the EC175, early next year. Canada refused to supply the originally specified Pratt & Whitney PT6C-67E for the Chinese version, and Avicopter implies that integration of a new engine, the Turbomeca Ardiden 3C (called the WZ16 in China), delayed the AC352.

Avicopter wants to complete a line-up of helicopters with gross weights of 1-13 tons. It still has gaps to fill in there, notably at about 10 tons. Asked whether Eurocopter may develop more helicopters with Avicopter, Eurocopter CEO Guillaume Faury says some ideas have been considered, but there is nothing definite in the pipeline. Eurocopter is quite satisfied with its experience in developing the EC175 with Avicopter, whose version is called the EC352. Faury says the 50:50 project is a model that could be used again.

“With the research and development of the AC311, AC313, AC352 and other civil helicopters, China has made great progress in civil helicopter fuel systems,” Avicopter says separately. “This includes a major breakthrough in crashworthiness technology. Our fuel tanks do not leak after they are dropped and impact at 17.3 meters per second [57 ft. per sec.]. Fuel lines can be sealed automatically in a crash, which significantly reduces the possibility of fuel leakage and fire.”

In another advance, a “supervisory computer” attends to the measurement and movement of fuel, and to the center of gravity, greatly reducing the burden on pilots. Avicopter also notes it has advanced its simulation technology, for analysis of fuel-line properties and crashworthiness.

The manufacturer says it has made similar progress in automation and simulation in relation to hydraulics, where a further step forward has been the use of 21-megapascal (3,000 psi) systems in the AC311 and AC352.

The AC313's 140-kw AC and DC hybrid electric power system uses a bus power-control unit, bus communications, digital control technology and relay control circuits. For auxiliary power, distribution is conventional. The system delivers excellent cold-starting capability at high-altitude fields, redundant supply and high-quality power, the manufacturer says.

But Avicopter admits it is behind in rescue equipment, much of which must still be imported, and it notes that the seats of the AC311 “have no anti-crash performance.” It also sees advantages in foreign environmental control systems as compared with what it has installed in the AC311 and AC313.

Editor's Note: This article was updated to correct the abbreviation used for the Advanced Heavy Lifter.