India’s state-owned National Aerospace Laboratories (NAL) soon will restart the flight test program for Saras, a 14-seat multirole military transport aircraft that has been beset by developmental problems.

There will be a test flight in April for Saras test aircraft one (PT1), NAL Technology Director Shyman Chetty tells Aviation Week. The Saras had its first test flight in 2004. There were two test aircraft built, PT1 and PT2. But PT2 crashed in 2009, killing all three people on board. That prompted NAL to make major changes to the aircraft’s design.

Chetty says PT1 has since been modified and a third test aircraft has also been built incorporating the new modifications. But NAL’s engineers are still “working on weight optimization” for PT3, and it will not fly until after NAL has test flown the modified PT1, he adds. The third prototype is about 500 kg (1,100 lb.) lighter than the original Saras, which had a maximum takeoff weight of 7,100 kg, Chetty says. NAL has achieved the weight savings through the use of more composite parts, such as a wing that features vacuum-enhanced resin infusion technology, he says.

The new Saras will still be powered by Pratt & Whitney Canada PT6 engines, but NAL has limited the thrust. The lower thrust will reduce fuel burn, Chetty says, adding that the aircraft has no need for so much thrust. He also says NAL is making sure the new Saras meets the Indian air force’s requirement for single-engine climb performance. That means if one of the aircraft’s two engines fails during takeoff, the aircraft will still fly. The air force has agreed to buy 15 Saras aircraft.

Once Saras achieves military certification, NAL plans to ask India’s Directorate General of Civil Aviation to certify it as a commercial aircraft, Chetty says, adding there is no reason why a military transport aircraft cannot also have a commercial variant.

NAL also makes the composite parts for the Hindustan Aeronautics Ltd. (HAL) Tejas light combat aircraft, another aircraft that is years behind schedule and has yet to receive full operational clearance. The Tejas Mk. I is powered by the GE F404, the same engine that runs the Korean Aerospace T-50 jet trainer. The Indian air force, however, wants it to have a more powerful engine, so HAL is developing a Mk. II Tejas that will have GE414 engines, the same engine that powers the Boeing F/A-18 Super Hornet.

Although the Mk. I has completed 2,000 test flights, it has only achieved initial operational clearance so far. That means it has yet to be approved to carry weapons. India’s air force chief, Air Chief Marshal N.A.K. Browne, estimates the Tejas will achieve full operational capability in 2015.

The Tejas’s airframe will have to undergo some major changes to accommodate the larger, heavier F414 engine. NAL’s Chetty says the rear fuselage will need to increase in diameter by 1 in. and the inlet will need to change to accommodate the larger engine. The fact that the F414 is heavier means it will affect the aircraft’s center of gravity. Chetty says they are looking at moving some equipment inside the aircraft to ensure it has the correct center of gravity.