NEW DELHI — Fresh troubles are delaying India’s indigenous Tejas Light Combat Aircraft program, with final operational clearance slipping by over a year to December 2014.

Testing challenges and performance-parameter issues have delayed flight testing, operational envelope expansion and certification, leading to the Indian air force (IAF) reluctantly agreeing to a 12-month slip in declaration of the aircraft as fully operational. The IAF is viewing this as a setback to timely delivery of production series aircraft, though squadron service is still set to begin in mid-2013 in the initial operational configuration.

The seventh limited series production aircraft, a replica of the Tejas in its production series configuration and already delayed by over six months, is slated to make it first flight this month. Different versions of the aircraft are currently undergoing weapons and sensor tests at three air bases in the country. The program is designed to integrate and test beyond-visual-range weapons, rockets and guided bombs, expand the platform’s flight envelope and improve turn rate.

A senior IAF officer says, “The parameters listed as untested during initial operational clearance in January 2011 — including all-weather clearance, lightning clearance and wake penetration — are yet to be proven on the Tejas. Certain other performance issues, including minimum/maximum g-limits and certain precision weapons tests, are to be demonstrated. The program has sought time beyond the deadline of June 2011.”

IAF leaders, who had grudgingly accepted initial operating capability in January after ceding certain marked-down performance parameters, are not happy. A year-long delay in deployment of the Tejas means further pressure on squadron numbers. The Tejas was to be deployed in a refurbished air base at Sulur in South India by July 2013, though it is now likely to be the end of 2013.

An official with the Aeronautical Development Agency (ADA), which oversees the Tejas program, says: “The IAF has agreed to a 12-month extension for final operational clearance, contingent on certain additional performance parameters. It is a minor delay that will be made up in tests. We have completed an important series of weapons tests both at day and night.”

Preliminary design and configuration studies of the $542 million Tejas Mk. 2 effort, to build a variant powered by the General Electric F414 turbofan, have been completed. The more powerful aircraft is expected to see prototyping by 2013 and a first flight by 2014 — right about the time the Tejas Mk. 1 is declared fully operational.

The IAF has said it will induct at least 83 Mk. 2 versions of the Tejas if it meets performance requirements, including a smaller maintenance footprint, shorter takeoff and better turn rate.

First Flight

In a parallel development, the Stobar (short takeoff but arrested recovery) version of the Tejas, the LCA-Navy, has finally been declared ready for its first flight, following a delay of more than 18 months. Defense Research Development Organization chief V.K. Saraswat indicated that concerns over platform safety had been overcome and that the team was finally confident about entering the flight-test phase.

Persistent doubts about the platform’s landing gear, recovery mechanism and approach control laws had pushed back flight tests. Following successful engine ground runs starting in September, then taxi trials, the program team is finally ready to put the jet into the air.

“There’s a great deal of pressure,” says a senior source on the LCA-Navy program. “This is India’s first indigenous naval carrier-borne fighter. We hope to shift testing to Goa by the middle of 2012 and begin testing at the Indian navy’s shore-based test facility for arrested recovery operations.”

Both the air force and navy variants of the Tejas have depended on technical consultations from EADS to optimize systems and speed up flight test and certification.