FILE: Air Force personnel march past a Sukhoi-30 fighter at the Air Force Station in Hindon near New Delhi (Associated Press photo)

India has grounded its entire Sukhoi-30 fleet and each aircraft is undergoing a thorough technical check following a recent crash near Pune - both pilots had ejected safely and were not injured.The grounded planes - nearly 200 of them - represent almost a third of the country's fighter jets."The fleet has been grounded and is undergoing technical checks following the latest accident in Pune. It would be back in air only after a thorough check," Indian Air Force spokesperson Wing Commander Simranpal Singh Birdi said.He did not elaborate on what sort of technical problems are being diagnosed or investigated. The entire Sukhoi fleet has been grounded twice in the past.The Sukhoi, which was first introduced in the Air Force in 1997, was for years considered a safe and reliable aircraft. The crash near Pune earlier this month was the fifth of its kind.Concerns about the reliability of the Sukhoi-30 MKI have been accruing in recent months with several planes reporting engine failure.Based on recent complaints, the Air Force has started servicing the engines of these fighter jets after 700 flying hours, instead of the stipulated 1,000 hours. The Air Force says this hits operations fairly hard because each plane is grounded for about a week.

As another precaution, the engines are also being modified according to specifications provided by the Russian manufacturer. That engineering is being handled in Odisha by HAL - Hindustan Aeronautics Limited, which is a state-run company. The engine modifications will be carried out in batches over the next 18-24 months, said sources. They will then go through extensive testing before being fitted for the fleet.Analysis by the Air Force shows that the Sukhois have been malfunctioning regularly since 2012. For the last four years, many of the fighter jets have been forced to make emergency landings using only one of the twin engines.