India and Russia on Friday signed two agreements for long-term support to the Su-30 MKI fleet of the Indian Air Force (IAF), which is expected to improve the maintenance and serviceability of the aircraft.

One of the agreements, signed between Hindustan Aeronautics Limited (HAL) that produces Su-30 MKI under licence, and PJSC United Aircraft Corporation of Russia, is for the supply of spares and technical assistance for five years.

The second agreement was signed by HAL with JSC United Engine Corporation for the supply of spares for engines of Russian origin.

India has around 230 Su-30 MKIs, designed by the Irkut Corporation specifically for India and produced by HAL at Nashik, Maharashtra. India has overall ordered for 272 Su-30 MKIs.

The frontline strike fighter of the Indian Air Force has suffered serviceability problems in the past.

A report of the Comptroller and Auditor General (CAG) in December 2015 said Su-30 MKI aircraft with the IAF suffer from poor serviceability, which is just around 55 per cent against the prescribed norm of 75 per cent.

In January 2017, the then Defence Minister Manohar Parrikar said the serviceability of the fighters has improved, and is now at 60 per cent. Informed sources said the present serviceability of the Su-30 MKI fleet is between 60 and 65 per cent.

Since its induction in the IAF in 2004, seven Su-30 MKIs have crashed, the last one on Thursday in Rajasthan.

Following a crash near Pune in October 2014, the entire SU-30 fleet was grounded for a month before it was allowed to fly again in November.

It was the longest period for which the fleet was grounded since 2009 when its operation was suspended for nearly three weeks following an accident.

A study conducted about aircraft's engine failure found out of total 69 cases in three years, 33 cases were due to presence of chips in oil; 11 cases are due to engine vibration as a result of bearing problem; and eight cases due to low pressure of lubricating oil.

Parrikar informed the Lok Sabha in May 2016 that on 34 occasions between April 2014 and March 2016, the fighter jet was forced to land with single engine after its another engine failed.

He said modifications in process of overhaul and manufacturing, proposed by Russian designers, have been implemented at Hindustan Aeronautics Limited (HAL) and the OEM.

The Russian manufacturers had also advised certain precautions and predictive maintenance during exploitation of engines which were implemented by the IAF.

The agreements were signed at the India-Russia Military Industrial Conference in presence of Defence Minister Arun Jaitley and Minister of Industry and Trade of the Russian Federation, Denis Manturov.