India is running out of patience with Russia and its shoddy military equipment. The most irritating issue, one that lasted more than five years, has been the low reliability of the Su-30MKI jet fighters. Fifty of these Russian designed aircraft were built in Russia and the rest of the 272 aircraft order are being assembled locally. Deliveries should be complete by 2019 and at the moment India is not keen on ordering any more. Most of the problems are related to engines and Russia says it has narrowed most of the problems down to difficulties related to ball bearings. The engines are also assembled in India, using Russian and Indian made parts. Russia has devised several fixes for the engine problem but the readiness (for combat) rate of the Su-30MKI is still about 55 percent (compared to 70 percent or higher for most other modern aircraft).
The Indian Air Force has lost five of its Russian designed Su-30MKI jet fighters since 2009. In 2011 the commander of the Indian Air Force took an hour-long flight in one of India's Su-30MKI to reassure Indian pilots that the Su-30MKI was safe. Two had crashed in 2009, due to mechanical failures and there were widely publicized reliability problems with the engines and many of the other Russian designed and built components of the aircraft. There have been two losses since 2013.
Indian pilots are understandably nervous about the safety of the many Russian warplanes they fly. The MiG fighters are the most dangerous but the more recent Su-30 models were believed to be a lot safer. Recent problems indicate this may not be the case. Russian efforts since then to fix the problems have not reassured Indian pilots or politicians.
The MiGs crashed so often that India decided to retire all of them. Over the last half century India bought 976 MiG-21s and over half were lost due to accidents. While India was something of an extreme case in this area (other users don't fly their MiG-21s as much), it's been typical of MiG aircraft. All this is part of the decline of the once feared, and admired, MiG reputation. Starting in World War II (the MiG-1 entered service in 1940), through the Korean War (the MiG-15 jet fighter), and the Cold War (the MiG-17/19/21/23/27/29), MiGs comprised the bulk of the jet fighters in communist, and Indian, air forces. But after the Cold War ended in 1991, the flaws of the MiG aircraft (poor quality control and reliability, difficult to fly) caught up with users, in a big way. In the last few years most of the bad news about military aircraft reliability, accidents, and crashes has involved MiG products. For example, all Indian MiG-27s were grounded several times over a few years because of reliability. The MiG-27 and Cold War era Russian warplanes in general do not age well. All Indian MiGs (except for 66 MiG-29s) are to be retired by 2025, if not sooner.
It’s not just mechanical problems. In 2012 India went public with yet complaints about an unspecified "design flaw" in the electronic flight control system for the Su-30. There were also problems with ejection seats and the new Russian “stealth” fighter (the T-50) which India is helping to develop. All this has led India to negotiate a deal to buy 129 French Rafale fighters and hope that this would persuade the Russians to improve the reliability of Russian aircraft.