So what exactly is wrong with the engines? We have a pretty good idea.

Parrikar attributed the failures to faulty bearings that contaminated the plane’s oil supply. It seems that metal fatigue led to tiny pieces of metal shearing off the friction-reducing bearings, which then entered the oil system.

This accounted for 33 of 69 engine failures.

Another 11 failures were the result of engine vibrations, while eight more arose from a lack of pressure in that same lubricating oil. New Delhi has not revealed the cause for the remaining 17 incidents.

The Air Force responded by taking the issue up with NPO Saturn, the Russian manufacturer. According to Parrikar, the company has come up with nine different modifications to help solve the problems.

India has already incorporated these “fixes” into 25 engines built at its plant in Koraput. In the future, the engines should benefit from an improved lubrication system, superior-quality oil and bearings that are a better fit.

However, a more general worry for the Air Force is the poor serviceability of the Su-30MKI fleet — meaning the number of aircraft actually available for operations on a daily basis.

Based on figures given by Parrikar, only 110 Su-30MKIs are “operationally available.” From a total of more than 200 aircraft that Irkut and HAL had delivered by February 2015, that means 56 percent are ready at any given time.

India’s Su-30MKI fleet has suffered five crashes since 2009.

To be sure, it’s not a great record, but it’s also not notably bad — especially when compared with the attrition rates of the Indian Air Force’s older fighters. It’s unclear what role, if any, the engine problems played in these accidents.

What’s perhaps more significant is the fact that engine deficiencies have bugged the Flanker from the start.

“The initial batch of 18 Su-30Ks and 10 Su-30MKIs were grounded as a result of engine issues, that were subsequently put down to design problems,” Indian defense blogger Shiv Aroor wrote.

At the end of last year, the Air Force’s fighter strength dipped to just 25 squadrons — its lowest in recent history. India has an officially sanctioned requirement for 42 fighter squadrons, and maintained 32 until recently.

As New Delhi withdraws its older MiG-21s and MiG-27s from service, the total number could fall to just 11 squadrons by 2024.

Casting an eye toward Pakistan and China, a parliamentary committee in New Delhi has argued that 45 fighter squadrons are the minimum India needs to cope with the demands of a “two-front collusive threat.”

Either way, that means India needs a lot of Su-30MKIs — and the jets have to work.