Air India is inspecting its fleet of Boeing 787 Dreamliners to check for performance issues and to test whether the jets are using up fuel faster than expected, news reports said Wednesday.

Rohit Nandan, chairman of India's state-run carrier, said at the ongoing air show in the southern city of Hyderabad that Air India knew that the Boeing (NYSE:BA) planes, which are made from lighter, composite materials not found in conventional airplanes, are seven tons heavier than they are supposed to be. To investigate if the planes are using up more fuel than the carrier had anticipated, Nandan said, Air India has collected data for the past 18 months through November 2013, but added that there were no plans to ground the aircraft yet, Reuters reported.

"As far as the fuel efficiency is concerned, when Air India received these planes, even at that time, we knew that the planes were heavier than what they were originally promised to be," Nandan said, according to Reuters.

Nandan added that Air India has received the compensation it expected from Boeing for delaying the delivery of its troubled 787 Dreamliners, but did not give an exact figure on how much the Chicago-based plane manufacturer had paid. India had originally sought $46 million as compensation from Boeing because of a three-year delay of the 27 planes ordered in 2005 by Air India for delivery in 2008. In February, local news reports said that Boeing offered $23 million as compensation and that Air India was continuing to negotiate with Boeing for a higher number.

Air India, like other carriers around the world, has faced several issues with the 787 Dreamliner, which was grounded by an FAA order early last year, after issues with the plane's lithium ion batteries. Air India's issues with its Dreamliner fleet include windshield cracks, overheating of on-board ovens, failed computers and one incident where the plane’s fuselage fell off on a flight bound from Delhi to Bangalore.

Between November 2012 and September 2013, Air India recorded 136 technical glitches in the planes, according to local reports. Last week, Boeing reported that it discovered “hairline cracks” in the wings of about 40 787 Dreamliners that are currently in production but claimed the finding would not affect its delivery schedule for 2014.

Nandan said that he had been reassured that the glitches have not compromised the plane's airworthiness and said: "These incidents are not unusual in a new fleet, in a new aircraft."

Air India plans to inaugurate 14 new Dreamliners by the end of March, which leaves another 13 to join the fleet in 2016.