India’s aviation regulator is inspecting all of the country’s airlines following a recent spate of non-fatal incidents to ensure they comply with safety standards, according to a document seen by Bloomberg News. 

The so-called special audit began on July 19 to tackle “engineering-related events,” the Directorate General of Civil Aviation said in the document. It will investigate if airlines have enough qualified manpower and check staff training, along with work-shift limits designed to reduce crew fatigue.

The DGCA said last week it grounded a pair of Airbus SE A320 planes operated by Go First, India’s second-biggest airline, after two domestic flights were diverted due to engine issues, while another was rerouted when its windshield cracked. The regulator also grounded an Air India Boeing Co. 787 following pressure loss on a flight from Dubai to Cochin in India’s south. The country’s biggest carrier, IndiGo, also diverted a flight due to a technical problem.

SpiceJet Ltd. has suffered several glitches on recent flights and was earlier this month summoned by the regulator to explain why no action should be taken against it for apparently failing to establish “safe, efficient and reliable air services.” The airline was given three weeks to respond to the July 5 notification, meaning the deadline is Tuesday.  

SpiceJet didn’t immediately respond to a request for comment. IndiGo, operated by InterGlobe Aviation Ltd., also didn’t respond, along with Go First and Air India, which is now part of Tata Group. A representative for India’s aviation ministry didn’t immediately respond to request for comment.

The DGCA will examine grounded planes and the latest maintenance data of all aircraft, according to the document, which was dated July 18. It will also check minimum equipment lists that allow flights to proceed when some gear is faulty but doesn’t affect safety and airworthiness. Carriers’ internal quality controls, spare parts and hangers will also be assessed.