The government has given temporary relief to Airbus A320neo operators IndiGo and Go Air, but is planning to increase scrutiny on Pratt & Whitney (P&W) engines.
The decision was taken after P&W engineers were able to convince the government that the mid-air shutdown of engines happened in rare instances due to glitches.
“We did a root-cause analysis of the incidents that happened with Airbus A320neo. It was found in-flight shutdown happened only in 0.001 per cent cases. The number is lower than the global benchmark. But, since the largest share of the engines are being operated in India, we have decided that the Directorate General of Civil Aviation (DGCA) will get in touch with US regulator Federal Aviation Administration and issue further safety protocol for the engines. It would be done in the next seven days,” said Civil Aviation Secretary Rajiv Nayan Choubey.
“Pratt and Whitney has been able to satisfy that most of the suggestive corrective actions have already been taken,” he added.
While particulars of the new protocols will be decided in next seven days, sources in the DGCA suggested that it may ask the operators to conduct boroscopic examination at 500 hours — down from earlier prescribed 1,500 hours. In this type of examination, aircraft engines are remotely checked for any defect.
Extra scrutiny means IndiGo and Go Air maintenance cost will increase. However, both the airlines are being compensated for possible commercial loss by Pratt and Whitney.
Also the regulator is unlikely to allow ETOPS (Extended Range Twin Operational Performance Standard) approval to the A320neo. ETOPS approval is required for twin-engine aircraft to operate routes where the nearest suitable airport to make an emergency landing is more than 60 minutes.
In the absence of the approval IndiGo and Go Air will have to fly the aircraft only on routes where an alternate landing airport is within 60 minutes.
The geared turbofan, a step-change in the efficiency of turbines for commercial aircraft, has been hit by a slew of design flaws that have grounded planes, delayed deliveries, and prompted millions of dollars in compensation claims.
In 2016, initially the aircraft started reporting oil metal detector warnings.
The third engine-bearing compartment had a seal which did not work correctly at high flight levels.
The thin air caused the air riding seal members to sometimes oscillate. This left metal particles in the engine oil, which gave warnings, pointing to a potential engine problem.
The manufacturer did a fix, which was a change to a more classical carbon seal.
The third problem was combustion chamber linings which had unforeseen hot spots, reducing the operational life. The fix provided was a combustion chamber with more pores which can provide more cooling.