India’s Directorate General of Civil Aviation (DGCA) is confident that technical issues with Pratt & Whitney PW1100G-JM geared turbofans are being adequately addressed but will not hesitate to take drastic actions—including grounding aircraft—if the growing number of incidents related to two issues does not subside as fixes are rolled out, the agency said.
A series of issues have plagued the geared turbofan variant—which is an option on the AirbusA320neo family—since it entered service in January 2016. India has been hit particularly hard, in part because of the country’s harsh environmental operating conditions, and because Go Air and IndiGo combined have about 30% of the 862-engine PW1100G-JM in-service fleet.
Problems with combustion-chamber distress as well as failures of knife-edge seals and no. 3 bearings that contributed to significant fleet-wide operational and new-production disruptions have largely been addressed. The current issues involve failures of the accessory—or main—gearbox (MGB) and low-pressure turbine (LPT) stage 3 blades, as well as “engine vibration.”
Figures released by DGCA show that through July 2019 the global fleet experienced 11 MGB failures that led to inflight shutdowns, turn-backs, or rejected takeoffs. Two of these involved Indian carriers. Comparable figures for all of 2018 were seven and two, respectively.
LPT-related issues are also on the rise, DGCA said. Global LPT failures leading to operational disruptions in 2019 totaled 17 through July, including seven involving Indian carriers. Last year’s totals were six and five, respectively.
Pratt has introduced new software to address the gearbox issue immediately through operational limitations designed to reduce the risk of gear fractures. A new gearbox design has been developed to solve the problem, and in-service engines are being upgraded. All new engines leaving the production line have the upgraded gearbox, and Indian carriers have received 20 engines modified in-service—14 for IndiGo and six for Go Air—DGCA said.
The MGB is separate from the gearbox between the fan and low-pressure shaft that gives Pratt’s “geared” turbofan its name. Pratt has reported no issues with the fan gearbox.
Pratt is addressing the LPT blade issue with a redesigned part. New engines have them, while in-service engines are getting them during shop visits. IndiGo had 47 engines with the new blades, while Go Air has seven, DCGA said.
The engine-maker is also incorporating a redesigned high-pressure compressor piston seal to address the vibration issue. “Although transient vibration may result in an engine removal, there is no inflight shutdown risk associated with” the issue, DCGA noted.
Indian carriers will not be receiving any new engines that don’t have the new MGB and LPT blade designs incorporated, DGCA said. In addition, any engines coming from MRO shops must have both modifications in place and there will be a “restriction” on accepting leased engines without the fixes. The agency also said it has asked Pratt to ensure there are enough spare engines available to Indian carriers to minimize groundings due to unscheduled engine removals.
“DGCA is continuously monitoring the performance of these engines,” DGCA said following an Aug. 28 meeting with airlines to provide an update and gather input on the issues. “With strong mitigation measures in place and strict adherence to [standard operating procedures] by the airlines, the problem is being contained.”
A320neo engine reliability issues have garnered significant attention in India, in part because the model provides about 40% of domestic lift. The meeting was called in part to address an increasingly vocal public call for action.
“Taking appropriate proactive safety measures as and when required, including the grounding of aircraft in the interest of safety and further remedial measure[s] if necessitated, will be taken,” the agency said following the meeting. “We will take the harshest action, if the needs arise.”
Pratt said it is “well-positioned to meet” DGCA’s “expectations” on rolling out upgraded engines to India’s carriers, adding that it has an “adequate supply of spare engines in India.”
The PW1100G-JM issues played a role in IndiGo opting for CFM LEAP-1As to power most of the remaining A320neos it has on order. The airline in July committed to an order that will see about 280 of its 340 outstanding A320neo-family aircraft equipped with LEAP engines. Delivery of IndiGo’s first LEAP-1A-powered A320neo is scheduled for 2020.