Sources familiar with the situation said the altitude restriction did not solve the problem. “Pratt and Whitney told us that flying at lower altitude is not a solution,” an airline official said.
Flying at lower altitude consumes more fuel.
A Pratt & Whitney spokesperson said they were telling airlines there was no requirement to change flight altitude. "This recommendation was intended to address component durability related to the No 3 seal. Since March, new engines and overhauled engines have incorporated improvements that have enhanced the engine’s durability," the spokesperson added.
In March, users of the engine, including IndiGo and GoAir, had implemented the altitude restriction after Pratt & Whitney proposed limiting the altitude to avoid the glitch. Sources said the combustion chamber of the engine was unable to withstand the freezing temperature at 36,000 feet, resulting in the wearing off of the No 3 bearing seal. Cold had caused the bleed system to freeze shut on occasions. In its instruction, Pratt & Whitney had said that 30,000 feet provided a better ambient pressure for the seal. Another operator across the world, such as US carrier Spirit, also adhered to the restriction.
IndiGo operates the world’s largest A320neo fleet. Faced with continuous snags, the airline, which has a contract with Pratt & Whitney for the first 150 planes, is planning to look at GE engines for its next 280 planes. IndiGo President Aditya Ghosh last week said the airline still had to choose the engines for the 280 A320neos beyond the first 150 aircraft. “We will absolutely keep watching the GE engines. We will absolutely keep looking at what is out there in the marketplace,” he said. The airline currently has 23 A320neos in its fleet.