Pratt & Whitney shipped 120 geared turbofan engines in the third quarter to stay on pace to meet an annual delivery target, but durability concerns still require diverting 12-15% of output to a spares pool and drive company officials to consider new design changes.

The third quarter deliveries help P&W recover from a slow start earlier this year and raise total geared turbofan shipments year-to-date to 254. The company is committed to deliver 350 to 400 engines in total by the end of the year and “Pratt remains well on track”, says Greg Hayes, chief executive of P&W parent United Technologies, on a 24 October earnings call with analysts.

Moreover, P&W is continuing to retrofit improved carbon air seal design for the No. 3 bearing of the PW1100G engine, which powers the Airbus A320neo family, Hayes says. A second durability problem that affects all versions of the engine —a faulty combustor liner — should be solved by a third redesign due to be certificated by the end of the year, Hayes says.

As the PW1100G approaches the two-year anniversary of entry into service in late January, P&W is continuing to evaluate potential design changes for the geared turbofan.

“While we’re still seeing some success with the actions we’ve taken to date, we’re also looking at design alternatives that are expected to further improve durability in the engine,” Hayes says.

P&W introduced the geared turbofan to reduce fuel costs by at least 15%, but the engine has been crippled in service since January 2016 by durability problems with components unrelated to the innovative fan drive gear system. Delivered engines meet reliability targets with a 99.8% dispatch rate, but the carbon air seal and combustor liners are wearing out faster. That requires airlines to remove the engine from the wing to install the new part, a process that can take days or weeks.

To keep a growing fleet of A320neo family aircraft and Bombardier CSeries in the air, P&W has enlarged the spares pool. By diverting the engines to the spares pool, however, P&W has slowed the pace of deliveries to assembly lines for Airbus and Bombardier. The situation will become even more pressured next year, as Embraer introduces the E190-E2 into service as P&W attempts to nearly double engine deliveries while still contending with the combustor liner durability problem.

Source: Cirium Dashboard