Groundings of Pratt & Whitney-powered Airbus A320neos are climbing fast as operators remove engines for accelerated inspections recommended by the manufacturer and mandated by regulators.

The percentage of the PW1100G-powered Airbus fleet on the ground stood at 19% at the end of September, or 267 aircraft out of 1,378 in the global fleet, an Aviation Week analysis shows. The figure is a 6% jump compared to August 31’s figure of 175 aircraft out of 1,358, the data show.

Mandates issued by the FAA and European Union Aviation Safety Agency (EASA) gave affected operators until late September to remove the first batch of engines flagged for inspections. The initial batch consisted of about 140 engines, Pratt said when it unveiled its fleet management plan to address potential cracks in certain high-pressure turbine disks and high-pressure compressor integrally bladed rotors (IBR).

Aviation Week’s analysis looks at ground days on an airframe-by-airframe basis. Anything that did not fly for at least 15 days is considered grounded. Not all of the idled aircraft are parked for the disk and IBR checks. Many have been parked for months awaiting repairs related to long-running durability problems on the PW1000 fleet, which powers some A320neo-family variants and all A220s and Embraer E2s. Some may be down for routine maintenance or operator-related reasons, such as capacity management.

September’s sharp rise in A320neo inactivity is almost surely linked to the new inspections, however.

Pratt has said the number of grounded A320neos is expected to approach 650 in the first half of 2024 as more deadlines approach and operators pull affected engines. Pratt calculates that about 1,200 of the 3,000 engines that have the suspect parts will need inspections by mid-2024. More than half of the initial checks are unscheduled, driven by revised inspection intervals required to ensure contaminated powder metal incorporated into the disks and IBRs do not lead to cracks.

The surge in unscheduled checks combined with hundreds of already planned overhauls and related need for parts means turnaround times (TATs) will grow to perhaps 300 days.

MTU, a PW1000 development partner and maintenance provider, said that capacity issues and parts shortages mean the so-called “hospital visits” to address durability issues have TATs of about 150 days—more than double a routine narrowbody engine overhaul.

The disk and IBR checks will be integrated into heavier workscopes that are closer to full overhauls to help keep the engines in service for as long as possible once they are back in the field.

The latest fleet management plan and the September deadline affects only A320neo engines. Inspection plans for the PW1500s on A220 and PW1900s on E2s are still being determined. Pratt executives have said they expect far less disruption in those fleets compared to the A320neos. Aviation Week figures showed 15% of the 292-aircraft A220 fleet and 11% of the 94-aircraft E2 fleet was on the ground on Sept. 30. The majority of these are likely linked to engines in shops to address long-running durability issues.