Delta Air Lines has been forced to turn to older aircraft while plagued by groundings of some of its newest Airbus jets. The Big Three US carrier has heavily gone in for models from the French manufacturer to bolster its narrowbody fleet in recent years. However, the rollout of these has not been without its issues.

Suspected Pratt & Whitney engine issues, struggles with certification of new business-class seating, and even software mishaps have all presented Delta and peers alike with hurdles. While the latter may have been a brief fix and delayed lie-flat seating certification, leaving it unused so far, the former has posed a far greater problem, taking aircraft out of action for months upon months. The result has been a reliance on some older Boeing models that Delta may well have wanted to part ways with much earlier.

Pratt & Whitney Engine Inspections

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At the core of the problem was a “rare condition” in the powder metal used in Pratt & Whitney’s PW1100 series. First flagged in July 2023 by the engine maker, the potential contamination of high-pressure turbines and compressor disks in the engines prompted the accelerated inspections of the power units used on the Airbus A320neo family.

Namely, planes with engines built between 2015 and 2021 were grounded as inspectors determined whether they included contaminated parts that were susceptible to cracking prematurely. Without being removed from the jets, stripped down, and fixed if needed, the potential issue raised the risk of the engines ultimately failing. All that goes to say that the stakes were high and the ramifications for airlines were great.

The scale of the effort required became apparent in the months after Pratt & Whitney identified the potential problem. Well over a thousand engines — used on the A320neo family, but also Airbus A220 and Embraer E2 — would need to be inspected during hundreds of additional shop visits. Perhaps the worst news for airlines was that each such shop visit could take 250 to 300 days to complete. All told, an average of 350 airplanes will be on the ground through 2026 as a result.

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The news would have been exceedingly unwelcome for Pratt & Whitney and the airlines that opted for its offerings to power the likes of their A320neos and A220s alike. RTX, Pratt & Whitney’s parent company, penned a sales charge of $5.4 billion associated with what it dubbed the “Powder Metal Matter” in 2023. Cut forward to today, and the firm is still grappling with the fallout, having noted in its last annual report that it anticipated the saga would cost it around $0.7 billion over the coming year alone.

Indeed, disruption remains almost three years after Pratt & Whitney’s initial announcement. Come last July, almost 30% of all jets powered by the geared turbofan engines in question were in storage. Specifically, 529 A320neo family aircraft were grounded compared with 1,249 in service. Some 75 A220s were stored versus 362 in service in the meantime. Airbus and Pratt & Whitney have since said all A220s involved should be back in service by the end of this year. However, a far greater number of A321neo variants tied up in inspections would suggest the industry is some way yet from drawing a line under the whole drama.

Admittedly, some airlines have been far more affected than others. India’s IndiGo, former US carrier Spirit Airlines, and Europe’s Wizz Air were among those with the highest proportion of PW1100-powered jets in their fleets when the issues emerged, for instance, according to Ch-aviation. In terms of those with overall numbers of such aircraft, few in the United States appeared to be as exposed as Delta.

Delta’s Large PW1100 Fleet

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Delta soon brushed off the threat of groundings. However, reassuring in September 2023 that it was only expecting a minimal impact. As it turned out, the airline had several tricks up its sleeve to mitigate the effects. That said, Delta’s exposure looked hefty, with the airline holding approximately 100 planes powered by the recalled PW1100 engines at the time, or “the largest such fleet in North America,” according to investment firm Morningstar.

For Delta, the mandatory inspections threatened its Airbus A321neos, Airbus A220-300s, and Airbus A220-100s. As of the time of writing, the ages of each of these at Delta averaged 2.3, 2.8, and 6.6 years respectively, based on data from Planespotters.net. Out of 99 A321neos, 42 A220-300s, and 45 A220-100s, a total of five of these were out of action in the meantime. While that may not sound like a lot on the surface, it was five models from among the youngest fleets, on average, that Delta boasted were out of active service at the time. In other words, millions of dollars worth of investment sat there, unable to generate any revenue for the time being.

These specific groundings may well have been unrelated to the Pratt & Whitney engine inspections, but in the absence of concrete confirmation from the airline as to the ongoing impact, some reading between the lines is required. Either way, we know the number of jets grounded at Delta as a result of inspections has fluctuated, given the nature of the process. Delta had grounded four A321neos and four A220-300s as of last July, for example.

Delta’s Diversified Fleet

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Delta’s executives may not have been overly worried about the prospect of groundings for two key reasons. While the airline did have the largest PW1100-powered fleet in the US when questions arose around the engines, this was naturally part of a much larger portfolio. Importantly, Delta’s inventory was, and still is, incredibly diversified.

That meant finding substitutes for any out-of-service A321neos, A220-100s, or A220-300s would always be easier than for peers with fewer alternatives on their books. Wizz, for instance, still faced 30 groundings as of March, equating to a fair chunk of its 262-strong fleet. For context, Delta boasted almost 1,000 aircraft when the Pratt & Whitney-related problems struck in 2023.

Delta fleet and orders as of 2025 financial year-end:

Delta’s fleet to this day incorporates Boeing 757 and Boeing 717 jets, as shown in the table above. Its increasing adoption of A220 and A321neo jets has actually, in part, been an attempt to replace such aircraft. At 24.8 and 27.5 years old on average, respectively, the phase-out of Delta’s 717s and 757s was always part of the natural modernization cycle at the airline. However, with issues keeping some of its newest Airbus alternatives out of service in the past few years, the older Boeing models have offered some flexibility. Add in its array of Boeing 737s, and Delta has been graced with plenty of options to cover any groundings.

Delta TechOps Set Up Pratt & Whitney MRO Wing Just In Time

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A diversified fleet is only part of the story, though. Delta, in line with repeated orders for Airbus and Pratt & Whitney products in recent years, has also expanded its maintenance, repair and overhaul (MRO) capabilities to cater to the particular models.

Delta TechOps, the airline’s MRO division, joined the geared turbofan network back in 2019, allowing the company to work on the specific line of engines from Pratt & Whitney in-house. A dedicated 155,000-square-foot (14,400-square-meter) geared turbofan maintenance facility was set up in Atlanta as part of the move.

As it turned out, the facility’s opening in early 2023 appeared to come just in time for Delta to handle an influx of inspections that would be required in just a few months’ time. The carrier probably could not have knowingly prepared itself better for what was coming. Built with some 60 engine bays, the warehouse was equipped to handle purely the very power units used on its A321neos and A220s and that would, more importantly, soon need to be detached, dismantled, and possibly even fixed, one by one.

Delta Not Put Off By Pratt & Whitney Issues

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Delta TechOps has proved invaluable in the airline’s efforts to mitigate the impact of groundings as a result. Not only has it allowed Delta to handle its own inspections, but it has also been able to support continued operation of older 717 and 757 variants. While Boeing itself may have finally pulled the plug on support for the 717 in May, Delta’s own MRO division meant the move by the manufacturer was far from a crisis for the airline, for instance. All this has meant keeping older models flying in lieu of some of its newest Airbus planes has been a pretty reasonable undertaking.

In-house maintenance capabilities have also likely swayed Delta to stick by Airbus and Pratt & Whitney, despite the headache of inspections. Regardless of recent groundings, Delta has continued to fork out for new Airbus narrowbodies. One only has to look back as far as February for the last time Delta increased its order for A321neo jets, with options for an additional 34 models exercised at the time.