One of Boeing's (NYSE:BA) top customers is not expecting the company's new 777X to debut in 2021 as planned, a fresh blow to Boeing's already troubled new plane lineup.

The 777X flew for the first time in January, but a top official at Emirates expects a combination of pandemic-related production slowdowns and an likely lengthy certification process will likely push deliveries into 2022. Adel Al Redha, Emirates' chief operating officer, told Bloomberg in an interview that his airline is considering swapping some of the planes for smaller 787 Dreamliners.

Boeing's 777 production line.

Image source: Boeing.

Emirates has 115 777Xs on order, a substantial part of the plane's 309 order backlog. The jet is an update to one of Boeing's largest planes designed for international flights, with new engines and composite wings designed to help boost fuel efficiency.

The 777X program had issues even before the pandemic. Engine problems delayed flight testing to 2020, and last September the airframe failed a high-pressure stress test.

With airlines expecting reduced demand for the foreseeable future due to the pandemic, Boeing and Airbus are facing challenges selling large planes like the 777. Boeing has announced plans to decrease production of 777s, both legacy planes and the new X models, from five frames per month to three by 2021.

Emirates is skeptical about Boeing's delivery schedule in part because of the heavy regulatory scrutiny the 777X is expected to attract before it is certified to fly. Boeing's 737 Max has been grounded since March 2019 after a pair of fatal crashes, and the investigation into what went wrong with that plane has raised questions about regulatory oversight of the company.

Bloomberg reported on Thursday that the Federal Aviation Administration has begun a formal investigation into allegations that Boeing placed "undue pressure" on employees who were charged with assessing new plane designs on behalf of the government.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.