(Sharecast News) - Boeing's troubled 737 MAX programme was facing production challenges, it emerged over the weekend, as fresh issues were found in a number of fuselages.

The aerospace giant announced on Sunday that a supplier had alerted it to a "nonconformance issue" in some fuselages, specifically related to mis-drilled holes that did not meet the required specifications.

President and chief executive officer Stan Deal said that while the issue did not pose an immediate safety risk to in-service 737s, it would necessitate rework on around 50 undelivered aircraft.

As a result, he said there could be further delays in near-term 737 deliveries.

"During the Quality Stand Down on the 737 program, many employees voiced frustration with 'travelled work' and how unfinished jobs - either from our suppliers or within our factories - can ripple through the production line," Deal said in the announcement.

"We have to maintain this discipline within our four walls and we are going to hold our suppliers to the same standard.

"We recently instructed a major supplier to hold shipments until all jobs have been completed to specification."

While that delay would affect the production schedule, Deal said it would improve overall quality and stability.

"We will take advantage of the days in the factory so that our teams can catch up on unfinished jobs across all 737 factory positions."

The production challenges came as Boeing faced increased scrutiny from both customers and regulatory authorities, particularly over the 737 MAX.

Federal officials in the US grounded the entire fleet of 737 MAX-9 aircraft after a door plug - a structure installed to replace an optional emergency exit door - blew out shortly after takeoff on an Alaska Airlines flight on 4 January, causing an uncontrolled decompression.

The blow-out was found to have been caused by faults in the bolts used to secure the plug in place, with loose bolts discovered on other 737 MAX-9 aircraft during inspection.

Regulators globally had grounded the entire 737 MAX fleet for almost two years from March 2019, after 346 people were killed in two crashes, which were found to have been caused by a piece of control software - MCAS - that Boeing had not adequately informed pilots and airlines about.

Reporting by Josh White for Sharecast.com.