CNN  —  A whistleblower has come forward Wednesday alleging parts of Boeing’s 787 Dreamliner planes were built in an unsafe manner – potentially leading to “devastating consequences.” Richard Cuevas, a mechanic at Strom, a contractor for Boeing manufacturing partner Spirit Aerosystems, claims that he witnessed holes that were improperly drilled into the forward pressure bulkheads of 787 planes at Spirit’s Everett, Washington, facility in 2021. The bulkhead is one of the primary parts of an airplane’s body and crucial for keeping the structure of the plane intact while it’s in the air. Cuevas claims that he filed a complaint in October 2023 to Boeing and Spirit about “substandard manufacturing and maintenance processes” he witnessed, and was fired just a few months later, according to the complaints filed by his attorneys and obtained by CNN. Boeing said it had previously investigated Cuevas’ allegations and they did not pose a safety problem. “A subcontractor’s employee previously reported concerns to us that we thoroughly investigated as we take seriously any safety-related matter,” the company said in a statement. “Engineering analysis determined that the issues raised did not present a safety concern and were addressed.” The company said it is reviewing the documents Cuevas’ attorneys made public Wednesday and will investigate any new claims. Spirit Aerosystems, Strom and the Federal Aviation Administration did not immediately respond to requests for comment. Cuevas said the gaps he observed in the plane’s forward pressure bulkheads appeared in two aircraft that he helped build and could potentially lead to “catastrophe.” Cuevas claims the workers were drilling holes slightly larger than Boeing’s specifications to “clear excess paint from the holes and speed up a slow process,” which, he believes, could compromise power and air pressure on the planes, creating serious safety risk for the passengers on board. Cuevas said he filed a complaint with Boeing’s ethics hotline, reporting to management that he believed Spirit was hiding the issues from Boeing. He also alleges that Boeing opened an investigation into Cuevas’ concerns in October 2023, alerting Spirit management to the complaints. During that time, Cuevas says his colleague remarked, “we’ve got a snitch among us,” and in March, Spirit suddenly fired Cuevas, according to the complaints. The complaints say Cuevas witnessed these problems with three planes he worked on and believes these issues may affect at least 10 to 12 planes either in production or already released to Boeing. A growing list of problems for Boeing The claims aren’t new: A previous whistleblower, Sam Salehpour, a Boeing engineer, said he found and reported similar gaps in 787 and 777 aircraft. For nearly two years starting in 2021, the FAA and Boeing halted deliveries of the new Dreamliners while it looked into the gaps. Boeing said it made changes in its manufacturing process, and deliveries ultimately resumed. More than a dozen whistleblowers have come forward against Boeing in recent years, and the number has grown substantially since a door plug blew off a 737 Max plane in January just after takeoff, leaving a gaping hole in the side the plane. Last week, for example, a current Boeing employee claimed that the company tried to shield broken or out-of-specification 737 Max plane parts from regulators and lost track of them – and he feared they may have been installed on planes that are carrying passengers. The FAA has opened multiple investigations into Boeing and the US Department of Justice said it may file criminal charges against the company because of its ongoing quality and safety failures. The FAA has said a six-week audit of Boeing’s facilities conducted in the late winter found multiple problems with Boeing’s production practices. A separate report found “gaps” in Boeing’s safety culture, including a disconnect between management and employees, and fears among employees about retaliation for reporting safety concerns. Boeing’s CEO Dave Calhoun last week apologized for Boeing’s recent safety failures in testimony delivered to a Senate committee but pushed back on claims that the company retaliated against those who brought safety issues to light. Calhoun said Boeing is “far from perfect,” and he acknowledged that the company will not easily regain the public’s trust.