About 100 planes around the world have been caught up in a scandal that would be cartoonish if it weren’t so terrifying. It saw a dubious company, with fake employees and an address that was a glorified PO box, sell and distribute fake airplane parts that ended up in planes belonging to some of the world’s biggest airlines. On Thursday night, American Airlines became the fourth, and so far final, airline to have found parts from AOG Technics in its aircraft. Southwest kicked off the disclosures from various airlines around the world in early September, when it became the first to announce it had located an unregistered part from AOG Technics.

American Airlines “identified the uncertified components on a small number of aircraft,” according to an emailed statement to Fortune, while Southwest told Fortune it had identified one engine that contained two parts from AOG Technics.

The parts scandal comes as the latest development in a series of difficulties that have embroiled the airline industry. It has had two consecutive summers plagued with seemingly constant flight delays and cancellations as “revenge travel” grips a worldwide public eager to get out after a pandemic-era hibernation. American Airlines and United both had to navigate the high-wire act of negotiating new pilots union contracts—and both did so successfully. But the prospect of faulty parts, albeit affecting a small fraction of the world’s fleet of roughly 25,500 commercial aircraft, is swiftly piling up delays. Regulators, airlines, and parts suppliers around the world are scrambling to track down possible bogus parts as the AOG Technics scandal spreads from the U.S. all the way to Australia.

The mysterious London-based firm stands accused of falsifying certain documents and shipping the suspect parts to airline repair shops around the world. Companies like AOG Technics are middlemen that supply parts to independent firms that airlines contract to do repairs on their planes. The parts in question were used to repair jet engines made by CFM International, a joint venture between GE and the French firm Safran, used in older models of Airbus and Boeing engines. CFM is now suing AOG Technics in London’s High Court to get access to documents that would illustrate the extent of its fraud, so that all the bogus parts can be tracked down. So far, CFM believes AOG Technics may have sold thousands of parts with fraudulent documentation.

“Parts are accompanied by a lifetime of paperwork,” said Robert Mann, president of the airline industry consulting firm R.W. Mann and Company. In the aviation industry, every part of a plane is carefully tracked to ensure its provenance and quality are accounted for. A single faulty part could have catastrophic safety consequences.

CFM, the engine manufacturer, became aware of the issues in June when a Portuguese repair shop alerted it to the existence of allegedly forged documents bearing its name, according to Reuters. By August, the UK’s Civil Aviation Authority (the country’s equivalent of the Federal Aviation Administration) had released a safety notice announcing it was “investigating the supply of a large number of Suspect Unapproved Parts” originating from AOG Technics. Airlines and maintenance shops that had purchased any parts from AOG Technics were encouraged to verify whether they had actually come from where the distributor claimed they did.

Europe’s aviation regulator, the European Aviation Safety Agency (EASA), released a notice around the same time confirming that certain documents had been forged to make it appear as if AOG Technics’ parts had come from legitimate manufacturers. “In each confirmed example, the approved organization, identified on the [Authorized Release Certificate], has attested that the form did not originate from within their organization, and the certificate has been falsified,” the EASA’s statement read. On Thursday the FAA became the latest regulator to issue a notice about AOG Technics’ bogus parts scheme.

A “deep fake” company in the gray market of airplane parts

“While there have always been gray and black markets in aircraft parts, mostly purchased by questionable customers, this is a case of a “deep fake” company masquerading as a legitimate supplier that deceived many legitimate buyers,” Mann said.

He told Fortune that gray market products are often component’s that are either certified or deemed repairable but don’t meet some other requirement and should therefore be scrapped. Instead these parts “get sold cheaply to customers who need inexpensive replacements.” Black market dealings can be slightly more nefarious in nature, often entailing sale of military technology to countries that are under international sanctions, such as selling spare F-14 fighter jets to Iran.

Mann also laid some portion of the blame at the buyers’ feet. “It is also disturbing that sophisticated customers who should have been able to properly vet the supplier were nonetheless duped, potentially placing safety of customers, employees, and aircraft at risk,” he said.

As of last week the EASA said “to date there have been no reports of problems resulting from the suspect unapproved parts.”

What do we know about AOG Technics and its founder?

AOG Technics was founded by Jose Alejandro Zamora Yrala in 2015, according to public filings in the UK. In addition to allegedly forging documents for airplane parts it appears that AOG Technics created several fake LinkedIn profiles claiming to be company executives, according to Bloomberg. The profiles listed for its chief commercial officer Ray Kwong and an executive sales representative Johnny Rico featured stock photos and employment histories that couldn’t be verified by any of their purported former employers.

A further look into other filings under Yrala’s name show he founded two other companies in the UK: real estate company Kensho Group LTD and ecom vendor Sunwave Solutions. Yrala’s business partner at Sunwave Ricardo Maquilon Chedrauy told Bloomberg the company sold kitchen appliances “on Amazon to kill time during the pandemic.” Kensho folded in January 2023 and Sunwave appears to still be operational—or at least hasn’t filed for dissolution.

Yrala’s filings offer some insight into businesses that were run in an unusual fashion. Several of the filings are riddled with typos, including misspelled executive titles and oddly capitalized words that appear to have happened when someone hit caps lock instead of the “A” key. Other documents show a series of shifting corporate addresses, some of which end up back at either a coworking space in London and the offices of a now-retired accountant in a sleepy West Sussex town.

A Certificate of Incorporation filed with the Registrar of Companies for England and Wales in January 2021 listed Kensho’s headquarters at the same London address of AOG Technics—the North Nova building just a few blocks from Buckingham Palace. Within the upscale, gleaming office tower AOG Technics rented a “virtual” address from coworking space The Argyll Club for $100 a month, according to Bloomberg. In April 2021, Kensho requested an address change to a residence in Haywards Heath, West Sussex that is the same address of Brian Cook Associates, a private accounting practice listed as an agent in the original certificate of incorporation. That same West Sussex address was used to incorporate Yrala’s ecom company Sunwave Solutions. (Brian Cook did not respond to a request for comment.)

AOG Technics’ website and LinkedIn profile are no longer active and a Google search for the company lists it as “permanently closed.” The company did not respond to a request for comment. Lawyers for Yrala and AOG told Reuters they are cooperating fully with an investigation opened by the CAA.

What airlines have found fake parts?

Southwest Airlines was the first major airline to disclose that it had found uncertified parts that originated from AOG Technics in its aircraft. It first became aware of the problem in August “and took necessary steps to ensure we do not have any parts in our fleet from AOG,” the company said. After Southwest’s suppliers conducted a review of its parts the company removed two low pressure turbine blades from one of its jets.

A few days later, Virgin Australia also found a turbine blade with forged documents had been used in its planes. The fact parts from a European supplier were found in airlines in Oceania and North America illustrated just how global an issue the industry was facing and how difficult it would be to track down every individual part that may have been allegedly sold under false pretenses. A week later Virgin Australia discovered another, different part, this time a turbine nozzle, had been used in a second jet. Both planes were grounded until replacements could be installed. A spokesperson for Virgin Australia said safety is the company’s “highest priority” and it applies a “highly stringent approach to maintenance” to ensure it is upheld.

Earlier this week, United became the third airline to disclose it had identified AOG Technics’ bogus parts in its airplanes. Two United jets were found to have had unregistered parts in their engines, the company said. Both planes are undergoing the requisite maintenance to replace the part before being used again. United will “continue to investigate as new information becomes available from our suppliers,” the company said. American Airlines said it would “continue working” with suppliers and the FAA “to ensure these parts are no longer in our supply or otherwise in use on our aircraft.”