A panel of global civil aviation authorities is expected to criticise the US Federal Aviation Administration's approval of Boeing's 737 MAX, which has been grounded for six months following two crashes, a source familiar with the matter said on Monday.The panel, known as the Joint Authorities Technical Review (JATR), was set up last April by the FAA amid criticism of the FAA'S close ties to Boeing.The FAA was the last global aviation authority to ground the 737 MAX after one of the aircraft crashed in Ethiopia in March, leaving 157 dead, a few months after another went down in Indonesia, killing 189.The JATR - which brings together experts from nine international aviation authorities as well as the FAA and NASA - was tasked with reviewing the approval procedures for the 737 MAX and make proposals to improve them.According to the source, the report, which must be submitted in the coming weeks, is critical of the FAA.In particular, it is expected to take aim at the lack of transparency in the way that the FAA permitted Boeing to evaluate systems and software for the MAX, the source said on condition of anonymity.The panel is expected to conclude that important changes to the design of the MAX were not properly reviewed by the FAA, according to the source.For example, it was Boeing employees who inspected the MCAS anti-stall system, which has been implicated in the deadly crashes, sources previously told AFP.'Safety first'The same sources reported alleged collusion under a program in which employees of Boeing are accredited by the FAA to assist in approving the aircraft as well as signing off on training procedures of pilots on new planes.The panel is also expected to criticise the FAA for failing to share data with its peers when certifying the MAX in 2017, the Wall Street Journal reported."We look forward to the publication of the JATR report when it is complete," a Boeing spokesperson said in a statement."Our team is determined to keep improving on safety in partnership with the global aerospace industry and broader community," the statement said, adding that: "We continue to work with global regulators to safely return the 737 MAX to service.""We will carefully review all recommendations and will incorporate any changes that would improve our certification activities," said a spokesperson for the FAA, which has defended the MAX.The panel's "focus on the certification of the aircraft is separate from the ongoing efforts to safely return the aircraft to flight", the spokesperson said.Steve Dickson, the new head of the FAA, said on Monday on the CNBC television channel that he was going to Seattle this week to test a MAX featuring the modified MCAS on a simulator.He also said that Boeing had still not submitted all the requested changes for the FAA to rule on lifting the flight ban on the MAX."It's really safety first and we're not on any specific timeline," he said.There are differences among regulators on the criteria for returning the MAX to service, with the Europeans indicating that they will inspect the aircraft themselves and, like the Canadians, want pilot training to include time in a simulator.