Mercedes driver Nico Rosberg of Germany (2nd L) celebrates next to second-placed Red Bull driver Daniel Ricciardo of Australia (L), Andy Cowell (2nd R), managing director of Mercedes AMG and third-placed McLaren driver Kevin Magnussen of Denmark (R) on the podium after the Formula One Australian Grand Prix in Melbourne on March 16, 2014. (IMAGE RESTRICTED TO EDITORIAL USE - STRICTLY NO COMMERCIAL USE SAEED KHAN / AFP)

LONDON - Engine boss Andy Cowell, a key man in Mercedes’ and Lewis Hamilton’s Formula One success over the past six seasons, will stand down on July 1, the reigning champions announced on Monday.

Mercedes said Cowell, managing director of Mercedes-AMG High-Performance Powertrains (HPP), would support the transition and consult “on a major future project” with Mercedes-Benz until early next year at least.

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I have decided that now is the right time to move on from my role and seek a new engineering business challenge

Andy Cowell, Managing Director, Mercedes-AMG High-Performance Powertrains

“I have decided that now is the right time to move on from my role and seek a new engineering business challenge,” Cowell, who has been with Mercedes for 16 years, said in a statement.

Hywel Thomas will now take direct responsibility for the Formula One power unit.

“Andy’s leadership of the team at HPP has been a key factor in our championship success in recent seasons,” said team principal Toto Wolff.

“Our philosophy has always been that a winning team is a dynamic organisation, and that change is a natural part of every company’s development,” added the Austrian, a shareholder in the team but whose own future role remains uncertain.

“I am particularly pleased that we have been able to work together to create a new leadership structure, by building on the strength in depth of the team in Brixworth. It puts us in a very strong position for the years ahead.”

Mercedes have dominated since the start of the V6 turbo-hybrid era in 2014, winning an unprecedented six successive driver and constructor title doubles.

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Britain’s Hamilton, now chasing a seventh championship to equal Michael Schumacher’s record, starts his season in Austria on July 5.

The 35-year-old Briton is out of contract at the end of 2020, but is expected to remain at Mercedes.