* Former Renault engineering head joins Williams
* Symonds was banned from F1 after 2009 Singapore crash scandal
* Coughlan leaves the former champions
By Alan Baldwin
LONDON, July 16 (Reuters) - Pat Symonds, the former Renault F1 engineering head who was banned from Formula One in 2009 after a Singapore Grand Prix crash scandal, has joined Williams as chief technical officer.
Williams, the former champions who have yet to score a point in nine races this season, announced the move on Tuesday and said their current technical head Mike Coughlan had left the team with immediate effect.
Coughlan had also joined Williams after serving a ban, a two-year one imposed in 2007 for his role in a spying controversy that led to McLaren being handed a record 100 million pound ($151.05 million) fine.
The highly-rated Symonds, who has been working with back-markers Marussia as a technical consultant under the terms of the ban that expires this year, will start work at the Williams factory on Aug. 19.
"I'm delighted that Pat is joining the team," founder Frank Williams said in a statement.
"His technical capabilities and sporting successes speak for themselves and I'm sure that his knowledge and leadership will contribute considerably to the success that all of us at Williams are working hard to achieve."
Symonds said he was honoured "to be asked to play a role in returning the team to its rightful place at the pinnacle of Formula One".
Williams have fallen on hard times since their years of dominance. Although they won in Spain with Venezuelan Pastor Maldonado in 2012, that was their first race victory in nearly eight years.
Symonds has been in Formula One for 30 years and has a formidable reputation as an engineer and strategist, working with the young Ayrton Senna at Toleman in 1984 and then seven times champion Michael Schumacher at Benetton.
With Spaniard Fernando Alonso at Renault he added more success to his resume and can boast of playing a part in 32 race wins, four drivers titles and three constructors' championships to date.
The 2008 Singapore Grand Prix was the win that stained his record, however, after the 'Crashgate' scandal broke a year later.
Symonds left Renault in 2009 along with flamboyant team boss Flavio Briatore after Brazilian driver Nelson Piquet Jr told the governing FIA that he had been ordered to crash deliberately into a wall so that Alonso - who was not implicated - could win.
"Mr Symonds, in the presence of Mr Briatore, asked me if I would be willing to sacrifice my race for the team by 'causing a safety car'," Piquet declared after being promised immunity from prosecution if he told the truth.
"Mr Symonds took me aside to a quiet corner and, using a map, pointed me to the exact corner of the track where I should crash," Piquet added in his statement.
Renault did not dispute the allegations and Symonds, who ran the race strategy and was Briatore's deputy, was banned initially for five years although that was later overturned.
Symonds, who had declared his "eternal regret and shame" at what happened in a letter to the FIA, agreed not to work in Formula One other than as a consultant until 2013.
"Williams' sporting and engineering heritage dictates that we secure the finest talent available," said Williams chief executive Mike O'Driscoll.
"Pat brings unrivalled technical and managerial skills in addition to a proven ability to deliver on track results. Our commitment to return Williams to winning ways is absolute and this appointment is yet more evidence of our collective desire to return the team to the position it deserves."