Greensmith rolled his Ford Puma onto its side on Saturday morning’s first stage, damaging the car’s engine cooling system.
It prompted a retirement after Greensmith had completed the day’s second test without a windscreen - having been kicked out to allow himself and co-driver Jonas Andersson to extricate a vehicle that hadn't been attended to by marshals.
Greensmith’s exit meant that all four works M-Sport cars had suffered retirements in Kenya to compound a miserable rally for the British squad, adding to the exits of Sebastien Loeb and Craig Breen on Friday.
A matter of moments after Greensmith’s accident, Fourmaux suffered a suspension failure that came after he'd hit a rock and suffered a puncture on the day's first stage.
In order to rejoin the rally on Sunday, Wilson told his drivers to swap their race suits for mechanic overalls to help with the rebuild.
“Malcolm took the opportunity to get Gus and Adrien to work on their cars,” said M-Sport team principal Richard Millener.
“Both of them have done a lot of work on the cars up until now in the workshop, but it was a good chance to do some work on a car that has actually done most of a rally.
“It was a good opportunity to give them a chance to get used to how to change things if it happens again.
“It is also important for them to understand what the mechanics go through as well.”
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It is not the first time Fourmaux has joined the M-Sport mechanics this year, after offering to help build up a new chassis following a violent crash at the Monte Carlo Rally in January. The Frenchman has come under pressure this yeah after a campaign littered by crashes.
Fourmaux told Autosport: “I spoke with Malcolm and he said, ‘Do you know what I want to do?’
“I said ‘I don’t know’, and he said ‘I want you to drive tomorrow, so you will drive tomorrow, but you will fix the car.’
“He said ‘It will be you and Alex [Coria, co-driver] and one other mechanic and then you will do it by yourself.’”
When asked if he felt Wilson was trying to teach him a lesson with this latest switch to mechanic duties, Fourmaux replied: “Probably, yes”.
The pair managed to help complete repairs to their respective cars for Sunday, an experience Greensmith admitted was a humbling one.
“It puts it into perspective how much they [mechanics] do,” said the Briton.
“These are the overalls that I must wear [this afternoon] because when you break your car, you must fix it yourself.”