A9 fatal crash car had broken suspension
An Edinburgh solicitor's car involved in a crash which killed his daughter, wife and a German doctor had a broken suspension system, a court has heard.
Collision expert Mark Littler told a jury it was "a possible explanation" for the head-on crash but conceded it was an "implausible explanation".
Andrew Houston, 48, denies driving carelessly on the A9 between Newtonmore and Kingussie on 9 July 2013.
His wife Abigail, daughter Mia and GP Dr Mohammed Ali Hayajneh died.
Mr Houston's Audi crossed white lines into the opposite lane and collided head-on with a Jeep Cherokee being driven northwards.
Mr Littler, a Greater Manchester policeman, said the more likely cause of the displaced coil spring in the rear near-side of the German-made vehicle, which had just passed its MOT test, was the collision.
He said: "However, I have never come across that before and I cannot rule out that it could have become dislodged before the accident."
The jury heard on the third day of Mr Houston's trial the coil spring had been found during Mr Littler's examination of the car.
The expert said: "It was jammed up into the sub-frame of the vehicle. It should have been vertical but it was horizontal.
"It was not mentioned in the police collision report and it should have been considered because it was a possible cause of the crash.
"If the Audi was travelling at 50mph, it would have gone 100 metres before Mr Houston had time to react. Normal reaction time is 1.75 to 3.5 seconds and he would have been in the northbound lane for three seconds before impact."
However, Mr Littler added that it would have required "a considerable impact" to displace the spring and it was unlikely it had worked loose.
Cross-examined by prosecutor Roderick Urquhart, Mr Littler said: "The most plausible explanation is that it became displaced in the collision and that is in my report."
All the evidence has been completed and the jury will retire to consider their verdict on Thursday.
Mr Houston denies causing the death of Abigail, Mia and 62-year-old physician Mohammad Hayajneh by careless driving and crossing into the opposite carriageway on the A9 at Ralia, near Newtonmore on 9 July 2013.
His Audi A4 collided head-on with a silver Jeep Cherokee being driven by Dr Hayajneh's wife, 59-year-old Ursula from Duisburg in Germany.
A Peugeot 206 carrying four Polish tourists managed to avoid a collision by swerving off the road and crashing into a road sign moments before.
Mr Houston suffered cracked ribs and a broken foot as a result of the crash.
The solicitor, whose 10-year-old daughter Lily was badly injured but survived, is a senior partner with McSporrans solicitors in Edinburgh.
He told police in an interview five months later he could not remember what happened.