A senior crash investigator has described how thorough examination of the aircraft's wreckage discovered no evidence of any malfunction.
Andrew Robinson, 59, an inspector with the Air Accidents Investigation Branch (AAIB), said he was shocked at the devastation left by the crash impact.
Mr Robinson was giving evidence at the fatal accident inquiry into the crash that claimed the lives of Mr McRae, his son Johnny and family friends Ben Porcelli, six, and Graeme Duncan, 37.
The helicopter came down in a wooded valley near the 39-year-old's Jerviswood home just outside Lanark in September 2007.
Under questioning from depute fiscal Kate Meikle yesterday, Mr Robinson, who has more than 30 years' experience and helped investigate the Lockerbie bombing, said he had found no fault in the Eurocopter Squirrel.
He said: "From the wreckage, we concluded that it wasn't a structural failure. We were convinced that the aircraft's engine was delivering power.
"There were no defects which affected the helicopter. It is unlikely the pilot would have flown the aircraft into the valley if he was experiencing problems with the flight controls.
"There was only a very narrow window of time in which a technical problem could have occurred and we found no evidence of this.
"We were confident that nothing had come off the aircraft prior to hitting the trees.
"It raised questions why the helicopter was flying in that direction. The flight was on a trajectory that really didn't make any sense."
He told Lanark Sheriff Court that the crash had happened after the helicopter's tail rotor struck a tree 50 metres from the ground.
He said an examination of the scene showed it had been travelling at "high speed".
He added: "I recall being quite surprised at the amount of energy that had been dissipated at the accident.
"We were told the aircraft was preparing to land and I was expecting to see a low-speed accident, but the amount of damage suggested a high-speed impact.
"There was damage to the airframe, the gearbox had been torn out and the main body was burnt out in an intense fire.
"The aircraft ceased to be a flying machine as soon as it hit the tree."
Mr Robinson added that a jammed valve connected to the aircraft's controls was unlikely to have contributed to the crash, describing the possibility as "extremely remote".Mr Robinson estimated the helicopter had crashed while travelling at a speed of 100 knots.
But under questioning from the McRae family lawyer, Paul McBride QC, he admitted that the AAIB had not been able to "positively determine" the exact cause of the crash.
He said: "We have given what we feel is the probability of certain technical faults. There could have been a technical malfunction, but there was a very limited opportunity. Mr Robinson also said a flight data recorder, known as a black box, could have provided further clues but none had been fitted.