The PA 30 Piper Twin Comanche airplane crashed 30 kilometres west of Kelowna, near Brenda Mines, on Monday.
John Cottreau, a spokesperson with the TSB, said inspectors will examine the mechanisms that control and steer the plane, as well as the plane's maintenance record and pilot's certifications.
"They are going to be looking at the control surfaces of the aircraft, that's the ailerons and the flaps, they are going to be looking at the engines, they are going to be documenting the entire site photographically as well as the wreckage," said Cottreau.
The victim has been identified as Jayson Dallas Wesley Smith, 30, of Vancouver. The names of the injured have not been released.
Cottreau said investigators will speak to the survivors at an appropriate time.
"To try and answer three basic questions: What happened? Why did it happen? And are there any lessons to be learned to prevent it from happening again?"
He said it could be weeks or even months before a report is complete.
The flight plan says the plane was to leave the Penticton airfield Monday afternoon, heading over Princeton en route to the Boundary Bay airport in Delta.
But not long after takeoff, the plane veered off course, northwards, said Captain Stu Robertson with the Rescue Co-ordination Centre in Victoria.
"The actual crash site was not a direct line from Penticton to Princeton. Why that was, I don't know. It could be weather or just following a topographical feature to get them en route," said Robertson.
Rescue crews parachute to scene, use chainsaws
The plane went down shortly after 3 p.m. PT near a forest service road off the Coquihalla Connector highway.
It crashed in a heavily wooded area, forcing rescue personnel to parachute into the crash zone and use chainsaws to get to the plane and the people on board.
"They did parachute into the area," said Annie Djiotsa, a spokesperson with Canadian Forces Esquimalt. "Had they used the road it would have taken longer to actually access the crash site."
Robertson said it's a good thing the pilot had an emergency locator on board. He said without it, locating the survivors in time would have been difficult.
CBC News has learned the plane was owned by Thorsten Johansson, president of Maplewood Landscaping, a small family run business in Delta, B.C. Johansson, who is not a pilot, was not on the aircraft at the time.
The plane, built in 1966, was recently listed for sale.
On Tuesday morning, RCMP confirmed a man and a woman had been airlifted from the scene by helicopter to Kelowna General Hospital.
A second woman was airlifted to Royal Inland Hospital in Kamloops, but RCMP said she may be taken to Vancouver General Hospital later on Tuesday.