Twenty-six deaths involving Ontario's troubled air ambulance service over the past six years were under investigation by the ministry of health.

Secret cabinet documents obtained by the Progressive Conservatives show the ministry investigated 145 incidents involving Ornge since 2007.

Forty of those incidents — five of which involved the death of a patient — were opened this year, after the government installed new leadership at Ornge.

The documents, dated May 23, suggest cabinet was briefed on the investigations last week.

The incidents include major delays in dispatching air ambulances, paramedics unable to perform CPR due to cramped conditions in the helicopters and running out of supplies like oxygen and medication.

In some cases, the ministry concluded that Ornge was not at fault or there wasn't enough evidence to substantiate complaints.

Paramedics unable to perform CPR, Tories say

Earlier this week, Conservative Frank Klees brought up five incidents between May and October 2011 that were related to the design of Ornge's new helicopter interiors.

They included jammed stretchers, patients unable to sit upright and paramedics unable to perform CPR. In all cases, the patients died.

Tom Lepine, who was fired as Ornge's chief operating officer, testified before a legislative committee Wednesday that he was aware of some of those incidents.

Ornge paid $6 million for the interiors and even sent a team — including Lepine, a former paramedic — to Switzerland to oversee the design.

But Lepine said he only discovered the problem with the medical interiors of the AW-139 helicopters in late 2010, after the first chopper went into service.

He insisted that paramedics could perform CPR in the new helicopters, except during take-off and landing.

"That's not to say it was an acceptable design," he told the committee Wednesday. "It wasn't."

Lepine also denied that he ignored warnings from paramedics about the design of the interiors or that he downplayed the problem as a "glitch."

Ornge is still looking for a permanent fix for the interiors. It said a temporary fix has been made to all the helicopters that addresses some of the most serious concerns.

The committee is also looking at other questionable business deals, high executive salaries and details about the for-profit companies set up by Ornge that are now being shut down.

Ontario's auditor general has criticized the government for failing to oversee Ornge, which receives $150 million a year from the province. It is under a criminal probe for "financial irregularities."