The Conservative government has agreed to accept new helicopters to replace Canada's 50-year-old fleet of Sea Kings even though they don't meet a key requirement recommended for marine helicopters by Canada's air safety investigator, CBC News has learned.

The government announced Wednesday it had finally signed a renegotiated contract with helicopter-maker Sikorsky for 28 new CH-148 Cyclone helicopters at a cost of $7.6 billion.

Now, CBC News has learned the details of what the government has agreed to forego in order to conclude a long-awaited new deal with Sikorsky, and it includes a formerly mandatory safety measure: a 30-minute run-dry standard for its main gear box.

The importance of the ability to fly for 30 minutes after a loss of lubrication in the main gear box was reinforced by an investigation into a deadly 2009 crash of a Sikorsky-built helicopter.

The gearbox is a kind of linkage between the helicopters engines and its rotor system. It's packed with lubricating oil that cools the gears and keeps power flowing to the rotors. If a helicopter loses oil in its main gearbox, the system will get too hot and either seize up or otherwise fail. That would lead to a loss of power in the rotor, forcing a helicopter from the sky.

A helicopter that meets the run-dry standard can continue flying for 30 minutes even if there's no oil in the main gear box — a critical feature for helicopters flying hundreds of kilometres out to sea.

"I am shocked, this is a very dangerous thing," said Jack Harris, the NDP's defence critic.

"This is a major safety requirement ... necessary for the safety of the aircraft operating in the maritime environment.

"This is a significant safety issue."

Mandatory requirement in original bids

Sikorsky has struggled for years against the allegation its main gearbox could not meet that 30-minute standard.

It was a mandatory requirement in the 2004 competition held to determine which helicopter would best serve Canada's interests.

Sikorsky won that competition, besting the AW 101, a helicopter that meets the 30-minute standard and flies search and rescue for the Canadian military today.

Critics suggest if Sikorsky could not meet that requirement, it ought not to have won the competition to replace Canada's Sea Kings in the first place.

"There are other helicopters that can meet that standard," Jack Harris said. "These guys signed a contract with this as a requirement. They said they could do it."

In an e-mail, Defence Department spokeswoman Ashley Lemire said the main gearbox on Canada's new Cyclones is designed to ensure the total loss of oil lubrication is "very remote."

"The Cyclone gear box lubrication system has many safety features, including a bypass valve than can be used to isolate the gearbox case from the oil cooler in the unlikely event of an external leak, to prevent further loss of transmission oil," Lemire said.

"The Royal Canadian Air Force stands by our high safety records, professional engineering standards, top-of-the line maintenance practices, and outstanding aircrew training. The Cyclone will meet all regulatory safety requirements," wrote Maj.-Gen. R.D. Foster, deputy commander of the RCAF, in an email sent to CBC News on Monday.



"Make no mistake, the RCAF will neither accept nor operate aircraft that are not safe to fly," he added.

Since Canada first signed with Sikorsky in 2004, the American company has been over budget and years behind schedule.

Last year, the government even took the unprecedented step of announcing it might drop Sikorsky and began looking at other choppers. But a consultant's report suggested the government recognize Sikorsky was essentially developing a military helicopter for Canada and accept it might have to let some promised items slip.

The government accepted that advice and the announcement last week was the conclusion of a process that saw the government reveal its bottom line on its requirements and Sikorsky lay out realistic capabilities and timelines.

In the end, the Cyclone helicopters Canada will get will feature several trade-offs when compared to the helicopter the government ordered a decade ago.

Government makes concessions

The 30-minute run-dry capability is just one of seven concessions the government has made.

The others include:

The ability to secure the helicopter's ramp in various positions during flight.

Crew comfort systems during extreme temperature operations.

Unobstructed hand and foot holds for technicians to conduct maintenance.

The ability to self start in very cold weather.

Cockpit ergonomics factors.

A system to automatically deploy personnel life rafts in emergency situations.

Lemire said the air force accepted those concessions because "there is no impact to overall operational capabilities and will not risk crew safety."

But it's hard to see how that's the case.

Sikorsky refers to Canada's Cyclone helicopters as H-92s. The H is used to identify the helicopter as a military aircraft. The H-92s are militarized and upgraded versions of Sikorsky's civilian S-92s.

When that lineage is understood, the lack of run-dry becomes more of a concern.

17 died in crash of Cougar S-92

A TSB photograph of the recovered Sikorsky-built S-92's oil filter housing showing one of three mounting studs broken and missing. Seventeen people died when the helicopter lost gear box lubrication and crashed in 2009. (Courtesy of TSB) In 2009, a Sikorsky-built Cougar Helicopter S-92 on the way from St. John's, N.L., to an offshore oil platform crashed into the sea when two titanium studs securing the main gearbox failed, causing a total loss of lubrication. All but one of the 18 people aboard died.

The Canadian Transportation Safety Board investigation made several recommendations but it also highlighted the problem with the helicopter's failure to meet that 30-minute run-dry certification.

"We recommend that all Category A helicopters, including the S-92, should be able to fly for at least 30 minutes following a massive loss of main gearbox oil," TSB chair Wendy Tadros told reporters in 2011.

Military helicopters are subject to different operating standards than civilian choppers, but in this case the government says Canada's upgraded and militarized versions of the S-92 will meet civilian airworthiness regulations.

That American standard, called FAR Part 29, allows for Sikorsky's design to fly, as it provides for an alternative to a run-dry requirement, provided the manufacturer can establish the total loss of lubrication is "extremely remote."

Qualification under that FAA regulation is what both the government of Canada and Sikorsky are relying on in order to get their deal done.

"Sikorsky and the Canadian government have agreed on all technical requirements for the CH-148 Cyclone helicopter," says Sikorsky spokesman Paul Jackson. "The gearbox meets all FAR Part 29 requirements by the FAA, including those related to loss of primary lubrication."

Following Tadros' investigation of the Cougar crash, the TSB chair said that extremely remote standard was not good enough.

"The 30-minute requirement is negated by the 'extremely remote' provision. Therefore, (the provision) needs to go. It's as simple as that."

The TSB urged U.S. regulators to amend the standard, pointing out other helicopter-makers were designing aircraft that could meet the 30-minute standard.

Defence spokeswoman Ashley Lemire says the military will make sure Canada's Cyclones meet American civilian regulations.

"Through extensive testing, proper operating procedures will be established to satisfy the required airworthiness regulations, including the civil run-dry requirement, to ensure the safety of the crew and aircraft," Lemire said.