Retired colonel ponders possible crash causes
HALIFAX — Larry McWha combs through potential scenarios that could have brought down a Cyclone helicopter off the coast of Greece.
The retired colonel is the former commanding officer of 423 Squadron, which flies CH-140 choppers out of 12 Wing Shearwater. The helicopter that crashed into the Ionian Sea late Wednesday was operating off the frigate HMCS Fredericton.
“The (military) said that they lost contact; that’s about all we’re told,” said McWha, a former Sea King pilot who lives on the Eastern Shore.
“That can happen because you were being followed on radar and all of a sudden you disappear.”
But it’s more likely, McWha said, that Fredericton and the other NATO warships it is sailing with lost their data link with the Cyclone that would show the helicopter’s position. “Then all of a sudden, the helicopter is no longer there.”
Normally a helicopter crew would check in via radio with the ship it is flying from, he said.
If the helicopter didn't show up by a specified time, that would be another way it could have lost contact with the ship, McWha said.
“What is most amazing is there has been no mention whatsoever of a distress call,” he said. “If you had a problem which was going to require you to not make it back to the ship, in other words, to have to ditch it, you would get on the radio and send out a mayday call. There has been no indication that there was any such call.”
This is similar, he said, to the March 12, 2009 crash that killed 17 people and injured one more when Cougar Helicopters Flight 491 — a civilian variant of the same Sikorsky helicopter the military uses — crashed into the Atlantic Ocean off Newfoundland.
“The tail rotor system failed because the gearbox had failed internally and they went out of control then crashed violently,” McWha said.
That created a debris field like the one reported off the coast of Greece, he said.
“So this sounds sort of like a daytime, violent impact with the water,” McWha said of the recent crash.
The crew in the Cougar case was under the impression they could fly the helicopter for 30 minutes after losing lubricant in the main gearbox, he said. “Which was not true.”
The Cougar helicopter crew lost control of their tail rotor, he said. “So they just started spinning and went into the water.”
It’s unlikely the Cyclone that crashed Wednesday was shot down, McWha said.
“That’s a possibility, but it’s not a theatre of hostility right now,” he said.
“Unless there’s some nut bar out there in a cigarette boat who has a hand-held anti-aircraft missile on his shoulder, it’s highly unlikely.”
Ship-based radar can cause trouble for helicopters, he said.
“The electro-magnetic radiation that goes out from a high-powered radar is sufficient enough, depending on how it hits the aircraft, to interfere with electronics on board,” McWha said.
“Another electronic signal of the right strength and frequency can cause things to go awry. And that’s why these systems have to be shielded. Particularly naval aircraft, which might be potentially landing on things like an aircraft carrier which has not only got it’s own highpowered radar spinning around on the island, but it’s got all those aircraft, each one of which has a high-powered radar flashing up in it. So it’s a sea of electro-magnetic radiation.”
Cyclones have an electronic flight control system dubbed fly-by-wire, he said.
“It’s always possible that there could be vulnerabilities there. Or vulnerabilities in the automatic flight control system, which is electronic. So that’s a possibility. It’s remote, but that’s the sort of thing that can happen.”
A Cyclone flying at night out of Shearwater experienced a sudden loss of altitude a few years back, McWha said. “There had been an uncommanded sudden drop in altitude because of a problem with the fly-by-wire flight control system,” he said. “It was called a significant bump in the night … Apparently the two fly-by-wire flight control computers – they’re always supposed to match up with each other — had a disagreement, is what I was told. So the aircraft suddenly decided to correct itself without pilot input.”
Sikorsky has only delivered 18 of the 28 Cyclones that Canada ordered, he said. “Obviously they’re still trying to put upgrades into them.”
It’s possible the Cyclone crew simply misgauged the helicopter’s altitude and flew into the water, he said. “That’s a probability if it happened at night. I can’t imagine it happening in the daytime where someone inadvertently flies into the water.”
It’s also remotely possible that wildlife caused the crash, McWha said. “You could always have a bird strike,” he said. “It would have to be a pretty bad one. You would probably have to fly into a flock of geese or something in order to cause that to happen. But that has brought aircraft down before.”
If Wednesday’s Cyclone crash was a controlled ditching, there is flotation gear designed to inflate when it contacts water, he said.
“The aircraft itself is not going to stay upright very long. It’s going to roll over.”