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First Air’s ATR42 combi page 3

Story and photos by Raymon J. Kaduck

The decision to select the ATR42 was also aided by the fact that aircraft operated by the defunct carrier Inter-Canadien were available immediately and at a good price. At the time, there was also a surplus of ATRs in the used marketplace. This has since dried up, as FedEx has specified the aircraft for use as a freighter.

“We eyed the Inter-Canadien airplanes very carefully,” says Orr. “There were certain advantages to buying Canadian-registered used aircraft. We could purchase the maintenance plan, among other things. They were available at a very low price and it appeared to us that there would be a good supply of candidate airframes in the future.”

Before the aircraft could be purchased, the company had to determine whether it was going to be technically and economically possible to meet the Transport Canada requirements for a combi aircraft. Regulations required the aircraft to have a Class C fire and smoke suppression system. That means that the bulkhead, which moves to accommodate different passenger and freight loads, would also have to seal against smoke penetration in the event of a fire in the cargo compartment.

“Preliminary engineering was done prior to purchase in spring of 2001,” Orr says. “We reviewed the regulations and how they could evolve in the future. Once there was a design that would actually comply, that was a real milestone, because it took months of engineering work to get to that point.

“Without a C compartment, there are restrictive loading requirements that we didn’t want to deal with,” Orr relates. “Basically, you need to have a centre aisle, which reduces the available volume of the aircraft. Avoiding the issue was not an option. It was decided to deal with the matter, fix it, and carry on business. That meant choosing the more difficult route of the C compartment.”

Designing and implementing are two different things. The project was tougher than it looked, and failure to meet their timelines was discouraging for the engineering team. The standard was strict.

“We couldn’t achieve the smoke penetration tests. Tolerance in the passenger cabin is zero, and in the flight deck, minor. Our preliminary plan was to certify in the spring of 2002, but we weren’t ready,” Orr explains.

“By August 2002, smoke penetration was no longer a problem. The Halon concentration test was the next big hurdle. The requirement is to flood the cargo compartment to 5% concentration and maintain 3% for the duration of the flight. With an ETOPS aircraft like an ATR, you want to fly for 60 minutes. We’re capable of going longer with more Halon.

“From that point, things get pretty routine, demonstration of loads and that sort of thing,” says Orr. “The cargo liner is a composite material we selected prior to purchasing the aircraft. The ATR is a very integrated product. For example, the restraint system is part of the fire containment design, so the engineers had to have a pretty clear idea from the start how this would all work.

“One of the major considerations when producing a combi is the reduced number of exits as you move the bulkhead. In a smaller airliner like the ATR or Dash 8, which typically have only one pair of exits, plus a forward pair of underwing exits, it’s important to understand the limitation and how to address it within Transport Canada’s regulations.

“It just so happens that the bulkhead configurations fit reasonably well into the ATR. As the bulkheads move, you have to figure out a way to make the seats work in all the configurations.”

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after roselawn
Sidebar by Raymon J. Kaduck

October 31, 1994, American Eagle Flight 4184, an ATR72, crashed near Roselawn, Indiana. The National Transportation Safety Board found that large supercooled raindrops and drizzle encountered during a long period in a holding pattern created a mixture of rime and clear airframe icing. The loss of control was caused by a ridge of ice that had built up on the upper wing surface behind the de-icing boots. When the crew attempted to descend, a rapid uncommanded aileron deflection caused the autopilot to disconnect. The aircraft rolled several times and crashed before the pilots could regain control.

The icing issue was a key concern for First Air. Most communities it serves are on water and icing in some form or other is common. While large supercooled drops are not the sort of icing that First Air usually encounters, Orr says that this issue was studied exhaustively before purchase: “It received a great deal of attention. We had to assure ourselves that we were going to have a safe product for our crews and our passengers.”

The major “fix” ordered by the NTSB was extending the de-icing boots farther back on the wing, but there were also changes to training. “Operating procedures were revised, not only for the ATR42, but for other types as well,” says Orr. “There is avoidance training and procedures to give increased awareness to the crew that there might be unusual flight characteristics. In other words, they take it off the autopilot. What the crew was not aware of was that the autopilot was compensating for the ice buildup.”

Since the Roselawn tragedy, the ice protection system of the aircraft has been thoroughly studied and improved. “This is likely the world’s most tested aircraft in icing conditions,” says President Robert Davis. | © 2011. All Rights Reserved