How are airplane evacuation slides made?

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(CNN) – “Arm Doors and Cross Check.”

Almost all airline passengers will have heard the instruction given by the flight attendant on the PA system before exiting the plane terminal gate.

For most travelers, it is part of a pre-flight ritual that often fades into the background, such as a safety briefing.

But that command is integral to the safety of passengers and crew, preparing an important device for immediate activation – the plane’s evacuation slides.

In the event of an emergency on the ground, inflatable slides are deployed through the door and out of the wing, giving passengers a quick way to escape from the aircraft. It is a technology that had its roots in the early 1950s jet age but was preceded by a simpler escape solution.

Escape early

The first passenger land plane all has one common feature – the tail wheel. This early aircraft of Ford, Fokker and De Haviland and then Douglas and Boeing usually had a gate near the ground, near the tail of the plane.

Passengers climbed a few steps, and then climbed onto their seats, with the upper corner of the cabin towards the cockpit. If evacuation is ordered by the captain, passengers will be able to exit using the main entrance.

As commercial aircraft grew larger, the wheelwheel configuration became uncertain for larger passenger and cargo loads. An aircraft equipped with a nosewheel was introduced, in which the cabin was leveled to the ground, but a long flight of stairs was required to reach the entrance.

In an emergency, it was unlikely that passengers could safely jump from the cabin to the ground, so a crude solution was developed.

“The first evacuation method on aircraft was rope knots to get people out of doors, and that was before the slides existed,” says Tony Pope, chief engineer of evacuation systems. Collins Aerospace.

“Then they brought flat pieces of fabric that were stretched between two arms, which people were supposed to hold to slide down. They call it chutes and we still call our slides chutes.”

Those simple fabric chutes have evolved into today’s sophisticated slides, inflated by a compact, compressed gas cylinder.

But knitted ropes can still be found on plane flight decks, available to pilots if they need to get out of cockpit windows or emergency hatches.

Six feet and more

Collins Aerospace and its predecessor, Goodrich, have been designing and producing inflatable slides for decades, dating back to the 1960s-era Boeing 747, the “Queen of the Sky”.

Materials and production techniques have evolved naturally since the first slides were introduced, but according to Pope, the basic concept and design of today’s evacuation slides has not changed much.

“Draw a ladder made of a flattable tube, with the fabric spread between the tubes. Now the steps in the middle, the purpose of that inflatable tube may be to keep the side tubes apart and not touch the fabric that spreads them. And you have the head. -End tube that interfaces with the aircraft and toe-end tube that interfaces with the ground. “

On the left is the evacuation slide for the Airbus A380.  The one on the right is designed for a Boeing 737.

On the left is the evacuation slide for the Airbus A380. The one on the right is designed for a Boeing 737.

Courtesy Collins Aerospace

When designing a slide, it is important to carefully consider the process used to fold it into its enclosure in an aircraft – a process similar to packing a parachute.

“When we do a new slide development program, we have a very skilled team of technicians who have packed most of their careers. We rely on them to develop packing schemes and we write a detailed set of instructions,” says Pope. Says the pope.

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U.S. The Federal Aviation Administration has developed a set of requirements for slides, which have changed over time as emergency deployments have occurred, giving regulators a reference to real-life events.

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Depending on the location of the slide – the specifications cover all aspects of the design including fabric strength, flammability and heat resistance, emergency lighting and maximum inflation time – between six and 10 seconds.

They must be properly positioned in all weather conditions, as cold as -40F and as hot as 160F, up to an inch of rain per hour, and with a wind of 25 knots hitting the slide from a 45 degree angle around the plane.

Passenger aircraft with a door bar six feet above the ground should be equipped with slides, and long-range jets usually carry slides with integrated life-rafts.

Unique design

The shape of the aircraft directly affects the design of its slides, each “chut” being generally unique to its location.

“Sometimes we can apply the same slide to multiple doors, but that is not the norm. Aircraft usually have contours, and we have to design our inflatables to meet contour requirements and properly attach the aircraft in all extreme conditions. Have to do, “says Pope.

The double decker Airbus A380 proved to be a challenge for Collins. The Mega-Jet has a total of 16 slides – eight on the upper deck and eight on the lower deck.

The designers had to ensure that the slide configuration was mash so that the slides on the upper and lower decks did not interfere with each other. Special attention should also be paid to space limitations for slide storage.

“It went through incredible tests. We’ll test the door condition a thousand times on the A380. A thousand deployments to develop it and then qualify it before it can be fitted to the aircraft,” explains Ritz Routenbeck, who works in business. Development for Collins Evacuation Systems.

“Simpler is better, but on the A380 we didn’t have the space to fit the traditional system and make it practical. We had to come up with a unique design for the inflation system.”

The shape of an aircraft directly affects the design of its slides.

The shape of an aircraft directly affects the design of its slides.

Courtesy Collins Aerospace

Collins, who works with aircraft manufacturers, must demonstrate that all passengers and crew can evacuate an aircraft in 90 seconds or less.

“We have an evacuation rate test, where we show that the slide can handle migrants in a variety of situations, such as high door seals, low door seals or night shifts. We test trained migrants, we test naive migrants. We make sure they have the right footwear and they are well dressed, “says Pope.

Like many safety-related aviation techniques, evacuation slides are rarely seen by passengers, but can save lives when they are needed. And he runs the team at Collins, Pope adds.

“I like what we do, build safety equipment. We don’t want to see it used and we hate the situation where it is used. But when we see it being used, and we show it to our people and They see what they do. It’s really important to do, it makes us all proud. “

Top Image: At the opening of EasyJet Plc’s European training facility at London Gatwick Airport in 2015, an employee practiced emergency evacuation using an aircraft slide. Credits: Chris Ratcliffe / Bloomberg / Getty Images

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