Loading Bridges and Inflatables

Ruminations from the Ramp

Loading Bridges and Inflatables

By Tony Vasko

March 2001

I deplaned at Newark the other day arriving back from Zurich and took a connecting flight out two hours later. Newark was an old, well-remembered acquaintance of mine as I used to be the Maintenance Manager for Eastern there. What caught my attention this day was the condition of the interior of one of the loading bridges. The wall panels were damaged and appeared to have been bulged back toward the outer skin. I smiled when I saw that as it brought back a memory of an incident at another airport.

With the advent of the requirement for inflatable evacuation slides, a new source of problems and delays emerged. Girt bars wouldn't latch into the floor locks and occasionally slides would fall off the door--which was somewhat disconcerting to the passengers. With widebodies it became necessary to power the cabin doors open. On the L-1011 and DC-10, the doors go up into the ceiling and this required assist devices. On Boeing and Airbus aircraft they opened outward in the good old time-honored way. These, too, were powered by assist devices. The power assist for the door can be dangerous.

Most of the time you want to open the door without the emergency opening device working and certainly without the slide deploying and inflating. On the other hand when it's an emergency you expect it to open and blow. To accomplish this they put an ARM-DISARM lever either on the door or adjacent to the door. In the DISARM position the door operated without the slide blowing, usually.

The early B-747s were notorious for blowing slides. Procedures and discipline were introduced to ensure that the slides (and the emergency door opening) were DISARMED before anyone tried to open the door to let the passengers out. At Kennedy, Eastern Air Lines finally got a few loading bridges after a long winter and spring of deplaning passengers into the snow and rain using motorized steps. These loading bridges were finicky and temperamental, being the first products of a Canadian company that was breaking into the business. They were also the last loading bridges that company built. After a few experiences with them we ordered new ones from more established companies. In the interim we had to live with them.

One fine afternoon the B-747 flight from Miami arrived, and the agent struggled to get the loading bridge lined up with the door. Around 350 passengers from Miami waited patiently to deplane. Those flight attendants on that run know how patient New Yorkers can be about deplaning. It was not that agent's day at all. He backed and twisted the controls and finally got the loading bridge aligned. In line with the procedures he knocked on the cabin door to signal the flight attendant. The flight attendant inside had disarmed the slide per instructions but unknown to her, the linkage had failed.

When she moved the handle, the agent outside was ready to assist by pulling on the door and swinging it back. The B-747 door is big. He was not needed however as the door assist bottle discharged and compressed gas opened the door. He managed to avoid being the meat in the sandwich as that door swung out and around against the fuselage. He then had to be damn agile and quick besides for the evacuation slide did its thing. It inflated and one must remember that the early B-747 had a small rocket-motor device inside that ignited and provided the mass of gas needed to fill the long slide. That slide came ripping and tearing down that loading bridge tunnel with the agent two steps in front of the wall of fabric. The slide tore up and burst the wall panels inside the loading bridge tunnel. The "patient" passengers had to wait a little longer. And that was the source of my smile this January at Newark. I recognized the signs of a deployed slide in the tunnel.

One of the funniest sights I was privileged to see naturally involved the B-747. The early birds of that breed were demanding airplanes and stretched the maintenance department's abilities to the utmost. Because of their proclivity for last-minute breakdowns, it was our practice to assign a technical supervisor to each departure. I was sitting in my van as the loading bridge came off. Since the ramp was icy, no engines were started until the big beast was pushed back to the taxi centerline. The tug disconnected and clearance was given and they cranked them up. The rampie on the headset decamped and I took a breath. So far so good. No problems. The right (starboard) side of the plane was presented to me, and I expected it to taxi at any moment. No movement. I drove out on the left side of the aircraft to try to see if the Captain was waving and asked our Ramp Control if they had any call from the flight.

I was trying to see up to the cockpit when the L1 door opened; that's the left most forward door. It opened violently under the impetus of the emergency door opening system. What was surprising was there was a uniformed person desperately clinging to that door handle looking like Harold Lloyd in the old-time thrillers. The slide belched out in a cloud of talcum powder and made itself into, well, a slide. The second officer, for that's who was hanging on the door, flailed around with his legs and finally hooked onto the slide. I could see the Flight Attendant inside collapsed with laughter for one must take what comfort you can for the now inevitable delay.

At the debrief, it developed they had an L1 door warning light on in the cockpit during pushback. The second officer put on his jacket and his hat for it was required that he look competent and official in front of the passengers. He made his way from the cockpit and down the spiral stairs. Disregarding training and placards he "only raised the handle a little way" intending to then slam it down to hopefully extinguish the warning light. The "little way" was enough to initiate the emergency sequence and the emergency door-opening bottle discharged. What made it so funny was his next statement, "I thought I could hold the door closed" which explained why he was still clinging to it as the power assist blew the door open. Give him an "A" for good intentions and an "F" for brains and thank God they weren't taxiing. The number two engine would have eaten that slide very nicely and maybe the second officer as well. At least it wasn't into the loading bridge.

Early on we didn't even have slides. Ropes were good enough. Then came non-inflatable slides. The first out had to make their way down the limp fabric and grab the bottom and hold it out for the rest to slide down. It may have been a bit much to expect from passengers decamping from a possibly burning airliner. The inflatable slides came next and then mutated into slide-rafts for overwater airliners. The life rafts that used to be carried in the cabin (and still are in high-density seating) mostly went away--a good thing for they were heavy, bulky, and hard to launch in the conditions of a sinking airplane.

The Constellations had their life rafts stowed in tub-like compartments recessed into the wing. The Super Constellations had four tubs aft of the rear spars. The life rafts were packed into them and hinged cover doors fitted over them. The doors were tight fitting and had seals to keep out the oil and rain. In the event of a ditching, it was intended that the passengers would egress through the over-wing exit hatches. Inside the frame of those exits were recessed raft release handles. The drill was simple. After the plane stopped and floated, the person in the seat would open the overwing emergency hatch. He or she would then pull the handle in the frame. A cable was attached running out to the life raft compartments. The doors would pop open and out would come the raft ready to go. It was a neat system, kept most of the rafts out of the cabin but sometimes could be difficult to adjust, particularly as there were several different types of valve heads for the CO2 bottles.

Two things had to happen to "blow" a wing raft. When you pulled the handle, the first part of the cable motion tripped the cover door lock. Continued motion pulled the split cable even further and "blew" the CO2 bottle that inflated the raft. In the chill of one Idlewild night, the mechanics who changed the wing rafts on a Connie were chagrinned to find a different type of valve head on the new rafts. The had some difficulty in getting the cables stretched far enough to hook to the valve. The door latch section of cable was fine but they had to fudge a little and the cable to the valves was somewhat taut. Rigging instructions for the life raft system were vague and even the inspector was satisfied so down went the door. It was latched, "breakaway" safety wire applied and everyone was happy.

With the morning came the sun. The cold metal of the Connie's wing soaked up the heat. Aluminum is quite expansive when heated, considerably more so than the stainless steel that made up the wing life raft cables. Experienced mechanics know you cannot properly rig an airplane unless the temperature is pretty well stabilized. Under the beat of the sun, the wing stretched and what little slack that was in the bottle cable was used up and the CO2 bottle valve was actuated. Unfortunately, there was plenty of slack in the door latch portion and it didn't release. The raft inflated, muscled the door upward, broke it and triumphantly expanded out only to deflate due to the rips it suffered in its victory over the door. A little while later, as mechanics were pushing stands up to find out what was going on, the second raft blew as well. It was probably just as well that it blew then rather waiting for the wing to flex in flight. I know of at least one military Connie model that had some problems with control due to a raft wrapped around an outboard fin.

Life rafts in the cabin were not trouble free either. Necessary as they are, they are often afterthoughts in the design of an aircraft. These are often stowed in the overhead ceiling panels, which require the installation of counterweight systems to prevent the raft from crushing the innocent flight attendant underneath. Some are stowed in coatrooms and closets and must be lugged by brute force to the nearest door.

One of a mechanic's easier tasks is a check of the emergency equipment. It is a tedious and lengthy job but it is inside the cabin making it a preferred assignment on cold, wintry nights. The Super Connie parked outside the hangar was jumping in its chocks under blasts of near Arctic air. Those of us who drew engine oil sumps and screens pulled long faces for it is no fun on a windy night. I was included in that unhappy quartet and would have to open firewalls and main cowling on all four engines and remove the main and scavenge oil screens and the magnetic chip detector plugs. The oil would be thick in the cold, dirty as always and would blow everywhere, as it was very windy. The smarter put raingear on, as much for a personal windbreaker as to keep our coveralls clean.

Miserable as we may have been, one person was happy. Mort had paid his dues yesterday in working a particularly dirty lavatory problem so in the name of equity, the lead mechanic gave him the cabin as his assignment. He disappeared upstairs determined to "milk" the job for the entire shift as we unfortunates moved stands and opened the "tin" on the engines. Mort started on a careful inventory of the life vests that were secured under the seats. Each vest was checked for having its pouch sealed and not having being past its expiration date. The Connie, snakelike and elegant, narrows considerably at the aft end. The two aft lavatories were separated by a partition and directly forward of them were two coatroom closets. A bulky raft was stored in the left-hand closet and Mort had to check it.

It was cold in the cabin and so Mort was well bundled. This may explain his clumsiness or maybe it was that he was working in the dark with only his flashlight to illuminate things. At any rate, he tugged at the raft to turn it for examination. He was horrified to hear the sound of the CO2 bottle inside the large yellow bag discharging. Wrong handle. He was even more dismayed as the big yellow raft burst the bag open. He found he was trapped by the writhing shape of the raft that was made to get big and round but was constrained by the coat closets, ceiling, floor, and Mort. The flashlight was lost in the folds of the raft and Mort found he was being pressed very firmly against a partition. The raft was doing its best to squash him when his hand found his tool pouch and he calmly (hah!) selected a common screwdriver and stabbed that raft to Swiss cheese. There were no dramatic pops for rafts are built not to explode like a balloon. It was not a fast deflation either for the raft had two separate compartments. It sounds funny now, but Mort was a very shaken mechanic when he came downstairs. His back was strained. The ceiling panel was pushed up and a closet door was broken too as testimonial to the power of expanding gas.