DC-10 and Tristar
That's the first I've heard that the Saudi accident involved the inability to dump cabin pressure, but it makes sense with the accounts of the inability of anyone inside or out to open any of the doors. One wonders how the absence of any emergency ability to dump cabin pressure made it through certification, or why there was no immediate Emergency AD after the event, especially given that competing designs seemed to have it.
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The in-and-up cabin doors on the TriStar were developed from those on the Electra.
Max cabin pressure differential for the TriStar appears to have been 9.4 psi ( exact data welcome ).
For a Type A exit dimensions are 42 x 72 inches, assuming 3,024 square inches for a rectangular form ignoring corner radii.
That gives a maximum force against each door of 28,500 lbs. The inward-pushing door springs were each apparently rated at 15,000 lbs. So two springs per door would be sufficient to overcome maximum cabin pressure. Will try to find a diagram of the door design.
Max cabin pressure differential for the TriStar appears to have been 9.4 psi ( exact data welcome ).
For a Type A exit dimensions are 42 x 72 inches, assuming 3,024 square inches for a rectangular form ignoring corner radii.
That gives a maximum force against each door of 28,500 lbs. The inward-pushing door springs were each apparently rated at 15,000 lbs. So two springs per door would be sufficient to overcome maximum cabin pressure. Will try to find a diagram of the door design.
On the subject of the 1011's S duct - I'd propose that it was one of the last swooshy bits of an aircraft that was designed by hand and possibly even slide rule. I'd love to be able to preserve one (It'd make a fab slide for grandchildren).
The L-1011 pax doors had a long curved rack on each side with gear teeth down its length. The gear teeth on the racks engaged with gears on a shaft above the door. At one end of the shaft was an electric actuator with a brake assembly incorporated. It normally operated the door. At the other end of the shaft was a counter-balance unit. Inside were gears and a stack of Bellville springs. As the door was closed, a small jackscrew insside compressed the springs. This provided the power to open the door in an emergency.
The racks on each side of the door had a series of small arms attached.. The other end of each arm was attached to the door. So except when down, the door was suspended from the arms. When, on closing, the door reached the bottom it engaged with a ramp that started to force it outward. The door could not go down any more but the racks, driven by the actuator could. The arms were down from the weight of the door but as the racks proceeded down the arms pushed outward forcing the door into its seat.
The counterweight spring on the shaft above was now fully compressed, It stored enough energy to rapidly raise the weight of the door AND the slide-raft pack attached to the door and drag the apron of the slide raft pulling out of the pack to deploy it. I can assure you there was not enough power there, nor the mechanical advantage of those arms on the rack to overcome any cabin pressure. I saw several emergency evac TESTS fail because the apron of the slide raft was improperly packed and the door did not have enough power to drag the chute out. It stalled at about 2 feet ope.
Sorry so lengthy. It actually was a very good door and, except for brakes that would slip after long use, casused little trouble. And yes, its design originated in the L-188 Electra.
The racks on each side of the door had a series of small arms attached.. The other end of each arm was attached to the door. So except when down, the door was suspended from the arms. When, on closing, the door reached the bottom it engaged with a ramp that started to force it outward. The door could not go down any more but the racks, driven by the actuator could. The arms were down from the weight of the door but as the racks proceeded down the arms pushed outward forcing the door into its seat.
The counterweight spring on the shaft above was now fully compressed, It stored enough energy to rapidly raise the weight of the door AND the slide-raft pack attached to the door and drag the apron of the slide raft pulling out of the pack to deploy it. I can assure you there was not enough power there, nor the mechanical advantage of those arms on the rack to overcome any cabin pressure. I saw several emergency evac TESTS fail because the apron of the slide raft was improperly packed and the door did not have enough power to drag the chute out. It stalled at about 2 feet ope.
Sorry so lengthy. It actually was a very good door and, except for brakes that would slip after long use, casused little trouble. And yes, its design originated in the L-188 Electra.
Sounds like the only thing Lockheed missed in the door was using a couple of hydraulic systems. Where’s 411A when we need him? Gone to Lockheed Heaven in Palmdale.
GF
GF
That's the first I've heard that the Saudi accident involved the inability to dump cabin pressure, but it makes sense with the accounts of the inability of anyone inside or out to open any of the doors. One wonders how the absence of any emergency ability to dump cabin pressure made it through certification, or why there was no immediate Emergency AD after the event, especially given that competing designs seemed to have it.
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My understanding was that the outflow valves remained closed with the engines still running - presumably with packs on.The result was that the aircraft remained pressurised with the doors unable to open. In spite of the firecrew being urged by maintenance personnel to cut the fuselage open they refused. A large number of fire service units were rolled or crashed attempting to get to the aircraft. The general incompetence resulted in a total revision of the Riyadh fire service. I have been on board the aircraft with a Lloyds fire investigator - horrifying experience,I also regularly removed serviceable parts to keep other aircraft flying. Getting to the aircraft involved driving past a Hawk SAM installation and the security would track us with heavy machine gun - was always extremely relieved to get back.
But the doors didn't open at that point (which in any case would already have been too late for the occupants) because nobody had at any time pulled any of the handles.
With the engines running and electrical power failed, there was no way to shut them down short of fire service foaming the engines - not easy to kill an engine this way.
With the engines running and electrical power failed, there is no way of shutting off the engine bleed air and no way of shutting off the packs.
With the electrical power failed, there is no way of running the outflow valves full open to relieve internal cabin pressure.
In this condition, pulling the emergency door opening handle would pull the lock pin and release the brake on the shaft but there is nowhere near enough energy stored in the counterbalance nor sufficient mechanical advantage for the door mechanism to force the door inward against any internal cabin pressure.
I agree that cutting the fuselage is the only option for relieving pressure. I remember at one time many aircraft had "cut here" markings on the fuselage. The L-1011 did however have a thicker than normal cabin skin making it more difficult to cut.
I can attest to the toxicity of the products of combustion from materials in the cabin. In my first post I mentioned the forward toilet tank shroud as having burned in the incident at KEWR. Afterwards, we cut off a small sample of the remaining shroud and in the maintenance office, in the presence of the Lockheed service representative, lit it on the edge. It burned robustly and we all hastily exited the office to escape the very irritating fumes.
On talking to Lockheed Engineering, in fact to the fellow responsible for interior stuff flammability, he informed us that we tested it the wrong way. We had held the sample on its edge vertically when we lit it and of course it burned. The approved way was laying the sample horizontally and applying heat to the middle of the sample. And oh yes, the fumes were toxic and if I remember correctly, he said there was cyanide in the brew..
Waiting for the fire to burn through the cabin skill would not help anyone inside, they would have perished long before.
By the way, do not forget some hundred plus emergency passenger oxygen generators down the length of the cabin. When an unoccupied TWA L-1011 burned at KBOS, some people who were there told me of the jets of intense flame as these generators cooked off. I strongly suspect that interior materials are no better on any other manufacturer's aircraft.
With the engines running and electrical power failed, there is no way of shutting off the engine bleed air and no way of shutting off the packs.
With the electrical power failed, there is no way of running the outflow valves full open to relieve internal cabin pressure.
In this condition, pulling the emergency door opening handle would pull the lock pin and release the brake on the shaft but there is nowhere near enough energy stored in the counterbalance nor sufficient mechanical advantage for the door mechanism to force the door inward against any internal cabin pressure.
I agree that cutting the fuselage is the only option for relieving pressure. I remember at one time many aircraft had "cut here" markings on the fuselage. The L-1011 did however have a thicker than normal cabin skin making it more difficult to cut.
I can attest to the toxicity of the products of combustion from materials in the cabin. In my first post I mentioned the forward toilet tank shroud as having burned in the incident at KEWR. Afterwards, we cut off a small sample of the remaining shroud and in the maintenance office, in the presence of the Lockheed service representative, lit it on the edge. It burned robustly and we all hastily exited the office to escape the very irritating fumes.
On talking to Lockheed Engineering, in fact to the fellow responsible for interior stuff flammability, he informed us that we tested it the wrong way. We had held the sample on its edge vertically when we lit it and of course it burned. The approved way was laying the sample horizontally and applying heat to the middle of the sample. And oh yes, the fumes were toxic and if I remember correctly, he said there was cyanide in the brew..
Waiting for the fire to burn through the cabin skill would not help anyone inside, they would have perished long before.
By the way, do not forget some hundred plus emergency passenger oxygen generators down the length of the cabin. When an unoccupied TWA L-1011 burned at KBOS, some people who were there told me of the jets of intense flame as these generators cooked off. I strongly suspect that interior materials are no better on any other manufacturer's aircraft.
On the C130K the cargo compartment material would give off phosgene gas (and other noxious fumes) when burning. It was this that killed everyone in the Belgian AF C130 crash at Eindhoven. Whether the materials were improved for the C130J i know not but I doubt it.
It is noticeable how safety initiatives gradually get airbrushed away over time. The British Midland 1989 East Midlands 737 accident led to accident report comment about understanding the route to emergency exits in a smoke-filled cabin. I was a regular on BMA in the 1990s and their safety briefings included a strong "To find the exit follow the floor lighting. It's down here. Look", and the floor lighting would be switched on and off by the lead FA to demonstrate it. I believe the BMA aircraft had a wiring mod done to allow this from the FA position. Once several years had passed, however, the emphasis for this very gradually faded away, the airline was merged, and now it gets mentioned, if at all, only in passing.
Last edited by WHBM; 20th Dec 2017 at 10:01.
Yes, and no.
My understanding is that there has never been a certification requirement for manufacturers to design cut-in areas, but where they have chosen to do so, there are regulations around how they should be marked.
Old thread on the topic here:
aircraft cut in area
My understanding is that there has never been a certification requirement for manufacturers to design cut-in areas, but where they have chosen to do so, there are regulations around how they should be marked.
Old thread on the topic here:
aircraft cut in area
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Musket.
Almost correct, it was one DC10 - if someone else doesn't do it first, I'll look in my logbook and give you the reg. later.
Another nice corner of BA that I inhabited.
I was the second most senior Captain on the fleet (there were about 10 of us - can't remember the exact no.).
The senior guy used to do the long Barbados every other week and I did the week in Vancouver (summer) and the week in Grenada (winter) every other week.
A very pleasant lifestyle for two years!!
Almost correct, it was one DC10 - if someone else doesn't do it first, I'll look in my logbook and give you the reg. later.
Another nice corner of BA that I inhabited.
I was the second most senior Captain on the fleet (there were about 10 of us - can't remember the exact no.).
The senior guy used to do the long Barbados every other week and I did the week in Vancouver (summer) and the week in Grenada (winter) every other week.
A very pleasant lifestyle for two years!!
yes plus a couple of others on seasonal leases too OO-xxx for one and one from Leisure AL iirc
occasionally a DC10 would be tech for a L/H charter
i was in Male going home to the UK and a Tristar landed much to the disdain of the waiting pax - the flight would not be non-stop but via BAH and no premium cabin
occasionally a DC10 would be tech for a L/H charter
i was in Male going home to the UK and a Tristar landed much to the disdain of the waiting pax - the flight would not be non-stop but via BAH and no premium cabin
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Looking in my logbook, BHDH was the only BA DC10 at Caledonian while I was on the fleet - the fleet continued, for about a year, after I had left it and NIUK may have come then.
G-NIUK was the one which operated for Kuwait Airways (blue bottom, white top with Kuwait Airways painted on the fuselage) for a long summer in 92?
It was used as a spare mostly for when either of the 2 BA Tristars, also on the contract, went sick or required maintenance.
We often did other work when required, KWI - BAH and return for example.
G-NIUK was the one which operated for Kuwait Airways (blue bottom, white top with Kuwait Airways painted on the fuselage) for a long summer in 92?
It was used as a spare mostly for when either of the 2 BA Tristars, also on the contract, went sick or required maintenance.
We often did other work when required, KWI - BAH and return for example.
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BA were nearly a dual-operator of the trijets before the BCal merger, in 1976 they were considering the DC-10-30R against the projected TriStar 500. Both RB.211 engined but the DC-10 variant was considered lower-risk and also had better seat-mile costs. TriStar fleet commonality doesn't seem to have been rated particularly important.
There were some nice models made at the time of the DC-10 in the Negus livery.
One of the factors that led to the TriStar 500 being selected was that Lockheed let BA switch the last six long-body orders to the 500, the European divsion was suffering from over-capacity at the time and that was a useful relief.
There were some nice models made at the time of the DC-10 in the Negus livery.
One of the factors that led to the TriStar 500 being selected was that Lockheed let BA switch the last six long-body orders to the 500, the European divsion was suffering from over-capacity at the time and that was a useful relief.
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Originally Posted by Basil
Bit less than stellar in its MD-11 incarnation.
Here's one going in to Nairobi-