General Category > DB Cooper
General Questions About The Case
georger:
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Register or LoginSo the 727 has the std (well ahead of its time really) three hydraulic circuits. That's fine. But the air stairs are hydraulically operated and I'd love to see the hydraulic circuits that control them on paper surely that has to exist somewhere. . I guess i was never convinced this pressure bump was the actual time of departure as I really don't think these stairs can come back up with any force as to produce any noticeable reading by the cockpit or anyone else. They supposedly reproduced this event shortly after is there written recorded evidence to this effect? I dunno...just asking questions......
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see photos of the sled test which literally show not only the rate/time of the air stair retraction, and how far the stairs in those tests closed. Any change or disruption of cabin pressure for any reason will be noted by the gauge. You can calculate all of these parameters using known distances on the plane. The photos are consecutive frames by a camera with a known shutter rate ...
Does Edward's book cover this?
73blazer:
It does, but I had just found his book yesterday ;D :rofl:
He says that it could be lowered and locked up to 300knots. He doesn't say it directly but I believe he's trying to say the stairs weren't locked during the sled test and they had to deliberately put them in this unlocked state in order to produce the pressure bump. I'm inclined to preliminarily agree with that, as hydraulic pressure should have zero problem to push those stairs down into the slip stream. Need a Boeing parts book for those hydraulic cylinders to see what their specs are. that exist anywhere?
Another interesting tidbit is I found from a Boeing maint. manual that the 2nd officers panel shows two aft airstairs lights. One is green and illuminates when the airstairs are down and locked. Another is amber and illuminates when the airstairs are not up and locked. Any if the statements or FBI materials mention which light(s) was illuminated?
georger:
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Register or LoginIt does, but I had just found his book yesterday ;D :rofl:
He says that it could be lowered and locked up to 300knots. He doesn't say it directly but I believe he's trying to say the stairs weren't locked during the sled test and they had to deliberately put them in this unlocked state in order to produce the pressure bump. I'm inclined to preliminarily agree with that, as hydraulic pressure should have zero problem to push those stairs down into the slip stream. Need a Boeing parts book for those hydraulic cylinders to see what their specs are. that exist anywhere?
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None of this changes the fact Cooper lowered the stairs and bailed during the time period ... the evidence is overwhelming regardless of the mechanics of the stairs.
73blazer:
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None of this changes the fact Cooper lowered the stairs and bailed during the time period ... the evidence is overwhelming regardless of the mechanics of the stairs.
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Nobody is disputing he lowered the stairs and bailed. Just questioning if the stairs were actually locked and the viability of a locked staircase bouncing back up. If the pressure bump was produced by something else, the time of bailing could possibly be completely unknown. How about that rear cabin door leading to the aft stairs, could that create a pressure change reading. Was that door already opened from the ground for the test? Did the sled test crew have to improvise to put these stairs in a somewhat difficult to attain unlocked position in order to get the stairs to bounce? Is there a light for that rear door on the 2nd officers station like the airstairs themselves? I'm just curious to dig some more and see exactly how those stairs and door work. I'm also with Edwards on wishing to see the sled test full report and how it was setup.
Shutter:
The stairs were never in a locked position. the crew states this as well as the stairs dragging on the taxi after landing. the stairs would more than likely be damage if in the locked position during a landing. as the plane slowed down on landing the stairs slowly came down and then caused some sparks from hitting pavement.
It's pretty simple. the stairs were engineered to open and close on the ground. they were designed to handle the weight of the stairs and not much more.
You will notice when the stairs were released and when they close. there is nowhere for the air to go since the plane is sealed except for the opening of the stairs.
The first sled test was done with someone on the stairs and Anderson reported the test did not replicate what happened on the night of the hijacking. the second test was done and they used rope to lower the sled down and release sled. Anderson reported that it was "identical" to what happened on the evening of the hijacking.
The first test had someone on the stairs which didn't allow the stairs to retract much. the second test left nothing on the stairs and they were able to retract easier and cause the "violent readings" to occur.
On YouTube type in Boeing 727 rear stairs and a video will show the operation of the stairs, including the lights on the engineers panel.
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