Author Topic: Clues, Documents And Evidence About The Case (Read 1420252 times)

Chaucer · « **Reply #6495 on:** May 31, 2021, 08:50:04 AM »

I don’t know how to articulate any more clearly, so let me ask it in the form of a question:

Do you think the aft stairs shown in the video that Nicky sharers in a previous post looks like it could “bounce like a springboard” as shown in the picture georger posted?

My answer is no, those stairs are too stiff. Therefore, what is the explanation for that discrepancy? Shutter has suggested that the stairs are malfunctioning or are being deployed incorrectly. Any video of a working, properly deployed aft stairs to compare?

Shutter · « **Reply #6496 on:** May 31, 2021, 10:19:19 AM »

Quote

Do you think the aft stairs shown in the video that Nicky sharers in a previous post looks like it could “bounce like a springboard” as shown in the picture georger posted?

Yes, even though they are not functioning correctly just the weight of the guy helped them down.

1 square foot has a wind load of 51 psf with 100mph winds..I believe the stairs would be somewhere around 40-50 square feet.

I believe the transition is not as forceful as a "springboard" I think it slowly went back up and then down a little..

I have shown the video of the stairs working properly TWICE?

Shutter · « **Reply #6497 on:** May 31, 2021, 10:50:09 AM »

Here is a Northwest Orient training video. it's a DC-9 but the same concept. he operates the stairs at 4:40 minutes into the video..

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Bruce A. Smith · « **Reply #6498 on:** May 31, 2021, 04:58:46 PM »

Hey, Shut, I never knew an airplane could move backwards. Interesting video. Reverse thrusters, eh? I thought they only slowed the plane down upon landing.

dudeman17 · « **Reply #6499 on:** May 31, 2021, 06:37:36 PM »

I've also wondered about the pressure bump. Another tell is the video from the Treat Williams movie. When the stunt guy jumps from those stairs, they do rebound a bit, but you can tell that the motion is dampened by the hydraulics. They don't appear that 'springy', they don't seem to nearly slam shut. I suppose there is room for variance in the hydraulic pressure from plane to plane, due to age, maintenance, and what-not.

R99 says that it shows that Cooper had limited knowledge of aerodynamics. It could also be that he simply overestimated the hydraulic strength.

Nicky, if you ever arrange that test jump with Mark, I want in on that! Test redundancy and all that...

Shutter · « **Reply #6500 on:** May 31, 2021, 07:31:35 PM »

I don't believe they slam shut. that's been said for over a decade. the movie, the stuntman said the fastest he would do the stunt was 150 knots. probably a dozen takes at different speeds, so who knows the actual speed of the jump they used in the movie.

Some of the DC-9's and 727's had the flaps that allowed reverse instead of using a push back. today, it's a waste of fuel. $$$$$

Robert99 · « **Reply #6501 on:** June 01, 2021, 12:43:58 AM »

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Hey, Shut, I never knew an airplane could move backwards. Interesting video. Reverse thrusters, eh? I thought they only slowed the plane down upon landing.

Propeller airplanes with a reverse pitch capability frequently just back into and/or out of their parking places. Pure turbine aircraft are doing it now. I think I remember recently seeing video of a C-17 backing around the ramp.

Robert99 · « **Reply #6502 on:** June 01, 2021, 12:59:34 AM »

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R99 says that it shows that Cooper had limited knowledge of aerodynamics. It could also be that he simply overestimated the hydraulic strength.

I'm not familiar with the stairs hydraulic system, but I frankly would expect that the stairs would be locked in the up position by some mechanical means. And perhaps the hydraulics to the stairs would then be simply turned off and stay off until the aircraft was on the ground again. But no one on the aircraft actually knew what to expect when Cooper tried to lower the stairs. However, it appears that Cooper's efforts resulted in the stairs just "free-falling" as they would on the ground with no hydraulics.

Maybe 377 has the handbook covering the stairs and could comment on this.

Shutter · « **Reply #6503 on:** June 01, 2021, 01:45:12 AM »

The stairs are raised up and down with help, or assistance. there is really no in between. the hydraulics give the power to lock the stairs in place. the weight alone wouldn't get them locked due to locking over center. they hydraulics assist the lowering and obviously to raise them.

Robert99 · « **Reply #6504 on:** June 01, 2021, 01:56:47 AM »

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The stairs are raised up and down with help, or assistance. there is really no in between. the hydraulics give the power to lock the stairs in place. the weight alone wouldn't get them locked due to locking over center. they hydraulics assist the lowering and obviously to raise them.

I think there has been information posted here some time back that when on the ground the stairs could free fall even without hydraulic pressure. My question is can they free fall in flight even if the hydraulic pressure is lost? Of course, whether on the ground or in flight, the stair lever has to be operated.

Shutter · « **Reply #6505 on:** June 01, 2021, 02:02:02 AM »

They will fall but they will not lock..you then use the pump in the lower control to pump 3000 psi into the accumulator and they should lock in place. then you need to use the pump to raise them.

Shutter · « **Reply #6506 on:** June 01, 2021, 02:12:25 AM »

This is why I suspect the pressure was low in the recent video. they will free fall but probably not all the way down. the hydraulics push the struts over center locking them in place. pressure stays in the systems up to 30 minutes after shutting down the hydraulics.

I think if the hydraulics failed they would still drop in the air. the lever unlocks them allowing them to free fall. they can't shutoff hydraulic B due to other critical function required to stay in the air.

System B controls the stairs, cargo doors, upper rudder, ailerons and elevators..

Shutter · « **Reply #6507 on:** June 01, 2021, 02:32:17 AM »

Each hydraulic system has two pumps and two switches that can be turned on and off. the reason being is to shut the electric pumps off when they are not needed to extend the pumps life. switching one pump off might shutdown something else, I'm not sure..

The switches are on the engineers lower panel and are usually off when you start the APU..

Robert99 · « **Reply #6508 on:** June 01, 2021, 01:14:09 PM »

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Each hydraulic system has two pumps and two switches that can be turned on and off. the reason being is to shut the electric pumps off when they are not needed to extend the pumps life. switching one pump off might shutdown something else, I'm not sure..

The switches are on the engineers lower panel and are usually off when you start the APU..

Is the APU operating during normal flight conditions on these early 727s? The onboard APUs were just coming into use when the Cooper aircraft was built in the mid-1960s and it seems to have had one since there is nothing to indicate that a ground APU was utilized during the time at SEATAC.

Shutter · « **Reply #6509 on:** June 01, 2021, 01:53:53 PM »

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Each hydraulic system has two pumps and two switches that can be turned on and off. the reason being is to shut the electric pumps off when they are not needed to extend the pumps life. switching one pump off might shutdown something else, I'm not sure..

The switches are on the engineers lower panel and are usually off when you start the APU..

Is the APU operating during normal flight conditions on these early 727s? The onboard APUs were just coming into use when the Cooper aircraft was built in the mid-1960s and it seems to have had one since there is nothing to indicate that a ground APU was utilized during the time at SEATAC.

It's for ground use only. one of the first things done in starting the aircraft giving power to the cockpit controls.

Poll

Do you believe Cooper lived or died. the option are below to cast a vote...

Author Topic: Clues, Documents And Evidence About The Case (Read 1420252 times)

Chaucer

Re: Clues, Documents And Evidence About The Case

Shutter

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Shutter

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Bruce A. Smith

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dudeman17

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Shutter

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Robert99

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Robert99

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Shutter

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Robert99

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Shutter

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Shutter

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Shutter

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Robert99

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Shutter

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