"Aluminum Overcast" damaged by gear collapse

Pat wrote:

James Robinson wrote in message ...
The B-17 bomber owned by the Experimental Aircraft Assn. was damaged
yesterday at Van Nuys airport when its main gear collaped.


Am I the only one who finds it a bit "suspicious" that both main gear
collapsed on this bird? If I recall correctly, they are two
independant systems. The common link would be in the cockpit... right
next to the flaps switch.

According to the Pilot Training Manual, the gear activation switch is located between
the recognition light switches and the landing light switches. It is not particularly
close to the flap switch. The flap switch is isolated, is not part of a row of
switches (as is the gear switch), and it has side guards to make it easy to
differentiate between it and other controls. Personally, I think the LG switch should
be the one that's isolated and guarded, but ....

Anyone else think that perhaps the gear
were inadvertantly retracted (pilot attempting to retract flaps)
rather than a mechanical failure...???

I doubt it. I think an electrical problem is much more likely on a 60 year old plane.

George Patterson
If you don't tell lies, you never have to remember what you said.

In article ,
"G.R. Patterson III" wrote:



According to the Pilot Training Manual, the gear activation switch is located
between
the recognition light switches and the landing light switches. It is not
particularly
close to the flap switch. The flap switch is isolated, is not part of a row
of
switches (as is the gear switch), and it has side guards to make it easy to
differentiate between it and other controls. Personally, I think the LG
switch should
be the one that's isolated and guarded, but ....

Both the gear and flap switches are toggle switches, they are within a
couple inches of each other on the center console. On the B-17 I flew
the gear switch had a cover that had to be lifted to activate the
rectraction. Even so our procedure was for the NFP to touch the flap
switch and say "Confirm flaps?"..the FP then would check to be sure the
flap switch was selected and reply "Flaps confirmed"...then and only
then would the flaps be retracted.


I doubt it. I think an electrical problem is much more likely on a 60 year
old plane.

The gear on the -17 are electrical. Each gear has it's own
motor...nothing ties the left side to the right side. The only common
item is the gear switch. The only failure I can think of that would
cause the gear to retract would be a failure in the switch that closed
the switch. The most likely failure would be human.

--
Dale L. Falk

There is nothing - absolutely nothing - half so much worth doing
as simply messing around with airplanes.

http://home.gci.net/~sncdfalk/flying.html

I watched the crash video frame-by-frame. The right main wheel appeared to
separate from the gear 1/10 second before the right main gear collapsed.
Then the left main gear collapsed, a few tenths after the right main.

Looks to me as if the right gear wheel axle may have failed.

G.R. Patterson III wrote:

Pat wrote:


James Robinson wrote in message ...


The B-17 bomber owned by the Experimental Aircraft Assn. was damaged
yesterday at Van Nuys airport when its main gear collaped.



Am I the only one who finds it a bit "suspicious" that both main gear
collapsed on this bird? If I recall correctly, they are two
independant systems. The common link would be in the cockpit... right
next to the flaps switch.



According to the Pilot Training Manual, the gear activation switch is located between
the recognition light switches and the landing light switches. It is not particularly
close to the flap switch. The flap switch is isolated, is not part of a row of
switches (as is the gear switch), and it has side guards to make it easy to
differentiate between it and other controls. Personally, I think the LG switch should
be the one that's isolated and guarded, but ....



Anyone else think that perhaps the gear
were inadvertantly retracted (pilot attempting to retract flaps)
rather than a mechanical failure...???



I doubt it. I think an electrical problem is much more likely on a 60 year old plane.

George Patterson
If you don't tell lies, you never have to remember what you said.

Buff5200 wrote:

I watched the crash video frame-by-frame.

Got a URL?

The right main wheel appeared to
separate from the gear 1/10 second before the right main gear collapsed.
Then the left main gear collapsed, a few tenths after the right main.

If the gear collapsed suddenly, then it was not inadvertently raised on the ground.
Retraction is by a screw mechanism and takes a few seconds.

George Patterson
If you don't tell lies, you never have to remember what you said.

"G.R. Patterson III" wrote in message
...


Buff5200 wrote:

I watched the crash video frame-by-frame.

Got a URL?

The right main wheel appeared to
separate from the gear 1/10 second before the right main gear collapsed.
Then the left main gear collapsed, a few tenths after the right main.

If the gear collapsed suddenly, then it was not inadvertently raised on
the ground.
Retraction is by a screw mechanism and takes a few seconds.

George Patterson
If you don't tell lies, you never have to remember what you said.

I don't know how the retraction system works, so I 'm asking..

1) Isn't the screw jack "sized" for air loads, with some sort of over
center mechanism to handle the ground loads?

2) If that's the case, does the gear retraction mechanism have enough power
to pull the gear back "under center" (?) while the aircraft is on the
ground?

3) Would the screw jacks fail in this case?

What I'm getting at is if someone flipped the wrong switch, could that
explain the collapse of both mains, and explain why there are apparently
broken screw jacks on both mains? Otherwise, I find it extremely unlikely
that both gear systems (they are independant, right?) would have a similar
mechanical failure at the same time...

KB

In article ,
"Kyle Boatright" wrote:


1) Isn't the screw jack "sized" for air loads, with some sort of over
center mechanism to handle the ground loads?

No "over center" lock.

2) If that's the case, does the gear retraction mechanism have enough power
to pull the gear back "under center" (?) while the aircraft is on the
ground?

Again, no "over center" lock. Yes, you can retract the gear on the
ground. On the B-17 I flew there was a "weight on wheels" switch to
prevent this but this was an add-on and might not be on all B-17s flying
today.

3) Would the screw jacks fail in this case?

I don't know.

--
Dale L. Falk

There is nothing - absolutely nothing - half so much worth doing
as simply messing around with airplanes.

http://home.gci.net/~sncdfalk/flying.html

"Dale" wrote in message news:me-

Again, no "over center" lock. Yes, you can retract the gear on the
ground. On the B-17 I flew there was a "weight on wheels" switch to
prevent this but this was an add-on and might not be on all B-17s flying
today.

The B-17 I was most recently involved with didn't have such a switch and the
engineer gave us specific warning not to bump the landing gear switch, ever.
(The master had to be on, but for safety we always assumed it was.)

-c

Kyle Boatright wrote:

1) Isn't the screw jack "sized" for air loads, with some sort of over
center mechanism to handle the ground loads?

No. The screw jack pushes against a knee-joint mechanism. The "hip" of this joint is
attached to the firewall bulkhead and the "ankle" is attached to the bottom of the
oleo strut. When the gear is full up, the joint is bent up into the housing and the
screw mechanism is fairly short. When the gear is down, the knee-joint is straight,
and the screw mechanism extended. The screw mechanism is also attached to the
bulkhead in such a manner that it is horizontal when the gear is up.

What I'm getting at is if someone flipped the wrong switch, could that
explain the collapse of both mains, and explain why there are apparently
broken screw jacks on both mains?

I doubt it. If someone raised the gear on the ground, the plane would just settle on
the wheels. Keep in mind that this mechanism was designed to handle at least 4 tons
more than this particular aircraft weighed at the time of the incident. On the other
hand, these things are ancient, so it might be possible.

George Patterson
If you don't tell lies, you never have to remember what you said.

Kyle Boatright wrote:

1) Isn't the screw jack "sized" for air loads, with some sort of over
center mechanism to handle the ground loads?

Thinking about it some more, you're probably right in a way. Although there isn't any
over-center mechanism, there would normally be little pressure on the screw mechanism
once that knee joint section straightens out. It's probably sized to keep the joint
straight and can't take the load when the joint begins to fold.

George Patterson
If you don't tell lies, you never have to remember what you said.

"G.R. Patterson III" wrote in message
...


Buff5200 wrote:

I watched the crash video frame-by-frame.

Got a URL?

Try this...
http://kcbs.dayport.com/launcher/2643/

It was listed on here...
http://cbs2.com/video/