Chalk seaplane NTSB says both wings had craks

[Jim Macklin]

Both Wings Cracked in Miami Beach Seaplane Crash, NTSB
Report Says

Monday, January 09, 2006



MIAMI - The seaplane that crashed off Miami Beach last
month, killing all 20 people aboard, had fatigue cracks in
both wings, a preliminary federal report said Monday.

The right wing of the Chalk's Ocean Airways plane separated
from the fuselage shortly before the Dec. 19 crash, and
investigators had earlier found cracks on the right wing's
support beam. But the new report by the National
Transportation Safety Board on Monday revealed that the left
wing had fatigue cracks as well.

The 58-year-old, G-73 Turbine Mallard plummeted into the
ocean minutes after taking off for the Bahamas.

The NTSB's final report will be completed later this year,
NTSB spokesman Paul Schlamm said.

After the crash, the Federal Aviation Administration
grounded all G-73 seaplanes until they could be inspected.
Chalk's was the only commercial operator of the planes.

The aircraft was built in 1947 as a Grumman Mallard. In
1979, it was modified to increase seating capacity from 10
to 17 passengers, and to replace the original engines.
Chalk's began using the planes the following year,
investigators said.

A message left after business hours Monday for Chalk's
general manager, Roger Nair, was not immediately returned.

[Joe Sterling]

Well Sir, that's alarming.

A 60 year old plane with cracks in both wings. And still allowed to
fly. No, fearful flyer, don't worry about the wings falling off.
Can't happen. Unless it does. Then, you're quite abruptly....dead.

But, Hey, cars are more dangerous, right. Statistics show....blah,
blah, blah.

[Grumman-581]

"Joe Sterling" > wrote in message
ups.com...
> Well Sir, that's alarming.
>
> A 60 year old plane with cracks in both wings. And still allowed to
> fly. No, fearful flyer, don't worry about the wings falling off.
> Can't happen. Unless it does. Then, you're quite abruptly....dead.

But we have redundancies... Two radios in case one goes south on us... Two
magnetos... To wings in case one decides to fall off...

[Sylvain]

Grumman-581 wrote:
> magnetos... To wings in case one decides to fall off...

are you sure that wings actually fall off? would have
thought the fuselage might, but not the wings...

--Sylvain

[Mike Schumann]

That explains why most early airplanes were bi-planes!

Mike Schumann

"Grumman-581" > wrote in message
...
> "Joe Sterling" > wrote in message
> ups.com...
>> Well Sir, that's alarming.
>>
>> A 60 year old plane with cracks in both wings. And still allowed to
>> fly. No, fearful flyer, don't worry about the wings falling off.
>> Can't happen. Unless it does. Then, you're quite abruptly....dead.
>
> But we have redundancies... Two radios in case one goes south on us... Two
> magnetos... To wings in case one decides to fall off...
>
>

[Capt.Doug]

>"Jim Macklin" wrote in message
> Both Wings Cracked in Miami Beach Seaplane Crash, NTSB
> Report Says

When the right wing seperated, and the load trnsferred to the other wing
which was also cracked as we now know, how come that wing didn't seperate as
well? The video footage of the fire bomber C-130 shows this happening but it
didn't happen on the Grumman.

D.

[Jim Macklin]

I was just passing on the news report about the NTSB. I
don't know if any of the cracks in the spar actually caused
the right wing to break. I have not seen any detailed
photos of the wing, the attach points or the spar.

Has anybody heard any reports about the inspections on the
remainder of the Chalk fleet?

I presume that the NTSB report will take a year, do you
think Chalks' will be able to fly before the final report?



--
James H. Macklin
ATP,CFI,A&P

--
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"Capt.Doug" > wrote in message
...
| >"Jim Macklin" wrote in message
| > Both Wings Cracked in Miami Beach Seaplane Crash, NTSB
| > Report Says
|
| When the right wing seperated, and the load trnsferred to
the other wing
| which was also cracked as we now know, how come that wing
didn't seperate as
| well? The video footage of the fire bomber C-130 shows
this happening but it
| didn't happen on the Grumman.
|
| D.
|
|

[Peter Duniho]

"Capt.Doug" > wrote in message
...
> When the right wing seperated, and the load trnsferred to the other wing
> which was also cracked as we now know, how come that wing didn't seperate
> as
> well?

For a couple of reasons. One is that the presence of a crack weakens the
wing, it doesn't guarantee that it will break. So, even if the load had
transferred to the other wing, that doesn't necessarily mean it would break.

The other is that to say that "the load transferred" is faulty thinking.
The load didn't transfer to the other wing; the airplane banked into the
missing wing. The load on the other wing remained the same initially, and
then as control was lost, probably actually decreased as that wing lost
lift.

> The video footage of the fire bomber C-130 shows this happening but it
> didn't happen on the Grumman.

From memory granted, but my recollection is that the C-130 wings both failed
nearly at the same time. I would guess that the two accidents are actually
quite different, even though they appear the same. That is, the seaplane
wing appears to have simply failed in unaccelerated flight, while the C-130
wings appear to have failed because of acceleration (pull-up).

So, while in the case of the seaplane, the wing simply gave out once it had
fatigued at the crack enough, in the case of the C-130, both wings were
pushed past their strength at the same time by the increased load, and
failed about the same time.

Just a theory, and I may be misremembering the footage. And of course, I'm
not a materials engineer, so my theories may be suspect in any case. :)

Pete

[Tony]

Pete, your point about the non-failed wing is valid. Think about the
torque at the wing root -, think about a see-saw. When both ends are
loaded or both wings are generating lift, there's a certain torque.
WHen the first one lets go, the other side experiences a decreasing
torque, it is accelerating that side of the airplane up. Back to the
see-saw: if it's in balance, the bending moments at the pivot are
equal. When on kid `jumps off, the other side's bending moment really
goes down: the other kid is in free fall,

[Morgans]

"Jim Macklin" > wrote \

> I presume that the NTSB report will take a year, do you
> think Chalks' will be able to fly before the final report?

"My" _totally_ uneducated guess is that they will be able to, after
prudent inspections take place. The only hold-up could be obtaining
insurance to keep them flying.
--
Jim in NC

[Morgans]

"Peter Duniho" > wrote

> Just a theory, and I may be misremembering the footage. And of course,
> I'm not a materials engineer, so my theories may be suspect in any case.
> :)
>
> Pete

Man, knock me over with a feather! You have taken a _giant_ step, by
admitting that you could be wrong. <bfg, ducking and running>
--
Jim in NC

[Jim Macklin]

I think so too, but beyond the insurance question, how many
passengers will there be? The insurance companies will look
at the odds and the inspections and rate the risk to their
money. Passengers will be worried about their safety
without really knowing about the facts. It will be a tough
sell for a while.

I haven't seen any good pictures of the wing and fuselage,
have you?


--
James H. Macklin
ATP,CFI,A&P

"Morgans" > wrote in message
...
|
| "Jim Macklin" > wrote
\
|
| > I presume that the NTSB report will take a year, do you
| > think Chalks' will be able to fly before the final
report?
|
| "My" _totally_ uneducated guess is that they will be
able to, after
| prudent inspections take place. The only hold-up could be
obtaining
| insurance to keep them flying.
| --
| Jim in NC
|