The news media report the plane was built in 1947. No mention of flight hours, maintenance record, or time since a last "C" check.

No shortage of speculation here!

That's quite understandable and predictable. Some of it even makes some sense if you assume a couple of facts that are not yet in evidence. We shall see which of the speculations are on point once a few more things have been established as fact.

There is a high probability that physical inspection of the wing at the point of separation/failure will reveal the means by which the structure was induced to fail. Evidence of corrosion, fatigue, overload or overheat will remain at and near the point of failure. Examination of the engines will reveal whether or not an uncontained rotor failure and case rupture or any other occurance caused a fire. More video of the aircraft flight prior to the wing separation may come to the attention of investigators than has been seen on television so far. If the installed CVR yields useful audio, crew conversation and background sounds may be of investigative value. The focus of speculation on the causes of this crash will be narrowed in incremental steps as the NTSB releases individual details of it's initial field phase inspection and subsequent lab analysis of recovered components. A press briefing has been scheduled for 19:30 EST at the Biscayne Bay Marriott. Perhaps some useful information will released at that time.

Westhawk

I hearby invoke every conceivable caveat that any lawyer would need for me to say this:

the right wing fell off, the fuel inside ignited, the fuselage and left wing largely intact fell out of control to the water where everyone was killed (all due respect to those poor people)

the right wing simply fluttered down to the sea/jetty. from what I have seen the right engine is largely intact as is the prop, though it is curled at the ends (rotating upon hitting?)


Why did the wing come off?
1. metal fatigue due to a harsh salt water environment, age or yet to be known reason.
2. explosion causing failure of the wing...fuel? engine? sabotage?

3. Odd situation like WHIRL MODE on Lockheed L188 electra back in the 50's.

what should be done: immediate inspection of all similiar aircraft with all non destructive methods.

OK, let's quit pussyfooting around.

The CVR may have a terrible metalic ripping sound on it and an oath by one or both pilots.

thoughts?

jon

jondc9 - well put.

But assuming the initial failure was the wing spar, what was the ignition source? It would have to be a high-energy spark if electrical.

And maybe some conversation between the pilots about a problem which they may have noted prior to the structural failure. We won't know unless or until that information is made available. One of the first things to be determined is whether a fire caused the failure or whether the wing failure caused the fire. The surfaces where the separation occurred will reveal the answer. Not much has been presented so far to support either theory. But it will.

Westhawk

I was annoyed that the CNN newscasters intently commented that the pilots chose a poor place to land, as their experts told them the water was rough in that area.

Once you have lost a wing, do you really have any choice at all as to how or where the plane will land?

Also, aside from knowing how to prevent this from happening again, does it matter if the wing was on fire before or after it came off the plane? From the video, it looked like it was burning briskly, but I don't know how fast a fire could start.

Condolences to all the souls on board. A very sad way to start the holiday season for their family and friends.

Rather Shocking !!

To answer a few questions raised here;

The G73T has
- Autofeather
- Main fuel tanks between the fuselage and the engine
- Wing Aux if fitted, outboard of the engine
- Floats carry fuel as well, although Chalks carried water ballast in there at times ?!
- Wing carry through spar stops at the inboard of the engine and the rest of the wing becomes a spar itself
- Beta equipped PT6-34, specially designed props to stop on the locks for immediate use on water start-up
- Hydraulics on the wings; Reservoir and Accumulator in the left wing, flaps gear and brakes operated by hydraulics
- Chalks CVR, GPWS equipped, am not sure on the FDR
- Comp wash carried out at the end of the flight day
- Inertial Seperater equipped
- One of the fuel filters is located at either leading edge between the engine and the fuselage
- Engine can be run only direct to the main tanks

Just another speculation, although I hate to;

One of the fuel hose could've come off between the main tank and the engine (submerged fuel pumps) and with high pressure wouldn't take much time to pump enough fuel into the wing section to blow it up with the exhaust sliding over the wing :ugh:

Smoothie....

Maintenance?
 

Seems like Chalks know what they are doing.

Salt water operation is a very tall order, though. :ouch:

Aside from knowing how to prevent this from happening again, no, except perhaps to help identify and understand the sequence of events that occured. If a fire precipitated the failure, the steps taken to prevent future occurances might be quite different than if the failure occured for other reasons like corrosion, fatigue or something else. That was the only reason I had for thinking it may be important to know. Time will tell.

Best regards,

Westhawk

I am so reminded of a C130a that lost a wing in california in June of 2002. It was captured on video too.. Also the RAAF has a special "patch" made out of boron fibre for their C130's.

kudos to the in depth data on the fuel system...do you mean to say that there is no crossfeeding? most 2 engine planes have a method of feeding the right engine from the left tanks and vice versa.

In 1974 I think chalks was hijacked to CUBA. AFter that time they claim not to carry enough fuel to get to cuba ( semi hard to believe)

IF the fuel ignited first causing seperation we might have something like TWA800 on our hands.

I listened to the CNN reporting quite closely. No one indicated that landing would be rough IF THE WING HAD COME OFF. Early reports showed a possible engine failure and a post crash flip over.

PS! CNN just reports metal fatigue cracks noted according to NTSB.

jon

The journalistic trolls are quite apparent in preceding posts, aren't they!

Having flown sea planes in warm climates in the past I am not at all surprised that this accident happened. You can actually see corrosion forming in front of your eyes if you look hard enough. My speculation is spar failure but we will leave it up to the experts. A few guys I flew with really liked to chuck the airplane around ie pulling a few G's, and my reaction was you can do it but with me watching from the dock.

This is truly a sad event for all involved.

Fatigue crack found in wing spar
 

CNN Report

I think what they mean is that fuel is only fed from the main tank, I;d imagine that the Aux's and Xfeed dump into the main tank which then feeds the engine. someone with more knowledge on the a/c is sure to correct me if I'm wrong


http://images.airliners.net/photos/m...4/5/338541.jpg


can anyone blow this up to read the fuel panel

THE PROOF OF THE PUDDING my fellow aviation people will be this:

When the NTSB takes the intact wing and fuselage and checks that wing for metal fatigue in the spar as in the seperated right wing.

You can all imagine...if the other wing shows stress problems/metal fatigue etc that's one thing. if it doesn't then what happened to the right wing?

I would also want to compare a grumman mallard that spent its life in a nice fresh water lake rather than the harsh salt water.

Even with spot on fresh water rinsing...yikes!


too bad we only chat like this after a crash!

jon

Hey jon - you want that Grumman should have designed it so both sides will fail simultaneously? :}

I'm not privy to TT, cycles, or inspection practices on this G73 - but a gross fatigue indication, discovered within a few days of the accident, sounds very much like a red flag that should have been found LONG ago.

FWIW - The early Martin 202 had a fatigue trap built into the lower sparcap, and an early fatal crash was due to it breaking. It was designed within a year or two of the G73, and several years before the Comet. There was not nearly the fatigue awareness in the design community that we have today. Let's just say the Mallard was more successful in this regard than either the Comet or the 202.

There were also spar problems with the Beech 18 (C-45); needed a sparstrap if I'm not mistaken. Also several B-26 (A26) firefighting aircraft were found to have broken spars.

rigpiggy , from top left, the switch says 'left fuel pump off/on' then underneath 'left engine from left tank 190 gals' and 'left engine from right tank 190 gals' . The other selector reads 'right from left' and 'right from right'.
The two centre items are marked 'ignition' and 'fuel cap'.

Chalk has voluntarily grounded the four aircraft in its fleet similar to the Grumman Mallard that crashed, and will conduct heavy inspections.

We are all test pilots:cool: