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:

Rigpiggy:

The picture you posted is for the original piston engine Mallard, not the Frakes turbine conversion Mallard that Chalks flys.

Cheers Big Ears. my eyesight or computer skills are obviously not up to par.

BPF I just went to the largest pic I could find. if somebody has a G73T cockpit photo pleas post it.

With regards the fuel feed system;
- Main Tanks to Engine....crossfeed available,, the aux if fitted and the float fuel will have to be pumped into the mains on the respective side to be of any use

The flying boat in this scenario was not fitted with FDR and ironically the CVR is reported to have not recorded anything.

Latest NTSB reports say cracks were found in the spar at the root of the wing!! Goodness,, seems like the cracks were so internal and critical to find that it probably would've needed dye tests to reveal them (once again, NTSB comments!!)

Anyone with more technical knowledge/information on these sort of spar inspections....?!?! especially for the one's that operate on the salt water for over 20k hrs ?! cycles may be around 1 per hour.

A Very Sad situation in the aviation History of flying boats in particular....:ugh:

Smoothie....

Ok

NOW we know the mallard had the plumbing to crossfeed fuel it can easily be understood that these lines may have broken and allowed the fuel to go "vapor" and ignite...either electrical bits or the hot bits of the engine(which seems quite intact as is the prop on the right side)

I will say I think that the wing came off and THEN all the fuel on the right side caught fire.

I will say that I think that some time ago some odd sort of stress happened which grew over time to the disaster we have seen. Could sal water corrosion be a part? sure. But maybe not.


HOW many on the forum remember the DC10 at chicago that went down in the late 70's because a crack in the mount was made by using an unapproved maintenance procedure in swapping engines?


The DC10 was grounded for about 3 weeks and a few others were found with cracks. (other factors to be sure in this crash)


Metal Fatigue is not new, stress cracks are a small section of metal fatigue.

I encourage you all to either read, "No Highway" by nevil shute, or see the movie called, "No Highway in the Sky" starring Jimmy Stewart. Both made PRIOR to the
COMET disasters of 1954 (age not a factor there!)

And to all you Britishers out there! You should be very proud of Mr. Nevil Shute and the work of the Royal Aircraft Establishment.

Oh, by the way, WW2 in the pacific would not have been won without Grumman Fighter planes like the Wildcat, Hellcat, BearCat, TigerCat. Neil Armstrong and Buzz
Aldrin would not have landed on the moon without the Grumman Lunar (excursion) Module.


Maybe all planes should be made with a time bomb on board. Big clock warns when it will go off to everyone getting on board.

20 year countdown and then get away from the thing!

Trouble with grumman is that this plane was too well made. 50 plus years is alot.

jon

jon, at last you have said something both easy to agree with, and pertinent to this investigation.

The rest is OT and/or fanciful.

I doubt the age of the aircraft is a factor. The inspection procedures and intervals might be.

Very Sad
 

I used to operate these aircraft for the company and they are a thrill to fly.

Old airframes, but heavy maintenence daily.

As for the spar, Grumman mandated that the spar for the larger ALBATROSS be replaced after a number of hours, replaced with TITANIUM spar at the cost of a million plus.

Very sad day for aviation indeed, highly probable that the oldest operating airline in the US will be closed for good.

My thoughts and prayers to the crew, passengers and their families.

Let the legend live in memory

Just to clarify on the stated Albatross spar issue;

The military versions were HU-16's with no spar life on them.

Grumman bought back or rather acquired around 16 I think back from the market and built them to 0 time naming them the G-111's. These had a Titanium spar cap installed and another emergency door installed and was certified for Charter. All these G-111's have a service life on them. Chalks operated few of these and now they are all parked in storage awaiting to go to a new home. The lowest time one is around 30 or 40 hrs or something like that !!

There's one G-111 for sure flying around happily operated by Mirabeela Yachts. This one used to be PK-PAM in Indonesia years ago.

Most of the other Albatrosses flying around are HU-16's either under a restricted or a experimental category.

Smoothie....

Sorry, probably not a coincidence. There is such a thing in the strange and often soul-less world of advertising called targeted ads. In CNN's case when there is news regarding a particular and pre-chosen subject, a related ad is automatically broadcast. The saddest part is that Honda Motor Corp will actually pay extra for this 'premium service' and have requested the insertion.

Until someone complains to Honda (Ad execs at CNN could care less), the airing of the Honda Jet ad will be paired with aviation matters (or whatever other key words trigger the insertion) including the video of that most unfortunate loss of the Mallard and her PAX and crew will continue in and out of rotation.

Once full convergence occurs (digital television , internet access and on-demand programming in one box/system) you can expect more specific ad-revenue generating insertions like this based on what you watch, when and likely even where you surf the net.

Not a pretty picture - but it's the future in the capital driven world of advertising.

jon:

While Nevil Shute Norway was in fact an aircraft design guy (dirigibles, I believe) with an appreciation for fatigue, and likely had some anticipation that future fatigue casualties would happen, Nevil Shute the author got much undeserved credit for guessing it would happen to (specifically) the Comet.

Americans and Brits (and others) all came to appreciate the durability of the Wildcat and Hellcat from the "Grumman Iron Works". But the Bearcat never saw WWII duty, and at least two F8F's broke up during postwar aerobatic exhibitions.

And Grumman's lunar vehicles were examples of outstanding performance-to-weight engineering, with just barely enough fatigue life to last one mission (that's certainly NO criticism of Grumman, just stating what they really accomplished!)

And the DC-10 problems were not fatigue-related at all, but overstress damage during unapproved maintenance procedures.

So, precious little of your original tome really addresses the current G-73 problem.

News from Avweb reporter.
 

December 22, 2005

Cracks Found In Crashed Mallard's Spar

By Russ Niles
Newswriter, Editor

Investigators have found a major fatigue crack in the spar of the wing that separated from a Chalk's Ocean Airways turboprop Mallard on takeoff from Miami on Monday. The wing was recovered Tuesday and fatigue was quickly apparent. "We've seen fatigue. We don't know why that fatigue appeared. That is what we're trying to determine," Mark Rosenker, acting chairman of the National Transportation Safety Board, told reporters Wednesday morning. "This crack appears to extend through a majority of the spar at the location of the separation." A total of 19 passengers, most of them from the Bahamas, and the pilot died. Rosenker suggested the crack may have been hard to spot on a routine inspection. "Inspection maybe would have found that [metal fatigue], but there would have had to have been a very serious type of inspection to have understood it and found it," he said. The airline has suspended regular service but airline officials say there is still strong demand for flights and they hope to resume service by Friday. Chalk's has been in operation since 1919 and had three Mallards before Monday's crash.


This is going to take allot time to properly sort out. These guy's are my neighbours at FLL. These aircraft are very well maintained. The very fact that they have had such a safety record and their dependebility are testiments to the viability of the fleet. Many years ago I worked for Walker's Cay and I spent allot of time working on N2954 our Mallard. They are extremely well built and a sea kindly design. The next flying boat I worked on was the PBY. I licensed three of them and Imported two of them. I was luckey enough to amass about fifty hours in them. Just 'cause it's a highly experienced airplane does not make it trash. If it's properly maintained it can soldier on ad infinitum

My company ran twenty vintage airliners hauling the Wall Street Journal. Our mission completion rate was over 99.9% and we never hurt anyone. I only wish I still could operate them now.

attn: Barit1
 

I encourage you to read nevil shute (norway)'s book, "Slide Rule". While he was involved with dirigibles ( and his was the first to fly from England to Canada) his expertise also includes designing the first retractable gear aircraft in England.

As anyone who knows anything about metal fatigue the first transportation accident due to metal fatigue was in 1842.

Stress and fatigue are kissing cousins for the purpose of this discussion.

You noted that the DC10 crashed for one reason and don't seem to think that the MALLARD could( i say again could, no proof) have crashed because someone backed a forklift into its wing during changeover to turboprop engine.

I see that you have a commercial single engine land certificate.

Good for you. I see you are an engineer. (B&O?) but I digress.

Why did I mention Nevil Shute's great work? so that people who aren't engineers or pilots might get a laypersons appreciation for what happened east of Miami.

If you would like to argue finer points of aviation, you have my e mail address.

I'd like to point out that just a few weeks prior to the Three Mile Island meltdown or near Melt Down a little movie came out called, "The China Syndrome".

Sometimes people who can't prove something still want to shout a warning so that someone might be alert. A book or a film can sometimes do just that.

Nevil Shute did that with "No Highway" and subsequent movie. He also warned us of the terrible consequences of Nuclear War in "On the Beach".

One quote might even help everyone on this forum out:

"airplanes do not crash in and of themselves, perhaps one crash in a thousand is truly an act of God, instead they crash because men are irresolute, careless or reckless" (from "Slide Rule).

so barit1, post what you like. I don't think too highly of what you have said so far.

Oh and I see Bearcat fighters all the time here in Reno at the air races! And they were just coming into use as the bomb was dropped on H and N.


[email protected]

The fracture photos point to stress raisers from holes, brackets or other drillings. Corrosion played no part whatever in this one.

The Vickers Viscount (VH-RMQ) that lost a wing in Western Australia in 1968 had spar stress raisers from sleeves through the spar that had been bashed in carelessly during major service.

Chalk's pilot's husband sets up foundation

BY DARRAN SIMON

[email protected]

Mark Marks last talked to his wife, pilot Michele Marks, on Dec. 18 when they rose before sunrise and he made her coffee. He told her he loved her, and to fly safe.

He found out she died when he saw the report Dec. 19 on TV that a Chalk's Ocean Airways seaplane had crashed off Miami Beach.

The couple's memories always seemed to come on the water's edge.

They met on a nine-day shark behavior ecology course in a South Africa fishing town. He asked her to marry him on the 10th day. Michele became Mrs. Marks on the San Diego coast.

''Everywhere I walk I see her. I smell her,'' Mark Marks told reporters Saturday at their Boynton Beach home. ``She was my soul mate, my best friend and my wife.''

Marks, 42, a renowned zoologist and research biologist who works with white sharks, said his wife of more than seven years loved wildlife and the ocean. He plans to start the Michele Lynn Marks Marine Conservation Foundation to give scholarships to college students for marine research.

The right wing of Chalk's Flight 101 separated from the fuselage in the crash. The seaplane plummeted into the water near the Government Cut jetty off Miami Beach. It had just left Watson Island, heading to Bimini. The 18 passengers and 2 pilots on board were all killed.

The cause of the crash is not expected for some time. But the Federal Aviation Administration issued a bulletin Friday saying it may now require mandatory inspection of all seaplanes. The bulletin said an FAA preliminary investigation showed stress fractures in the 58-year-old Grumman G-73 Turbine Mallard seaplane's right wing support that could have played a role in the crash.

Chalk's voluntarily grounded its four other G-73 aircrafts after the National Transportation Safety Board discovered the fractures.

Mark Marks said he didn't know much about the investigation but has to be patient.

''I really want to know what happened, for her, her co-pilot, the families of the other 15 passengers and three children that died,'' he said. ``I don't know how to honor her better than to find out the truth.''

Michele Marks, 37, loved seaplanes and worked for Chalk's about three years, flying twin-engine Grumman G-73T Mallards.

Chalk's promoted Marks, who had an unblemished flying record, according to the FAA, from first officer to captain this year.

Her husband wore her white gold wedding band with a green emerald around his neck.

The ring was one of the few items he has received from the medical examiner.

``I don't know how I am going to do this without her.''

He sobbed while talking and held a photo of his wife wearing a pilot's uniform.

''This is the single-most difficult thing I ever went through,'' he said.

Marks was teaching the shark behavior ecology course in 1998 when he met his wife. She was a few inches taller and attractive, he recalled. ''Oh man, I'm in trouble,'' he remembered saying when he first saw her.

They married on Sept. 23, 1998 -- her birthday.

She tempered him. He was loud, she was less confrontational. She wasn't the cook or the domesticated one. In fact, she just learned to boil spaghetti. She usually left a trail a clothes on the floor on her way to the shower.

She was the adventurer -- hiking mountains, swiming with white sharks in South Africa.

''She was fearless. She was absolutely fearless,'' her husband said.

He introduced her to hiking. They spent three months hiking across the country on their honeymoon. She was teaching him how to sail.

''I've lost my teacher as well,'' he said. She helped steer the Chondros, a 38-foot Irwin he owned from Naples to South Florida. The Chondros -- Latin for ''cartilaginous fish'' -- is docked at the couple's Boyton Beach complex.

The family held a service for her on Friday. Chalk's employees, mechanics, customs agents, and others from Bimini and passengers who flew with Marks showed up.

''I just feel so lonely without her,'' he said. ``She'll never come home, but I want her to come home so bad.''

http://www.miami.com/mld/miamiherald/13481687.htm

That is one hell of a reach to decide whether you see trans granular cracking vs intergranular cracking in that 1 X photo.

Corrosion can occur anyplace, especially in drilled holes after- production where the surface may have a course texture. Of course I would not care to extrapolate from a internet photo. However the two different sides of the hole do appear to have two different types of fatigue initiations at their surface which in my view could possibly consider abusive machining or corrosion on one side and secondary initiation on the other.

I’m only a pilot, but I presume that the question on the engineering community's mind is why there are two offset drill holes in this particular location which have removed so much material (say 15% of the width) from the horizontal leg of the lower spar cap. The drill work does not look very skillful in my inexpert opinion.

Again IMHO, I venture to speculate that fatigue induced failure (whether corrosion related or not) would seem to have been an inevitable consequence and just a matter of time and cycles, once these offset drill holes were made.

No engineer am I - but I have to wonder at what appear to be two drill holes, not parallel to each other and apparently merging together. I sometimes achieve the same effect in a wall when installing an Ikea curtain rod. It would seem to me that such an action would create a stress concentration.

FAA issues AD
 

Frakes Mallards grounded until inspection completed: AD (pdf)

Given the nature of the defect that apparently initated the crack, why is the inspection limited to Turbo Mallards? Why not R-1340 powered ones?

(I could even ask - why limited to Mallards?)