Chalk Crash

Anyone else have a theory about this tragedy? It is my belief that, as the engines were throttled up for take off, a fuel line burst, sprying the engine with fuel and causing a fire. This fire continued to grow, and when the tank exploded, it blew off the wing. Sucks for them, I estimate that they were only about 30 seconds from a safe water landing. R.I.P. Chalk

I wouldn’t rule out metal fatigue or corrosion. After all, the airframe was over fifty years old. While in the Air Force, I served on several aircraft accident investigation boards. One thing I learned was not to jump to conclusions. Sometimes what at first glance appears to be the obvious cause of a crash turns out to be a red herring once all the facts are in.

My heart goes out the the families and friends of those who lost their lives in this tragedy.

The aircraft was a Grumman Mallard that was converted to turbo props. That is a whole lot of stress to add to an airframe. It could just as easily been brought down by a catestrophic malfunction of the engine. When a turbine lets go the parts that are spinning at 100,000 rpm become schrapnel that cut and puncture everything in the area. The malfunction could easily be caused by a bird ingestion. However, as previously stated it is to soon to diagnose the cause until the facts are in. It could take a year or more to determine the cause. The loss of life is tragic. NTSB will get to the bottom of the cause so it can be prevented in the future.

The latest news on CNN is that the NTSB has found a stress fracture on the starboard wing spar. Not sure if this has been confirmed.

Would make sense, putting turboprops on an old airframe often doesn’t work (coughShackleton cough), but that just doesn’t explain to me the fire. Wouldn’t a stress fracture result in a break instead of a burn? And there was white smoke when the plane was still airborne, as seen in the video, so that seems to indicate that a small bit of fuel was burning in the engine. Also, I am a major IL-2 fan, and I noticed that if you leave a wing on fire for long enough, it will suddenly explode and shear off while the plane enters a spin, but not on fire. The wing will remain on fire until it hits the ground.

The stress fracture could allow the wing outer section to flex more than normal. The flexing allows the fuel tank in the wing panel to be flexed and crack or allows a fuel line to be pulled free. The fuel then gets on a hot engine and , whala FIRE. Flames being fueled by av-gas or jet fuel and being blown at 150 mph are like a blow torch. Off comes the wing panel. Please do not misunderstand I am not making light of the crash and the loss of life.

The up rated turbo props added stress the the airframe AND these aircraft are seaplanes. Their airframes take a pretty good beating with every landing and takeoff from the water. Add to this the fact that they operate in salt water and the corrosion problem is multiplied. I think we will see a grounding of these aircraft for a full inspection of the wings and engine mounts. Time will tell.

I dearly love the Grumman Mallard. It is a mini Albatross. I got to fly in one while on duty in California. It was privately owned and painted like an HU-16 in USAF SAR colors. Most folks thought it was an Albatross. I did.

Makes sense, unfortunately, I believe that all of the Mallards will now be withdrawn because of this terrible accident. Maybe they will be replaced by and Alb, or some other modern seaplane. Maybe a SeaStar.

Matt90

If the cause is determined to be cracks, the FAA may require a fleet wide (read: every aircraft of that model in the air) inspection of the effected area, with repair or replacement of the damaged parts found. Also haveing a bearing on grounding is the question of how much will the cost of a new aircraft be. The Beech 18 has had known spar problems for at least 30 years. Raytheon (Beechcraft) has been trying to ground the 18 for at least 20 of those years because they have to keep a design office open to keep track of the maintenance performed and any further problems found during the required inspections. However, because the aircraft is still in widespread use as a commercial aircraft (hauling checks, parts etc at night) the cost of replacement of the nation wide fleet would be prohibitive to the owners, the FAA so far refuses to ground them. However, the Mallard is no where as extensively used as the 18, so it could very easily be grounded, or only those models with turboprop engines may be grounded. We’ll just have to wait and see.

And as a side note, the military phased out the Grumman SA-16 because the entire fleet was approaching the design hour limit on it’s wings (and they were starting to find cracks in the wings). It was determined there was no fix for the problem and it was cheaper to replace the SA-16 with C-130s and helicopters (which also had much more utility than the 16) than manufacture new wings for the entire fleet.

Truly a tragedy with the loss of 20 lives. A newspaper article this morning said they found cracks in the main wing spar. If they were very big, that certainly could lead to catastrophic wing failure. The wing departing the fuselage, (they said the engine was still attached to the wing), would probably have caused ruptured fuel tanks and/or fuel lines which would be a source for the fire and smoke seen just prior to the crash.

Mechanical machines such as airplanes do have a finite life span, even when extended with lots of TLC and SLEP programs. I guess that is why we see so many of what looks like good, flyable military aircraft at Davis Monthan in the bone yard.

Darwin, O.F. [alien]