Discussion in 'Hangar Flying' started by TarDevil, Jun 3, 2015.
I met Jeremy Monett and talked to him briefly when I attended the Sonex weekend workshop back in 2010. I remember he was awaiting word of his wife going into labor and mentioned to all attending that he may have to leave. It saddens me to think of his child who is probably now around 5.....Very very sad. Two men taken from this Earth at much too young an age.....I offer my sincerest condolences to the families involved.
This is very, very saddening. My heart goes out the these men's families.
Sad day in the experimental world........
Nobody should outlive their child. My thoughts go out to John and his family, and the entire team at Sonex.
more details trickling in
So what happened?
Near as I can tell, The NTSB has not done a final report, so no probable cause has yet been released. When they do the final report, it may or may not include a probable cause. However, the photos and reports in the DMS will provide some clues as to which leads the investigation followed.
Sounds like the turbocharger wasn't turning, for one thing. "The engine's turbocharger could not be rotated by hand. Disassembly of the turbo found static marks corresponding to compressor blades without any smearing or deformation of the blades."
Mentions an incident a few weeks earlier where a turbo had partially seized, and the plane was able to maintain altitude but not climb.
Don't know if there's enough justification for the NTSB to rule on a Probable Cause. The last paragraph of the factual may indicate where they're going for contributing factors.
That's how I read it, too. Plus the statement about the intersection takeoff... what's the line about "runway behind you"?
NTSB if they find a mechanical problem, will bird dog that problem and see if they can make it the root cause. They only close the file when they can write the root cause. They will balance it with pilot error and pick the one with the most evidence. The one I was involved in had no injuries and it took almost two years. Someone being killed will have them really wrapped up.
An obstruction in the exhaust will cause loss of power. I doubt the NTSB will cite an intersection takeoff as a contributing factor unless it can be factually shown that full length would have prevented the mishap.
There's plenty of investigations that do not reveal a smoking gun. The NTSB reports the facts, speculation usually won't fly on a final and that's all they can do.
Very true. There are plenty of finely detailed NTSB Factual reports that really seem to indicate a particular cause, but the Probable Cause comes out, "Engine failure due to undetermined causes." More than a quarter of homebuilt accidents involving loss of engine power are eventually ruled that way.
I've read a lot of NTSB factual reports, and for me, that statement about the intersection takeoff really seemed unusual in its positioning...as "Additional Information" at the end. Remember, the NTSB board makes the Probable Cause ruling, not the investigator. This seems like the investigator wanted the board specifically aware of the circumstances of the takeoff point selection. This is why I think it'll end up as a contributing factor in the PC.
As for whether it made a difference. Never know for sure, of course. But the plane took a 1700-foot takeoff run and the problem had apparently manifested itself about 2150 feet later. That was about 3900 feet from the start of the takeoff run...roughly a quarter mile past the end of the runway. Without the intersection takeoff, there would have been about 1800 feet of runway remaining.
The "ground run" of 1700 ft sounded suspicious to me for an airplane that advertises a 400 ft or less takeoff distance. That's like 4x more distance than what should have been needed. Perhaps the problem manifested itself at the time of power application? Otherwise, if I planned a takeoff with a modified takeoff profile and didn't have a grasp on how that would affect the numbers, I'd stack the deck in my favor and use a longer runway. If it was unplanned, as some point you just got to throw in the towel and discontinue the takeoff.
I just see mention of the runway and intersection departure as factual tidbits.
Just curious but do other turbocharged airplanes mitigate the risks of a compressor bearing failure somehow?
A seized turbo assembly will cause a very large reduction in power, perhaps as much as 50% below naturally aspirated levels due to massively restricted induction airflow and exhaust flow. Certainly critical during takeoff.
We've used manual air bypass valves on some centrifugal supercharged and turboed Experimentals.
There is no reason to have these sorts of failures on genuine Garrett journal bearing turbos assuming they are fed cool, clean oil at the correct pressures, drainback is designed properly, don't swallow any FOD and operated within their N1 and TIT limitations.
Foreign made clones can be another matter.
I'm not a big fan of ball bearing turbos for aviation use.
We don't know what turbo was used here or what the system layout was like nor any of the operational limits observed.
One time I had an engine failure at about 40' on takeoff at a large airport. I will NEVER accept an intersection takeoff, never.
Never seen or heard of then used on aircraft but suction doors have been used on autos to reduce turbo lag in the old days of blow through carburetor systems. I suppose something similar could be set up with an Aircraft turbo. This incident has made me consider this option because the turbo I'm kind of forced to use (RHB31) has a less than stellar record.
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