Seamax m22 Crash East Hampton NY

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duchamp

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duchamp
I am not a pilot but a few days ago a friend of mine was killed when one of the wings of his airplane fell off during level flight. Looking into the accident database on this AC type I find that it happened at least once before, and a third fatal crash resulted in strewn wreckage which may or may not have been caused by a catastrophic structural failure. The one other fatal crash was pilot error.

This is my first post so I cannot post any links.

How is it possible for wings to fall off new aircraft in level flight? What are your thoughts about this?
 
Sorry to hear about your loss.

As unsatisfactory as this answer may be, it’s really best to wait for the official NTSB report.
 
Last edited:
duchamp said:
I am not a pilot but a few days ago a friend of mine was killed when one of the wings of his airplane fell off during level flight. Looking into the accident database on this AC type I find that it happened at least once before, and a third fatal crash resulted in strewn wreckage which may or may not have been caused by a catastrophic structural failure. The one other fatal crash was pilot error.

This is my first post so I cannot post any links.

How is it possible for wings to fall off new aircraft in level flight? What are your thoughts about this?
Click to expand...
What aircraft was it?
 
duchamp said:
I am not a pilot but a few days ago a friend of mine was killed when one of the wings of his airplane fell off during level flight. Looking into the accident database on this AC type I find that it happened at least once before, and a third fatal crash resulted in strewn wreckage which may or may not have been caused by a catastrophic structural failure. The one other fatal crash was pilot error.

This is my first post so I cannot post any links.

How is it possible for wings to fall off new aircraft in level flight? What are your thoughts about this?
Click to expand...
It's rare (especially for strut-braced wings like the Seamax) but it does happen.

This model of Seamax has wings that are designed to fold. If the fold mechanism doesn't lock the wing properly (either due to design issues or the pilot's failure to engage it properly), the wing may fold in flight and aerodynamic forces may cause it to separate completely from the aircraft.

http://www.kathrynsreport.com/2022/10/seamax-aircraft-seamax-m-22-n46pd-fatal.html

The previous case of a separated wing occurred to a Seamax in Italy. I can't read Italian, but the preliminary report put out by the ANSV (Italian equivalent of the NTSB) may be of interest. A lot of discussion and pictures of the wing fold mechanism...not surprising, after a wing-failure accident...but I can't tell if they found anything wrong.

https://ansv.it/vigevano-pv-seamax-m-22-marche-i-7608/

Ron Wanttaja
 
skier said:
Sorry to hear about your loss.

As unsatisfactory as this answer may be, it’s really be to wait for the official NTSB report.
Click to expand...
NTSB findings are generally useless

9/10 odds it will say "pilot's failure to maintain flight after wing separation"


duchamp said:
How is it possible for wings to fall off new aircraft in level flight? What are your thoughts about this?
Click to expand...
Very sorry about your loss. Wing separations are one of my irrational fears when it comes to flying. As noted above, planes that have folding wings make me particularly uneasy. Unfortunately at the end of the day aircraft are just machines, and machines do sometimes break.. when I pre-flight I always give the wings a fairly robust wiggle and listen for anything unusual or weird movement. Many sale planes have folding wings as well, my brother-in-law used to be a sale plane pilot and we always gave the wings a good shake after securing the fold mechanism
 
*sail, not sale. Stupid gen-pop algorithmically derived speech to text. Artificial intelligence my @$$
 
I believe that a BRS is at least an option on those, don't know if that one had it. The article reproduced in KR has a few unfortunate quotes, such as that a wing couldn't just fall off unless there was bad maintenance, and also mentioning that the pilot did stunts (hopefully in another bird.)
 
The Italians did an impressive job of finding even the smallest debris.

My skill with the language is depleted with time, but they seem to have found the points of failure, and produced a first class report.
 
wanttaja said:
It's rare (especially for strut-braced wings like the Seamax) but it does happen.

This model of Seamax has wings that are designed to fold. If the fold mechanism doesn't lock the wing properly (either due to design issues or the pilot's failure to engage it properly), the wing may fold in flight and aerodynamic forces may cause it to separate completely from the aircraft.

http://www.kathrynsreport.com/2022/10/seamax-aircraft-seamax-m-22-n46pd-fatal.html

The previous case of a separated wing occurred to a Seamax in Italy. I can't read Italian, but the preliminary report put out by the ANSV (Italian equivalent of the NTSB) may be of interest. A lot of discussion and pictures of the wing fold mechanism...not surprising, after a wing-failure accident...but I can't tell if they found anything wrong.

https://ansv.it/vigevano-pv-seamax-m-22-marche-i-7608/

Ron Wanttaja
Click to expand...
There’s a certain degree of eloquence in the first article from Kathryn’s report.
 
Plane partner of the victim here. Just to keep the fact straight... the plane was only 6 months old with an A/W date of 4.22.2022. The wings have NEVER been folded since it was assembled by SeaMax and certified by the FAA in Florida in early April 2022. The fixed wing version was purchased but the FW version was delivered. SeaMax didn't even send the cradles necessary to perform the wing folding function until months after purchase and there has never been any intent or need to do so since it was hangar kept. The plane was flown by this pilot from FL to NY with a specialized instructor who spent a week here training the pilots on every detail of flying this aircraft. SeaMax sent its own A&P up to do the 50 hour inspection early (at 40 hours) and the oil change. On the day of the crash, SeaMax's head engineer was on a plane en route to the area to perform the 100 hour inspection the next day. Thorough preflights and inspections were done every single flight and nothing was ever seen to be visibly wrong. No unusual stress was ever put on the plane outside its normal operating range. We actually have a spectacular aerobatic plane too for that purpose in the hangar next door, so there was no reason to ever do anything with the SeaMax but enjoy it as an amphibian plane. This wing did not fall off due to any lack of diligence or action by the owner or pilot. Hopefully the NTSB will be able to shed light on several questions, including why a critical bolt at the strut/wing attachment was found with no nut and no damage to the threads. We will just have to be patient for their final report.
 
@flyfox that sounds like an absolute horrible, no good, absolutely worst case scenario. New plane, treated with utmost care and a worst-case outcome. I'm really sorry for the loss of your friend, and that you've been let down so badly. I hope the results of the investigation come in early, and with a minimum of doubt.
 
Sorry for your loss, it will be interesting to see what an investigation discovers. Hopefully the engineers from the company get involved.
 
wanttaja said:
The previous case of a separated wing occurred to a Seamax in Italy. I can't read Italian, but the preliminary report put out by the ANSV (Italian equivalent of the NTSB) may be of interest. A lot of discussion and pictures of the wing fold mechanism...not surprising, after a wing-failure accident...but I can't tell if they found anything wrong.

https://ansv.it/vigevano-pv-seamax-m-22-marche-i-7608/

Ron Wanttaja
Click to expand...

My Italian is rough, but it really doesn't seem to make any conclusions as to cause, just a lot of information on wreckage, etc... It appears that a wing folded and the plane went pretty much straight down. They do have one wing lock pin that they couldn't account for (others were present). Mostly they gripe about the safety of the certification process with the Italian Aero Club (I assume this is roughly their equivalent of the EAA).
 
flyfox said:
...Hopefully the NTSB will be able to shed light on several questions, including why a critical bolt at the strut/wing attachment was found with no nut and no damage to the threads. We will just have to be patient for their final report.
Click to expand...

Looking at the photos of the bolts in both the Hampton and Italy crash, I wouldn't say that there is no damage to the threads. It's hard to tell from the relatively low-res photos, but it looks to me to be similar to the thread damage we saw on nuts and bolts when Steve Smith (aero phD) and I were tensile testing the hardware used on RV-8 landing gear legs. We found that under tension, the nuts would actually swell up and "leapfrog" over the theads on the bolts. This would round the threads over a little, but still leave them mostly intact. I haven't posted enough here to include links, but you can see our test results on the Vans Air Force forum by searching on the thread title "Breaking News."

All that said, I have a fair amount of faith that the NTSB will indeed arrive at a reasonable probable cause. They don't always do their best work when experimental airplanes crash, but an in-flight primary structural failure of a production aircraft usually gets their attention.
 
arffwg.org

NTSB Prelim: Seamax Aircraft M-22 - ARFFWG | ARFF Working Group

The Entire Right Wing Was Separated From The Main Wreckage And Located In A Tree Location: East Hampton, NY Accident Number: ERA23FA007Date & Time: October 6, 2022, 12:29 Local Registration: N46PDAircraft: Seamax Aircraft M-22 Injuries: 1 FatalFlight Conducted Under: Part 91: General aviation –...
arffwg.org arffwg.org

"The entire right wing was separated from the main wreckage and located in a tree. The right aileron remained attached to the right wing. The right flap was separated from the right wing and located in the vicinity of the right wing. The right wing strut was separated from the right wing. The bolt attaching the right strut to the right wing remained attached to the right wing and was not fractured; however, the nut was not present. In addition, the bolt threads did not exhibit significant damage. The right and left wing strut assemblies were retained and sent to the NTSB Materials Laboratory for further examination."
 
Bacho said:
That looks like one application I would like something other than a ny-lock.


View attachment 122383
Click to expand...
That doesn't look a very good structural design, period. I presume it's done that way to allow it to pivot while folding the wings, but the bolt being offset from the strut centerline creates a bending moment on the strut and the fitting, which could create a bolt load significantly higher than the strut tension... up to double the design load based on the picture. It will also tend to dump all of that increased load on the lower side of the nut instead of evenly around it. And any relative motion could lead to the nut unscrewing. Nylocks are never supposed to be used on rotating joints.
 
I use nylock nuts to keep the license plate from falling off my folding utility trailer. That's a perfect use for a nylock.
The pivot of the trailer is a pair of clevis pins, each secured with a washer and cotter pin. That's a good way to do a pivot joint. This is on a $500 trailer.
 
Is there now a certified version of the Seamax ?
 
I thought nylocs were not to be used where rotation is possible/designed in. So if that’s a pivot, in addition to the aforementioned moment created by non-congruent centerlines, seems like not a place for a nyloc.
 
A flex-lock nut with a cross-drilled bolt for safety wire/Cotter key looks like it would be prudent vs a Ny-loc.
 
wanttaja said:
I can't read Italian,
Click to expand...

Google translate worked. They seem to have changed the interface, I had to download the Italian doc, point google at it and then download the translation.

I will try to upload it here. Looks good, 5M is not so much now.

Google Translated preliminary report follows.
 

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