Larry, the aircraft involved in the NJ incident was a T337G manufactured in 1973. The 150 gallon tanks were offered later though I am unsure as to when. It may have been an option in 1974 and may have been a standard in 1975. I have one customer who operates a fleet of 24 Skymasters and they only fly those with the long wing. From my records they fly both the G and H models. The "long wing' aircraft have "hat" stringers that extend out to WS177. On the "short wing" aircraft these "hat" stingers extend to WS150. Outboard of the "hat" stringers is a spice to a "J" stringer. Additionally, the spar caps on the "long wing" aircraft have a "T" configuration of the spar cap which extends to WS177 and from that point outboard they become an "L" shaped cap. On "short wing" aircraft this transition happens at WS150.

The upcoming AD for aircraft modified with Flint Aero extended wing tip fuel tanks will only be for "short wing" 337s modified with Flint Aero extended wing tip fuel tanks as far as we can tell right now. Until the FAA signs off on our findings we can only speculate but I can say that I am very comfortable with the work of my engineer and the feedback I have received from the FAA on our preliminary findings.If you don't have the Flint Aero tips you would not be effected by this AD. If you have wing tip extensions manufactured by Aviation Enterprises you would be required to follow the instructions in that AD. However, the accident in Avon Park may bring into question the non-modified 337 wing. Since the accident in New Jersey the focus has been only on 337s with extended wing tips.

A replacement of the spar will not be required in addressing the issues incorporated in the forthcoming AD for 337s modified with Flint Aero tip tanks. There may be other ways to address the issue but we think our solution is one that addresses the issue in the most economically feasible way. According to my engineer, and he has been in this trade for many years, this has been done before on other aircraft.

Second C337 Down Due To Wing Failure
 

Copy of email message sent today :

----- Original Message -----
From: Alfonso Diaz del Castillo
To: Dennis Hamblin ; jose.obregon@ntsb.gov ; william.o.herderich@faa.gov
Cc: Alfonso Diaz del Castillo
Sent: Friday, December 03, 2010 9:51 AM
Subject: SECOND C337 DOWN DUE TO WING FAILURE

Hello Dennis and (Jose and William), it has been sometime since our last communication. I hope you all are doing well.

Dennis, thank you for posting in the Cessna Pilot Association’s (CPA) web board, your article of the additional and pending Airworthiness Directive (AD) for the Cessna Skymasters. Please email me the complete list of all the Skymaster forums that are out there, as it will be very helpful. I am a member of CPA, but it is not a Skymaster forum per se.

In your article posted in CPA you mention that the recent C337 incident in Avon Park, Florida, does not have wing tip extensions. Have you check with the NTSB or the FAA to verify that it positively did not have now or before Aviation Enterprises winglets? I believe the winglets could provide for bending, pulling and pushing effects on the wing, and could have had some effect in both incidents, in addition to the fuel wing tip extensions.

Thank you for your input and best regards,

Alfonso Diaz del Castillo - (C336 - N695AD)

Phones: Cell 202-309-3969 - Office 571-227-2208 - Home 301-934-9100 - Fax 301-934-2111

----- Original Message -----
From: Alfonso Diaz del Castillo
To: jose.obregon@ntsb.gov ; william.o.herderich@faa.gov
Cc: Fiestair@erols.com
Sent: Friday, March 26, 2010 8:09 AM
Subject: THREE PICTURES OF A SKYMASTER WINGLET


Good morning William and Jose.

Enclosed are three pictures of a winglet on a Skymaster C337 that I took on Oshkosh last year (I believe it is an Aviation Enterprises winglet). It may be helpful to you in visualizing how big it really is and how it may have affected the flexing of the wing on the accident C337 aircraft under your investigation, especially if it is not perfectly aligned with the centerline of the aircraft. I hope these pictures are helpful to you.

Best regards,

Alfonso Diaz del Castillo - N695AD

Phones: Cell 202-309-3969 - Office 571-227-2208 - Home 301-934-9100 Fax 301-934-2111

Here we go
 

Well, here we go. It appears Aviation Enterprises, though guilty of creating an unsafe condition and I quote from the AD 2010-21-18

"Unsafe Condition
This AD was prompted by a wing overload failure and by reports of cracks in the upper wing
skins on certain Cessna airplanes that are now or have ever been modified by Aviation Enterprises STC SA02055AT, SA02056AT, SA02307AT, or SA02308AT. We are issuing this AD to detect and correct damage in the wings and to prevent overload failure of the wing due to the installation of the STCs. Damage in the wing or overload failure of the wing could result in structural failure of the wing, which could result in a loss of control.

At first they were willing to accept responsibility. Then they asked for proof that the work was done. Then they wanted all the engineering data (I speculate so they could copy it and use it to create a fix for the remaining aircraft) and finally they finished off by asking me for the "weight and balance for every flight since the STC was done". Of course that information does not exist.

Instead of doing the right thing they have decided to hide and hope that myself and the other aircraft owners will just go away. Well, I can't speak for the others but I can tell you right now that I will not go away until I am reimbursed for the damage caused. I have availed myself to one of the legal firms that my company uses in Tennessee and I will be litigating. They did over $21,000 damage to my aircraft.

When I am finished I am told the cost to them including legal fees and damages will approach or exceed $100,000. The firm I am using has extensive experience in this area.

Update for further information
 

I just spoke with my engineer and he did say he was wrong in his assessment of the zero fuel weight (the gross weight of the aircraft) for the "short wing" 337s. It appears that will be 3,400lbs. You do need to keep at least 12 gallons of fuel in each tip tank until your weight drops to this point. Once the aircraft is reinforced this will go back up to 4,330lbs. I am still waiting on hearing how much fuel you need to keep in each tip at higher gross weights. Right now I would say keep your tips full until you get your weight down to 4,330lbs and then transfer some fuel out of the tips but you need to keep at least 12 gallons in each tip at 4,330lbs.

Again, this will only effect the "short wing aircraft." If you have the factory 150 gal tanks you are fine with the STC as it is currently written.

Also, I think it is important to add that our engineering numbers only deal with a total gross weight of 4,700lbs and below. Technically, our STC only provides a GWI up to 4,630lbs (that of a non-turbo 337G).

Unfortunate
 

It's unfortunate, Gord. I would think that they (Aviation Enterprises ) would want to get things straight. Resorting to attorneys makes attorneys happy. Unfortunately, I think that Aviation Enterprises would end up being not happy. I know of a similar case, and the plaintiff ended up owning the company, or at least it's assets.

Good Work
 

Thank you for keeping us apprised, Dennis.

This notice of Final Ruling on the Modified wing AD recommends inspection of those aircraft with the winglets in suit with the procedures outlined for wing extension modified aircraft.

During my next annual I will be looking very seriously at the identified locations per the AD. I will be at the second year anniversary with the winglets installed and I have had one flight with severe turbulence. I looked at the wings very close last year when the SAIB came out and did not find any concerns. When I installed the winglets I planned on following the suggested installation instructions but from the suggestion of the paint shop I used rivnuts were installed on all fasteners instead of using sheet metal screws. I will keep the message board updated with the inspection results.


http://www.regulations.gov/contentSt...ontentType=pdf

Hi Larry, do you know how I can get in touch with N5ZX?

Of interest is a colleague of mine had similar damage and AE covered 2/3s of the repair.

Ae
 

Hi Folks, Been a while since I posted on the site here.

Have you every wondered why AE is not listed on this websites web page listing or about their past quality history?

Reading about the quality of the wing extensions and the problems resulting from them made me wonder!

Maybe you should too!

Jerry

send email
 

Follow this link.
http://www.337skymaster.com/messages...highlight=n5zx
Then, click on the user, N5ZX, and you will have the ability to send a PM (not recommended, because the last login was some time ago), or an email, through the message board.

Hello, Jerry, good to hear from you again.

As one of the Webmasters for this page, I would like to say that Aviation Enterprises' absence from our list of web sites has less to do with the quality of their work and more to do with the fact that AE's owner, Owen Bell, did not emphasize their web site. Although it's better now, AE's website of years past was below average -- often just pages with pictures and bullets, with negligible design. Had Owen asked for us to include AE in our list of websites, we would have done it.

The question of quality is, of course, on everyone's mind. But, as a mechanical engineer like you, I think it's more about pushing the envelope. You push here, and something gives elsewhere. It's often hard to anticipate all the areas that need to be examined when you are modifying a complex item like an aircraft. Or maybe some corners were cut, like a test that wasn't performed or one where the test conditions didn't fully simulate reality. Hopefully, time will tell where the mistakes were made.

Ernie

Correction
 

Without going into details, AE's website was removed after some issues were raised.

ae
 

Thank you Ernie, nice to her from you again. And, thank you Larry for your wise response.

Larry, you are correct not to get into details nor will I. However Ernie, Just to set the record straight, you reasoning why AE is not listed on the web site listing page is in error. It predates many of the people that now enjoy this site today and even predates Larry as the webmaster. But enough of that.

For the sake of all you good readers on this web site, when it comes to after market changes to our aircraft, soundly check the vendor out completely. BBB, FAA record etc. Don't jist take other peoples opinion of the vendor. They may not have all the facts. Remember, when you and your loved ones are flying in the plane, the vendor is not with you. There are some very good after market vendors out there and likewise some not so good!

Jerry

"Wink wink, nudge nudge, say no more"
 

Thank you guys for putting up this website. I appreciate the posting of information about the old aircraft we fly and maintain. With all due respect though: This information is absolutely useless.

My 337C is currently in Owen Bell's hangar getting air conditioning, a rear engine cooling mod, and a cargo pod installed. Should I abort the project or not? Is there another source for Skymaster A/C or rear engine cooling mod?

Is there a way to search the FAA record for actions against companies or individuals? Are there any against Aviation Enterprises or Owen? What exactly is the concern with AE? Fill us in. Is it bad tip tanks? Aren't the Flint tanks subject to similar speed limitations? What about the O-2 at Avon Park? Maybe Cessna made a mistake.

Did you pay too much for something? Did you buy a used engine part and then he didn't warranty the entire engine when the used part damaged it? Would you pay for all the repairs to an airplane's wings when you had no way of knowing if the Va limitations were followed?

Until I have more information I will continue to use my own observations to formulate how I regard Owen: A guy who loves Skymasters and is willing to put a large amount of his energy and resources into making them better and keeping them flying.

Randy Hurt

it's your money
 

Randy, like all of us, you make your decisions based on your observations. If it is working for you, that's great.