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Author Topic: Ouch!  (Read 408 times)

donv

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Ouch!
« on: June 10, 2019, 11:01:19 pm »
So, in anticipation of my paint job (see thread below), I decided to replace the horizontal stabilizer boots. They were pretty beat up, with patches and so on, and it would be ugly to have new paint and these patched up boots. I think they take a lot of rocks and debris on takeoff, since my wing boots are fine.

So, they pull off the old boots... and find a crack in the leading edge. And, to make matters worse, Twin Commander now specifies a new, thicker leading edge... with the result that they can't replace just one side, they have to replace both!

Oh well... the good news is that Twin Commander has them in stock. The bad news is 70 hours of labor per side.

I've had pretty good luck with this airplane, so I really shouldn't complain... so I'm not.

And, since someone will ask, no, apparently it can't simply be repaired, even though it's a very small crack.

Adam Frisch

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Re: Ouch!
« Reply #1 on: June 10, 2019, 11:42:02 pm »
Wow! Is it the same procedure on the main wings should they find a crack? Doing mine soon.... :-\
Slumming it in the turboprop world - so you don't have to.

donv

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Re: Ouch!
« Reply #2 on: June 11, 2019, 12:25:46 am »
I don't know... ask Dan Black. Hopefully yours doesn't have any cracks! The wings take less of a beating along the leading edge, from what I can tell.

I also don't know if the leading edge is all one piece... I would guess it is not, which limits the risk a bit.

Steve binnette

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Re: Ouch!
« Reply #3 on: June 11, 2019, 12:58:28 am »
I had my tail boots replaced in 2015 when I did everything else.  Not sure how much they cost.  They still look great and I think you are doing the right thing?  New paint needs good boots and lenses for lights.

The tail boots always take a bigger beating than the wings for the all the reasons Don mentions plus the radius is smaller.

That just makes it worse.

SKYFLYER

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Re: Ouch!
« Reply #4 on: June 11, 2019, 07:20:36 am »
Maybe I have Just been lucky... But I have never heard of a leading edge wing crack unless some impact damage caused it.

Which begs the question...  how many Commanders are flying around with cracks???  Never to be discovered unless the boots are removed.

Clearly there must be some overlying reason for the cracks if Twin Commander already has a "thicker" fix.

MY boots were all replaced new during the purchase years ago and I have not needed to replace any of them.  So I am now wondering what I might have under mine.

donv

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Re: Ouch!
« Reply #5 on: June 11, 2019, 11:52:23 am »
There is no way to know how many have cracks. Mine is quite low time (4300 hours), but maybe that means mine has also had fewer boot replacements, etc.

My wife was asking about "how bad is it?" from a safety point of view. I told her that if there was any sort of safety issue, they would have issued an AD, or at least a service bulletin. I don't think there is even a service letter-- the thicker skin is simply a "product improvement."

This is just a tiny little stress crack between two rivets, but what can you do?

Adam Frisch

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Re: Ouch!
« Reply #6 on: June 11, 2019, 09:00:18 pm »
Not bad at all. Also nice to get rid of the lumpy hangar rash under, right?
Slumming it in the turboprop world - so you don't have to.

donv

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Re: Ouch!
« Reply #7 on: June 12, 2019, 11:12:00 am »
Yes. I don't think that was actually hangar rash-- my guess is it was from a rock thrown up by the props.

If I was cheap, I might have been able to source a used part and saved some money, but I don't really think that is the right way to go, especially for this airplane, which has had a continuous history of owners who did things "the right way."

I found out that the thicker skin change actually happened at the end of 980 production-- probably in preparation for the 1000.

Steve binnette

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Re: Ouch!
« Reply #8 on: June 12, 2019, 12:31:56 pm »
Do you know if there Is a serial number cutoff where they changed the skin thickness?

donv

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Re: Ouch!
« Reply #9 on: June 12, 2019, 12:34:12 pm »
I was told 95085. Of course, the last 980 was 95084, so I'm guessing that means it starts with the first 1000...

Adam Frisch

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Re: Ouch!
« Reply #10 on: June 12, 2019, 06:16:39 pm »
Was that due to that tail that came off in a thunderstorm? I do seem to recall that was a lot later than when the 1000-model was released, sometimes in the 90's. But was there another reason for this change?
Slumming it in the turboprop world - so you don't have to.

donv

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Re: Ouch!
« Reply #11 on: June 12, 2019, 08:33:58 pm »
I do not think so. I believe there were some tail-related ADs, and I think for the 695B and Australian certification they had to strengthen the tail, but I doubt this was a part of that program. Could be, though, I guess.

Since they mentioned a serial number, I'm assuming it was a change made while the airplanes were still in production. I don't think the 980 was officially discontinued for a few years, even though they didn't make any after the 1000 came out (they did make some later 840s, though).

Bruce Byerly

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Re: Ouch!
« Reply #12 on: June 13, 2019, 12:06:13 am »
Both sides? Thatís a new one Don.  :(  Iím going to have to look into that ...

Adam - no, the wing leading edges arenít comparable.  There has been a ďsqueeze testĒ forever in the horizontals. They can take a beating in the ice.

donv

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Re: Ouch!
« Reply #13 on: June 13, 2019, 01:12:29 am »
Bruce, if you find out something different I'd be interested to know. Aero Air's inspection department is pretty thorough, and I believe they verified this with Twin Commander (I asked them to), but who knows...

Bruce Byerly

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Re: Ouch!
« Reply #14 on: June 13, 2019, 01:11:50 pm »
Bruce, if you find out something different I'd be interested to know. Aero Air's inspection department is pretty thorough, and I believe they verified this with Twin Commander (I asked them to), but who knows...

Don, I have great respect for Aero Air. Always have. In response to my question, our DOM said heís comfortable changing one side only. If thereís something precluding that from being legal, and there may be, Iíd be interested. Maybe itís interpretation and/or they donít think itís a good idea to change the stiffness from side to side?