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Brumby elevator issue


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Was looking at the low wing Brumby that is online at a flight school the other day and saw this bolt... I know it's probably never likely to happen but it worries me a bit. This bolt is on the inside of the elevator servo, or balance tab, with a few mm clearance to the fixed part of the horizontal stabiliser.

 

The first photo below shows the head of the bolt, the second photo shows the cavity that could very easily trap said bolt head if it ever came loose, even a small amount. Resulting in a jammed elevator...

 

Anyone else noticed this? and have had any thoughts about it? Just looks like a potential problem that could possibly be eliminated by replacing bolt with something else, or at least tie-wiring it.

 

IMG_8265.jpg.710bb2b30cd010794a77c826d094ce3e.jpg

 

IMG_8267.jpg.1b30d2d2057d0fb59aa0294cccc3cc7a.jpg

 

 

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How old is this Brumby? Notice the fizz in the top photo?

Looks like corrosion has started, I'm surprised. I also wonder how old it is and whether it is a hangared aircraft.

 

 

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It should be Ok, as mention above, it should be have a castle nut and a split pin as the locking medium. If however it is a Nylock nut, then yup it can be a cause of concern.

 

 

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Normally if a bolt and nyloc nut are done up somewhere, as a permanent fixture, it can be regarded as a set and forget item.

 

However the bolt in question is possibly clamping a lead mass weight, and with time and vibration, lead can creep allowing the bolt to lose tension.

 

Loose enough for the bolt to fowl the controls?

 

Probably not, and very noticeable signs of the looseness would be apparent before the bolt had enough movement to bind.

 

 

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  • 2 weeks later...

Dear Mr Tomo , In regards to your recent post that bolt goes through and holds a counter weight with a Nyloc nut that bolt does not turn and should never have lock wire or any form of castle nut as suggested . If you have a concern it is far better to contact the manufacturer than have any form of advice from forums or advise you that could lead to the incorrect advice .

 

Paul Goard

 

 

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Even though all factory aircraft use nyloc nuts in certain applications, there is no denying the fact that a castle nut with a cotter pin is more secure than a nyloc nut.

 

 

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I have seen too many castle nuts with missing split pins.

They must not have been installed or not installed correctly. My 12 years working on military aircraft I never once found a cotter pin missing. It must be s civilian thing.

 

 

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And missed at the duplicate inspection. I vaguely recall a serious military accident resulting from something like this.

 

 

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All our critical systems like flight controls, fuel system etc had 3 inspection sign offs. Tradesman, Progressive Inspector then lastly the Independent inspector.

 

Even with all of these safety steps in place nothing is infallible. But it is pretty close.

 

 

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Dear Mr Tomo , In regards to your recent post that bolt goes through and holds a counter weight with a Nyloc nut that bolt does not turn and should never have lock wire or any form of castle nut as suggested . If you have a concern it is far better to contact the manufacturer than have any form of advice from forums or advise you that could lead to the incorrect advice . Paul Goard

Thanks for that Paul, and I apologise if any harm was done by putting it on the forum. I was just curious to know how it was fitted and thought it was a good place to have a discussion. Which I think has been resolved and everyone is now the wiser to how they are built!

 

all the best

 

Tom

 

 

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