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How Does This Happen?

RoundTwo

By RoundTwo
in General Mooney Talk

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RoundTwo Mentor

RoundTwo

Posted
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Posted
  On 2/11/2023 at 12:21 AM, Fly Boomer said:

Are you asking about the paint, or the "sucked in" inspection covers?  I too have some inspection covers like those, so I'll be watching this space for answers.

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The covers. They look all beat to hell.

Guest

Guest

Posted
Posted

Unlike older generations of Mooney inspection cover, these are made with a backup ring which is riveted to the wing skin with pop style Alex rivets and the cover held on to the ring with screws.  Both the backup ring and cover are made of very soft aluminum alloy, they deform over many years of use.  It has as much to do with the alloy as it has to do with maintainers.  Older Mooney’s don’t suffer the same issues.

RoundTwo Mentor

RoundTwo

Posted
  • Author
Posted
  On 2/11/2023 at 12:58 AM, M20Doc said:

Unlike older generations of Mooney inspection cover, these are made with a backup ring which is riveted to the wing skin with pop style Alex rivets and the cover held on to the ring with screws.  Both the backup ring and cover are made of very soft aluminum alloy, they deform over many years of use.  It has as much to do with the alloy as it has to do with maintainers.  Older Mooney’s don’t suffer the same issues.

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Based on their current condition, is it feasible to replace the cover and backing ring with a stiffer material so they maintain their shape better?

1980Mooney Grand Master

1980Mooney

Posted
Posted
  On 2/11/2023 at 12:58 AM, M20Doc said:

Unlike older generations of Mooney inspection cover, these are made with a backup ring which is riveted to the wing skin with pop style Alex rivets and the cover held on to the ring with screws.  Both the backup ring and cover are made of very soft aluminum alloy, they deform over many years of use.  It has as much to do with the alloy as it has to do with maintainers.  Older Mooney’s don’t suffer the same issues.

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@RoundTwo Out of curiosity what model and vintage Mooney are we looking at? I don’t see it in your profile. As @M20Doc says I have never seen this in phenomena on an early ‘80’s mid-body. 

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Guest

Posted
Posted
  On 2/11/2023 at 1:06 AM, RoundTwo said:

Based on their current condition, is it feasible to replace the cover and backing ring with a stiffer material so they maintain their shape better?

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Yes you could make new ones with some basic sheet metal tools and skills.

0TreeLemur Grand Master

0TreeLemur

Posted
Posted

This is a great question.   On my '67C all the inspection panels looked like factory new.  Straight and flush.   On my '83J several of them look just like the ones in the photos above.  :angry: 

BTW- first time I've ever used that "pissed off" emoji on MS...

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1980Mooney Grand Master

1980Mooney

Posted
Posted (edited)
  On 2/11/2023 at 2:12 AM, M20Doc said:

The drain hole in the corner would suggest it isn’t.

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You are correct- that line of rivets aft of the panel is the front bulkhead for the main tank. If the seam on the bulkhead leaks avgas will find its way out that hole near the root and forward cavity in the wing. 

Edited by 1980Mooney
1980Mooney Grand Master

1980Mooney

Posted
Posted (edited)
  On 2/11/2023 at 3:03 AM, Steve0715 said:

Are these standard sizes?  They would be a nice project for a water jet cutter.

would these be OPP?  could they be made out of carbon fiber?  

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It looks like there are 4 different basic sizes and shapes.  However, there are a lot of differences within the same size/shape.  Look at all the different part numbers in your parts manual.  Sometimes the LH and RH wing application are slightly different with different part numbers. An example of RH and LH being different on early J models is #12 - which is in the panel in the picture with the weep hole.  It is just another thing adding complexity to an already complex wing  

wing.png.8efab9e424e9f18ac95932e31bed70d8.png

Edited by 1980Mooney
Austintatious Experienced

Austintatious

Posted
Posted

 have several the same way... they drive me nuts if I look at them too long.  Mine (84 M20K)  are held in by "pop" rivets.... I had an avionics shop give me a heart attack when they suggested this wasn't even legal and That I may have to have them all re done with screws and backings.

 

I would bet money if all mine were fixed I would gain 5 knots.  I'm tempted to try pulling them out with a car body suction cup.

Raymond J1 Rising Star

Raymond J1

Posted
Posted
  On 2/11/2023 at 3:03 AM, Steve0715 said:

Are these standard sizes?  They would be a nice project for a water jet cutter.

would these be OPP?  could they be made out of carbon fiber?  

Expand  

A sheet of duralumin, a compas, a ruler, a tracing point, a hand shear and you will have cut 5 or 6 inspection hatches before starting the waterjet cutting machine...
I agree that the old hatches are better designed and that the riveted rabbet on the hatch reinforces that... But it is at the expense of the skin of the wing that the screw heads tear.

Guest

Guest

Posted
Posted
  On 2/11/2023 at 5:00 AM, 1980Mooney said:

It looks like there are 4 different basic sizes and shapes.  However, there are a lot of differences within the same size/shape.  Look at all the different part numbers in your parts manual.  Sometimes the LH and RH wing application are slightly different with different part numbers. An example of RH and LH being different on early J models is #12 - which is in the panel in the picture with the weep hole.  It is just another thing adding complexity to an already complex wing  

wing.png.8efab9e424e9f18ac95932e31bed70d8.png

Expand  

There are indeed several different variations on the newer wings.  The oval ones come in screwed on with its backup ring and riveted on flush ones, rectangular screw on with backup ring and riveted on flush ones.

Guest

Guest

Posted
Posted
  On 2/12/2023 at 6:11 AM, Austintatious said:

 have several the same way... they drive me nuts if I look at them too long.  Mine (84 M20K)  are held in by "pop" rivets.... I had an avionics shop give me a heart attack when they suggested this wasn't even legal and That I may have to have them all re done with screws and backings.

 

I would bet money if all mine were fixed I would gain 5 knots.  I'm tempted to try pulling them out with a car body suction cup.

Expand  

I hope that you didn’t listen to them?

Guest

Guest

Posted
Posted
  On 2/12/2023 at 7:12 AM, Raymond J1 said:

A sheet of duralumin, a compas, a ruler, a tracing point, a hand shear and you will have cut 5 or 6 inspection hatches before starting the waterjet cutting machine...
I agree that the old hatches are better designed and that the riveted rabbet on the hatch reinforces that... But it is at the expense of the skin of the wing that the screw heads tear.

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The old one which are fitted from inside the wing are fine as long as you don’t drive the screws in with an electric drill.  

skykrawler Proficient

skykrawler

Posted
Posted

I think the inspection port covers near the wing root are a structural type.

The others held in with pop-rivets less so.  The problem is these screws are often over-tightened and then removing them requires excessive amounts for down pressure on the screw to break it loose which deforms the backing plate.  This is partly because of the aluminum/steel interface of the screw.    My first annual I had to drill out a half dozen of the screws because the heads were wrecked and they were over tight.     

The advantage of this type of installation is a flush fitting cover - until the've been buggered up.   The tabs on the backup ring can be reformed to return the cover to a flush position.   I keep spares of these screws and replace the screw at the first sign of head is getting wrecked.

Who knows the torque for AN509-8R6 screw?

 

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