Wing spar repair

[Alan Fox]

Taking on an interesting project .. Having to replace the left forward lower spar cap ,  It is a piece of aluminum angle , 3/4  x 3/4 by probably 1/8 thick , It is straight , and about 59 inches long ..  We are going to replace it by deriveting it , removing two outboard ribs , and sliding it out (outboard and through an inspection panel )  , has anyone ever donr this job ?  planning on about 60 hours work...  Any advise or info would be great...  No we are not sending it outside , we repair planes....   The corrosion is at the spot where the Steel splice plates are at the second lap joint , Seems to originate from the huck bolts....

[LANCECASPER]

31 minutes ago, Alan Fox said:

Taking on an interesting project .. Having to replace the left forward lower spar cap ,  It is a piece of aluminum angle , 3/4  x 3/4 by probably 1/8 thick , It is straight , and about 59 inches long ..  We are going to replace it by deriveting it , removing two outboard ribs , and sliding it out (outboard and through an inspection panel )  , has anyone ever donr this job ?  planning on about 60 hours work...  Any advise or info would be great...  No we are not sending it outside , we repair planes....   The corrosion is at the spot where the Steel splice plates are at the second lap joint , Seems to originate from the huck bolts....

I'm sure more shops than I'm aware of have done this, but the only ones I know of that have done it are Dugosh in Kerrville, Dave Mathiesen up in NE USA and Don Maxwell in Texas. I think 60 hours may be a little light (unless you're using a Sawz-All ). 

From personal experience on much smaller things, David Behrens at Dugosh and Don Maxwell are usually very good about taking a phone call and sharing information.

[Alan Fox]

13 minutes ago, LANCECASPER said:

I'm sure more shops than I'm aware of have done this, but the only ones I know of that have done it are Dugosh in Kerrville, Dave Mathiesen up in NE USA and Don Maxwell in Texas. I think 60 hours may be a little light (unless you're using a Sawz-All ). 

From personal experience on much smaller things, David Behrens at Dugosh and Don Maxwell are usually very good about taking a phone call and sharing information.

I am no stranger to the sawzall , But this looks like it can be done without deskinning the wing , I have seen Mathissien deskin and replace sparcaps on Erics plane , with the wing on the plane , Jigged to the floor with wooden sawhorses...   Very impressive...

 

[Fly Boomer]

12 hours ago, Alan Fox said:

Taking on an interesting project .. Having to replace the left forward lower spar cap ,  It is a piece of aluminum angle , 3/4  x 3/4 by probably 1/8 thick , It is straight , and about 59 inches long ..  We are going to replace it by deriveting it , removing two outboard ribs , and sliding it out (outboard and through an inspection panel )  , has anyone ever donr this job ?  planning on about 60 hours work...  Any advise or info would be great...  No we are not sending it outside , we repair planes....   The corrosion is at the spot where the Steel splice plates are at the second lap joint , Seems to originate from the huck bolts....

Progress reports and pictures would be appreciated.  I've seen a de-skinned wing being worked on at Maxwell, but this is the first I have heard of your process.  Hope it goes as planned.

[MikeOH]

Dumb question:  Is there sufficient access to buck all those rivets that were drilled out with all the skins still in place?

[Alan Fox]

40 minutes ago, MikeOH said:

Dumb question:  Is there sufficient access to buck all those rivets that were drilled out with all the skins still in place?

Yes , also a large number of them are huck bolts , so will be easier than bucking , using HI-LOCS to replace them , Obviously the lowers rivet to the skin...  

[A64Pilot]

Not a Mooney, but I’ve participated in replacing many Crop Duster lower spar caps. (They time out at 5400 hours.) on the old aircraft.

Once the cap is removed find a way to exactly index a piece of strap or angle, then transfer the holes to it from the original cap, then use the piece of strap or angle as a drill guide to transfer the holes to the new cap.

This may help some. Ideally you want a transfer punch, that’s a punch that’s exactly the same size of the hole with of course a centering point, it precisely marks the exact center, transferring the holes starts at #4 in the attached document. You’ll be surprised at how precisely you can transfer the holes, as you drill holes temp install some fasteners to keep precise alignment for drilling

https://thrushaircraft.com/support/technical-publications/Custom Kits/ckag40-revision-a WING SPAR UPGRADE.pdf

Use a drill press to ensure every hole is exactly straight.

Shoot the heck bolts wet with epoxy primer, this prevents any water ingress and I believe prevents future corrosion.

[1980Mooney]

@redbaron1982 has posted multiple times that he had Don Maxwell replace the right stub spar cap during 2022-23.  Not sure if that is the same spar cap as you are contemplating.  Based on the months he said it was at Maxwell’s and the price he has quoted here on MS, it was way, way more than 60 hours. 
 

Considering the angst he has posted on line several times, I suspect that he would share details with you. 

 

[redbaron1982]

I don't have much to add about this, just a few data points:

• Original estimate given by Don was 13k, he ended up sending me an invoice for 28k.
• Original time estimate given by Don was 2 to 3 weeks, but it took over 40 weeks to have the airplane ready.

[1980Mooney]

15 minutes ago, redbaron1982 said:

I don't have much to add about this, just a few data points:

• Original estimate given by Don was 13k, he ended up sending me an invoice for 28k.
• Original time estimate given by Don was 2 to 3 weeks, but it took over 40 weeks to have the airplane ready.

How many shop hours were quoted and how many were billed?  @Alan Fox is estimating 60 hours. 

[redbaron1982]

5 minutes ago, 1980Mooney said:

How many shop hours were quoted and how many were billed?  @Alan Fox is estimating 60 hours. 

Quoted I don't remember exactly, billed 196hrs + painting (which was a flat rate, not detailed how many hours/materials).

[LANCECASPER]

1 hour ago, redbaron1982 said:

I don't have much to add about this, just a few data points:

• Original estimate given by Don was 13k, he ended up sending me an invoice for 28k.
• Original time estimate given by Don was 2 to 3 weeks, but it took over 40 weeks to have the airplane ready.

How much of that delay was in getting a new stub from Mooney?

[redbaron1982]

7 minutes ago, LANCECASPER said:

How much of that delay was in getting a new stub from Mooney?

roughly 20 weeks.

[Guest]

2 hours ago, redbaron1982 said:

I don't have much to add about this, just a few data points:

• Original estimate given by Don was 13k, he ended up sending me an invoice for 28k.
• Original time estimate given by Don was 2 to 3 weeks, but it took over 40 weeks to have the airplane ready.

Guessing that the bloom is off the rose!

[Guest]

2 hours ago, 1980Mooney said:

How many shop hours were quoted and how many were billed?  @Alan Fox is estimating 60 hours. 

I think Alan is doing the main spar outer section 

[EricJ]

On 4/23/2023 at 5:44 AM, Alan Fox said:

I am no stranger to the sawzall , But this looks like it can be done without deskinning the wing , I have seen Mathissien deskin and replace sparcaps on Erics plane , with the wing on the plane , Jigged to the floor with wooden sawhorses...   Very impressive...

Take pics and post them!   If your trick works it'll be interesting to see and could help keep some other airplanes flying.

[Alan Fox]

The empty holes are huck bolts , that have been removed , We have found it easier to drill and break off the heads , as opposed to splitting the collars , once the heads are broken off , they punch out with ease... You will see on that we ground out , but it took forever , and it was surprisingly easy , to drill into the hucks...   A64Pilot  , great Idea for making a drilling jig , out of aluminum stock , we werte going to cut the the bottom of the L channel off to match drill it , but your Idea , is better , as far as the skin goes , when the holes for the web side are done , we will bolt it in , and match drill the skin...  As far as parts go , the corroded piece appears to be a 3/4 inch piece of 7075T6 angle , so no parts downtime....

[Alan Fox]

Removed it , about 30 hours in , no skin removed... Spar on floor..

[hammdo]

Wow, nice job Alan!

-Don

[EricJ]

Nicely done!   Was hoping for a pic of it coming out the inspection plate.

Def post pics of the replacement.   Good stuff.

[Fly Boomer]

1 hour ago, Alan Fox said:

Removed it , about 30 hours in , no skin removed... Spar on floor..

Seems pretty fast compared to peeling back the skin, and then putting it back in place.  Looking forward to the replacement and reassembly pics.

[Alan Fox]

18 hours ago, EricJ said:

Nicely done!   Was hoping for a pic of it coming out the inspection plate.

Def post pics of the replacement.   Good stuff.

I am mostly supervising an A&P on this one , I came in yesterday and it was on the floor....

[chriscalandro]

On 4/24/2023 at 7:01 AM, redbaron1982 said:

I don't have much to add about this, just a few data points:

• Original estimate given by Don was 13k, he ended up sending me an invoice for 28k.
• Original time estimate given by Don was 2 to 3 weeks, but it took over 40 weeks to have the airplane ready.

The amount of pissed off I would be if this were me is not measurable in human readable metrics. 

[Alan Fox]

6 hours ago, chriscalandro said:

The amount of pissed off I would be if this were me is not measurable in human readable metrics. 

Couple of things to consider Chris, they may have replaced more than this one piece , And the Job isn't finished yet....

[chriscalandro]

11 hours ago, Alan Fox said:

Couple of things to consider Chris, they may have replaced more than this one piece , And the Job isn't finished yet....

But at some point in the other guys example it would have become clear that replacing the wing was far more economical. 
 

to go from a reasonable 13k to more than double 28k, plus the extra time?