Not sure of the correct term.
These are attached to the fuselage when there are small fatigue/corrosion cracks.
If the aircraft is re painted or has a C/D Check are these removed and a more permanent repair done?.
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Re: Patches/Re inforcing plates
I'm assuming you're talking about the doubler. As far as actually replacing it, I don't think they would. What would you really accomplish other than making it look like it's in one piece.
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- bennett123
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Re: Patches/Re inforcing plates
Sorry.
I think a Doubler is the word I was looking for.
I have a picture of a Southwest B737 with several doubler that I am trying to ID.
Based on your answer, if I found a later picture of the same aircraft, it would have the same doubler unless more had been added.
An aircraft without doublers could be ruled out.
I think a Doubler is the word I was looking for.
I have a picture of a Southwest B737 with several doubler that I am trying to ID.
Based on your answer, if I found a later picture of the same aircraft, it would have the same doubler unless more had been added.
An aircraft without doublers could be ruled out.
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- ArcticFlyer
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Re: Patches/Re inforcing plates
No the doublers do not get replaced and it is possible to stack more than one doubler in the same place.
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- ReverseFlow
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Re: Patches/Re inforcing plates
Aren't there also temporary doublers that would be permitted for x flight cycles until the next bigger check where something more permanent/better can be done?
Sort of end drill the crack, stick a doubler on and then repair properly when there's more time?
Sort of end drill the crack, stick a doubler on and then repair properly when there's more time?
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- bennett123
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Re: Patches/Re inforcing plates
ReverseFlow wrote:Aren't there also temporary doublers that would be permitted for x flight cycles until the next bigger check where something more permanent/better can be done?
Sort of end drill the crack, stick a doubler on and then repair properly when there's more time?
When the more permanent/better repair was done, would you be able to see that there had previously been a doubler?.
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- ReverseFlow
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Re: Patches/Re inforcing plates
bennett123 wrote:My comment was a question to others.ReverseFlow wrote:Aren't there also temporary doublers that would be permitted for x flight cycles until the next bigger check where something more permanent/better can be done?
Sort of end drill the crack, stick a doubler on and then repair properly when there's more time?
When the more permanent/better repair was done, would you be able to see that there had previously been a doubler?.
I vaguely remember hearing about such a thing many moons ago when I was doing a placement.
But what I have seen are internal doublers where you have the plate internally and a flush plate where the damage was.
https://blogger.googleusercontent.com/i ... 1/182.webp
Usually used when aerodynamics is affected.
So when painted over you will probably just notice it on the odd shape and fastners visible under the paint.
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- SteelChair
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Re: Patches/Re inforcing plates
This used to be done routinely. A basic scab patch was a basic repair that every mechanic in the USA was trained to do. Standard repairs are in AC43.13. And many airlines also have a bunch of standard repairs. Back in the day, the forward fuselage of DC9s looked like they had been repaired from machine gun damage in the area of the forward baggage bins (from so many carts hitting the airplanes). Never had a problem with one of them. Then, Aloha happened and the lightly built 737 opened up like a can opener. "Aging aircraft" regulations took over and such repairs are controlled much tighter now.
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- Wacker1000
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Re: Patches/Re inforcing plates
ReverseFlow wrote:Aren't there also temporary doublers that would be permitted for x flight cycles until the next bigger check where something more permanent/better can be done?
Sort of end drill the crack, stick a doubler on and then repair properly when there's more time?
You'll never stick a doubler over a crack in today's world and fly revenue service short of being in a third world country with relaxed safety standards. You always cut out the damage to eliminate the chance of it propagating and causing a larger failure.
ArcticFlyer wrote:it is possible to stack more than one doubler in the same place.
Technically no since more than one doubler would be a doubler/tripler repair.
Whether the doubler remains on forever depends on whether it is a premature, interim, or temporary repair. From the time it is installed, a temporary repair has to be removed after a certain number of flights. An interim repair in theory could be on the aircraft forever but it has to be repetitively inspected. If there is a finding, it will then be removed and a new repair will be accomplished. Permanent repairs are becoming increasingly rare since most primary structure has some sort of fatigue requirement.
Re: Patches/Re inforcing plates
There are rules as to the relative spacing of adjacent doublers. If you have a single one installed and there is a nearby damage requiring another repair, you may have to remove the first one and make a single larger one. I've also seen at major checks entire skin sections replaced due to having a large number of repair doublers. This was really common on the 727 belly skins.
I worked structures for many years and very rarely did an internal repair. They did happen but usually only in the area around the static ports, where aerodynamic smoothness was a huge requirement.
We did change out temp repairs during a C or HMV check. The temps are usually installed with blind fasteners that don't require access to the inside of the structure. The temp fasteners typically have a repetitive 200-500 hr inspection until major check when the aircraft interior can be accessed. Many times we would cut out the entire area of the temp and install a large doubler over the entire area. This sounds crazy but reusing the temp fastener holes is usually not an option. Many times the new fasteners called out for high tolerance fit holes. That was the only way to get a repair that only needed to be visually inspected at the next C Check.
As for adding a repair over a repair, no it is not allowed. Whenever you see stacked repairs they are a single repair from the beginning. The 737 Jurassic and Classics typically had doupler/tripler repairs at the door cutout corners. That was the only way to get the strength required in those areas.
I worked structures for many years and very rarely did an internal repair. They did happen but usually only in the area around the static ports, where aerodynamic smoothness was a huge requirement.
We did change out temp repairs during a C or HMV check. The temps are usually installed with blind fasteners that don't require access to the inside of the structure. The temp fasteners typically have a repetitive 200-500 hr inspection until major check when the aircraft interior can be accessed. Many times we would cut out the entire area of the temp and install a large doubler over the entire area. This sounds crazy but reusing the temp fastener holes is usually not an option. Many times the new fasteners called out for high tolerance fit holes. That was the only way to get a repair that only needed to be visually inspected at the next C Check.
As for adding a repair over a repair, no it is not allowed. Whenever you see stacked repairs they are a single repair from the beginning. The 737 Jurassic and Classics typically had doupler/tripler repairs at the door cutout corners. That was the only way to get the strength required in those areas.
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