Certainly balancing flight controls is important, and and assuring that balance after new paint equally important. Generally a metal airplane strip and paint has a pretty good chance of not fussing it up, but it still needs to be checked – that is a maintenance activity, as there is no provision to declare the airplane airworthy with flight controls which do not conform to the manufacturer’s required balance limits. It’s a design change if you seek, and receive approval for different balancing limits. I have issued two such approvals over the years, both in cases where the original service manual was so poorly worded/thought out, that conforming balancing after appropriate painting was not possible. In one of those cases (a very early meal Cessna), balance was required, and the maximum mass of balance weight prescribed. The problem was, as the paint shop showed me, that the flight control wound not even balance with the maximum balance mass with no paint! Further research revealed that Cessna built that (and other) flight controls with differing skin thicknesses (so weights), but did not account for this possible difference in appropriate balancing instructions.
If your airplane is being painted, your maintenance shop must be involved. As they are, they should know what the correct practices will be – without making the event a design change!
I find myself agreeing with Pilot_DAR, the document is badly written and some on here are putting the most restrictive interpretation on a poor document and the resulting conclusions are unworkable.
Over the years I have seen a lot of re-finished aircraft the usual shortcomings being the lack of mandatory placards and control surfaces that have clearly not been balanced.
The average metal aircraft paint job is not too bad and some ( like Mick Allen ) would produce superb work . However the real problems start when composite aircraft are involved, removing the old paint is troublesome as chemical strippers are likely to damage the structure and re-balancing of the flying controls is so critical that only small changes to the weight of the control surfaces may put them out of balance limits.
The biggest paint fail I have seen was a two seat training glider that emerged from the paint shop looking superb with an almost glass like finish however when they put it on the load cells for the weight & balance it was found that so much paint ( weight ) had been added to the glider it could only fly with one pilot.
There must be more to it.
My maintenance shop recently had a visit from the Croatian CAA to check on the naintenance procedures and all – because there is a Robin registered in Croatia which is based and maintained there.
Was apparently constructive and fair, thus much better than the LBA audits :-) , but nonetheless…
Peter wrote:
particularly if foreign registered airplanes are concerned.They should be outside the local CAA’s jurisdiction, no?
Well, no, it is not. If a plane registered in EASA country A has some work done in a shop supervised by EASA country B, then it is very much the jurisdiction of B’s CAA that the shop makes the work in accordance with regulations! That’s only logical, among all CAA, it is B’s CAA is in the best position to inspect the shop, rather than A’s CAA which would have to travel out. And imagine the poor shop having to undergo inspections from 31 CAAs! That would completely destroy the EU+EFTA-wide “free trade” of maintenance!
Peter wrote:
Flutter is something which occurs on the control surface itself – it is a very local resonance
It’s a resonance/lock-in phenomenon due to aerodynamic forces combined with weight, CG and the elasticity of the control linkages. Making the linkage stiff enough will prevent it. But this is close to impossible with long cables or push rods. Play will for sure trig flutter, if it’s large enough. It’s not the power of the hydraulic that prevents flutter, it’s the removal of long (and elastic) control linkage.
Peter wrote:
or is ar*se-covering
That’s one of the main problems with all of EASA regs and the way they are supposed to be implemented. It’s a truly perverted system built around the idea that as long as you cannot be blamed, all is OK. Somewhat understandable, but it looses sight of the fact that in the end, reality is always right and reality is what counts. It also causes a “interesting” culture.
Flutter is something which occurs on the control surface itself – it is a very local resonance. Having minimal play in the control linkage and in the control surface bearings suppresses the onset of flutter but it will still “try it”. So having lots of power in the hydraulics may not help.
However this is not related to the Q of paintwork needing a design approval (which AIUI is a Part 21 job and very expensive).
I think this is potential bad news because revenue generation within the Part M business will latch onto anything. All the time I see people grounded for months because they are waiting for some part, while an obviously perfectly serviceable part is readily available but without the right (or any) paperwork. On an N-reg that would simply not happen (unless the N-reg is maintained by a Part M company and “their” A&P is also clueless or is ar*se-covering).
Mooney_Driver wrote:
were done with i.e. the control surfaces in place
On many homebuilts it’s of main importance to keep the control surfaces as light as possible. Any painting must be done before balancing. On faster aircraft the ailerons and/or elevator (typically) must be balanced to prevent flutter. This of course means that any re-painting requires re-balancing. I don’t think the average car painter knows about this, yet alone how to do proper balancing. On an airliner with hydraulic actuators and much heavier construction, I’m not sure if this is even an issue.
Well….. Maybe this did not originate in English: “Changes to Type Certificate” are what the type certificate holder (but no one else) may request of the authority to define a changed type design. So… “Changes to a type design” are what could be undertaken by the design approval holder by Type Certificate change, or anyone else by application for an STC.
Could an “External livery change” be a change to the type design? Well… if the change is outside the approved – and defined – design of the aircraft, than yes. Otherwise, no.
If an airplane type design specifies a placard or marking, maintaining it airworthy, including replacing it if required, is not a change to the type design, unless you change what it says, which yes, would require a design approval. If you put the same words back where they are required, what you did is called “maintenance”, even if it’s after a new paint job!
If you’re introducing a corrosion initiator to an aircraft, you’re dumb, and it’s still not a change to the type design, it’s just a dumb thing to do to a plane!
If a composite airplane has specific external coating limitations, requirements, colours, than yes, repainting to the contrary would be a change to the type design, which requires approval. But, if you follow the aircraft manufacturer’s recommended practice for painting/decalling, it’s not a design change. If a colour is not specified, you can paint it any colour you like (but yes, some airplane manufacturers do specify a colour, so you di have to use that colour). That said, there is a requirement for colour contrast for registration markings, but that’s contrast, not specific colour limitation. If the airplane has adhesive film, and it corrodes underneath, the resolution of that is “maintenance”.
If you’re painting an airplane, and you have affected the static port, you have introduced a maintenance defect (unless you deliberately changed the static port – why?). A maintenance defect is not a design change, it’s just a defect which requires rectification. If you make a change which reduces the inspectability of the airplane, yes, I could argue that up to needing an STC, but why!?!, just undo the error in thinking on that, and make sure inspection and defected detection is at least as easy as it was before…
This advisory material is weak and misleading, which is unusual for EASA, they usually think things out better than that!
Mooney_Driver wrote:
Given that a total respray of an airplane can cost easily 30k or more, it certainly is interesting to find that some shops can offer it for 4-5k. Clearly there must be a difference in what they do which is more than just the fact that labour costs are a sight cheaper.
asked google about the average salary for Switzerland and Poland. It’s respectively 78k and 20k CHF per annum
therefore If a paint job in Switzerland costs 30k than the same process with the same materials done in Poland should be what? 10K?
Bottom line is that doing something in “the east” will be a lot cheaper than in “the west” not because it’s of inferior quality but because of the above mentioned difference
particularly if foreign registered airplanes are concerned.
They should be outside the local CAA’s jurisdiction, no?
Quite a few of those cheap paint jobs were done with i.e. the control surfaces in place rather than having them taken off to be done properly, which may cause damage or improper sealing e.t.c.
Sure, but this has been done quite a lot (control surfaces attached, etc). I could not understand how… A big thing is paint stripping around rivets; this can take a huge amount of time. “Threads possibly related to this one” below have good stuff in them. But I don’t think this is a regulatory issue; the CAA doesn’t care if the job is crap so long as the paperwork is right (IF paperwork is needed!).
I suspect this reg will be misapplied and will cause lots of people lots of hassle, particularly if changing maintenance companies which is where stuff tends to be picked up (same principle as changing AMEs – always suspicious 
).
