A restoration doubt…

[Sean Curtiss]

One doubt I have when restoring an aircraft is how far you must go to be faithful to the factories original blueprints. In the end what matters is what the public sees of the outside of an aircraft or does the inside also counts? Some flying aircraft have modified cockpits, i.e., some have new avionics otherwise they wouldn’t be safe or have FAA approval to fly. For a static plane, replacing some types of gauges for others affects the fidelity based on the original blueprint? I may think that for the lack of options, some restorers put similar gauges in place. For example, if I wanted to assemble an instrument panel and didn’t find a particular gauge, could I substitute it with a similar one with the same function, but with different markings? Would that still validate my project? I know that this may sound a bit too vague, but…

It’s like something this:



Cheers,
SC.

[RNDMTRS4EVR]

I would say it is better to have something there than nothing at all. But if you cannot find an orginal you have to make do. Another thing you can think of is this; when aircraft were out in the field or say in service, mechanics did not always have all of the orginal parts on hand so they had to make do with what they could get. I'm sure some where along the line in WWII a fighter, bomber, or transport may have had a gauge in there that was not off the factory blueprint. just my 2 cents.....
Scott......

[51fixer]

On a variety of parts they were built to a spec, say AN. There could be several different manufactures who made that part, each would look different but fulfill the requirement. So you might have different instruments in the same type of aircraft as they left the production line. They all met the requirement of what ever spec.
In terms of instruments, today you have issues with the radium that was used on the faces and needles. You will probably not be able to match exactly to an original due to that.
Rich

[T33driver]

On another authenticity front, when I was researching the original markings for my T-33, I referenced a tech order diagram that showed guidance/measurements for markings placement. What I found in looking at different photos of T-33s is the placement of standard Federal Identification Program markings was slightly different on every aircraft. Apparently the maintenance troops took liberties in their application, using a more more convenient method than taking multiple measurements--like referencing their placement on nearby panel lines, rivet rows or whatever. It's proof that whatever guidance or data the factory or military manuals offer, the guys in the field often improvised and redefined for restorers what was "authentic". In the end, I placed my Canadian AF markings as close as I could to actual photos of my airplane and when certain areas of the airplane weren't visible in the photo (top/bottom of wings), I followed the tech order.

[Jet Mech]

How far back to factory depends on how many field mods were done in the lifetime of the airframe.

In WWII many field mods were incorparated into the production line. Just like the nose turret on B-24's.

In jet age, the F-105Gs were post production mods on the existing F models to make them True Wild Weasels.

The KC-135 were all built as A's and now they flying as R's. So you can research what happened to your series of airframe, and restore to the point in history which fits your abilities to reach.

[bdk]

I've seen plenty of static displays (especially instrument panel displays) where the gauge face was a color photocopy. Most observers wouldn't notice. The instrument core itself is generally of low value (unless you are talking about a German or Japanese instrument) so I don't see it as a big detractor.

[tom d. friedman]

i'm for originality, but the wallet dictates practicality. as for vintage instruments w/ radium, your tv produces more radiation. there are now "radium sanitized instruments" on the market, how do they do it.... no clue is it legit?? no clue. but it's candy for the mind to hear that claim if you are buying. their are numerous memorabilia sellers that are touting these as safe. i don't doubt it, but it's a gimmick nonetheless.

[Forgotten Field]

Two problems with instruments of that vintage:

1. Overhaulable
2. Somebody who can actually overhaul it.

BTW, I have a tachometer just like the one pictured (original)

[JDK]

Hi Sean,
You've asked a good question there, and got some great answers. If I may add a bit... As usual, there's a lot of 'it depends', and I'm not clear what type of museum and whose aircraft we are talking about, but that's never stopped me before.

One doubt I have when restoring an aircraft is how far you must go to be faithful to the factories original blueprints.

As has been touched on, the original blueprints are an indication of how it should have been, rather than necessarily being how it actually was. Generally a museum won't be aiming for restoring an aircraft to 'factory drawings' but to as original as possible, where factory drawings are a great guide, but not the objective themselves. Paul's comment on the T33 are a great illustration of this.

In the end what matters is what the public sees of the outside of an aircraft or does the inside also counts?

Depends on the museum's objective. For the highest standard, and assuming we aren't talking an active or airworthy aircraft, the 'plane is regarded as an artefact, which can be used as a research tool to show how it really was in use. Therefore original parts and paint should be kept as far as possible, any damaged or degraded parts stabilised rather than replaced (as far as possible) any parts replaced with as original parts as are obtainable, but these should be marked as replacement, not original to that airframe, and any parts replaced with dummies (such as colour copies) likewise marked as such. This is 'conservation' rather than 'restoration'. The superficial view (e.g. a look at the cockpit) should ideally look as 'original' as possible, but documentation of discrete tags should show the status of those parts - which is why documentation is important.

Some flying aircraft have modified cockpits, i.e., some have new avionics otherwise they wouldn’t be safe or have FAA approval to fly.

When dealing with active aircraft, obviously there have to be compromised for certification and safety, and items like new wiring and cables, to modern rather than period standards are obvious. However replication of the original 'look' is moving ahead all the time, with the recent wiring in Ron Fagan's (?) P-40 restoration for instance. An airworthy aircraft isn't able to achieve the highest standard of originality for that airframe, but it fulfils another important role of demonstration. Which is why we need, and have both fliers and top quality static restorations. However, there's no such thing as 'just like the original' or that contradiction in terms 'better than original'. It's either original, or not. Any replication will fail some tests of originality, and could mislead future students of how that original aircraft was really made.

For a static plane, replacing some types of gauges for others affects the fidelity based on the original blueprint? I may think that for the lack of options, some restorers put similar gauges in place. For example, if I wanted to assemble an instrument panel and didn’t find a particular gauge, could I substitute it with a similar one with the same function, but with different markings? Would that still validate my project? I know that this may sound a bit too vague, but…

If it's your project, it's validity is up to you. (The only issue I can think of is if you misrepresent something for sale, knowing it's not actually original.) You set and achieve the standard that matters to you. If it's a group museum, then it's a good idea to have an agreed standards and objectives document or statement, so everyone agrees and aims for the same thing - for instance, lookalike semi-scale aircraft are great, provided they aren't mis-represented as original.

For national museums, or state owned aircraft, national museum standards should be set and achieved and documented.

A great book on this area is Robert Mikesh's 'Restoring Museum Aircraft'. Recommended.

Just some thoughts, don't know if it helps much!

[JDK]

Just a *bump* as someone hadn't seen the latter posts.