View Full Version : How hard is it to restore an aircraft?

9th Oct 2004, 22:00
Please excuse my ignorance: this is a genuine question.

I have restored a few cars in my time, and know various things you can and cannot do.

But when I walk around aircrft museums I often wonder how difficult would it be to take a static aircraft and return it to flying condition??

As an example, lets take an old warbird, complete with old engine. Given enough man-hours, how difficult can it be to return it to flying status??

I mean, and engine is an engine and an engine rebuild is surely just an engine rebuild. Ditto chassis/ airframe.

Rather then a MOT, get the CAA to check on workmanship, but a wing is simply a collection of almuinum pieces which needs to be repaired or replaced- long winded and time consuming, yes. But I cannot see where this is complicated or expensive, or where a specialist is required. I could take a wing apart, clean all pieces, repair/ replace if necessary then put back together again. From what I have seen, it seems very stratight forward. Just time consuming.

What I am trying to say is: why aren't all the aircraft at somewhere like Duxford in flying condition? Why restore to 100% accuracy, just for display purposes?

You would certainly not bother with a car- not unless they were going to be driven at some point.

Again, please excuse my ignorance: a genuine question!

Genghis the Engineer
9th Oct 2004, 22:23
From my own experience which is two major rebuilds of private crashed aeroplanes, I'd say potentially rather longer than building one from scratch.

Every part must be treated as suspect, huge amounts of bonding, painting, etc. to be removed and redone (much harder than doing from new). Far greater depth and rigour of inspection and NDT than I'd expect on newly made parts.

You have really got to want that aeroplane. Speaking for myself, although I learned a huge amount from both rebuilds - I'd rather build one from plans (probably including designing it as well) than do a rebuild again.

Costwise - it depends upon how you count the man-hours. At what I normally charge for my time, both those rebuilds cost considerably more than buying a near-perfect second hand aeroplane of the same type.


10th Oct 2004, 07:52
Ghengis has pretty much hit the nail on the head here:

Every part must be treated as suspect, huge amounts of bonding, painting, etc. to be removed and redone (much harder than doing from new). Far greater depth and rigour of inspection and NDT than I'd expect on newly made parts.

So for a warbird, lets say a Vampire 1950's jet, to get to flying status
Wooden Fuselage, depending on how the a/c has been stored, has the wood rotted? If so how much? Has it/is it, delaminating? is it still possible to get a similar type of wood and treated appropriately that can do the job. If not where do you get it? Whom can supply the relatively small batch you'd need. Assuming yes, who can do the repair to a required standard?
Aluminium/Alloy wings, How much corrosion has occurred? If taking a panel off and it fails inspection, where do you get the correct spec material from to replace it? When it arrives who has the skill to cut/form/treat the metal to the final spec?.
Okay now we're on the wings, get the rubber fuel cells out, have they perrished?, if so who can make new ones?, same for the tyres, where do you get stock for a 50 yr old aircraft. Some Mfg people can make batches for operators, but the small production runs and design process can make them very expensive indeed. Hydraulics/electrics are similar, a key element is that aircraft are not built in the same number that road vehicles generally are, so you cannot get the interchangeability that you may get with the benefit of similar road vehicles. Instrumentation/transparencies, finding stock or remanufacturing is a real challege. An area lacking in aviation nowadays is engineering skills, I think the average age of an aircraft engineer is well into his 40's. There are very few people with the appropriate skills nowadays, so if you're not doing everything yourself, you'll have to potentially pay the going rate. Arguably for road vehicles you could change materials without too much problem. with an aircraft it not possible or needs certifying. What a lot of what you pay for is the skill, and somewhere to do it, (hangers aren't cheap).

11th Oct 2004, 04:10
Well lets see...

Planning to restore a DC6.

We need,
4 propellors to be overhauled
4 pressure carburators overhauled
Fuel cells replaced (a ten tanker...so we have six rubber cells)
Outer wing attach fittings to be replaced
Fuselage crown skin repairs (figure 400 man hours...if we're lucky)
Landing gear overhaul
Engine accessory items overhauled

Well, the list goes on....and on.

Still, in the end, a very nice aeroplane...in fact the finest 4 (piston) engine aeroplane ever produced.

Donald Douglas (Sr) got it right...even if Jr (recently deceased) was a pain.

Sudden thought...the 1649 Constellation wasn't bad either.
Flew 'em both.
Superb machines.

11th Oct 2004, 07:42
411A - do you reckon the DC6 was better than the DC7C? That seems to have been pretty successful as the last of the big props. Long before my time, but an ex-colleague flew them with BOAC and the lifestyle they had back then was something which modern airliner drivers could only dream about!

Or were those massive engines just too complicated to be sufficiently reliable?

Orange Arm Waver
11th Oct 2004, 07:56
Don't forget that your materials must be of airworthy standard and all paperwork must be kept for an audit trail if you want it to fly.
IIRC I was told of the DC-3/C-47 that was painted in D-Day colours and ferried to Coventry years ago had to be scrapped because there was no paper trail to confirm the materials used in the restoration / repair prior to arrival at Coventry were of the correct standard for airworthiness and such no ticket would be issued...

11th Oct 2004, 07:57

The DC-6 is widely regarded as the best of the propliners becuase of its relative realiability and very good economics. The straight DC-7 was also said to be a good aeroplane but was beginning to suffer from the complexity of its engines: the power recovery turbine idea seemed a bit like trying to get something for nothing. The DC-7C was a towering acheivement but really pushed the engines to the limit. I've heard it said by someone who flew all marks of Seven that the C was just a bit too big for the available power.

I've also heard that the engines were routinely run at high cruise power to meet the expectations of a travelling public with its eyes on the jets. Finally, with the high octane fuel these engines were designed to run on becoming unavailable, the really big turbo-compounds can no longer be used as intended, rendering the final propliners unworkable. Carlos Gomez would disagree with me (and more power to him - I hope his 7B is a great success for him).

11th Oct 2004, 08:07
Thanks for that!

I wonder what it was like to have all that thrashing ironmongery running at high power all the way across the Pond....?? Must have made a wonderful noise though!

11th Oct 2004, 14:58

The 1649 Constellation (same engines as the DC7 series) was a delight to fly, and was a bit faster that the DC7.
The engines, operated at normal cruise power, had a very delightful sound, and as they were mounted rather far outboard, were quieter than the DC6.
310 KTAS was not uncommon.
When 115/145 avgas disappeared, so did these aircraft, as they had to be operated in low blower only...and autorich, with lower octane fuel.
The power recovery turbines were a good idea, but tended to overheat, and as a result, had a rather short MTBF.

11th Oct 2004, 15:33
310KTAS - not bad at all!

High Octane aviation gasoline seems to have been a very efficient fuel, as I understand that some very impressive payload/range figures were obtained with those turbo-compound engines when used as the designers had intended.

Lucky you to have flown the Constellation and DC6! Aviation must have been a lot more glamorous then than it is now. The aeroplanes certainly were.

11th Oct 2004, 17:23
Back to the original question...

Taking warbirds, the principles and logic of the rebuilds are very simple - hell, even I could sketch out a Spitfire wing construction, and I'm just a journo; but the right materials, certified and rebuilt in the correct jigs... That's alongside Genghis' remarks on the other hand!

The most telling remark is the old saw about 'when the weight of paper = the weight of the a/c you can fly it'...

For a more detailled answser, most of the vintage aviation magazines carry rebuild stories regularly. I can't provide a comparitave choice of these as it's :mad: here. Happy to discuss by PM though.

Otherwise, Williamp, just have a chat with one of the chaps in Hanger 2 at Duxford, or any other organisatiion - they'll be happy to discuss (as a rule) provided you take the open approach you have here. "Why are you so slow?" doen't go down so well... :D


13th Oct 2004, 07:29
Myself and a couple of mates were planning on acquiring a 3/4 scale Spitfire replica that has been in bits for a while in France. After reading some other posts on the Key Forums about restoring a PA28, I thought better of it, and although we could still bring the thing back and get it up to static condition, to get air beneath the wheels would be much more daunting.

I'll build my Spit from plans - or have someone design me something that is a bit easier to build than the Isaacs Spit, like the one HERE (http://home.cogeco.ca/~mockflying/spitfire.htm)

Just my 2p worth...

Genghis the Engineer
13th Oct 2004, 09:21
Be very careful of replicas for a different reason. The UK has a very rigorous system of approvals for all aircraft designs, and replicas are no exception. Unless you are a retired airworthiness engineer looking for a challenge, don't even think of buying something abroad without ensuring it has UK approval already, and PFA (/CAA / BMAA) will be happy with getting a permit to fly on that individual airframe.

Unless, as you say, it's for static display only - like that gorgeous SE5a replica hanging in the shopping mall in Farnborough !


13th Oct 2004, 11:19
We were fairly fortunate - this one had been a PFA project, and had flown for a few years in the UK before the owner had flown it to France. It was in bits (although mostly complete) when I was offered it (and a Lycoming O-235), but I think the cost of rebuilding it to fly would have been equal to the cost of scratch-building one (maybe two) Isaacs Spits!!

I'd spoken to someone at the PFA about it, and he had offered to look out the necessary paperwork on it when we got it back to the UK.

However, I am looking for someone who might be able to help with the smaller replica..!!

Genghis the Engineer
13th Oct 2004, 11:40
Looks rather cute, do you have any specs for it?


13th Oct 2004, 11:53
I can tell you that the fuselage used to be a Taylor Titch... ;)

Here's what I have from my bumf:

60% scale Spitfire MkXIV

Wingspan - 21ft. 6in.
Wing area - 74.sq.ft.
Length - 17ft. 5in.
Height - 4ft. 5in.
Wing loading - 12lb./sq.ft.
Power loading - 13.57lb./hp.
Load factor - +/-6G
Empty weight - 606lb.
Gross weight - 950lb.
Never-exceed speed - 200mph
Stall - 45mph
Climb rate - 500fpm @ 75mph
Cruising speed - 115-120mph @ 2300-2400rpm

(note: This isn\'t the Isaacs Spit. I like this one because it has a 3-piece wing, and is a lot lighter and almost as fast for less power)

Mr Proachpoint
14th Oct 2004, 11:37
I'd pay money (lots of) to fly in an aircraft that guzzles high octane gasoline like a student 21st party, spits the remnants on a turbine in the hope to get more power from a 2 tonne engine in company with 3 others to propel a pretty polished aluminium airliner through todays dull traffic lanes.


14th Oct 2004, 11:58
Me too - I harbour a hopefully-to-be-fullfilled-one-day ambition to take a ride in a Connie, any of the DC-propliners, etc...

Rabbit, the replica that ended up in France - was that a Jurca?

14th Oct 2004, 12:26
No, it was an O-D job, built by an ex-BOAC pilot, registered as G-KUKU...

14th Oct 2004, 12:32
Blimey, I remember that, the Pfalzkuku! Saw it at Blackbushe once... many many years ago (still got the anorak!)

14th Oct 2004, 13:14
That's the one! Currently in bits in a hangar in France.