Least resource intensive/easy to maintain aircraft of WW2?

[MikeMeech]

And Mike, this is all good when addressing REPAIRS, especially when dealing with aircraft being flown in combat which is obvious. It's also evident that some scheduled maintenance will be undertaken at this time. The amount of time and effort it takes for repairs will obviously vary between aircraft and units. For example, I can have a training unit of 12 Spitfires of which 10 are flying at any given time and are just used for training, then I have another squadron of the same number experiencing heavy combat, it going to be quite obvious which unit was going to see more downtime, so to get a better picture of operations, you separate the normal SCHEDULED maintenance from the repairs and this will give you a true matrix of were you stand for both situations.

Hi
I have worked on aircraft (RAF), Squadron level, major servicing and bay work, but that was over 40 years ago even so there are differences between what I was involved with then and WW2. The part work 'Aero Engineering Volume III Maintenance and Overhaul' has specimen examples of schedule of inspections for the mid 1930s period. This is based on the Avro Anson and the structure would be closer to the Hawker Hurricane, this is for the Rigger (airframes) other trades are also included in the publication:

Mike

 

[FLYBOYJ]

Hi
I have worked on aircraft (RAF), Squadron level, major servicing and bay work, but that was over 40 years ago even so there are differences between what I was involved with then and WW2. The part work 'Aero Engineering Volume III Maintenance and Overhaul' has specimen examples of schedule of inspections for the mid 1930s period. This is based on the Avro Anson and the structure would be closer to the Hawker Hurricane, this is for the Rigger (airframes) other trades are also included in the publication:
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Mike

Excellent Mike - and what is shown here is SCHEDULED maintenance (and inspection). There are specific tasks broken down by hourly increments. If one wanted to get "into the weeds" these specific tasks can be analyzed and task hours can be attached to them (as commonly done with many different types of aircraft). Finding discrepancies, whether it's wear and tear or battle damage that goes beyond the scope of this document changes the effort in getting the aircraft back into service. You apparently understand this.

 

[Geoffrey Sinclair]

Serviceability is defined as the amount of effort it takes to perform a maintenance task.

So when a unit reports x% of its aircraft serviceable, how much effort does that represent?

"Effort?" You're asking for an enigma. It depends on how many aircraft are in the unit, what scheduled maintenance is due and how many aircraft are "mission capable," (term is mentioned below)

So the effort is an enigma but also a definition?

You determine available aircraft to conduct a certain mission based on maintenance required and those aircraft that are broke. Some of this is determined by some equipment that is allowed to be non-operational as opposed to being full functional. The terms are "Mission Capable" and "Fully Mission Capable."

Can you point me towards a WWII document using these terms? Also how did Fighter Command determine it mission and so serviceable strength day to day in 1940?

"Mission Aborts" cannot be normally predicted as you don't have a crystal ball to predict something that is going to happen in the future, however if you're large fleets of aircraft flying on a regular basis, you can probably come up with a statistical average. When you schedule 10 aircraft for a mission, the plan is to have 10 aircraft fly.

My point about aborts was the rate comes into ideas about reliability. Agreed over a period of time predictions of abort rates can become more accurate, things like the more dangerous a mission the higher the abort rates, as crews rightly require everything working well for such operations. The 8th Air Force had spares, aircraft that would take the place of aborting aircraft or return to base to try and ensure the planned number of sorties were sent. Not something other Air Forces usually did.

Why add the mention of repair, which by definition tends to be non scheduled, in "line servicing and depot servicing"? So something unexpected, the need for a repair, can be scheduled?

No because once again you're not grasping this, probably because you never worked or been around this environment. Again a repair is a non scheduled maintenance action.

My first sentence was the definition, the second a rhetorical question.

I am well aware of how the USAAF classified mishaps and in my previous posts I've showed how it evolved in to the mishap rating system,

The USAAF damage levels were there as part of the original text I wrote for a (much) earlier query, left in so people could read the definitions I was using, nothing to do with assumptions of ignorance or otherwise.

you're posting meaningless numbers that have absolutely no bearing here as you're convoluting maintenance into operational statistics and still discussing "unscheduled maintenance" into the fray. You can't wrap your head around the fact that Scheduled Maintenance is a known quantity.

Actually from where I sit, from my original poor explanation you are now looking for anything that hints I do not understand. The B-17 and B-24 figures are stand alone, at face value a higher percentage of battle damaged B-24 made it back than B-17, but the accident reports say on average B-24 took more damage in an accident that B-17 and battle damaged aircraft tend to crash more than land. Leading to the question. On this evidence, which was the more rugged? That is able to take more damage but make it home? Nothing to do with routine maintenance, repairs or abort rates.

My rule when participating in online discussions is release zero personal data/experience. The aviation information has to stand on its own, plus it avoids the usual "you voted for", you are Venusian etc. as ways of dismissing the information.

 

[FLYBOYJ]

So the effort is an enigma but also a definition?

If you want to define it that way

Can you point me towards a WWII document using these terms? Also how did Fighter Command determine it mission and so serviceable strength day to day in 1940?

I cant speak for the RAF. USAAF I believe it was TO 30-50A1 and eventually it morphed into AFI 21-101

My point about aborts was the rate comes into ideas about reliability. Agreed over a period of time predictions of abort rates can become more accurate, things like the more dangerous a mission the higher the abort rates, as crews rightly require everything working well for such operations. The 8th Air Force had spares, aircraft that would take the place of aborting aircraft or return to base to try and ensure the planned number of sorties were sent. Not something other Air Forces usually did.

This is true and is still the case today

My first sentence was the definition, the second a rhetorical question.

OK

The USAAF damage levels were there as part of the original text I wrote for a (much) earlier query, left in so people could read the definitions I was using, nothing to do with assumptions of ignorance or otherwise.

Well at the end of the day you still place scheduled maintenance into a different "bucket," I don't kow how much more you can beat this to death.

Actually from where I sit, from my original poor explanation you are now looking for anything that hints I do not understand. The B-17 and B-24 figures are stand alone, at face value a higher percentage of battle damaged B-24 made it back than B-17, but the accident reports say on average B-24 took more damage in an accident that B-17 and battle damaged aircraft tend to crash more than land. Leading to the question. On this evidence, which was the more rugged? That is able to take more damage but make it home? Nothing to do with routine maintenance, repairs or abort rates.

Again battle damage vs aircraft maintenance. Not to say that data can't be analyzed but it's still a different from scheduled maintenance

My rule when participating in online discussions is release zero personal data/experience. The aviation information has to stand on its own, plus it avoids the usual "you voted for", you are Venusian etc. as ways of dismissing the information.

Well you should think about that. You can read all the books in the world, if the data gathered is from second hand, inexperienced or convoluted sources your information is corrupt and at that point one becomes nothing but an armchair analyst. Those who actually worked around these machines will make a challenge to this! So Geoffrey, please put this to bed!

 

[ThomasP]

Ran across this the other day.

This is from the Old Machine Press website re Air Ministry evaluations of the MB.2 in 1939 and in comparison to the Hurricane and Spitfire. Old Machine Press articles/subjects are usually very well researched. "Martin-Baker MB2 Fighter"

2 men could remove the MB.2's armament, eight Browning .303 (7.7 mm) machine guns, in under five minutes (compared to 60 minutes for the Hurricane and 70 minutes for the Spitfire).

2 men could reload the MB.2 (300 rounds per gun) in 15 minutes (compared to 16 minutes for the Hurricane and 60 minutes for the Spitfire).

I remember running across an Air Ministry memo on the internet giving similar numbers for the Hurricane and Spitfire, but have not been able to find it again . . . yet.

 

[c1951]

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[BarnOwlLover]

One thing that I read that was interesting about the F-82 Twin Mustang is that North American demoed and engine change on one for a USAAF officer on one of the prototypes. A full engine change done by people who were unfamiliar with the aircraft took less than half an hour, a full swap of every thing forward of the firewall took less than 45 minutes. And experienced crew could probably do it even faster.

It should also be noted that the P-51H and the XP-51F/G used a similar power unit arrangement to the F-82.

 

[fannum]

One thing that I read that was interesting about the F-82 Twin Mustang is that North American demoed and engine change on one for a USAAF officer on one of the prototypes. A full engine change done by people who were unfamiliar with the aircraft took less than half an hour, a full swap of every thing forward of the firewall took less than 45 minutes. And experienced crew could probably do it even faster.

It should also be noted that the P-51H and the XP-51F/G used a similar power unit arrangement to the F-82.

I'm surprised at that quick engine change on F-82. I worked on some surplus Merlin P-51Ds, and it was a day long procedure for decent mechanics ... this was in '50s.

The Germans learned a lot from difficult DB600 series engine changes, and in the FW190 adopted a power egg concept with few mounting bolts and all hydraulic/electrical connections easily accessible, usually on the firewall.

By contrast, a regular feature of Armed Forces Day in the 50s would be when they'd land a T-33/F-86, taxi it in front of the reviewing stand, and a crew would descend on it, pull the tail, swap an engine, pilot would hop in and take off in less than an hour.









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[BarnOwlLover]

Well, this was done at NAA's facility in CA, so that probably helped even with an unfamiliar maintenance crew. That was from a portion of the P-51 Mustang Warbird Tech book about the F-82.

 

[fannum]

I'm sure that most of the site members know that the military tech manuals are written by the manufacturers, and part of the purchase contract deliverables. Some of the early TO's almost read like sales brochures.
They always contain all of the pertinent data, but often the way it's presented uses a lot of side info ... usually favorable ... and some creative wording.

 

[gruad]

Several comments: We seem to have wandered far afield. To compare maintainability, you have to compare like to like ... aircraft that perform the same role. (not roll, btw) Comparing a Cub to a Concorde is ridiculous.

Second, we must consider the whole maintenance picture from parts supply chain to aircraft ready to go on the flight line. A single source manufacturer unable to keep up demand for unique and critical winglenuts will keep a whole wing of strategic bombers grounded in North Dakota. Also, do they need special tools or skills. The '60s A-5 Vigilante designers considered the complexity of their supersonic nuclear bomber, and designed a companion trouble shooting cart that could plug in and diagnose tricky systems ... much like the computerized auto diagnostic bench machines of the '80s, now reduced to hand helds. The only problem is the North American testing unit, the size of a tiny car, was susceptible to salt air, and crews spent more time trouble shooting the test unit than the airplane.
McDonnell designed the F-4 Phantom to be maintained aboard Navy ships with limited access to parts warehouses, so used the same fuel transfer pump in multiple locations ... needed to move JP between the many internal tanks and up to three external droppable tanks. The problem arose when the Air Force found their dozens of fighter bomber designs developed in the '50s unsuitable for wars like Viet Nam, and also ordered the Navy Phantom. Their supply philosophy had the AF order several years of pumps in advance of the need, and suddenly there were none available for the Navy as the AF had the plants locked up with production contracts. We found Navy and Marine aircraft unable to carry more than one external tank, and sometimes none ... just because they didn't have enough transfer pumps on hand.
Touching on the Spitfire vs. Hurricane issue, despite using the same Merlin, Mitchell based his machine on elegance and lightness, using stressed skin, aluminum monocoque construction, much of it with compound curves requiring special tools and skills to form ... like a thoroughbred race car. By contrast, the Hurricane used welded steel tube structure, and skins were not structural ... just tacked on with screws or Dzus fasteners, or even fabric over wood stringers. It should be obvious which would absorb more punishment, and be easier to repair ... also requiring less skills or tools.
Finally, Jeffery Quill's "Sigh for a Merlin" describes the difference between the Rolls Royce built Merlins, and those licensed to Packard and US manufacturers. The British tooling and techniques had sloppiness and variations in them, and those assembling engines were diligent craftsmen, measuring and matching things like pistons to fit bores and with equal weights. Beautiful work, but time and skill intensive. American machine tools were much more precise, and this hand fitting and matching was dispensed with.
Cheers, Bob

The Packard is superior is a myth.

RR produced the vast majority of the Merlin and it is entirely illogical that it would not have encompassed learning from Packard and vice versa

 

[gruad]

The Lancaster was very easy to maintain compared to all other British bombers.

It was built in sections which meant a section could be ripped out and replaced by another section that had been repaired and then the damage section would go off to be repaired again.

 

[fannum]

The Lancaster was very easy to maintain compared to all other British bombers.

It was built in sections which meant a section could be ripped out and replaced by another section that had been repaired and then the damage section would go off to be repaired again.

-------------------------

That was the case for Many WWII A/C, especially trainers, and even including the B-29.

Boeing learned their lesson with the non-modular B-17, and changed that with B-29.

btw - Remember the training and especially Waco troop gliders were designed to be dissassembled and erected often and quickly.

Also, the DC3 was so interchangeable that one Chinese DC3 had a DC2 shorter wing bolted in place for an emergency ferry flight.

 

[fannum]

The Packard is superior is a myth.

RR produced the vast majority of the Merlin and it is entirely illogical that it would not have encompassed learning from Packard and vice versa

Sorry gruad. Well established fact, based on Wright Field/Farnborough WWII studies.

Yes, they both learned from each other, but this was a real issue with early Merlin engines.

 

[GregP]

I keep hearing that the Packard was superior is a myth, and I basically agree.

That does NOT mean they are equal. It means they are equivalent.

The guys I know here want Packards because we have more Packard parts and are more familiar with them. The European guys have more Rolls Royce part availability and are familiar with them. Both run great when they are assembled and running, but interchanging the parts is sometimes not simple. Many times, it is, depends on the parts and the fit required.

That's what I hear when I talk with Merlin owners, anyway. Nobody says one or the other is better. They say they want parts that their engine was built with, if at all possible. Once running, nobody cares what parts were used, but they do pay attention to the labor invoice when the engine is ready. Everyone wants it to be smaller. Putting Packard parts into Packard engines and Roll parts into Rolls engines just seem to make the labor invoice come out better.

Again, owners talking, not me. I don't own either.

 

[EwenS]

The Lancaster was very easy to maintain compared to all other British bombers.

It was built in sections which meant a section could be ripped out and replaced by another section that had been repaired and then the damage section would go off to be repaired again.

A new HP Halifax leaving its place of manufacture at the Fairey, Heaton Chapel factory in 1941 for final assembly and flight test at Ringway (today's Manchester Airport).

 

[MIflyer]

Piper L-4. The crate they were shipped in cost more than the aircraft.

 

[SaparotRob]

Piper L-4. The crate they were shipped in cost more than the aircraft.

The same goes for the B-17. The B-24 cost more.

 

[gruad]

The same goes for the B-17. The B-24 cost more.

Same for Lanc and Halifax.

Biggest thing with P47 vs P51 is it cost twice as much though it was a fantastic multirole plane and much nicer plane for the pilot survivability.

I'm guessing the relative costs of WW2 planes has been done to death, but as a commander you would prefer to have twice of something for the same cost...

 

[Ovod]

Same for Lanc and Halifax.

Biggest thing with P47 vs P51 is it cost twice as much though it was a fantastic multirole plane and much nicer plane for the pilot survivability.

I'm guessing the relative costs of WW2 planes has been done to death, but as a commander you would prefer to have twice of something for the same cost...

P-47 was twice the price of the P-40 - I don't think it was twice the price of of a P-51D. Twice the price of an earlier allison powered P-51A maybe.