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How many combat sorties can a fighter perform between maintenance?

totoro

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I am not talking about small day-to-day maintenance here. More like stuff that you'd need to pull a fighter from, say, an aircraft carrier, as they don't have the required infrastructure (or parts, or personnel) to perform that particular aircraft check.

I know carriers are also limited with other stuff, so please don't go into carrier ops. The planes could just as easily be in an Air force base.

I am also aware that not all sorties are the same, depending on the loads, maneuvers and flight hours, but I am just looking for a ballpark figure.

If there are some concrete figures for any planes out there, even if they're older ones like F-16 or F-18, that'd be great.
 

DWG

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Day to day maintenance isn't necessarily small, you're talking about tens of man-hours per flight-hour in general
 

stealthflanker

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I think RAND has a paper on it regarding sortie generation rate.

They have a simple formula for maintenance time per sortie :

MT=3.4+0.68*FT

Historically we have Israel which manage to provide sortie rate of 4 sorties per day during 1973 war. This because not only decent training of their personel, short distance and development of new technique such as Hot-refuelling and rearming. It however also came with some risk as they cutting corners with safety. More typical ideal value would be 3 and 2 would be of normal.

Here i attached the part of interest.
 

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totoro

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Thanks, that is an excellent resource for the question of how much down time there is between two sorties and sortie rates per day.

But I was asking about something else. If a plane flies, say, 3 hours per sortie. And it does 100 sorties. Maybe it does them one sortie per day or even two sorties per day. When will it hit some big maintenance requirement that doesn't allow it to perform a sortie during one day (or more) as the maintenance check simply lasts a day (or more)? How many flight hours (or flight cycles) is that? How long does that first check last (in days)? And when is the next, even bigger, check that might take perhaps a week? (does it take a week?)

I can read that F-16s require some undefined maintenance when they hit 300 or 400 hrs (sources differ by year and operator, thus also possibly by variant of the plane). But I don't know the context. How serious is that maintenance check? Is it done on base? By regular personnel? Or by special personnel? Does it take a day? Or more?
 

Fluff

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1571503290604.png

Sorry but this is B**l**ks

Unless there is something seriously wrong with the F16. I worked fast jets and taught new groundcrew.

Re-arm 50 minutes, what your sending one armourer out?

Even allowing for a non-hot refuel/re-arm, you could do it all in 30 minutes. And I have never seen an aircraft need 5 minutes to start engines, 1 minute is plenty.

Moving on the aircraft maintenance etc.

Start of day -
remove covers, check fuel(Should have been fueled last night)
Walk round, open canopy, connect ground power.
Crew arrive, assist strap in, couple of minutes, start 1, start 2, remove undercarriage pins and stow, remove weapon pins and stow, quick control check, remove ground power, chocks away. anything more than 15 minutes is bad.

Aircraft returns, intend to lauch again.
Marshall aircraft, chocks in.
Stop engines. Fit undercarraige pins, and any weapon pins.
fit ladder, crew exit.
assuming 2 groundcrew, one tidies cockpit and checks topside- for damage etc.
other connects ground power, checks bottom, tires, jetpipes etc for damage, etc.
Tanker arrives, refuel connected, 10 -15 minutes, disconnect.
Armourers arrive, load new weapons - anything from 3-6 men, armourers are idiots, and need a SNCO with them to allow them to breath and move, sometimes at the same time. again 15 minutes.
Thats it ready to go.

Moving onto flight to ground maintenance hours, its the hours burned in the deep maintenance that effect the ratio.

Day to day operation - no faults, your probably getting 1 hour flying, to 1 or 2 hours operations, as above, plus moving, towing in/out etc.

Then you have basic failures, radio fails, quick test, idiot light says its the main LRU, go to stores, get new LRU, take out failed, fit new, press idiot light, idiot light says all good. Take old oneback to stores, do some paperwork, go for tea.

Eventually you have maybe a 500 hour check - some panels removed, grease etc applied to certain items(over and above daily checks) a lot of measuring for wear, stress etc. Lots of minor panels have stress cracks, drill out, measure, and monitor. 500 hour check might use 100 hours of groundcrew time. Full engine inspection, oil samples taken and sent for analysis, borescope checks for wear etc.

Eventually your aircraft needs a major service, literally this is what you do with your 30 year old sports car - all panels off, engines out, ejector seats out, can include a full rewire - I think the cables we used were rated for 10 years life. Repaint, new tyres, new hydraulic actuators, clean the fuel tanks, everything is serviced. This could take 4 to 6 months per aircraft,. and when you include the work done away from the aircraft, i.e. refurbishing the ejector seat, then you are into 10's of thousands of hours. Incorporation of modifications, lots of mods, some mandatory, some advisory, some only needed for certain weapons, etc.

Location of your major service, depends on how big your aircraft fleet is, RAF - small fleet, often done at the one airbase operating that aircraft. Large fleet, several bases, then done at one central base, could be civilian manned. i.e RAF St. athan,

Above that, would be a complete refurbishment, major service plus disassembly of the sections of the aircraft, wings off, etc. Usually done by the manufacturer, or industry. Literally done when you are going beyond the original design life. Major upgrades installed, new systems added etc.
 

totoro

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Eventually you have maybe a 500 hour check - some panels removed, grease etc applied to certain items(over and above daily checks) a lot of measuring for wear, stress etc. Lots of minor panels have stress cracks, drill out, measure, and monitor. 500 hour check might use 100 hours of groundcrew time.
And how quickly is that 500 hour check performed? 100 hours of groundcrew time doesn't mean a lot unless there's an average number of ground crew personnel included, or at least the maximum plausible number of crew personnel, so they don't get in the way of each other. Are we talking 4 people (25 hours?) or 10 people (10 hours?)

Eventually your aircraft needs a major service, literally this is what you do with your 30 year old sports car - all panels off, engines out, ejector seats out, can include a full rewire - I think the cables we used were rated for 10 years life. Repaint, new tyres, new hydraulic actuators, clean the fuel tanks, everything is serviced. This could take 4 to 6 months per aircraft,. and when you include the work done away from the aircraft, i.e. refurbishing the ejector seat, then you are into 10's of thousands of hours. Incorporation of modifications, lots of mods, some mandatory, some advisory, some only needed for certain weapons, etc.
Are you saying here that the 500 hour check is the first big check (something similar to A check for commercial airliners)? And that the next big check is this major service event which takes 4-6 months to perform? Or is there another service event between these two?
 

Fluff

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Eventually you have maybe a 500 hour check - some panels removed, grease etc applied to certain items(over and above daily checks) a lot of measuring for wear, stress etc. Lots of minor panels have stress cracks, drill out, measure, and monitor. 500 hour check might use 100 hours of groundcrew time.
And how quickly is that 500 hour check performed? 100 hours of groundcrew time doesn't mean a lot unless there's an average number of ground crew personnel included, or at least the maximum plausible number of crew personnel, so they don't get in the way of each other. Are we talking 4 people (25 hours?) or 10 people (10 hours?)

Eventually your aircraft needs a major service, literally this is what you do with your 30 year old sports car - all panels off, engines out, ejector seats out, can include a full rewire - I think the cables we used were rated for 10 years life. Repaint, new tyres, new hydraulic actuators, clean the fuel tanks, everything is serviced. This could take 4 to 6 months per aircraft,. and when you include the work done away from the aircraft, i.e. refurbishing the ejector seat, then you are into 10's of thousands of hours. Incorporation of modifications, lots of mods, some mandatory, some advisory, some only needed for certain weapons, etc.
Are you saying here that the 500 hour check is the first big check (something similar to A check for commercial airliners)? And that the next big check is this major service event which takes 4-6 months to perform? Or is there another service event between these two?
500 hour check - peacetime, a week - don't forget your also running normal ops, with the same groundcrew, so this fits in around ops, and normal breakdowns. The work is assigned by trade - more work for airframe and engine guys, less work for electrics and electronics team.

Wartime - get the engineering officer to grant a waiver. Your not going to take a serviceable aircraft out of use for this.

You would do 500's every 500, each aircraft is different, other items will have other intervals, engines etc.

But again, your aircraft has flown happily for 500 or 5000 hours - a few more aren't going to hurt, so in wartime you would not start these, and in fact your deep maintenance depot would be throwing aircraft back together, to get replacements out to the squadrons - not many countries have 'reserve' aircraft anymore.

In addition you have battledamage repair going on, this literally is about patching holes, and you get a lot of holes, from AA fire, missiles etc. patch em up, test systems, back into use.

Hope that helps.
 

totoro

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It does, thanks. Basically, in wartime there are no rules and planes might be forced to fly until they literally crash due to malfunction? So a plane flying two sorties per day, for 100 days straight, or even 200 days straight is plausible? (If enough personnel is available)
 

Foo Fighter

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Can you really see a modern conflict lasting 200 days?
 

Arjen

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Syria. Yemen.
 

Fluff

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You would push the limits, but common sense still applies, engine oil hyd oil would be topped up, you would review all the lifed items, some don't matter regards to airworthiness, i.e. inspection date for liferaft - it gets lifed at say a 2 year inspection, be fine for a further 6 months, but if the APU is on a 1000 hour strip down, you may decide to waive it to 1200, but after that you will swap it.

Also I'm talking about Nato conflict with Russia, you would fly everything, if your talking about the RAF, its been dropping bombs in Iraq/Afghan/Syria for years, all the normal rules will be applied, for sure, every item will be on full inspection etc.

also if this is against a peer, you will be losing aircraft and pilots, and pilots don't grow on trees. Plus your bases will be getting hit, by cruise missiles, bombs, ground attacks, protests etc. losing aircraft and air and groundcrew, who also need to defend the base. Frontline units would be bolstered by trainees, reservists etc.
 

DWG

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It does, thanks. Basically, in wartime there are no rules and planes might be forced to fly until they literally crash due to malfunction? So a plane flying two sorties per day, for 100 days straight, or even 200 days straight is plausible? (If enough personnel is available)
If they crash due to malfunction, the engineering officer probably screwed up. As Fluff says, some things can be waivered, some things shouldn't be. You're also going to start to see airframes condemned for being over-stressed. Even in npn-wartime/civilian use lots of aircraft have had issues with cumulative stress leading to major rebuild programmes, wing-boxes are a favourite for this, cf the Hercules. WWII has a bunch of examples where aircraft had problems with airframe failures: Typhoon aft-fuselage, Mosquito wings (in the tropics only), SB2C's disintegrating in glide attacks, and so on.

But the other issue you'll run into is aircrew (and groundcrew) fatigue, and fatigued personnel make mistakes, so past a certain point you'll need to rotate squadrons, or at least pilots, out of the line.
 
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