Lockheed Martin F-35 Lightning II Joint Strike Fighter (JSF)

OK, somewhat akin to Precision and Accuracy...

Hypothetically, given a fighter jet engine that has a specified 2500 hour TBO, but runs out of hot cycle counts (say turbine blade life) at or around 1700 hours.
- The engine does not have the durability to make it to the specified TBO.
- But the engine almost always runs out of HCC at about 1700 hours +/- 100. You can rely on that - as long as you do not exceed the HCC *.

(*which you are assiduously tracking via your engine monitoring system). (The posts that popped up as I was typing actually say it better than I did.)

Bringing it back to the F-35, I have never seen an accounting comparison between the F100 engine (with three-level maintenance; Organizational (Flightline), Intermediate (Base or Queen-Bee) and Depot ) and the F119 engine (with two-level maintenance: Organizational and Depot).

I suspect that this "improvement" has driven cost up and availability down, with more maintenance being driven to the Depot than down to the Flightline.
 
aim9xray said:
OK, somewhat akin to Precision and Accuracy...

Hypothetically, given a fighter jet engine that has a specified 2500 hour TBO, but runs out of hot cycle counts (say turbine blade life) at or around 1700 hours.
- The engine does not have the durability to make it to the specified TBO.
- But the engine almost always runs out of HCC at about 1700 hours +/- 100. You can rely on that - as long as you do not exceed the HCC *.

(*which you are assiduously tracking via your engine monitoring system). (The posts that popped up as I was typing actually say it better than I did.)
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This actually happened with the F100 engines. The TBO had been based on how pilots were using the J79s, but the F100s had so much more power that the pilots were using a lot more throttle movements while dogfighting.

Which led to the F100 being (I believe) the first engine with TBOs etc being counted in cycles, not in hours. CFM56 is also measured in cycles, not flight hours.


aim9xray said:
Bringing it back to the F-35, I have never seen an accounting comparison between the F100 engine (with three-level maintenance; Organizational (Flightline), Intermediate (Base or Queen-Bee) and Depot ) and the F119 engine (with two-level maintenance: Organizational and Depot).

I suspect that this "improvement" has driven cost up and availability down, with more maintenance being driven to the Depot than down to the Flightline.
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What kinds of work was done at the Intermediate level?
 
We can always ask for more but when I read that the USMC gets 66+% of availability out of their VTOL fleet, only years after their huge ramp-up, I think that this engine is not bad at all.

What were the numbers when the Harrier started to join the RAF and then Marines en-masse?
 
Scott Kenny said:
What kinds of work was done at the Intermediate level?
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Ah... revealing my arm-waving, are you? ;)

I don't have any direct experience with the F100, just the TF34-100A (and F110, remotely). At the time I was there, DM had the I-level engine shop and was Queen-Bee for several off-site locations (such a Nellis who shipped their BCM engines down).

From memory, DM would break the engines down to modules (say for FOD). They would recondition (grind new honeycomb liner liners in the case of excessive turbine blade tip clearance). From memory, there was an overlap of capability between Depot and I-level so workload could be balanced. One major effort was the -100 to -100A HSLI (Hot Section Life Improvement) durability improvement. (HSLI allowed additional "headroom" in ITT so that the engines could be uptrimmed (manually, sonny) further (hotter) to maintain performance longer before coming off wing for I-level maintenance.

One maintenance mishap is illuminating. A "new from engine shop" engine was hung in the #2 position on an A-10. Short story: it would not start, hanging at sub-idle. A 3-level was sent up into the engine (as a "training under supervision" opportunity). The problem was diagnosed (per the Job Guide) as a Fuel Control mis-rig. The task was to cut the safety wire and turn the knob on the fuel control several clicks in the specified direction (per T.O.). He did, and a restart attempt failed. Lather, rinse, repeat. Finally, as a last result, the left engine was started, the APU was shut down (with the engine supplying a higher volume of air on cross-bleed than the APU could). Still no joy with no. 1 at 101% NG. We shut down again, for good - that dog was not going to hunt.

At this point, the headscratching really started and it was finally discovered that the mech had inadvertantly adjusting the positioning of the actuator arm (secured by a castellated nut and safety wire) for the fifth stage IGVs rather that adjusting the Fuel Control
(a castellated nut and safety wire). The effect was that the IGVs were "closed" WRT engine schedule, and the hot part of the engine was being starved of air.

At this point, the engine was coming off-wing for tear-down (with zero-hours of run time) because there was absolutely no way to properly and reliably re-index and rig an individual compressor IGV stage at O-level.

The point of the story here is that the I-level shop was about a mile down the flight line and the engine was squeezed into sequence and re-rigged and came back to the flightline rather quickly.

The nearest Depot was (McClellan, I think) a good 700 miles by truck, or even GE Lynn (a good 2000 miles away). You can see (in this anecdata example) the operational advantages of having a local deep maintenance capability as it related to time in maintenance cycle (nothing like the DCM reviewing the engine shop's priorities) and cost (time in the local shop specific to that engine).

That's it for tonight's flightline bedtime story!
 
TomcatViP said:
What were the numbers when the Harrier started to join the RAF and then Marines en-masse?
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In the 60's and 70's? This was the era of arbitrarily time-limited parts, rather than Engine/Performance Monitoring and On-Condition Maintenance.
 
The question was raised... Would we happen to have the answer here (where do they intend to store all those non-delivered airframe?)?
Lockheed Martin (NYSE: LMT) signed a lease for 136,165 square feet of industrial space at Fort West Commerce Center at 3101 NW Centre Drive in Northwest Fort Worth, according to Dallas-based real estate firm Holt Lunsford Commercial.

The newly built, three-building industrial park along Interstate 820 includes 531,601 square feet of space on about 32 acres.
The company said the new space will primarily be used as a storage facility.
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www.wfaa.com

Defense giant Lockheed Martin leases 130K-plus square feet in Fort Worth

Site is about 7 miles from where the company produces F-35 jets
www.wfaa.com www.wfaa.com
 
can we keep this thread free of political bickering? (although yes I understand it can be challenging as it has influence on acquisitions)
 
aim9xray said:
OK, somewhat akin to Precision and Accuracy...

Hypothetically, given a fighter jet engine that has a specified 2500 hour TBO, but runs out of hot cycle counts (say turbine blade life) at or around 1700 hours.
- The engine does not have the durability to make it to the specified TBO.
- But the engine almost always runs out of HCC at about 1700 hours +/- 100. You can rely on that - as long as you do not exceed the HCC *.

(*which you are assiduously tracking via your engine monitoring system). (The posts that popped up as I was typing actually say it better than I did.)

Bringing it back to the F-35, I have never seen an accounting comparison between the F100 engine (with three-level maintenance; Organizational (Flightline), Intermediate (Base or Queen-Bee) and Depot ) and the F119 engine (with two-level maintenance: Organizational and Depot).

I suspect that this "improvement" has driven cost up and availability down, with more maintenance being driven to the Depot than down to the Flightline.
Click to expand...
F119 was a 3+ level maintenance program - Organizational, Limited Intermediate (USAF, 8 hour tasks, test cell, deployable), Full Intermediate (contractor, on base, capable of everything except rotor unstack and balance), and Depot module overhaul.

F135 is a 2+ level maintenance. Organizational is on wing and off wing module replacement with no test cell required, and Depot level for module overhaul and repair. If module repair requires test cell, such as for turbine blade replacement run-in, depot has to assemble modules into an engine, do the test cell run, then separate the modules for shipment back to base. This is part of the reason for the long depot repair turn times. Cost effective, but not conducive for engine availability when durability falls below expectations.
 
Thank you for the correction on the F119 vs F135 which I conflated - greatly appreciate it. ;)
 
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GTX said:
www.twz.com

F-35s Back On The Table For Turkey

After being kicked out of the Joint Strike Fighter program, Turkey could be let back in, if it abandons its Russian-made S-400 missiles.
www.twz.com www.twz.com
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It seems to me the US could probably give Turkey market value for the S400s and donate them to Ukraine in exchange for F-35 sales being back on, or some kind of S400 for F-35 trade. Seems like a potential win win that would give people what they want. Turkey would probably also need to be approved for MIM-104 sales, but I think that already happened when they were considering the S400s in the first place.
 
Josh_TN said:
It seems to me the US could probably give Turkey market value for the S400s and donate them to Ukraine in exchange for F-35 sales being back on, or some kind of S400 for F-35 trade. Seems like a potential win win that would give people what they want. Turkey would probably also need to be approved for MIM-104 sales, but I think that already happened when they were considering the S400s in the first place.
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That would never work. For starters, Turkey and Russia are neighbours and they have been rivals for the last 500+ years. This means that any transfer of systems without Russian consent means a breach of end user contract, and it would have grave consequenses for Turkey.

The US may afford to provoke Russia since there's an ocean between them but any risky move Turkish government does will have lasting consequences for not just Tukish-Russian relations but for the whole Black Sea region.
 
snne said:
That would never work. For starters, Turkey and Russia are neighbours and they have been rivals for the last 500+ years. This means that any transfer of systems without Russian consent means a breach of end user contract, and it would have grave consequenses for Turkey.

The US may afford to provoke Russia since there's an ocean between them but any risky move Turkish government does will have lasting consequences for not just Tukish-Russian relations but for the whole Black Sea region.
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So contract law depends on or relates to some mysterious mathematical combination of geographic proximity and / or length of historical animus then?

Or are we talking negative consequences that aren’t entirely in the scope of or don’t relate to contractual clauses?

Or maybe some people like to dress up their threats with words they appear to not really understand?
 
There may well be limitations of transfer on the S400s; such things are common in international arms deals.
 
So what will happen if Turkey does get rid of the S-400s? Will they go for the THAAD system? And how many F-35s will they buy? Considering that Turkey already has the KAAN coming out.
 
snne said:
That would never work. For starters, Turkey and Russia are neighbours and they have been rivals for the last 500+ years. This means that any transfer of systems without Russian consent means a breach of end user contract, and it would have grave consequenses for Turkey.

The US may afford to provoke Russia since there's an ocean between them but any risky move Turkish government does will have lasting consequences for not just Tukish-Russian relations but for the whole Black Sea region.
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Yes, we wouldn't want Russia to threaten grain shipments in the Black Sea or something ...
 
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Funny that
- A and C version compatibility is stated for a Navy program but not the B
- MACE is SpeedRacer for Lockheed Martin
 
F119Doctor said:
F119 was a 3+ level maintenance program - Organizational, Limited Intermediate (USAF, 8 hour tasks, test cell, deployable), Full Intermediate (contractor, on base, capable of everything except rotor unstack and balance), and Depot module overhaul.

F135 is a 2+ level maintenance. Organizational is on wing and off wing module replacement with no test cell required, and Depot level for module overhaul and repair. If module repair requires test cell, such as for turbine blade replacement run-in, depot has to assemble modules into an engine, do the test cell run, then separate the modules for shipment back to base. This is part of the reason for the long depot repair turn times. Cost effective, but not conducive for engine availability when durability falls below expectations.
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Seems foolish to take test cells out of the hands of the squadrons or their local Intermediate level...
 
I do not consider myself frenchified. Having grown up with SI-units, I'm flummoxed by 'god-given British Thermal Units/hour'.
- 1,000 Btu/h is approximately 0.2931 kW
 
Scott Kenny said:
Seems foolish to take test cells out of the hands of the squadrons or their local Intermediate level...
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There were many who shared your opinion. But without the intermediate level engine shop to perform module repair, the need for a test cell was greatly reduced.

The F135 does have a neat trick - the High Speed / Low Thrust MBIT. After an engine has been thru O-Level off wing maintenance and is installed, the ground crew can start the engine, activate this MBIT, and run the engine up to Mil power speeds with only wheel brakes and chocks for vibration and leak check, including cold flowing each of the AB zones individually. The F135 control system keeps the variable vanes cambered to reduce airflow and the exhaust nozzle open to keep engine pressure ratio low to achieve the “low” thrust levels while the high and low rotors are at high speeds.

This MBIT accomplishes much of what the I-level test cell would do, but is not sufficient to perform module run-in tests. And, you have to remove the engine from the airframe if you find a problem you can’t fix while installed. Definitely a success oriented program.
 
snne said:
+ and an undisclosed amount of B model. Although they never made an official request, the Navy had even begun to train pilots by the time Turkey got kicked out.
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TCG Anadolu's based on Juan Carlos I, so her F-35B loadout would probably be c10-12 aircraft in a mixed airgroup, 20-25 in a pure F-35B, which suggests a likely buy somewhere in the 15 to 35 range when you allow a few aircraft for training/spares.
 
F119Doctor said:
The F135 does have a neat trick - the High Speed / Low Thrust MBIT. After an engine has been thru O-Level off wing maintenance and is installed, the ground crew can start the engine, activate this MBIT, and run the engine up to Mil power speeds with only wheel brakes and chocks for vibration and leak check, including cold flowing each of the AB zones individually. The F135 control system keeps the variable vanes cambered to reduce airflow and the exhaust nozzle open to keep engine pressure ratio low to achieve the “low” thrust levels while the high and low rotors are at high speeds.

This MBIT accomplishes much of what the I-level test cell would do, but is not sufficient to perform module run-in tests. And, you have to remove the engine from the airframe if you find a problem you can’t fix while installed. Definitely a success oriented program.
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Oh, that's slick!

And I wouldn't want to perform run-in tests with just the brakes set anyways. Aren't those several hours of run time?
 
A Tentative Fleet Plan said:
ESM, EOTS and APG-81/-85, or at least more so than other tactical aircraft.
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Think we're going to need to see users moving to Advanced EOTS in time as the original capability is getting a little long in the tooth (based on the original Sniper pod kit). The world has moved on and pods like Litening V have far, far greater capability. But....you have to wonder how advanced 'Advanced' EOTS will be if and when it enters service....it needs to go on Block IV jets but will be over 10 years old when they start to arrive....
 
Scott Kenny said:
Oh, that's slick!

And I wouldn't want to perform run-in tests with just the brakes set anyways. Aren't those several hours of run time?
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Different engines have different run-in procedures. On the F119, there were two different run-in test profiles depending on whether it was just an new/overhauled fam module, or if the core / HPT / LPT involved.

The full run-in consisted of several slow accells and decels to increasing rotor speeds each time until you reached Mil power, then Mil power dwells to reach thermal equilibrium followed by snap decels to Idle. These were all to progressively rub in the blade tip and knife edge seal clearances without taking too big of a rub all at once while keeping the clearances as small as possible. Took about 45 minutes, if I remember correctly. Given the shared family history, I would expect the F135 run-in would be similar.
 
F119Doctor said:
Different engines have different run-in procedures. On the F119, there were two different run-in test profiles depending on whether it was just an new/overhauled fam module, or if the core / HPT / LPT involved.

The full run-in consisted of several slow accells and decels to increasing rotor speeds each time until you reached Mil power, then Mil power dwells to reach thermal equilibrium followed by snap decels to Idle. These were all to progressively rub in the blade tip and knife edge seal clearances without taking too big of a rub all at once while keeping the clearances as small as possible. Took about 45 minutes, if I remember correctly. Given the shared family history, I would expect the F135 run-in would be similar.
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Huh, that's quite a bit less time than I expected...

I was expecting several hours of MIL power till oil consumption stabilized.
 
Scott Kenny said:
Huh, that's quite a bit less time than I expected...

I was expecting several hours of MIL power till oil consumption stabilized.
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None of the turbine engines that I have been associated with had any run in requirements for the oil system. High oil consumption is usually due to a leaking hose/tube, or a failed shaft seal resulting in excessive breather pressure. It is not like seating piston rings against a cylinder crosshatch finish.
 

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