The Hidden Troubles of the F-35 [DefenseNews]

Discuss the F-35 Lightning II
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quicksilver

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Unread post12 Jun 2019, 18:32

marsavian wrote:LMT have to eventually fix it, free of charge. The F-35 program will give them decades of profit, the buyers of the F-35C product, USN, are owed a product built to full product specification.


If one reads what VADM Winter says, that sounds like what they’re doing.

However, just so you don’t live a life of disappointment, aircraft (take your pick) are rarely “built to full product specification.”
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ricnunes

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Unread post12 Jun 2019, 18:59

zerion wrote:LMT response

Lockheed Martin Comments on Defense News Reporting
Lockheed Martin // June 12, 2019

Below, please find comments from Lockheed Martin on improvements underway addressing the items identified in Defense News’ June 12 article series.

Overall Comment

The F-35s today are meeting or exceeding performance specifications and delivering unprecedented capability and safety compared to legacy fighter aircraft. The feedback we receive from F-35 pilots is exceptional – and any pilot who has flown a legacy jet consistently relays back that if they are being sent in to harm’s way – they want the F-35, every time.

These issues are important to address, and each is well understood, already resolved or on a near term path to resolution. We’ve worked collaboratively with our customers and we are fully confident in the F-35’s performance and the solutions in place to address each of the items identified...

https://www.f35.com/news/detail/lockhee ... -reporting


Thanks Zerion! :thumb:

So the majority of those "F-35 issues" are no-issues at all (i.e. already solved) and the minority of those "issues" are on the verge of being solved.

Regarding the "F-35B and F-35C Horizontal Tail Durability at Sustained Supersonic Flight" "issue":

The F-35B and C deliver on all performance requirements. The potential for tailboom or horizontal tail damage during prolonged supersonic speeds was found in the highest extremes of flight testing conditions that are unlikely replicated in operational scenarios. In fact, there have been no cases of this issue occurring in the operational fleet. Additionally, this is not identified as a safety of flight concern.

We implemented a change to the coatings on the horizontal tails and tail boom beginning in Lot 8 that increases durability and resolves this concern. This update allows the F-35B and C to deliver on all performance requirements with no tail boom or horizontal tail damage concerns.


So this was a one-off event which only happened during an extreme test and didn't repeat and never occurred in operational aircraft. Moreover, this issue was supposedly solved on Lot 8 aircraft and afterwards.
A 4th/4.5th gen fighter aircraft stands about as much chance against a F-35 as a guns-only Sabre has against a Viper.
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magitsu

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Unread post12 Jun 2019, 19:48

Meanwhile in DC:

Trump arranged a special flyover of F-35 to Polish president Duda.
https://twitter.com/p_zuchowski/status/ ... 8753049600
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Unread post13 Jun 2019, 01:05

marsavian wrote:LMT have to eventually fix it, free of charge. The F-35 program will give them decades of profit, the buyers of the F-35C product, USN, are owed a product built to full product specification.


Nice cop-out.

The Navy has been unable to replicate the issue despite multiple attempts. That indicates it is probably caused by something that was either unique to the test aircraft, the day of the test, or a variable that isn't known (for instance a combination of flight testing leading up to the flight that reported the issue that will never be duplicated again). So what exactly is the problem that they are going to fix? And, since they have changed the coatings and there have been no further incidents, how do you know if it is still a problem? Even then, given that they couldn't replicate the issue in testing, how do you prove the new aircraft have fixed the problem? Since it was listed as the outside of the envelope, and the aircraft can attain M1.6, I would guess it is at a fairly low altitude, how often do F-35B/C fly supersonic for extended periods of time on the deck?

But hey, good virtue signalling.
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Corsair1963

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Unread post13 Jun 2019, 01:09

What a load of BS..... :?


Also, of these minor issues. Anybody want to guess the aircraft in question are early production examples??? :doh:
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Unread post13 Jun 2019, 05:02

According to the statement of LM and JPO, the coating damage was happened during an extreme test, and this phenomenon only occurred once, even they have tried to replicate the same conditions.

It sounds not like a consistent and common problem, but why it still be classified to the category 1 deficiencies ?
Last edited by taog on 13 Jun 2019, 06:38, edited 2 times in total.
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Unread post13 Jun 2019, 05:11

taog wrote:According to the statement of LM and JPO, the coating damage was happened during an extreme test, and this phenomenon only occurred once, even they have tried to replicate the same conditions.

It sounds not like a consistent and common problem, but why it still be classified to the category 1 deficiencies ?



Because JPO's category 1 deficiency definition is much broader than the services.
If the coating damage ever blocked some mission critical test it gets labeled at Cat 1.
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Unread post13 Jun 2019, 05:22

marauder2048 wrote:
taog wrote:According to the statement of LM and JPO, the coating damage was happened during an extreme test, and this phenomenon only occurred once, even they have tried to replicate the same conditions.

It sounds not like a consistent and common problem, but why it still be classified to the category 1 deficiencies ?



Because JPO's category 1 deficiency definition is much broader than the services.
If the coating damage ever blocked some mission critical test it gets labeled at Cat 1.



Honestly, very disappointed in Defense News. As all they did was post sensational negative headlines. Yet, after reading the articles. To find out the titles where very misleading and the issues in general minor....

If, they keep this up. We may find the Defense News on the grocery aisle next to the "National Enquirer" at our local Super Market???
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Unread post13 Jun 2019, 08:14

This is not a non-issue as F-35B/C now have 40-50s time restrictions at being at Mach 1.3. Maybe the new coating is a complete fix but Vice Adm. Mat Winter when talking about it does not give that impression implying fundamentally it's a thermal materials issue that could be solved further down the line with new composites.

https://www.defensenews.com/air/2019/06 ... h-coating/

At extremely high altitudes, the U.S. Navy and Marine Corps’ versions of the F-35 jet can only fly at supersonic speeds for short bursts of time before there is a risk of structural damage and loss of stealth capability, a problem that may make it impossible for the Navy’s F-35C to conduct supersonic intercepts.

The Defense Department does not intend to field a fix for the problem, which influences not only the F-35’s airframe and the low-observable coating that keeps it stealthy, but also the myriad antennas located on the back of the plane that are currently vulnerable to damage, according to documents exclusively obtained by Defense News.

The F-35 Joint Program Office has classified the issues for the "B" and "C" models as separate category 1 deficiencies, indicating in one document that the problem presents a challenge to accomplishing one of the key missions of the fighter jet. In this scale, category 1 represents the most serious type of deficiency.

Both deficiencies were first observed in late 2011 following flutter tests where the F-35B and F-35C both flew at speeds of Mach 1.3 and Mach 1.4. During a post-flight inspection in November 2011, it was discovered the F-35B sustained “bubbling [and] blistering” of the stealth coating on both the right and left sides of the horizontal tail and the tail boom.

During similar tests of the F-35C in December 2011, “thermal damage” that compromised the structural integrity of the inboard horizontal tail and tail boom were apparent.

Vice Adm. Mat Winter, who leads the F-35 program on behalf of the Pentagon, told Defense News that the department has taken steps to mitigate the problem with an improved spray-on coating, but added that the government will not completely fix it — instead accepting additional risk.

As justification for the decision, Winter noted that the issue was documented while the jet was flying at the very edge of its flight envelope. He also said the phenomenon only occurred once for both the B and C models, despite numerous attempts to replicate the conditions that caused the problem. “How often do we expect something like that to occur?” he said. “It's very, very small.”

Greg Ulmer, Lockheed Martin’s F-35 program head, said there have been no cases of this problem occurring in the operational fleet and that incidents have been limited to the “highest extremes of flight testing conditions that are unlikely replicated in operational scenarios.”

Winter acknowledged that the deficiency could keep the Navy from accomplishing its supersonic intercept mission — as the documents charge — if similar issues were being experienced more widely across the F-35C inventory.

“If you had that performance on all of your fleet, then you would have a problem. That’s not the case,” he said.

“We have put into place what we believe are the appropriate technical fix to ensure that our F-35Cs have the full envelope and capability to do the high-speed mission, if needed. That’s where we are. Right now, our United States Navy and Marine Corps flying the sea agree with that,” he said.

The new coating, which was introduced in Lot 8, allows the jet to withstand hotter temperatures caused by the afterburner, the documents stated. Winter characterized the material as able to withstand “what we call the thermal shock wave,” but declined to specify how the coating works or how much protection it provides.

“It may be some future advanced materials that can withstand the pressure and the temperature,” Winter said. “Then we see that, and we go, ‘Hey, look, we've got this on the book,’ [and] we do a test check to see if that new material solves that problem.”

The Defense Department has also instituted time limits on the number of seconds the F-35B and F-35C can fly at speeds in excess of Mach 1.2 while at full afterburner.


However, those restrictions are somewhat complicated, and it is unclear how pilots are expected to monitor their compliance to the limits while in flight.

For example, an F-35C can only fly at Mach 1.3 in afterburner for 50 cumulative seconds, meaning that a pilot cannot clock 50 seconds at that speed, slow down for a couple seconds and then speed back up. However, the time requirements reset after the pilot operates at military power — an engine power setting that allows for less speed and thrust than afterburner — for a duration of three minutes.

The F-35B can fly for 80 cumulative seconds at Mach 1.2 or 40 seconds at Mach 1.3 without risking damage.

But for both the C and B models, flying at Mach 1.3 over the specified time limits poses the risk of inducing structural damage to the aircraft’s horizontal stabilizer.

It is infeasible for the Navy or Marine Corps to operate the F-35 against a near-peer threat under such restrictions, the documents acknowledge.

“Pilot observed timers are not practical/observable in operationally relevant scenarios,” one document read. Another document said that “pilots will be unable to comply with time limit in many cases due to high mission workload, resulting in lost missions due to aircraft damage.”

And when those timer violations occur, they will result in “degradation of [stealth], damage to [communications, navigation and identification] antennas, and/or significant [horizontal tail damage],” one document explained.
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Unread post13 Jun 2019, 10:30

They have restrictions of Mach 1.3 at that part of the envelope.

A complete fix would imply the problem reproduces consistently enough for a fix to be completely validated.
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Unread post13 Jun 2019, 11:23

But for both the C and B models, flying at Mach 1.3 over the specified time limits poses the risk of inducing structural damage to the aircraft’s horizontal stabilizer.


Shouldnt the A model have the same problem and restrictions and why not? The horizontal stabs are the same for all 3 models.
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Unread post13 Jun 2019, 12:12

The horizontal stabs are larger on the F-35C and the nozzle is a little shorter / closer to the fuselage on the B. Most importantly however, the F-35A has notably less transonic / supersonic drag.

Because this is primarily about how long the rear surfaces are exposed to afterburner heat, it seems that the faster acceleration / lower drag has resulted in the A variant not yet experiencing this issue.

Remember too that the B and C issues are deficiencies specifically because they happened once each; without it happening on the A there's no justification to also attach a deficiency (and corresponding restrictions) to it, even if theoretically the F-35A should also suffer damage after sufficiently long use of the afterburner (perhaps 50 seconds at Mach 1.5+ for instance).
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Unread post13 Jun 2019, 13:13

When Def News was bought a few years ago, they let Vago Muradian and others go in favor of ‘reporters’ with far less/zero defense reporting experience; it was about the financials. Hence, we get the reporter line up they/we have now. The modern journalism business model is about ‘speed to market’ but Def News seems to have largely forgotten that for most people who follow defense and aerospace matters, ‘credibility’ still counts. On that count (credibility), they get low marks on this effort and my bet is the acute spike in click hits they likely got will not be sustained.

I’ll check around, but I think some of the confusion may be because the mod that releases a jet from the Mach restriction is an ‘on condition’ change; in other words, it won’t be mod’d unless it is damaged or otherwise out of service for other mods or depot work. The LRIP8 jets (and beyond) come off the prod line with the fix.
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Unread post13 Jun 2019, 13:43

quicksilver wrote:Hatchet job in front of the FRP/MY decision. Jet is probably doing too well in OT and the DOT&E weenies needed something to whine about, so they leak a Cat 1 DR list. Few in the public domain understand ‘deficiencies’ in a test context because they tend to understand jets like they understand cars; my wife in the kitchen — “...why would we buy something with ‘deficiencies’...?” DefNews editor needs some click hits so he or she tags the story with ‘previously unreported.’ Unreported to whom? The items made the DR list for bleeps sake.

Reminder: some DRs are never resolved. There are fighters flying around in service today after decades in service with still-unresolved DRs. I’m surprised some of the F-35 list are CAT 1s — eg the sea search mode. And, stealth coating stuff? Sounds like the tailplane heating when you spend lotsa time in max AB.

New aircraft always have stuff like this that you have to handle with for a while. Anyone who has flown new designs in the fleet early in the their design life knows this because they’ve lived it.

Cue POGO hysteria — 3, 2, 1...

AFM backups 'QS' & yep the 'old news' dump was a bit overwhelming for me (I was seeing 'posted 5 minutes ago' notices).
Lockheed: Reported Deficiencies in F-35 Already Fixed or Being Resolved
12 Jun 2019 John A. Tirpak

"Lockheed Martin took the unusual step June 12 of issuing a point-by-point rebuttal of a press report describing deficiencies with the F-35 family of aircraft. The company claimed that deficiency issues identified in reporting by Defense News on June 12 are each “well understood, already resolved or on a near-term path to resolution.” The company said it has “worked collaboratively with our customers” on the issues and “are fully confident in the F-35’s performance and the solutions in place to address each of the items identified.”

The Defense News stories, timed to coincide with the F-35 CEO meeting in Arlington, Va., collected deficiency reports harvested from internal Joint Program Office and Pentagon documents, and combined these with reporting on other deficiencies identified by Pentagon test organizations. Some of the problems noted had been discussed publicly, and in Government Accountability Office audits, while others had not. The reports largely go back to late 2018 and ​early 2019, when the F-35 had just begun Initial Operational Test and Evaluation, the graduation exercise that will allow it to progress to the next program milestone...." [then more or less the LM PR rebuttal is repeated]

Source: http://www.airforcemag.com/Features/Pag ... olved.aspx
RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
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ricnunes

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Unread post13 Jun 2019, 17:01

quicksilver wrote:I’ll check around, but I think some of the confusion may be because the mod that releases a jet from the Mach restriction is an ‘on condition’ change; in other words, it won’t be mod’d unless it is damaged or otherwise out of service for other mods or depot work. The LRIP8 jets (and beyond) come off the prod line with the fix.


Exactly!

By reading the article that spaz posted:
http://www.airforcemag.com/Features/Pag ... olved.aspx

We can read the following:
Defense News asserted that F-35B and C aircraft stealthy control surfaces can delaminate at supersonic speed above Mach 1.2, causing structural damage and affecting flight safety. Lockheed said “the potential” for such an event after prolonged supersonic flight was discovered during test conditions unlikely to be seen in normal operations. However, a “change to the coatings on the horizontal tails and tail boom beginning Lot 8 … increases durability and resolves this concern.”


which can also be read on the LM's rebuttal.
So it seems to me that the issue above (F-35B/C supersonic flight damage to coating/structure) is solved in Lot 8 aircraft and afterwards.
Of course one can argue if pre-Lot 8 aircraft still have this issue but IMO this doesn't matter much since these can be fixed anytime, right? Moreover, the vast majority of F-35's (namelly -Bs and -Cs) will be post Lot-8 anyway...
A 4th/4.5th gen fighter aircraft stands about as much chance against a F-35 as a guns-only Sabre has against a Viper.
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