F-35 Cancelled, then what ?
Ecce Homo! Loquitur...
U.S. Navy maintains grounding order for F-35 fighter jets
(Reuters) - The U.S. Navy maintained a grounding order for F-35 B-model and C-model fighter jets built by Lockheed Martin Corp (LMT.N), saying it was still not clear what caused a massive engine failure on an Air Force F-35 jet last month. The fleetwide grounding order kept three Marine Corps F-35 B-model jets and one British F-35B from traveling to Britain for widely publicized appearances at two air shows.
"At this time, I do not have sufficient information to return the F-35B and F-35C fleet to flight," Vice Admiral David Dunaway, who heads the Navy's Air Systems Command, said in an update to a grounding order issued by U.S. officials on July 3. A copy of the document was obtained by Reuters. In the document, Dunaway said he was committed to returning the F-35 fleet to flight as soon as possible, but there was still "no discernible event that represents a root cause."
The memo emerged after a lengthy meeting on Friday of the officials responsible for determining the "airworthiness" of the F-35, according to sources familiar with the matter........
Marine Lieutenant General Jon Davis, deputy commandant for aviation, told Reuters late on Friday that the jets might not appear at the Farnborough air show, which begins next week......."Until the grounding is lifted, the U.S. Marine Corps and Britain will not be able to ferry the F-35B aircraft to Britain for the jet's planned international debut at two air shows there this month - the Royal International Air Tattoo, the world's largest military air show that began on Friday, and the Farnborough air show, which starts on Monday and runs until July 20".....
Dunaway said the Navy and other services are continuing to investigate the incident, and planned to update the flight directive no later than July 16 - two days after the start of the Farnborough air show outside London.......
Dunaway's memorandum did not rule out the possibility that the most advanced U.S. fighter jet could still appear toward the end of the Farnborough air show, but the prospects of that occurring appeared to be dimming fast. "There are specific additional evaluation conditions required to support the Farnborough air show in the UK, including the ferry flight across the Atlantic and performance in the air show itself. Additional work is required in order to understand and mitigate air show unique risks," it said......
Dunaway said the current analysis would have to be refocused to allow the F-35's participation in the Farnborough air show. The jets need a full day in Britain to allow for any maintenance or repairs before they participate in flying demonstrations. Dunaway said officials were looking at possible operational restrictions for the jets while the issue was being investigated, and would also likely implement repeated engine inspections to monitor for any indication of a future problem. But those measures would take several more days to complete.
It remains unclear what caused the third stage of the Pratt engine to break apart. The incident severed a fuel line, which then caused a fire.
Frank Kendall, the Pentagon's chief weapons buyer, told U.S. lawmakers on Thursday there was "growing evidence" that the incident was an individual event and had not been caused by a systemic issue. He said all existing engines had been inspected and that no similar issues had been found, but he said safety was the Defense Department's top priority.
(Reuters) - The U.S. Navy maintained a grounding order for F-35 B-model and C-model fighter jets built by Lockheed Martin Corp (LMT.N), saying it was still not clear what caused a massive engine failure on an Air Force F-35 jet last month. The fleetwide grounding order kept three Marine Corps F-35 B-model jets and one British F-35B from traveling to Britain for widely publicized appearances at two air shows.
"At this time, I do not have sufficient information to return the F-35B and F-35C fleet to flight," Vice Admiral David Dunaway, who heads the Navy's Air Systems Command, said in an update to a grounding order issued by U.S. officials on July 3. A copy of the document was obtained by Reuters. In the document, Dunaway said he was committed to returning the F-35 fleet to flight as soon as possible, but there was still "no discernible event that represents a root cause."
The memo emerged after a lengthy meeting on Friday of the officials responsible for determining the "airworthiness" of the F-35, according to sources familiar with the matter........
Marine Lieutenant General Jon Davis, deputy commandant for aviation, told Reuters late on Friday that the jets might not appear at the Farnborough air show, which begins next week......."Until the grounding is lifted, the U.S. Marine Corps and Britain will not be able to ferry the F-35B aircraft to Britain for the jet's planned international debut at two air shows there this month - the Royal International Air Tattoo, the world's largest military air show that began on Friday, and the Farnborough air show, which starts on Monday and runs until July 20".....
Dunaway said the Navy and other services are continuing to investigate the incident, and planned to update the flight directive no later than July 16 - two days after the start of the Farnborough air show outside London.......
Dunaway's memorandum did not rule out the possibility that the most advanced U.S. fighter jet could still appear toward the end of the Farnborough air show, but the prospects of that occurring appeared to be dimming fast. "There are specific additional evaluation conditions required to support the Farnborough air show in the UK, including the ferry flight across the Atlantic and performance in the air show itself. Additional work is required in order to understand and mitigate air show unique risks," it said......
Dunaway said the current analysis would have to be refocused to allow the F-35's participation in the Farnborough air show. The jets need a full day in Britain to allow for any maintenance or repairs before they participate in flying demonstrations. Dunaway said officials were looking at possible operational restrictions for the jets while the issue was being investigated, and would also likely implement repeated engine inspections to monitor for any indication of a future problem. But those measures would take several more days to complete.
It remains unclear what caused the third stage of the Pratt engine to break apart. The incident severed a fuel line, which then caused a fire.
Frank Kendall, the Pentagon's chief weapons buyer, told U.S. lawmakers on Thursday there was "growing evidence" that the incident was an individual event and had not been caused by a systemic issue. He said all existing engines had been inspected and that no similar issues had been found, but he said safety was the Defense Department's top priority.
Do a Hover - it avoids G
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ORAC
That would appear to answer my question to LO. Thanks.
However it is a typical quote/report from somebody who does not really understand things otherwise they would not just say third stage. They would appreciate the engineering significance of whether it was a third stage at the front or at the back.
It remains unclear what caused the third stage of the Pratt engine to break apart.
However it is a typical quote/report from somebody who does not really understand things otherwise they would not just say third stage. They would appreciate the engineering significance of whether it was a third stage at the front or at the back.
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Investigators have narrowed their focus to the third stage turbine of the F135 engine as the likely source of a fire that erupted June 23 as an F-35A fighter was preparing for takeoff at Eglin AFB, Florida, last month.
The third stage turbine is the second stage in the low-pressure turbine section. It is common to all F135 variants – the A, B and C F-35 aircraft.
In addition to the flight grounding, "We cannot run any engines," including those in testing at the contractor’s facility, as a result of the fire, U.S. Air Force Lt. Gen. Christopher Bogdan told Aviation Week during a July 3 interview.
The third stage turbine is the second stage in the low-pressure turbine section. It is common to all F135 variants – the A, B and C F-35 aircraft.
In addition to the flight grounding, "We cannot run any engines," including those in testing at the contractor’s facility, as a result of the fire, U.S. Air Force Lt. Gen. Christopher Bogdan told Aviation Week during a July 3 interview.
Unfortunately there was a possibly related issue in 2013.
21-February-2013, the Pentagon ordered a grounding for all F-35 aircraft, after a routine check at the Edwards Air Force Base revealed a crack in a low pressure turbine blade in an engines of a F-35A.
It was a F-135 engine with 700 hours, of which 409 flight hours. The aircraft was the F-35A test aircraft AF-2. The half-inch long crack was found in a turbine blade of the low pressure turbine section. This makes it unlikely that it is caused by so-called FOD (Foreign Object Damage), such as a bird strike, because such an object has to pass the Fan Section (3 stages) Compressor Section (6 stages), combustor and high pressure turbine section before reaching the low pressure turbine section.
It was a F-135 engine with 700 hours, of which 409 flight hours. The aircraft was the F-35A test aircraft AF-2. The half-inch long crack was found in a turbine blade of the low pressure turbine section. This makes it unlikely that it is caused by so-called FOD (Foreign Object Damage), such as a bird strike, because such an object has to pass the Fan Section (3 stages) Compressor Section (6 stages), combustor and high pressure turbine section before reaching the low pressure turbine section.
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Apparently P&W is objecting to the description of a third-stage LPT failure, but will not be more specific.
TD
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The turbine failure seems to have been a fairly kinetic event. Some reports have parts of the engine departing the jet through the top of the fuselage. If true, it's not hard to imagine either punctured or ruptured fuel tanks / lines sourcing the subsequent fire. What will be interesting is whether or not fire suppression systems removed earlier to save weight would have mitigated the fire.
FARNBOROUGH: No F-35 appearance for opening day - 7/13/2014 - Flight Global
The comms aspect of this situation just continues to deteriorate. The bloody jets are on the ground in bloody Pax and the Navair boss has announced that there will be no decision before Wednesday, so announcing that there will be no F-35s flying at Farnborough tomorrow is not exactly hold-the-effin-front-page news.
The comms aspect of this situation just continues to deteriorate. The bloody jets are on the ground in bloody Pax and the Navair boss has announced that there will be no decision before Wednesday, so announcing that there will be no F-35s flying at Farnborough tomorrow is not exactly hold-the-effin-front-page news.
...and what a difficult moment for the signing of the contract to buy more of the grounded jets for the Secretary. Janes have an interesting take on it.
Pentagon suspends F-35 contract negotiations until latest failure resolved - IHS Jane's 360
Pentagon suspends F-35 contract negotiations until latest failure resolved - IHS Jane's 360
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Rub a Dub Dub - three blades in a tub....
'Excessive' rubbing of engine blades caused F-35 failure: Pentagon
13 Jul 2014 Andrea Shalal
'Excessive' rubbing of engine blades caused F-35 failure: Pentagon | Reuters
13 Jul 2014 Andrea Shalal
"(Reuters) - The engine failure that has grounded the entire fleet of Lockheed Martin Corp F-35 fighter jets was caused by "excessive" rubbing of fan blades in the plane's Pratt & Whitney engine, but does not appear to be a fundamental design flaw, the Pentagon's chief weapons buyer said on Sunday.
Defense Undersecretary Frank Kendall told reporters on Sunday there was still a chance that the grounding order could be lifted in time for the F-35 to make its international debut at the Farnborough air show....
...He said detailed inspections of engines on the fleet of 97 F-35s already built had not shown signs of the kind of excessive rubbing founded on the engine that broke apart, although there were signs of milder rubbing in several other engines.
Kendall said the evidence being compiled did not point to a systemic issue, but the analysis was still going on. In this case, engineers found evidence of significant rubbing by the fan blades against a cowl.
"We’re not noticing it throughout the fleet," he said. "The design allows for a limited degree of rubbing, but it was enough in this case to cause a structural reaction that ultimately led to failure."..."
Defense Undersecretary Frank Kendall told reporters on Sunday there was still a chance that the grounding order could be lifted in time for the F-35 to make its international debut at the Farnborough air show....
...He said detailed inspections of engines on the fleet of 97 F-35s already built had not shown signs of the kind of excessive rubbing founded on the engine that broke apart, although there were signs of milder rubbing in several other engines.
Kendall said the evidence being compiled did not point to a systemic issue, but the analysis was still going on. In this case, engineers found evidence of significant rubbing by the fan blades against a cowl.
"We’re not noticing it throughout the fleet," he said. "The design allows for a limited degree of rubbing, but it was enough in this case to cause a structural reaction that ultimately led to failure."..."
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Interesting link, Spaz, thanks.
I seem to remember (reading somewhere) that the fan blades of the EJ200 were designed with an abradable tip, would this kind of blade tip be found further back in the turbine section of the engine as well? And would the P&W engine employ similar blades, possibly?
-RP
I seem to remember (reading somewhere) that the fan blades of the EJ200 were designed with an abradable tip, would this kind of blade tip be found further back in the turbine section of the engine as well? And would the P&W engine employ similar blades, possibly?
-RP
Given the tolerances involved in building modern engines, it makes no sense that some can rub and others don't. The problem is that you can't just file a couple of mils off all the blades. My concern now is that this could be a far more fundamental snag than we thought. I'm a big fan of P&W engines, they served me well, I trust they will rise to this challenge.
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Odd, at least in the T700 engine there's an ablative (probably not the correct term) seal on the gas generator turbine that allows the turbine blades to creep. I figured that was some type of universal modern turbine design. Guess i was wrong.
Ecce Homo! Loquitur...
Recurring problem due to the engine running 190F hotter than planned? There is history...
Joint Strike Fighter F135 Engine Burns Hotter Than Desired
F-35 Report: overview of problems with F-135 engine
..........Conclusion
The repeated problems with the same part of the engine may be indications of a serious design and structural problem with the F-135 engine.
A future F-35 fleetwide grounding will paralyze the Western Airpower. Also, the lack of reliability will contribute to low service ability and to high operating and support costs of the F-35 fleets in several countries putting more pressure on the low defence budgets.
Since the F-35 will be the cornerstone of the NATO airpower and US homeland defence the next decades, the problems with the F135 engine need attention of the highest political decision makers.
Joint Strike Fighter F135 Engine Burns Hotter Than Desired
F-35 Report: overview of problems with F-135 engine
..........Conclusion
The repeated problems with the same part of the engine may be indications of a serious design and structural problem with the F-135 engine.
A future F-35 fleetwide grounding will paralyze the Western Airpower. Also, the lack of reliability will contribute to low service ability and to high operating and support costs of the F-35 fleets in several countries putting more pressure on the low defence budgets.
Since the F-35 will be the cornerstone of the NATO airpower and US homeland defence the next decades, the problems with the F135 engine need attention of the highest political decision makers.
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Recurring problem due to the engine running 190F hotter than planned? There is history...
Joint Strike Fighter F135 Engine Burns Hotter Than Desired
F-35 Report: overview of problems with F-135 engine
..........Conclusion
The repeated problems with the same part of the engine may be indications of a serious design and structural problem with the F-135 engine.
A future F-35 fleetwide grounding will paralyze the Western Airpower. Also, the lack of reliability will contribute to low service ability and to high operating and support costs of the F-35 fleets in several countries putting more pressure on the low defence budgets.
Since the F-35 will be the cornerstone of the NATO airpower and US homeland defence the next decades, the problems with the F135 engine need attention of the highest political decision makers.
Joint Strike Fighter F135 Engine Burns Hotter Than Desired
F-35 Report: overview of problems with F-135 engine
..........Conclusion
The repeated problems with the same part of the engine may be indications of a serious design and structural problem with the F-135 engine.
A future F-35 fleetwide grounding will paralyze the Western Airpower. Also, the lack of reliability will contribute to low service ability and to high operating and support costs of the F-35 fleets in several countries putting more pressure on the low defence budgets.
Since the F-35 will be the cornerstone of the NATO airpower and US homeland defence the next decades, the problems with the F135 engine need attention of the highest political decision makers.
"Some aerospace officials contend the F135's over-heating problems will cause it to have trouble meeting Stovl requirements and they say Pratt & Whitney has been working on the problem for some time without solving it. Others think it's a predictable issue that comes with high-performance, stealth aircraft designs that have been made somewhat tougher by high-temperature Stovl ground ops.
BUT FOR THE STOVL ENGINE, ground operations (including hovering because it is done only for short periods) are not the most stressing part of the envelope, Gostic says. Where durability is most threatened is during "low-altitude, high Mach-number" operations, he contends."
Handy that...
Do a Hover - it avoids G
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Glad rag
When one goes flying in any fast jet with the benefit of a fuel flowmeter it is clear that the highest fuel flows are to be seen when flying flat out at low level on a cold day.
Just common sense really. The air mass flow is greatest then which gives you more oxygen to use for burning fuel. Throw in some pitch rate (think gyroscopic loads) and high g (obvious) and you have a good old stressing corner point on any engine
In the case of the Harrier these high speed low altitude fuel flows are greater than those in the hover when the poor old donk has to suck in its air as opposed to having it rammed in. But nobody believes that do they? Why? -'cos back in 1960 something a reporter said that the problem with a VTO or hovering is the high fuel consumption. Watching or flying a hover for a whole minute is so boring. Flying flat out (when needed) is something that tends to go on for rather more than a minute to put it mildly. But did TD ever say that flying flat out was not really on 'cos of the fuel consumption. Not that I recall.
Hey ho.
Where durability is most threatened is during "low-altitude, high Mach-number" operations, he contends."
Just common sense really. The air mass flow is greatest then which gives you more oxygen to use for burning fuel. Throw in some pitch rate (think gyroscopic loads) and high g (obvious) and you have a good old stressing corner point on any engine
In the case of the Harrier these high speed low altitude fuel flows are greater than those in the hover when the poor old donk has to suck in its air as opposed to having it rammed in. But nobody believes that do they? Why? -'cos back in 1960 something a reporter said that the problem with a VTO or hovering is the high fuel consumption. Watching or flying a hover for a whole minute is so boring. Flying flat out (when needed) is something that tends to go on for rather more than a minute to put it mildly. But did TD ever say that flying flat out was not really on 'cos of the fuel consumption. Not that I recall.
Hey ho.
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The engine failure that has grounded the entire fleet of Lockheed Martin Corp F-35 fighter jets was caused by "excessive" rubbing of fan blades in the plane's Pratt & Whitney engine, but does not appear to be a fundamental design flaw, the Pentagon's chief weapons buyer said on Sunday.
I seem to remember (reading somewhere) that the fan blades of the EJ200 were designed with an abradable tip, would this kind of blade tip be found further back in the turbine section of the engine as well?
TD
