OBOGS Suspects After F-22 Grounding

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Unread post10 May 2011, 03:32

After Grounding Raptors, USAF Eyes Other Jets' Oxygen Systems By DAVE MAJUMDAR 6 May 2011

http://www.defensenews.com/story.php?i= ... =AIR&s=TOP

"The U.S. Air Force, which on May 3 grounded its F-22 Raptors, has now identified which other aircraft might be affected by defective oxygen generators.

Since at least November, the service has been investigating the On-Board Oxygen Generation Systems (OBOGS) aboard the F-35 Lightning II Joint Strike Fighter (JSF) and other tactical aircraft and trainers. The service grounded the F-22s after a spike in incidents potentially related to hypoxia.

"No other airframes have been stood down due to this investigation; however, a parallel investigation is taking place on the on-board oxygen generation systems on the A-10, F-15E, F-16, F-35 and T-6 aircraft," said Capt. Jennifer Ferrau, an Air Force spokeswoman for Air Combat Command (ACC), the service's primary body for training and equipping the combat air forces.

Equipment such as the OBOGS is fairly standardized across multiple aircraft types, said Hans Weber, who sat on the U.S. Federal Aviation Administration's Research, Engineering and Development Advisory Committee, and is the president of Tecop International, a San Diego consulting firm.

"It's a big deal if you're at high altitude and you run out of oxygen," Weber said.

At 50,000 feet, a human being has less than 10 seconds of useful consciousness, he said.

Air Force Gen. William Fraser, commander of ACC, ordered a stand-down of the entire 158-plane F-22 fleet on May 3, Ferrau said. The service has not determined how long the Raptor fleet will remain grounded, nor has the exact nature of the problem been identified, she said.

"We are still working to pinpoint the exact nature of the problem. It is premature to definitively link the current issues to the OBOGS system," Ferrau said. "The safety of our airmen is paramount and we will take the necessary time to ensure we perform a thorough investigation."

There have been nine suspected cases of hypoxia during F-22 operations since mid-2008, and recently there has been a jump in the number of such incidents.

"Over the last week, we have experienced five additional F-22 'Physiological-Hypoxia Like' events across the Air Force, which led Commander of Air Combat Command to establish the current F-22 stand-down," Ferrau said.

Fraser has ordered an OBOGS Safety Investigation Board to get to the cause of these incidents, which now total 14.

Most of the incidents are characterized as "increased frequency of pilot reported physiological incidents such as hypoxia and decompression sickness," Ferrau said.

Air Force sources said that an OBOGS malfunction was suspected in a November crash outside Joint Base Elmendorf-Richardson, Alaska, that claimed the life of Capt. Jeff Haney of the 525th Fighter Squadron.

Despite the known OBOGS incidents, the Air Force will not officially link the November crash to the oxygen generator malfunctions.

"It is inappropriate for us to comment on the F-22 crash in Alaska, since the accident investigation board report has not concluded," Ferrau said.

Lockheed Martin, which builds the F-22, has dispatched a five-person team of engineers to help with the Air Force OBOGS investigation, company spokeswoman Stephanie Stinn said."
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Unread post10 May 2011, 03:54

Honeywell [F-35 OBOGS] "Suck it and See" [if it woiks]

http://www.jsf.org.uk/JSF-UK-Industry-T ... ywell.aspx

"Honeywell Aerospace is a leading global provider of integrated avionics, wheels and brakes, engines, systems and service solutions for aircraft manufacturers, airlines, business and general aviation, military, space and airport operations.

Honeywell Aerospace in the UK produce and supply Air Management and Life Support Systems for civil and military aircraft. It has vast experience and capability in Life Support, from a background of traditional, high pressure, stored gaseous and liquid oxygen to today’s On Board Oxygen Generation Systems (OBOGS). The consolidation of experience on the B-1B, B-2, F-22 and Eurofighter aircraft, and other state-of-the-art systems made it capable of being readily tailored to many different single/twin seat and multicrew aircraft and, ultimately, selection for the F-35.

Developed in the 1980’s at it’s facility in Yeovil, Somerset, Honeywell’s OBOGS technology allows an aircraft to generate its own oxygen from a conditioned air supply during flight, giving significant advantages in reliability, safety and performance over older gaseous and liquid oxygen systems. OBOGS takes advantage of a molecular sieve material, Zeolite, which traps nitrogen molecules when air is passed through it, allowing it to act as a molecular sieve.

At ground level humans breathe air with a 21% oxygen concentration in order to oxygenate the bloodstream and, hence, sustain life. The pressure exerted by the oxygen component of air is termed the Partial Pressure of Oxygen (PPO2). It becomes progressively more difficult for humans to take in oxygen as PPO2 decreases in direct proportion to air pressure with increasing altitude. At higher altitudes this will lead to insufficient oxygen being present in the bloodstream, a condition known as hypoxia, and eventually death. The OBOGS is controlled by a solid state monitor/controller that monitors the PPO2 level of the OBOGS product gas, and adjusts the cycling of the beds to produce the desired level of oxygen concentration. To prevent hypoxia in military aircrew it is necessary, as a rule of thumb, to maintain the minimum of PPO2 to the equivalent of altitudes in the range 8,000 feet to 10,000 feet in order to perform normal levels of work."
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Unread post10 May 2011, 04:09

NASA Onboard Inert Gas Generation System/Onboard Oxygen Gas Generation System (OBIGGS/OBOGS) Study Part I: May 2001

http://ntrs.nasa.gov/archive/nasa/casi. ... 074913.pdf (8,6Mb)

ONLY relevant to large commercial jet aircraft but may be useful info therein.
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Unread post10 May 2011, 04:33

JSF/F-35 Pollution Prevention Activities 22-23 May 2006
http://www.asetsdefense.org/documents/W ... s-F-35.pdf (4.4Mb)
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Unread post10 May 2011, 06:38

GAS SEPARATION TECHNOLOGY: STATE OF THE ART Thomas L. Reynolds - Boeing - Seattle Phantom Works

http://fire.nist.gov/bfrlpubs/fire02/PDF/f02178.pdf (244Kb)
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Unread post11 May 2011, 00:43

Analysts Chew Over USAF'S OBOGS Groundings By DAVE MAJUMDAR : 10 May 2011

http://www.defensenews.com/story.php?i= ... =AIR&s=TOP

"An abundance of caution likely motivated the U.S. Air Force to launch investigations into the oxygen-generation systems found on board a number of fighter and trainer aircraft, analysts said.

"When you get to life-support systems, that is something the Air Force and any service tends to take a very hard line with," said Mark Gunzinger, an analyst at the Center for Strategic and Budgetary Assessments in Washington and former Air Force pilot. "They are very, very cautious and risk-averse because we're not just dealing with the loss of a major weapon system, but the loss of a human life."

On May 6, the service identified the F-16, F-15E, A-10, F-35 and T-6 aircraft as being under investigation for problems with their On-board Oxygen Generation Systems (OBOGS).

The revelation came on the heels of news that the Air Force had effectively grounded its fleet of F-22 Raptor stealth fighters on May 3.

"They want to be doubly sure that the problems that they are experiencing with the F-22 OBOGS is not something that could be common to other systems and other aircraft," Gunzinger said. "It's something that's very, very prudent, and a very smart thing to do."

Had the Air Force specific information on a particular problem, the aircraft in question would be grounded, Gunzinger said.

However, the service has not pinpointed the exact cause for concern on the OBOGS systems on board the various aircraft.

"The OBOGS safety investigation is looking at all oxygen generation systems, casting a broad net for comparison of designs and functionality, thereby peeling back all aspects to seek any peculiarities of design, operation, and performance," said Capt. Jennifer Ferrau, an Air Force spokeswoman representing Air Combat Command, which trains and equips the combat air forces. "No particular sub-system had stood out as an area of concern, so this investigation seeks to identify any area of concern."

The Air Force has commissioned an OBOGS Safety Investigation Board, headed by a flag officer, which consists of safety investigation officers, pilots, doctors, engineers, maintainers among other specialists to get to the root of the problem.

Hans Weber, who sat on the U.S. Federal Aviation Administration's Research, Engineering and Development Advisory Committee, and is the president of Tecop International, a San Diego consulting firm, said that the Air Force likely does not yet have a good idea of what the problem with the OBOGS is.

"I'm sure it's a surprise to everybody with a system that has been in operation for decades that all of a sudden they run into problems with it" he said.

OBOGS systems have been used for many years, and each generation of aircraft improves upon the technology, Weber said.

It is possible that during the drive to shrink and lower the weight of the OBOGS for the F-22, engineers may have inadvertently induced some sort of problem. It could be that there is something unique about the F-22 OBOGS design, Weber said.

"We haven't had any such problem for a long, long time; that tells us something," he said.

The Air Force would not release any other details about the investigation except that the OBOGS specific investigation started in January. Nor would the Air Force say whether pilots flying aircraft other than the Raptor had experienced hypoxia-related incidents.

The fact that the service ordered a fleetwide standdown of the Raptor indicates a potentially significant problem, but it does not indicate a systemic issue with the U.S. tactical aircraft fleet, Gunzinger said.

"There is not a huge major problem with the entirety of the tactical aviation force, but it's better to be safe than sorry," he said.

However, Weber said the fact that the entire Air Force tactical fighter fleet is being investigated suggest that a wider problem with the OBOGS exists.

"The fleet investigation has a fairly high hurdle. There has to be something that is a big question mark or something that is a suspect part or system," he said. "What they're telling us here is that the investigation has not fingered any particular part."

Both agree that there is a particular problem with the Raptor however.

"The F-22 grounding itself implies that this is probably something that is a little more than a normal thing with the system," Gunzinger said.

However, problems with subsystems are not unusual. The B-52, for example, has had problems with its brakes in previous years, he said.

"This is not unprecedented," he said.

The most likely problem with the OBOGS is the long-term reliability of certain components, Weber said. Parts that operated normally during tests might be wearing out more quickly than anticipated, he said. Which could lead to the eventual modification and replacement of the parts as a potential fix, Weber said.

If the cause of the problem is a subsystem that can be easily replaced, the grounding should be resolved fairly quickly, Gunzinger and Weber both said. However, deeper structural defects with the OBOGS will take longer to fix.

In either case, in the longer term, modifications are likely to be necessary to resolve the problem, Weber said.

However, "I wouldn't anticipate that this would be a very lengthy grounding," Gunzinger said.

Weber said that of the aircraft named, the F-35 is most likely at risk for a similar problem.

Both the F-22 and F-35 use late-model OBOGS designs built by Honeywell. The other aircraft are at less risk because they are older systems which are built by another manufacturer: Cobham.

Neither company offered substantial comment.

The F-35 program office said that while the F-35 had absorbed many lessons from the F-22 program, the systems onboard the newer jets have little in common with the Raptor.

"The F-35 and F-22 have common aircraft and oxygen system suppliers; but the systems are very different. The program has leveraged the lessons learned from F-22 development to enhance the F-35 across all subsystems, including the Onboard Oxygen Generating System," said F-35 program office spokesman Joe DellaVedova.

The F-35 program is supporting the investigation into the Raptor OBOGS problem, DellaVedova said.

"At this time the program office does not see any commonality in the potential causal factors that the F-22 program is investigating," he said.

The U.S. Navy had not responded to queries asking if the F/A-18 Hornet is under a similar investigation. The jet is known to use an OBOGS analogous to those on Air Force planes."
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Unread post11 May 2011, 01:55

Honeywell F-22 Oxygen Systems Probed [Maybe a COBHAM System will get the nod in future?]
By Tony Capaccio - May 11, 2011

http://www.bloomberg.com/news/2011-05-1 ... robed.html

"A Honeywell Inc. system for providing oxygen to F-22 pilots is being investigated as a possible source for malfunctions that prompted the Air Force to ground its premier fighter jet after reports of five incidents since late April, according to officials.

“The inquiry is not solely focused” on Honeywell’s on- board oxygen generating system, Air Combat Command spokeswoman Captain Jennifer Ferrau said in an e-mail. “However, that is one area investigators will look at.”

Honeywell Aerospace spokesman Bill Reavis said “the company will provide appropriate technical and program support in the evaluation of this matter.”

The Air Combat Command on May 3 temporarily halted flights of the F-22 “until further notice,” according to an e-mailed statement from the command, based at Langley Air Force Base, Virginia. The Air Force has taken delivery of 160 of the stealth F-22 jets.

“The stand-down is a prudent measure following recent reports of potential oxygen system malfunctions” and gives Air Force officials time to investigate the system, the command said. The F-22 Raptor is the U.S. military’s most advanced fighter.

The grounding order was spurred by a five instances since late April of F-22 “physiological-hypoxia-like” events that may be indications of potential malfunctions, the Air Force said.

‘Physiological Symptoms’
One incident involved a pilot assigned to the 302nd Fighter Squadron in Alaska who “scraped the underside of the aircraft on trees during a landing approach,” an e-mail to congressional defense committees said. “The pilot does not recall the incident and is being treated for physiological symptoms.”

Prior to the five recent F-22 events, nine incidents were reported between June 2008 and February, the Air Force said.

Those nine incidents trigged a safety board investigation of the Honeywell system. The five additional incidents in quick succession triggered the F-22 grounding, however, Ferrau said.

“We are still in the early stages of investigating the reports” and “working to pinpoint the exact nature of the problem.”

A parallel investigation is reviewing the F-35 Joint Strike Fighter’s oxygen system, also made by Morris Township, New Jersey-based Honeywell, she said. The Pentagon plans to buy more than 2,400 F-35s, made by Lockheed Martin Corp. (LMT), of Bethesda, Maryland.

‘Very Different’ Systems
The two systems “are very different,” the military’s F-35 spokesman, Joe DellaVedova, said in an e-mail. “The program has leveraged the lessons learned from F-22 development to enhance the F-35 across all subsystems, including oxygen system,” he said. “The F-35 program was immediately made aware of last week’s F-22 incidents,” he said.

“At this time, the program office does not see any commonality in the potential causal factors the F-22 program is investigating,” he said.

Lockheed Martin spokeswoman Laurie Quincy said in an e-mail that the F-22 and F-35 oxygen systems have “unique differences” but “as a precaution the F-35 team is reviewing” the Raptor system “design and performance to gain additional insight to improve the F-35 system if required.”

DellaVedova said F-35 program officials continuously monitor “issues present in other aircraft” while “assessing applicability to our current design.”

‘Monitoring Future Findings’
“The F-35 program has both contractor and government engineers supporting the investigation,” he said. “The F-35 will continue to play an active role monitoring future findings and applying them to the F-35 system as appropriate.”


The estimated cost of the F-22 is about $411 million per jet in inflation-adjusted dollars that amortize research, development, production, maintenance and construction of support facilities. That’s about triple the $139 million-per-plane equivalent estimated cost as the program proceeded into full development in 1991, the U.S. Government Accountability Office said in its latest annual report on weapons systems.

F-22 jets are based in Virginia, New Mexico, California, Florida, Alaska and Hawaii."
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Unread post17 May 2011, 05:56

Oxygen-generator inquiry covers all AF fighters By Dave Majumdar - Staff writer Monday May 16, 2011

http://www.airforcetimes.com/news/2011/ ... s-051611w/

"The Air Force investigation into problems with the F-22’s oxygen-generation systems extends beyond the Raptor and includes fighters the service has been flying for decades.

A safety investigation board, headed by an Air Force flag officer, is looking at problems with the On-Board Oxygen Generation Systems of the F-16, F-15E, A-10, F-35 and T-6 aircraft, service officials said May 6, three days after all F-22s were grounded because of a spike in hypoxia incidents during flight.

“The OBOGS safety investigation is looking at all oxygen generation systems, casting a broad net for comparison of designs and functionality, thereby peeling back all aspects to seek any peculiarities of design, operation and performance,” said Capt. Jennifer Ferrau, an Air Force spokeswoman representing Air Combat Command.

“No particular subsystem had stood out as an area of concern, so this investigation seeks to identify any area of concern,” she said.

The board conducting the investigation includes safety investigation officers, pilots, doctors, engineers, maintainers and other specialists.

Hans Weber, who sat on the Federal Aviation Administration’s Research, Engineering and Development Advisory Committee and is the president of Tecop International, a San Diego consulting firm, said the Air Force likely does not yet have a good idea of what the problem with the OBOGS is.

“I’m sure it’s a surprise to everybody with a system that has been in operation for decades that all of a sudden, they run into problems with it,” he said.

Each generation of aircraft improves upon the technology, Weber said.

It is possible that during the drive to shrink and lighten the OBOGS for the F-22, engineers may have inadvertently introduced a problem; there may be something unique about the F-22’s OBOGS design, Weber said.

“We haven’t had any such problem for a long, long time; that tells us something,” he said.

The Air Force would not release any other details about the investigation, except that the OBOGS-specific investigation started in January. Nor would the Air Force say whether pilots flying aircraft other than the Raptor had experienced hypoxia-related incidents.

The fact that the service ordered a fleetwide stand-down of the Raptor indicates a potentially significant problem, but it does not indicate a systemic issue with the U.S. tactical aircraft fleet, said Mark Gunzinger, an analyst at the Center for Strategic and Budgetary Assessments in Washington and a former Air Force pilot.

Just to be safe
“There is not a huge, major problem with the entirety of the tactical aviation force, but it’s better to be safe than sorry,” he said.

However, Weber said the fact that the entire Air Force tactical fighter fleet is being investigated suggests that a wider problem with the OBOGS exists.

“The fleet investigation has a fairly high hurdle. There has to be something that is a big question mark or something that is a suspect part or system,” he said. “What they’re telling us here is that the investigation has not fingered any particular part.”
Both agree that there is a particular problem with the Raptor, however.

“The F-22 grounding itself implies that this is probably something that is a little more than a normal thing with the system,” Gunzinger said.

However, problems with subsystems are not unusual. The B-52 bomber, for example, has had problems with its brakes in previous years, he said.

The OBOGS’ most likely problem is the long-term reliability of certain components, Weber said. Parts that operated normally during tests might be wearing out more quickly than expected, he said, which could lead to the eventual modification and replacement of the parts as a potential fix.

If the problem’s cause is a subsystem that can be easily replaced, the grounding should be resolved fairly quickly, Gunzinger and Weber said. However, deeper structural defects with the OBOGS will take longer to fix.

In either case, in the longer term, modifications are likely to be necessary to resolve the problem, Weber said.

However, “I wouldn’t anticipate that this would be a very lengthy grounding,” Gunzinger said.

Weber said that of the aircraft named, the F-35 is most likely at risk for a similar problem. Both the F-22 and the F-35 use late-model OBOGS designs built by Honeywell. The other aircraft are at less risk because they have older systems built by another manufacturer, Cobham.

Neither company offered substantial comment.

The Pentagon’s F-35 program office said that while the F-35 had absorbed many lessons from the F-22 program, the systems onboard the newer jets have little in common with the Raptor.

“The F-35 and F-22 have common aircraft and oxygen-system suppliers, but the systems are very different. The program has leveraged the lessons learned from F-22 development to enhance the F-35 across all subsystems, including the Onboard Oxygen Generating System,” said F-35 program office spokesman Joe DellaVedova.

The F-35 program is supporting the investigation into the Raptor OBOGS problem, DellaVedova said.

“At this time, the program office does not see any commonality in the potential causal factors that the F-22 program is investigating,” he said.


The Navy said the F/A-18 fighter is not under investigation. The jet is known to use an OBOGS similar to those on Air Force planes that has had problems in the past."
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Unread post17 Jun 2011, 19:15

F-22 grounding continues as oxygen safety probe widens By Stephen Trimble :16/06/11 :Flight International

http://www.flightglobal.com/articles/20 ... idens.html

"More than six weeks after the US Air Force indefinitely grounded all Lockheed Martin F-22A Raptors, the scope of the safety investigation has widened beyond the Honeywell-supplied onboard oxygen generating system (OBOGS).

Although internally described as the "OBOGS safety investigation", the probe launched after the 3 May safety stand-down of the F-22A fleet is "not limited" to that particular system, Air Combat Command (ACC) said in emailed responses to questions.

"We are still working to pinpoint the exact nature of the problem," the ACC said. "It is premature to definitely link the current issues to the OBOGS system."

The stand-down was originally linked to five reports by F-22 pilots of potential oxygen system malfunctions, including one reported instance when an F-22 scraped treetops on final approach. The pilot could not remember the incident after landing, exhibiting a classic symptom of hypoxia.

The OBOGS is not the only device involved in the supply of oxygen to the pilot. Wedged into a space behind and slightly below the pilot's seat, it uses a molecular sieve to filter pressurised air diverted from the engine compressor section into pure oxygen.

In between the OBOGS and an F-22 pilot's lungs, the filtered oxygen passes through two major components - the MBU-22P oxygen mask and the breathing regulator/anti-g (BRAG) valve. The latter "ensures safe delivery of oxygen to the pilot" through the face mask, according to a fact sheet published by the USAF human systems integration office.

"The BRAG is fast-acting due to the manoeuverability of the aircraft and [is] compatible with the existing upper and lower g-garments, which keeps blood in the upper portions of the body during aircraft manoeuvres," the fact sheet added.

The USAF investigation is also comparing the F-22's life support system with other strike aircraft in its fleet, including the Lockheed F-35A Lightning II, Fairchild Republic A-10, Boeing F-15, Lockheed F-16 and Hawker Beechcraft T-6A, the ACC said.

The review is aimed at casting a "broad net for comparison", the command added.

Complaints about the F-22's OBOGS equipment had not surfaced until recently. In January, the ACC ordered the fleet to remain below a service ceiling of 25,000ft (7,620m). The order came two months after an F-22 crashed near Joint Base Elmendorf-Richardson, Alaska. That accident, in which the pilot was killed, is under investigation and has not been linked to the oxygen system concerns."
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Unread post10 Jul 2011, 19:21

F-22 Raptor Deliveries Halted July 10th, 2011

http://defensetech.org/2011/07/10/f-22- ... eliveries/

"The two-month long grounding of the F-22 Raptor fleet is not only preventing the Air Force from flying its premier fighter but it’s keeping the service from getting any new ones.

Raptor-maker, Lockheed Martin, and government test pilots can’t perform the check-flights necessary to accept new jets into USAF service, as a result of the grounding. The entire F-22 fleet was on altitude restrictions for months after the December crash of an F-22 in Alaska was suspected of being caused by the failiure of the craft’s oxygen generating system. On May 3, that flight restriction was replaced with an all-out grounding of the fleet. At this point, it’s unkown when the fleet will take to the skies again. All this will probably create a backlog in deliveries of the final Raptors, according to Defense News:

Technically, four aircraft have been delivered to the Air Force, but are being stored at Marietta pending the lifting of the flight restrictions. When the Air Force resumes F-22 flight operations, those aircraft will be flown to Langley Air Force Base (AFB), Va.

Two further aircraft, 4182 and 4183, have been completed, but the company and DCMA can’t do required flight testing on those jets, Stinn said. The aircraft are being stored in a near-flight-ready status, she said.

Aircraft “4182 and 4183 were scheduled to deliver in July, but they’re not in a position to do any sort of test flights, so we can’t deliver,” Stinn said. “Maybe early August, but we don’t have a definitive date.”

Aircraft 4182 and onwards, which have not undergone any of their acceptance flights, have yet to receive their final stealth coatings. The coatings are applied only after a number of flight tests have been completed, and as a result, a backlog is slowly building up.

Before the stealth coatings are applied, the aircraft fly coated only with a primer.

Let’s hope something like this doesn’t happen to the F-35 Joint Strike Fighter fleet when it makes up the vast majority of U.S. tactical fighters."

http://images.defensetech.org/wp-conten ... flight.jpg

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Unread post10 Jul 2011, 19:33

The F-22 blog on OBOGS has mistakenly added to the F-35 forum. Nothing has tied the F-22 OBOGS problem to the F-35 program. Please, Please move this back where it belongs, the F-22 forum.

Thank You,

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Unread post10 Jul 2011, 19:41

neptune: Why is the F-35 mentioned in these news reports. Just a few entries above we have this quote: "...The USAF investigation is also comparing the F-22's life support system with other strike aircraft in its fleet, including the Lockheed F-35A Lightning II, Fairchild Republic A-10, Boeing F-15, Lockheed F-16 and Hawker Beechcraft T-6A, the ACC said.

The review is aimed at casting a "broad net for comparison", the command added...."
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seruriermarshal

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Unread post10 Jul 2011, 23:35

I think they update new system for F-22 :

The flight restriction applies to all F-22 crews, but test pilots at Edwards AFB, Calif., are operating under a flight waiver that allows them to fly certain test sorties. Air Force officials at Edwards could not immediately say what kind of test sorties those aircraft are flying.

http://www.defensenews.com/story.php?i= ... =AME&s=AIR
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Unread post13 Jul 2011, 03:09

Seems like 'grounding' an aircraft means different things to different people if this observer is being truthful....

http://pogoblog.typepad.com/pogo/2011/0 ... -f-22.html

"Brueschke [in comments section of main story (a rehash of all of the above)]

I live within two miles of Joint Base Elmendorf Richardson and if the F-22 is "stood down" or "grounded", then there are a lot of sorties of F-22 breaking the rules. I've seen three pairs of them this morning over head.

My understanding is that they are currently restricted from -.1 to -.3 G at altitudes where the pilots have to be on OBOGS because thats the envelope where the system fails. It works above -.1G and at below -.3 G and it has something to do with a valve in the OBOGS.

The Alaska F-22 fleet was very active during the recent Northern Edge '11 and while where was a lag in operations back in March for a radar and software upgrade, they've been flying since April."
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Raptor_DCTR

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Unread post13 Jul 2011, 06:22

Those were F-18s and F-15s flying, not F-22s.
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