BAe Hawk vs T45

[rb1957]

I was reading in Flight that the US version of the BAe Hawk, the T45 Goshawk, has trouble with it's O2 system.

I assume this is a US system since ...
a) no history of a BAe Hawk O2 system problem, and
b) other US types have O2 problems.

do you think I'm right ? If so, I wonder what makes the US O2 system different to the rest of the world's ?

another day in paradise, or is paradise one day closer ?

 

[WKTaylor]

RB... update on grounding and USN solution RE T-45.
T-45 Goshawks Are Flying Again


Air Boss Lifts Operational Pause April 17

Vice Adm. Mike Shoemaker, Commander, Naval Air Forces (CNAF), announced April 15 that the operational pause for the T-45C would be lifted on Monday, April 17.

Flight operations were expected to resume early this week using a modified mask, successfully tested by Naval Air Systems Command (NAVAIR), that circumvents the aircraft's On Board Oxygen Generator System (OBOGS).

Initially, instructor pilots will conduct warm-up flights, after which they will brief the remaining pilots and students in their squadrons on use of the modified equipment. As the week progresses all instructor pilots will complete their warm-up flights, followed by warmups and training flights for student pilots.

"After briefings and discussions with our aircrew, their training wing leadership, the engineers, and aeromedical experts, we have identified a way forward to resume flight operations safely by limiting the maximum cabin altitude to below 10,000 feet in order be able to operate without using the OBOGS system," Shoemaker explained. "We will be able to complete 75 percent of the syllabus flights with the modified masks while we continue the important engineering testing and analysis at PAX River [Naval Air Station Patuxent River, Maryland] to identify the root cause of the problem. This will remain our top safety priority until we fully understand all causal factors and have identified a solution that will further reduce the risks to our aircrew."

Finding the root cause is a challenge on this complex, highly sophisticated platform. "We have energized the force, are working with outside agencies, and established an Integrated Project Team (IPT) at NAVAIR, along with an aeromedical crisis action team of flight surgeons, physiologists and toxicologists. All teams are immersed in this effort and working with the same sense of urgency to solve our physiological episodes across the fleet," Shoemaker said.

In addition to the IPT and aeromedical crisis action team, the congressionally mandated Independent Review Team (sourced from NASA) recently visited Naval Air Station Meridian as part of an ongoing independent review of physiological episodes.

(Source: U.S. Navy news release. Image from file)

FMI:

http://www.navy.mil/local/PEs

http://www.aero-news.net/annticker.cfm?do=main.textpost&id=5305363e-05de-4f48-88c6-6a4d6f71aa25

NOTE.
The OBOGS system in possible culprit: T-45 solution allows by-pass to LOX or GOX system if OBOGS is inop.

I suspect that the UK BAE Hawk has a LOX or GOX system, ONLY.

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[rb1957]

yes will, I saw that on Flight and started thinking. I haven't heard of similar issues with the UK operated a/c so thought the T45 had a US system.

cheers

another day in paradise, or is paradise one day closer ?

 

[WKTaylor]

RB.

It seems that OBOGS is a great idea that has had many in-service difficulties, various reasons. Whereas LOX and GOX systems are remarkably simple/reliable... assuming a good supply of LOX or GOX for servicing... which is the reason OBOGS seems so desirable. However the article implied that the T-45 has a secondary O2 system [GOX?]... just-in-case the OBOGS fails. Hmmm.

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[rb1957]

belts and braces ?

another day in paradise, or is paradise one day closer ?

 

[WKTaylor]

RB...

A reliable supply of aviators breathing oxygen is mandatory for all USAF fixed wing aircraft operations [OK there are a few exceptions]. Aircraft are not authorized to fly missions with a depleted O2 system.

In-theory, a reliable OBOGS frees acft from the need for a constant re-supply of Aviators GOX or LOX...

NOTE.
The one centralized point on any Air Base [USAF/USN/USMC... or local area supply-source] that is highly vulnerable to mechanical/reliability/quality issues and/or sabotage and/or direct attack, is the GOX/LOX generation/storage 'facility'. NOT to forget that there is a lot of work [time-effort-equipment-personnel-$$] involved in refreshing aircraft LOX or GOX tanks before missions.

So, as a back-up, most OBOGS equipped acft have-to-have a small GOX system.

Also... there is a battle-damage reason against large capacity LOX and GOX systems. These systems, when damaged, can release a frightening amount of pressurized oxygen into aircraft cavities that represents a high over-pressure/fire/explosion potential.

A large USAF tactical jet experienced a LOX bottle vent blockage due to ice formation [plug] in the pressure relief vent. When the pressure of gaseous O2 in the LOX bottle/converter exceeded system ultimate, the resulting 'over-pressure blow-out event' severely damaged the forward/side fuselage. Aircraft was taken apart and shipped back to the Air Depot for major repairs/rebuild.

A small USAF jet was inadvertently serviced with 1500-PSI O2 into a ~400-PSI limit GOX Bottle. The 'over-pressure blow-out event' separated the aft fuselage just behind the wing. The aircraft was scrapped.

Another Jet suffered a small/confined electrical cockpit fire under an aluminum GOX tube. WHEN the tube failed due to softening/melting the small/confined electrical fire was fed with 400-PSI pure oxygen... and the fire instantly became a raging inferno in the cockpit feeding on plastic parts, nylon fabrics, parachute packs, helmets, and eventually the fuel tank under the structural deck. ONLY one crewman survived ejection... badly burned with a damaged parachute... The aircraft crashed trailing a massive fiery tail... 'like a comet'.

NOTE... just-in-case these terms are unfamiliar to others...

OBOGS = On-Board Oxygen Generation System
LOX = Liquid OXygen
GOX = Gaseous OXygen [low-to-high pressure compressed O2]

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[rb1957]

will, you have a lot of sobering stories ...

another day in paradise, or is paradise one day closer ?

 

[3DDave]

This is from an EgyptAir failure of the O2 system.

Off topic: The article is in connection with the MH370; I put it as the leading theory that explains the MH370 disappearance in fitting the observations without any conflicts. Looking at the EgyptAir results on the ground with fire crews only a minute or so away, I can imagine the same thing happening at altitude being terrifying and rendering the plane out of communication and uncontrollable.

http://www.dailymail.co.uk/news/art...owned-missing-jet-claims-London-law-firm.html

 

[WKTaylor]

... and a similar terrifying event [in aft fuselage] of an RC-135V RivetJoint during Takeoff Roll...

All crew were evacuated 'safe'... but estimated repairs are ~$62M.

USAF RC-135V Rivet Joint Oxygen Fire

http://aerossurance.com/safety-management/usaf-rj-oxygen-fire/

Photo...

http://files.engineering.com/getfil...&file=usaf-rc135v-rivet-joint-fire-damage.jpg

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[rb1957]

not to make light of it, but O2 is a good fuel for fire ...

another day in paradise, or is paradise one day closer ?

 

[3DDave]

O2 is good for turning anything else into fuel, though F is even better.

 

[Sparweb]

The author of this website has some thoughts on O2 systems:

http://www.code7700.com/oxygen.htm

If you scroll down to near the bottom of that page, you'll see (in yellow text) an anecdote about pilots made ill by their O2 system. Certainly not a hazard I was aware of before. The source of the hazard (contamination in the lines) could be from a unique source, from a systematic source due to local environment or a particular owner's practices (explaining a different set of problems between one fleet and a similar fleet owned by someone else) or from a source inherent in the design.

Pursuit of the real story behind the webpage anecdote may turn up more info.


STF

 

[moon161]

Tangential and interesting to me is the 'raptor cough' which affects pilots of the F-22 and possibly the F-35, both using OBOGS.

https://duckduckgo.com/?q=raptor+cough&t=ffab&ia=news

Some of the stuff I've read

https://www.quora.com/What-was-the-reason-for-the-black-cough-of-F-22-pilots

indicates what I'd expected, that they're breathing or even concentrating something harmful that the zeolite isn't catching. IDK if a LOX system would prevent this or not.