radargeek
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Engine Drops Out of B-52 During Training:

Thu Jan 05, 2017 6:00 am

http://www.defensenews.com/articles/engine-drops-out-of-b-52-during-training-at-minot-air-force-base


MINOT AIR FORCE BASE, N.D. — An engine dropped out of a B-52 bomber during a training flight on Wednesday, the Air Force has confirmed following questions from Defense News.



Because the B-52 runs on eight Pratt & Whitney TF33-P-3/103 turbofan engines, pilots were able to land the aircraft safely without any injury to the five personnel on board. The Air Force has since dispatched a UH-1N Huey helicopter to recover engine debris, which was found located in an unpopulated area about 25 nautical miles northeast of Minot Air Force Base, an Air Force spokesman said in a statement.

There were no weapons onboard the B-52, which belongs to Minot Air Force Base's 5th Bomb Wing and was conducting a training mission, he said.

The service was not able to provide the root cause of the mishap, but the spokesman said an initial safety investigation has been initiated.

The incident could also ignite debate about whether and how to re-engine the service’s B-52 inventory. The Boeing-manufactured bomber has been flying since 1952 and is expected to remain operating until around 2040, depending on when it is fully replaced by the Northrop Grumman’s B-21.


Defense News
USAF Looking at B-52 Engine Options
In 2015, Lt. Gen. Mike Holmes, deputy chief of staff for Strategic Plans and Requirements, said the service was especially interested in a public-private partnership, which would keep it from having to funnel procurement dollars into a new engine program.

"The idea is in a public-private partnership, somebody funds the engine and then we pay them back over time out of the fuel savings, which are generated out of the new engines," he said then.

Pratt & Whitney has proposed an upgrade package for the TF33-P-3/103 engines that would make them less expensive to maintain.

Analysts have also floated the Pratt PW2000, known as the F117 when installed on military aircraft, as a potential substitute for the TF33. Engine manufacturers General Electric and Rolls-Royce could also offer their own replacements.

There are currently 76 B-52’s in the Air Force’s inventory.
 
LightningZ71
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Re: Engine Drops Out of B-52 During Training:

Thu Jan 05, 2017 2:25 pm

The RR BR7XX series engines are, in at least one version, almost a drop in fit for the existing nacell. They are relatively inexpensive, still in commercial service, offer equivalent thrust with a much lower specific fuel consumption. Obviously, engine controls and the insides of the existing nacell will need to be reengineered, but it won't require completely redoing the entire nacell. Also, the RR BR7XX is not heavier than the existing engines, reducing structural effects on the wings.

There is no need to go with some ultra expensive state of the art engine for a plane that will be around no longer than 20 or so more years. Especially one that requires major changes to the airframe and nacell aerodynamics.
 
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AirlineCritic
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Re: Engine Drops Out of B-52 During Training:

Thu Jan 05, 2017 6:50 pm

If you lose one engine from the B-52, do you always lose two? They seem to be residing in one case...
 
apfpilot
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Re: Engine Drops Out of B-52 During Training:

Thu Jan 05, 2017 7:36 pm

The dreaded 7 engine landing.
Opinions are my own and do not reflect an endorsement or position of my employer.
 
iamlucky13
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Re: Engine Drops Out of B-52 During Training:

Fri Jan 06, 2017 5:45 am

What do they mean by dropped? As written, it sounds like the entire engine broke away from the pylon. Or did they had an uncontained failure, and perhaps "losing" an engine was misinterpreted?

If the entire engine was somehow lost, that sounds less like something that "reignites" the re-engining debate, and more like either an installation mistake, or unnoticed fatigue.

Several others news sites are claiming the aircraft literally dropped an entire engine, but all of them cite the article the OP linked as their source.

apfpilot wrote:
The dreaded 7 engine landing.


An oldie, but a goodie. :thumbsup:
 
Flighty
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Re: Engine Drops Out of B-52 During Training:

Fri Jan 06, 2017 10:17 am

apfpilot wrote:
The dreaded 7 engine landing.


THEY MADE IT!
:santahat: :santahat: :santahat:
 
iamlucky13
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Re: Engine Drops Out of B-52 During Training:

Fri Jan 06, 2017 10:49 am

I found an article from the Minneapolis news that has more detail, but not necessarily more useful detail:
http://www.twincities.com/2017/01/05/en ... orce-says/

"They do believe at this point that it was really a catastrophic failure of that one engine. Another way of putting that is it disintegrated and then fell out of the aircraft upon disintegration,"


I'm getting the impression they really do mean the whole engine detached from the pylon, but this is a weird way of describing it, because it sounds like something more complex than a failure of the mount points.
 
AWACSooner
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Re: Engine Drops Out of B-52 During Training:

Sat Jan 07, 2017 3:21 am

LightningZ71 wrote:
The RR BR7XX series engines are, in at least one version, almost a drop in fit for the existing nacell. They are relatively inexpensive, still in commercial service, offer equivalent thrust with a much lower specific fuel consumption. Obviously, engine controls and the insides of the existing nacell will need to be reengineered, but it won't require completely redoing the entire nacell. Also, the RR BR7XX is not heavier than the existing engines, reducing structural effects on the wings.

There is no need to go with some ultra expensive state of the art engine for a plane that will be around no longer than 20 or so more years. Especially one that requires major changes to the airframe and nacell aerodynamics.

They actually investigated re-engining the planes with just 4 of em a few years back...the problem is that, if you lose one on one side, with the shortened rudder of the H model (vs the D model), you can't get enough rudder to overcome the asymmetric thrust.
 
jetblueguy22
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Re: Engine Drops Out of B-52 During Training:

Sat Jan 07, 2017 4:11 am

Must have been a real adventure trying to find all the pieces. Minot has gotten absolutely pummeled the last month or so with snow
Look at sweatpants guy. This is a 90 million dollar aircraft, not a Tallahassee strip club
 
ThePointblank
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Re: Engine Drops Out of B-52 During Training:

Sat Jan 07, 2017 5:32 am

AWACSooner wrote:
LightningZ71 wrote:
The RR BR7XX series engines are, in at least one version, almost a drop in fit for the existing nacell. They are relatively inexpensive, still in commercial service, offer equivalent thrust with a much lower specific fuel consumption. Obviously, engine controls and the insides of the existing nacell will need to be reengineered, but it won't require completely redoing the entire nacell. Also, the RR BR7XX is not heavier than the existing engines, reducing structural effects on the wings.

There is no need to go with some ultra expensive state of the art engine for a plane that will be around no longer than 20 or so more years. Especially one that requires major changes to the airframe and nacell aerodynamics.

They actually investigated re-engining the planes with just 4 of em a few years back...the problem is that, if you lose one on one side, with the shortened rudder of the H model (vs the D model), you can't get enough rudder to overcome the asymmetric thrust.

I think the plan was that all of the engines would run derated at around 75% anyways, and if there was an engine out scenario, the FADEC and avionics would automatically kick the other engine on the failure side to max power, and reduce the thrust on the other side. Theoretically, it would be enough.
 
mmo
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Re: Engine Drops Out of B-52 During Training:

Sat Jan 07, 2017 11:50 am

AWACSooner wrote:
LightningZ71 wrote:
The RR BR7XX series engines are, in at least one version, almost a drop in fit for the existing nacell. They are relatively inexpensive, still in commercial service, offer equivalent thrust with a much lower specific fuel consumption. Obviously, engine controls and the insides of the existing nacell will need to be reengineered, but it won't require completely redoing the entire nacell. Also, the RR BR7XX is not heavier than the existing engines, reducing structural effects on the wings.

There is no need to go with some ultra expensive state of the art engine for a plane that will be around no longer than 20 or so more years. Especially one that requires major changes to the airframe and nacell aerodynamics.

They actually investigated re-engining the planes with just 4 of em a few years back...the problem is that, if you lose one on one side, with the shortened rudder of the H model (vs the D model), you can't get enough rudder to overcome the asymmetric thrust.


Not quite. While the rudder on the D is taller, the rudder is not hydraulically powered. The VMCA is much higher in the D than in the H. The H has a powered rudder which provides more authority. However, the H also has more thrust than the D and in a 4 engine out on one side, it is a handful, but it is easier to handle than the D was.

Personally, the thought of any re-engine on the H makes me cringe. The entire rudder will have to be redesigned if new engines are installed.
If we weren't all crazy we'd all go insane!
 
LightningZ71
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Re: Engine Drops Out of B-52 During Training:

Sat Jan 07, 2017 3:06 pm

Which is why I suggest the BR725. It has almost exactly the same thrust as the TF33 in current use, about the same fan diameter, about the same weight, yet uses 33% less fuel per lbf per hr. It can also be used with all of the existing ground handling equipment for the TF33. No matter what, any new engine will require changing the existing mechanical controls to stuff that works with FADEC engines, so it's still going to be a big tear-up.
 
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Aesma
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Re: Engine Drops Out of B-52 During Training:

Sun Jan 08, 2017 12:37 am

AWACSooner wrote:
LightningZ71 wrote:
The RR BR7XX series engines are, in at least one version, almost a drop in fit for the existing nacell. They are relatively inexpensive, still in commercial service, offer equivalent thrust with a much lower specific fuel consumption. Obviously, engine controls and the insides of the existing nacell will need to be reengineered, but it won't require completely redoing the entire nacell. Also, the RR BR7XX is not heavier than the existing engines, reducing structural effects on the wings.

There is no need to go with some ultra expensive state of the art engine for a plane that will be around no longer than 20 or so more years. Especially one that requires major changes to the airframe and nacell aerodynamics.

They actually investigated re-engining the planes with just 4 of em a few years back...the problem is that, if you lose one on one side, with the shortened rudder of the H model (vs the D model), you can't get enough rudder to overcome the asymmetric thrust.


If that was true then the incident we're talking about could have been dramatic, as it seems it was an engine "blowing up", those can often result in a turbine disc departing, and in the case of the B-52, that could very easily destroy the other engine in the nacelle.
New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
 
LightningZ71
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Re: Engine Drops Out of B-52 During Training:

Sun Jan 08, 2017 9:23 pm

Which is a condition and risk that they are already comfortable with. Uncontained engine failures are rare these days (when compared to combined total fleet hours of operation), so that risk is tiny. Modern wngines, especially ones used in commercial applications, are even less likely to do so.
 
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richcam427
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Re: Engine Drops Out of B-52 During Training:

Mon Jan 16, 2017 7:39 am

I think the engines are the least of concerns for the B-52. The remaining fleet is literally rusting out. I'm not quite sure how the USAF plans to keep them flying for as long as they are because they're on their last leg.
 
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Channex757
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Re: Engine Drops Out of B-52 During Training:

Mon Jan 16, 2017 10:41 am

richcam427 wrote:
I think the engines are the least of concerns for the B-52. The remaining fleet is literally rusting out. I'm not quite sure how the USAF plans to keep them flying for as long as they are because they're on their last leg.

They are not airliners, in the air for 16 hours a day every day. The fleet also gets constant attention from the ground crews, as well as continued upgrading from the supporting companies.

The B-52 remains what it is, a flying plank on which to hang weapons systems. In that role it's almost perfect for the job. The low usage of the fleet means service length is way longer than an equivalent 737 or other civil airframe. That very simplicity of being a flying plank is what makes it priceless as most of the usage for bomber type planes is for something sturdy and not cutting edge technology based,

Boeing originally specified a project for a rebuild using the RB211-535E4 engine. Four would replace the eight Pratts. RR USA could build and support the engine, which has widespread experience and easy availability of spares as well as proven reliability (the most important factor) and much lower fuel burn. Might that be worth dusting off? The original proposal was rejected by the USAF but there were apparently errors made with the viability costings and since then fuel prices have also increased. Costing the re-engine makes more sense calculated with fuel delivered to the plane via tanker, whereas the USAF calculated the savings just at ground supply values.
 
ThePointblank
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Re: Engine Drops Out of B-52 During Training:

Tue Jan 17, 2017 2:59 am

Channex757 wrote:
richcam427 wrote:
I think the engines are the least of concerns for the B-52. The remaining fleet is literally rusting out. I'm not quite sure how the USAF plans to keep them flying for as long as they are because they're on their last leg.

They are not airliners, in the air for 16 hours a day every day. The fleet also gets constant attention from the ground crews, as well as continued upgrading from the supporting companies.

The B-52 remains what it is, a flying plank on which to hang weapons systems. In that role it's almost perfect for the job. The low usage of the fleet means service length is way longer than an equivalent 737 or other civil airframe. That very simplicity of being a flying plank is what makes it priceless as most of the usage for bomber type planes is for something sturdy and not cutting edge technology based,

Boeing originally specified a project for a rebuild using the RB211-535E4 engine. Four would replace the eight Pratts. RR USA could build and support the engine, which has widespread experience and easy availability of spares as well as proven reliability (the most important factor) and much lower fuel burn. Might that be worth dusting off? The original proposal was rejected by the USAF but there were apparently errors made with the viability costings and since then fuel prices have also increased. Costing the re-engine makes more sense calculated with fuel delivered to the plane via tanker, whereas the USAF calculated the savings just at ground supply values.

However, corrosion management IS a concern with the B-52, as corrosion occurs over time, not how much the aircraft is flown. The B-52 was built at a time when the effects of corrosion on metals and possible treatments for the metals to prevent it wasn't well understood.
 
LightningZ71
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Re: Engine Drops Out of B-52 During Training:

Tue Jan 17, 2017 6:22 am

It was also overbuilt as a result of that same lack of understanding. There are also many spare frames stored in the desert as replacements.
 
ThePointblank
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Re: Engine Drops Out of B-52 During Training:

Tue Jan 17, 2017 7:16 am

LightningZ71 wrote:
It was also overbuilt as a result of that same lack of understanding. There are also many spare frames stored in the desert as replacements.

Nope. The B-52 was built to the same standards as other aircraft at the time, and the effects of corrosion on aircraft wasn't that well understood until the 1980's. In fact, little to no attention was placed on corrosion prevention in the 1950's and 1960's, which was when the B-52 was designed. Only very recent aircraft have had extensive corrosion prevention measures built into the aircraft as a result of the massive increase in understanding on how corrosion affects aircraft structures and the need for extensive corrosion prevention maintenance to prevent failures in flight.

The 1988 Aloha Airlines incident is the best example of this. While metal fatigue was the primary cause of the accident as pointed out by the NTSB, the report also declared that the cause of this incident was due to the failure of the operators maintenance program to detect corrosion damage. Investigations pointed to corrosion accelerated fatigue of the fuselage skin panels as the failure mechanism.
 
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Channex757
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Re: Engine Drops Out of B-52 During Training:

Tue Jan 17, 2017 1:07 pm

ThePointblank wrote:
LightningZ71 wrote:
It was also overbuilt as a result of that same lack of understanding. There are also many spare frames stored in the desert as replacements.

Nope. The B-52 was built to the same standards as other aircraft at the time, and the effects of corrosion on aircraft wasn't that well understood until the 1980's. In fact, little to no attention was placed on corrosion prevention in the 1950's and 1960's, which was when the B-52 was designed. Only very recent aircraft have had extensive corrosion prevention measures built into the aircraft as a result of the massive increase in understanding on how corrosion affects aircraft structures and the need for extensive corrosion prevention maintenance to prevent failures in flight.

The 1988 Aloha Airlines incident is the best example of this. While metal fatigue was the primary cause of the accident as pointed out by the NTSB, the report also declared that the cause of this incident was due to the failure of the operators maintenance program to detect corrosion damage. Investigations pointed to corrosion accelerated fatigue of the fuselage skin panels as the failure mechanism.

sort of brings us round to vintage car thinking.

Cars in the 1950s and 1960s were built from uncoated steel and subsequently rusted away. Vintage cars from that era still get used daily by people who have kept their maintenance up, applied anti-corrosion treatments and also kept usage moderate. The B-52 may have been built in those less enlightened times but it doesn't mean time has stood still aboard them. Issues like different metals touching are now known and sections can be isolated to stop corrosion spots at joins. The planes get regular heavy maintenance visits where treatments and modifications can be applied, just like the C-5M is now getting.
 
LightningZ71
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Re: Engine Drops Out of B-52 During Training:

Tue Jan 17, 2017 2:55 pm

I wasn't implying that they were built to a "heavier" standard as compared to other aircraft of their era (though there is absolutely a lot of "millions spec" toughness to them). It was more a comment about aviation design as it existed in that era. Lots of parts had more material than was essential for their function. This was due to a lack of computer simulated load limits, exhaustive machine based testing of failure modes, etc. Over time, more advanced alloys, production processes, and computer aided design has allowed the industry as a whole use thinner skins, smaller ribs, struts, spars etc. and included the production time baking in of anticorrosion properties. This has enabled the empty airframe mass to go down as a function of volume over time.

Corrosion is, of course, a concern. But, with parts as overbuilt as they were in that era, with regular maintenance, it won't be a long term use issue. Just a maintenance headache.
 
mmo
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Re: Engine Drops Out of B-52 During Training:

Tue Jan 17, 2017 4:00 pm

LightningZ71 wrote:
I wasn't implying that they were built to a "heavier" standard as compared to other aircraft of their era (though there is absolutely a lot of "millions spec" toughness to them). It was more a comment about aviation design as it existed in that era. Lots of parts had more material than was essential for their function. This was due to a lack of computer simulated load limits, exhaustive machine based testing of failure modes, etc. Over time, more advanced alloys, production processes, and computer aided design has allowed the industry as a whole use thinner skins, smaller ribs, struts, spars etc. and included the production time baking in of anticorrosion properties. This has enabled the empty airframe mass to go down as a function of volume over time.

Corrosion is, of course, a concern. But, with parts as overbuilt as they were in that era, with regular maintenance, it won't be a long term use issue. Just a maintenance headache.


I think you mean MIL SPEC or military specification......have never heard of millions spec!!!
If we weren't all crazy we'd all go insane!
 
LightningZ71
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Re: Engine Drops Out of B-52 During Training:

Tue Jan 17, 2017 6:33 pm

Argh! Darn you autocorrect and my lack of proofreading while mobile!
 
iamlucky13
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Re: Engine Drops Out of B-52 During Training:

Tue Jan 17, 2017 6:40 pm

I'm still curious to better understand what they mean when saying the engine "disintegrated" and fell from the wing. The latest update I can find is less committal as to the cause, which suggests to me earlier comments were speculative, as they don't seem to know much about the actual failure progression:
http://www.minotdailynews.com/news/loca ... e-dropped/

Jet engines, generally don't "disintegrate." Even in crashes, the engines usually remain relatively intact, because they're dense, solidly constructed assemblies - thick central shafts, heavy bearings and bearing housing, fairly substantial struts connecting to the outer casing, and large, hardened pins connecting the casing to the pylon. Likewise, for uncontained disc failures, there is significant damage around the failed area, but the rest of the engine remains mostly intact.

I assume there's two likely, related scenarios:

1.) Uncontained failure with debris damaging the engine mounts, causing separation. If any of the mounts are in line with any of the turbine discs, this seems very credible.

2.) Failure initiating at the mounts themselves, such as due to fatigue, corrosion, or maintenance damage.

In either case, the cowling would doubtless be unable to support the weight of the severed engine.
 
f4u
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Re: Engine Drops Out of B-52 During Training:

Wed Jan 18, 2017 11:19 pm

Unable to find any pics of the damaged aircraft?
 
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AirlineCritic
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Re: Engine Drops Out of B-52 During Training:

Thu Jan 19, 2017 6:32 pm

Iamlucky: I suppose engine faults causing vibration could easily also lead to a separation event.

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