Perris Skyvan ?

[sundevil777 93]

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>Was this an un-contained engine failure?

Yep. No blades left on the turbine that I can see.

Commercial turbofans have bulletproof jacket-like protection surrounding the blades, right? Don't turboprops? Engines like those on otters are still centrifugal flow hot section, is the compressor also a centrifugal type? Did it happen at a low power setting, after jumpers exited?

I've spent a lot of time having fun checking out the engines up close on 777s, not too familiar with centrifugal flow types.

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[ZigZagMarquis 8]

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Commercial turbofans have bulletproof jacket-like protection surrounding the blades, right?

Yes and No... without dragging out the specifics of the specs... part of the design is to contain a certain amount of "failure"... however... anything beyond what is designed for, you can expect to see parts coming through the side of the motor.

99% of my experience is on military stuff. I was on the flight line one day when a GE404 shelled out... it was "contained" in that no parts came through the side of the motor, but lots of bits of blades did come out the ass end and all over the ramp... shut-down flight ops until it was cleaned up (FOD hazard).

I've also read HazReps where the turbine disk failed. Needless to say, that was not contained... in lay-man's terms, it cut the taill off the aircraft as it left. I've read other HazReps where after a motor shelled out and not all the bits got blown out the back end, but rather "hung up" inside and wound up rubbing on other metal parts as things continued to go round and round... the result being a titainium fire... "bad".

Furthermore, wasn't there an incident a few years ago where one of the motors on an MD80 or DC9 shelled out, fan blade parts came through the cowling and into the passenger compartment in the back of the jet?

Basically, if you desiged a turbofan case to be so strong as to never ever allow anything to come through it if all that spinny stuff inside starts munching itself, it would be so heavy that you'd never be able to fly the plane you bolted it to.

[pilotdave 0]

The Skyvan's engines have a 2-stage centrifugal compressor and a 3-stage axial turbine (I don't think there's such a thing as a centrifugal turbine but I might be wrong).

Not sure if that's true for all models, but this is what I could find. Also not sure if that's the engine model that was on the perris skyvan.

Attached is a cutaway drawing...

Also, no, most (older) turboprops aren't going to have any protection from turbine's flying apart, depending on exactly how the turbine fails. One or two blades might be contained, but a failure of the turbine disc is BAD.

Dave

[kallend 1,623]

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Commercial turbofans have bulletproof jacket-like protection surrounding the blades, right?

Yes and No... without dragging out the specifics of the specs... part of the design is to contain a certain amount of "failure"... however... anything beyond what is designed for, you can expect to see parts coming through the side of the motor.

99% of my experience is on military stuff. I was on the flight line one day when a GE404 shelled out... it was "contained" in that no parts came through the side of the motor, but lots of bits of blades did come out the ass end and all over the ramp... shut-down flight ops until it was cleaned up (FOD hazard).

I've also read HazReps where the turbine disk failed. Needless to say, that was not contained... in lay-man's terms, it cut the taill off the aircraft as it left. I've read other HazReps where after a motor shelled out and not all the bits got blown out the back end, but rather "hung up" inside and wound up rubbing on other metal parts as things continued to go round and round... the result being a titainium fire... "bad".

Furthermore, wasn't there an incident a few years ago where one of the motors on an MD80 or DC9 shelled out, fan blade parts came through the cowling and into the passenger compartment in the back of the jet?

Basically, if you desiged a turbofan case to be so strong as to never ever allow anything to come through it if all that spinny stuff inside starts munching itself, it would be so heavy that you'd never be able to fly the plane you bolted it to.

United 232 (DC10) crash at Sioux City, IA in 1989 was due to an uncontained disk failure taking out the flight controls. Only brilliant work by the crew prevented a total disaster.

...

The only sure way to survive a canopy collision is not to have one.

[Remster 24]

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Commercial turbofans have bulletproof jacket-like protection surrounding the blades, right?

From talks with people involved in aircraft design, they actually design the control systems and locate it in such a way to minimize (not eliminate) the damage that can be done to them from a turbine blowing up, ie, they expect some debris to make it to the fuselage.

Remster

[billvon 2,395]

>Commercial turbofans have bulletproof jacket-like protection surrounding the blades, right?

They may be bulletproof but they sure aren't turbine-blade-proof. A recent incident here at LAX resulted in the destruction of a 767 (I believe) when a full power runup resulted in an uncontained turbine failure. One blade was found 2500 feet from the explosion. Fortunately the plane had no passengers and the crew evacuated safely.

See below for one picture from that. Note that this is the GOOD engine; the turbine has been thrown from the bad engine, gone through the fuselage and lodged in the other engine.

>Did it happen at a low power setting, after jumpers exited?

Yes. On direct-geared-engines, though, the turbine always spins at the same speed (as long as the prop is spinning at the same speed, which it usually is.) Engine start and beginning of descent will be the largest thermal transients the engine will see, and during engine start the turbine isn't spinning as fast.

[sundevil777 93]

I understand that the protection is designed for a certain level of damage, not a worst case scenario. I saw the high speed footage for a 777 engine, can't remember which mfg, I think 2 compressor blades were caused to fail for that test.

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[azdiver 0]

comparing apples to oranges here it seems like havent seen any skyvans with 777 engines on them, though it would be alot better if it did, little quiter

light travels faster than sound, that's why some people appear to be bright until you hear them speak

[JakGramley 2]

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Major question for us in NorCal: what are the chances it will be fixed in time for the Byron Boogie in 2 weeks? It was supposed to be the main aircraft.

For those of you that are interested, I spoke with Pat Conatser this afternoon (10/3) and he asked that I post this for him. The Skyvan will be down for at least a month, probably longer.

For those of you wondering why jump ticket prices cost what they do, this little "fix" will cost over $100,000 (probably WELL over $100,000). Also, having spent a few days at Perris in the past, I know that Pat, Ben and their mechanics won't let the Skyvan back in the air until everything is right. Ask Pat sometime why he puts such effort into aircraft maintenance and safety. His stock answer is, "My family and friends are on those planes". Of course, he also might be flying one of them, so I guess there is a big incentive to get things right.

Jack Gramley

[squirrel 0]

I sure hope the skyvan continues to fly...its the type of plane we got married in down at DeLand...I simple love the skyvans.

________________________________
Where is Darwin when you need him?

[ltdiver 3]

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I wonder if it got them a new "bad spot" truck.

Maybe a boat. Oh, wait, it would have sunk then, wouldn't it have?

ltdiver

Don't tell me the sky's the limit when there are footprints on the moon

[Zing 2]

When A Skyvan engine cane apart on me, pieces went everywhere. Although the cowling stayed in place for me, it, the fuelage and wing were peppered with holes of various sizes. Mechanics later told me that close to 200 lbs of engine departed the airplane ... mostly out the tailpipe. I was impressed.

Zing Lurks

[ltdiver 3]

Thanks for the update, Jack. Glad to see you're still lurking the forums here.
ltdiver

Don't tell me the sky's the limit when there are footprints on the moon

[skylord 1]

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Commercial turbofans have bulletproof jacket-like protection surrounding the blades, right?

From talks with people involved in aircraft design, they actually design the control systems and locate it in such a way to minimize (not eliminate) the damage that can be done to them from a turbine blowing up, ie, they expect some debris to make it to the fuselage.

Well, not exactly. I'm going to be replying to both your post and Billvon's.

The DC-10 was never designed that way. Subsequent accidents involving the aircraft did lead to today's philosophy of routing hydraulics and other system critical items through different parts of the aircraft structure. Cases in point:

-an accident in Turkey, I think, where the cargo bay door came open in flight at cruise altitude, and the cabin floor collapsed onto the control cables during the depressurization, jamming them in the nose down position. No way for hydraulics to compensate since the hard wired steel control cables ran underneath the cabin floor.

-Chicago, 1979. Port engine comes off just after rotation. The separation tore all three hydraulic lines that were routed within inches of each other. Asymmetric retraction of slats, and a port wing stall caused the aircraft to roll left and crash even after the captain flew a flawless engine out procedure.

-UAL232, tail engine blew apart, took out all hydraulics since it was an uncontained engine failure and it was the original design as to hydraulics (all lines within inches). With zero control, they used engine thrust to get back on the ground, something they never trained for. The Captain is Al Haynes, and his crew are forever heroes to me.

No, the containment sleeve is not bulletproof. It is resistant, but under some circumstances will fail. There was a Delta MD-80 or DC-9 in Atlanta, I think, that killed a passenger and injured several others after the turbine came apart. Remember, these are hundreds of pounds of metal spinning at 25,000 plus RPM. And as another post alluded to, this can decide to leave through various exits.

I had not heard of the LAX issue, and I am tracking down further details as best I can with my Air Traffic Control co-horts.

Bob Marks

"-when you leave the airplane its all wrong til it goes right, its a whole different mindset, this is why you have system redundancy." Mattaman

[sundevil777 93]

The 777 was one of the first, if not the first to require that a 10 sq.ft. hole in the cabin (I believe it was that size), would not take out all of a systems redundant components and tubing/wiring paths.

I don't know if it was a regulation or Boeing internal requirement, but of course the reason for it was to reduce the potential for catastrophic damage from an explosion.

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[JakGramley 2]

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Thanks for the update, Jack. Glad to see you're still lurking the forums here.

Yep, I check DZ.com everyday, but I figure it's better to let the current skydivers do the posting instead of a "used to be" skydiver. Linda and I miss Perris and our skydiver friends. We hope to be out for the Xmas Boogie. Might come out of retirement to jump the jet. Wanna video a tumbling exit?

Jack

[ltdiver 3]

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Wanna video a tumbling exit?

Gonna jump the jet camera-less for the jump, then I'm game after that!

ltdiver

Don't tell me the sky's the limit when there are footprints on the moon

[Eule 0]

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Commercial turbofans have bulletproof jacket-like protection surrounding the blades, right? Don't turboprops?

In a non-skydiving discussion in another forum, someone posted this report about the blades failing on a commercial jet. Fortunately it was shortly after takeoff and the aircraft turned around and landed with no injuries to the passengers or crew. (That page is a summary; download the PDF for the full report with pictures.)

In that same discussion, I had mentioned the apparent thicker piece of metal in line with the prop on the side of a Twin Otter. I figured it probably wouldn't stop a loose prop blade, but might help with gravel or dirt being kicked up by the prop. A cold-country pilot said no, it's mostly for shedding ice that is flung by the prop.

Back to the Skyvan engine failure, it doesn't seem to have shown up at the FAA yet. I realize it may not show up immediately but I figured a week would be long enough - does anybody (diverdriver?) know how long these usually take?

Eule

PLF does not stand for Please Land on Face.

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[dorbie 0]

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There was a Delta MD-80 or DC-9 in Atlanta, I think, that killed a passenger and injured several others after the turbine came apart.

MD-88 Pensacola, 1996, killed two passengers:

http://www.ntsb.gov/publictn/1998/AAR9801.pdf

See attached image.

[otterboy 0]

A PT-6 engine spins at about 42,500 RPM (makes it easier to understand why parts can come out the side of a case). Anybody know what the RPM of a Garret is? I don't ever remember hearing a number. I assume it is close to the same, although if memory serves correctly a cintrifugal compressor (garret) is more efficient than an axial flow (pt-6) (please correct me if I am wrong). I will try to ask in school monday what a CFM spins at (GE engine found on some Boeings, and Airbus's). Typically we just learn RPM as a percentage.

The AA 767 threw an entire compressor disk. It also severed one or more fuel tanks. If memory serves they said the airplane would be a total loss. Airplane had rejected a T/O cause it couldn't make power. The mechanics were maintenance running it when it let go. (no pax on the plane)

You are correct the thickened skin on an Otter is for ice.

The DC-10 report is a wonderful read, if you have the opportunity listen to Capt. Hanes speech on the event. I agree the guy was a hero. Also someone was watching that flight. The area hospitals were inbetween shift changes, IE double staffed, National Guard was on maneuvers, and the airport had just recently done a disaster drill. Makes even a heathen like me think.

It takes more than just an engine failure to trigger an NTSB report. If the aircraft ended up not having a "successful" landing afterwards, or if there was a passenger that got "hit" by the shrapnal then it probably would. Going off memory it requires overnight stay in a hospital, broken bone, loss of limb, hearing, sight, or $20,000 of damage to trigger the NTSB. The engine expense alone will not trigger the $20,000 threshold, airframe damage, or something it hit would.

Mark

[mx757 4]

The AA 767 threw an entire compressor disk. It also severed one or more fuel tanks. If memory serves they said the airplane would be a total loss. Airplane had rejected a T/O cause it couldn't make power. The mechanics were maintenance running it when it let go. (no pax on the plane)

The aircraft did not have a rejected T/O The AA mechanics were running it up testing engines, as after it arrived from JFK captain wrote that one engine wasn't reaching full takeoff power.

good thing the mechanics were running this up instead of Captain ready to take off.. funny thing is the engine was only some 600 hours out of overhaul from Tulsa.

[otterboy 0]

Thanks for the correction.

Mark