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Do Any Aircraft Purge Waste  
User currently offlineSidewinder From , joined Dec 1969, posts, RR:
Posted (9 years 2 weeks 4 days 1 hour ago) and read 2867 times:

My brother who lives under the den flight path says he witnessed a aircraft drop a chunk of blue ice. He believes it was frozen toilet water. The ice struck a roof causing damage. Has anyone heard of this before? Could it be deicing chemical falling off?

16 replies: All unread, jump to last
 
User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 1, posted (9 years 2 weeks 4 days 1 hour ago) and read 2861 times:

Happens all the time... but not on purpose. If the lav drain valve is leaking, waste water will leak out in flight and freeze to the fuselage. When the aircraft decends to warmer air, the frozen waste water warms and falls off the plane.

[Edited 2005-09-01 00:29:59]


"It's not the size of the dog in the fight, but the size of the fight in the dog"
User currently offlineSidewinder From , joined Dec 1969, posts, RR:
Reply 2, posted (9 years 2 weeks 4 days ago) and read 2855 times:

I will forward this to my brother. Thanks

User currently offlineOPNLguy From , joined Dec 1969, posts, RR:
Reply 3, posted (9 years 2 weeks 4 days ago) and read 2841 times:

While any aircraft can have a problem with leaky lavs, the 727 and 737 family of aircraft used to see a bunch of them.

One of the side effects for the 727 was that any ice from a leaking forward lav could break off and be injested into the #3 engine. The common result was that the engine (at cruise power) seized and torqued itself right off the aircraft. National Airlines (v1.0) had an incident back in the 1970s; AA had one in the 1980s (both over New Mexico), and Northwest had this one in Florida:


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The FAA had subsequent airworthiness directives out to modifiy the dump valves, and the problem has largely gone away, just like the 727 fleets. Still happens (on all aircraft) once in awhile...


User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 4, posted (9 years 2 weeks 3 days 19 hours ago) and read 2772 times:


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On the B737s there was a Plug placed at the Outer end of the Service panel as backup.
Quite common to find Blue streaks on this Aircraft.
regds
MEL



Think of the brighter side!
User currently offlineBoogyJay From France, joined May 2005, 490 posts, RR: 4
Reply 5, posted (9 years 2 weeks 3 days 10 hours ago) and read 2689 times:

Quoting OPNLguy (Reply 3):
the engine (at cruise power) seized and torqued itself right off the aircraft.

Do you mean the engine simply fell of the sky  eyepopping  ?


User currently offlineOPNLguy From , joined Dec 1969, posts, RR:
Reply 6, posted (9 years 2 weeks 3 days 8 hours ago) and read 2667 times:

Quoting BoogyJay (Reply 5):
Do you mean the engine simply fell of the sky ?

Yes. See the picture of the NWA 727 with the missing #3 engine. Same thing happened to the National and AA 727s some years earlier...


User currently offlineBoogyJay From France, joined May 2005, 490 posts, RR: 4
Reply 7, posted (9 years 2 weeks 3 days 7 hours ago) and read 2633 times:

Wow! Scary...

OPNLguy, I have now more questions.

A piece of ice must be around the same weight as a bird (not a sparrow, but a duck or stork...). And engines are tested to ingest birds. Yet you said this ice made engines separate from the fuselage. Am I wrong by comparing bird and ice, stiffness is not the same. But I would tend to say that a bird coming on an engine blades at 200mph (320kph) is rock hard.

Are engines more fragile at cruise power? If yes, what is it due to? (lower rotating speed?).

If so, some ducks travel at very high altitudes. What would be the effect of a duck ingested by a GE90 at FL340? If the engine would simply fall of the sky, the plane would probably crash as it'd be completely unbalanced due to a missing heavy GE90, right?

Thanks for your infos. Much appreciated.


User currently offlineOPNLguy From , joined Dec 1969, posts, RR:
Reply 8, posted (9 years 2 weeks 3 days 4 hours ago) and read 2601 times:

I seem to recall that the ice blob that affected the National (v1.0) 727-200 back in the 1970s was supposedly about the size of a basketball. What I can't recall is whether I read that somewhere, or whether I heard that from a National mechanic at IAH that I knew at the time.

I don't think the engines are "fragile" per se, it's mostly a matter of a sudden, sharp reduction in internal rotation speed, the torque from which overpowed the ability of the 3 engine cone bolts to keep the engine attached to the aircraft. Keep in mind that back in the 1960s (when the 727 was designed) this was the engineering philosophy in place, i.e. allowing a really bad engine to shuck itself from the aircraft so as not to risk the aircraft itself.


User currently offlineVC-10 From United Kingdom, joined Oct 1999, 3701 posts, RR: 34
Reply 9, posted (9 years 2 weeks 3 days 1 hour ago) and read 2555 times:
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Quoting BoogyJay (Reply 7):
A piece of ice must be around the same weight as a bird (not a sparrow, but a duck or stork...). And engines are tested to ingest birds.

The birds used to test engines aren't as hard as ice or frozen.


User currently offlineKaddyuk From Wallis and Futuna, joined Nov 2001, 4126 posts, RR: 25
Reply 10, posted (9 years 2 weeks 3 days ago) and read 2537 times:

Quoting OPNLguy (Reply 8):
Keep in mind that back in the 1960s (when the 727 was designed) this was the engineering philosophy in place, i.e. allowing a really bad engine to shuck itself from the aircraft so as not to risk the aircraft itself.

That is still the idea, the B747 engines apparently will break off and rotate up then OVER the top of the wing.

The amount of energy required to halt a rotating jet engine from top RPM to zero in a short time is beyond recognition. If it were to remain attatched, you could guarentee the wing snapping off maybe even snapping the fuselage...



Whoever said "laughter is the best medicine" never had Gonorrhea
User currently offline777WT From United States of America, joined Jan 2005, 876 posts, RR: 1
Reply 11, posted (9 years 2 weeks 2 days 20 hours ago) and read 2488 times:

Quoting BoogyJay (Reply 7):

In the Building of the 777 video set, they showed an 777's engine going through testing.
It involved shooting blocks of ice into it! The best estimate I can tell you judging from my tv is that the ice blocks looks like a foot by a foot but it is long and shot from an air cannon.

Birds are also shot in it, there's an slow motion of a blade cutting thru it like it's butter. And the birds looks like orange juice after it went through the blades!

The engines are more fragile at high power settings since the blades tends to creep during overspeed and will grind or break.

Compressor stalls, they're like backfires in an turbofan engines. Some can be damaging, some not.
For the same type of compressor stall, an GE engine may break some blades internally while a P & W may not. They both go through boroscope inspection after it occured.


User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 12, posted (9 years 2 weeks 2 days 20 hours ago) and read 2486 times:

Quoting Kaddyuk (Reply 10):
That is still the idea, the B747 engines apparently will break off and rotate up then OVER the top of the wing.

What type is the Fuel Supply hose Is it QAD to cater to such Events.Presumingly the Hydraulic hoses to the Engine Are.
regds
MEL



Think of the brighter side!
User currently offlineDC8FriendShip From United States of America, joined Apr 2005, 242 posts, RR: 2
Reply 13, posted (9 years 2 weeks 2 days 8 hours ago) and read 2422 times:

Quoting BoogyJay (Reply 7):
If the engine would simply fall of the sky, the plane would probably crash as it'd be completely unbalanced due to a missing heavy GE90, right?

If you recall the American airlines DC-10 that crashed in ORD in the late '70's the loss of the engine did not cause an out of balance condition. that aircraft flew until the speed was reduced to V2, and the left wing, with slats retracted due to the loss of hydraulics, stalled and the right wing, engine still attached, lifted and careened the aircraft onto its side and into the ground.



Come fly the Friendly Skies of United
User currently offlineBoogyJay From France, joined May 2005, 490 posts, RR: 4
Reply 14, posted (9 years 2 weeks 2 days 8 hours ago) and read 2418 times:

Quoting DC8FriendShip (Reply 13):
with slats retracted due to the loss of hydraulics

I thought that in case of loss of hydraulic, flaps actually extended (under their own weight I guess).
Wouldn't it make more sense?


User currently offline777WT From United States of America, joined Jan 2005, 876 posts, RR: 1
Reply 15, posted (9 years 2 weeks 2 days 5 hours ago) and read 2396 times:

Quoting DC8FriendShip (Reply 13):
If you recall the American airlines DC-10 that crashed in ORD in the late '70's the loss of the engine did not cause an out of balance condition. that aircraft flew until the speed was reduced to V2, and the left wing, with slats retracted due to the loss of hydraulics, stalled and the right wing, engine still attached, lifted and careened the aircraft onto its side and into the ground.

The loss of the engine was due to the prodecure of removing/installing the engine/plyon as a one piece unit by the use of the forklift. This prodecure data was approved by the FAA.

The old engine/plyon was removed and the plyon was installed on the new engine. Then it was put up by forklift into the plane, only the front mounting bolt was installed then the techs went on a lunch break.
During the lunch break, the forklift seals slowly leaked letting hyd oil out of the lifting actuators, the front of the engine was partically hanging now while the back was driven up even further due to the engine's weight. The engine is heavy in the front with the plyon attached to it.
When they returned, they just adjusted the forklift and installed the rear bolt.
The damage already has been done without the rear bolt installed, the area near the very back of the plyon already stressed the wing mounting area.

So when it was ready for takeoff on that day, the rear structure gave out, released the rear plyon attachment and the engine under full power continued to pull and pivoted around the front attachment which then it broke off and flew over the wing taking the hyd lines out with it too.
Hyd fuses wasn't avail in this area at that time, if it was, the loss of hyd fluid would have been limited.

In return, the slats retracted causing the stall speed to be higher on that wing, it banked to the left due to the higher lift on the right wing and crashed.

In the investigation, CO, DL, UA were doing engine changes the same was AA did on that DC-10. After that crash, the prodecure was stopped and it had to go by the way the manual said which to remove the engine THEN the plyon. Not as a one piece unit anymore which they did to save time.

There is a excellent documentary DVD on this, it's from A&E, title is "The crash of flight 191"

[Edited 2005-09-02 20:25:09]

User currently offline777WT From United States of America, joined Jan 2005, 876 posts, RR: 1
Reply 16, posted (9 years 2 weeks 2 days 4 hours ago) and read 2393 times:

Quoting BoogyJay (Reply 7):
If so, some ducks travel at very high altitudes. What would be the effect of a duck ingested by a GE90 at FL340? If the engine would simply fall of the sky, the plane would probably crash as it'd be completely unbalanced due to a missing heavy GE90, right?

There is a number of cases which engines have fallen off and the pilots didn't realize it.

The most recent one would be the cargo operated 747 which lost an engine over lake michigan, the FAA tried to find it but unsucessful, it's believed to be on the bottom in one lake.

727's had engines fall off without pilots noticing it, other than gettin out of the plane and be suprised when they don't see a engine there.

In the 777, the TCO computer compenstates the rudder from an shut down or InOp engine. During the early design stages, it was so good that the pilots couldn't even notice it in flight.

One thing I notice is that to the pilots who flew without noticing an engine fell off, the gauges and instruments would go off incidating broken or InOp, yet they still think the engine is still there running.

Also on the DC-10 and MD-11, does the tail engine (#2) break off in the same conditions as the wing mounted engine would?


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