Re: Virgin 747 birdstrike

From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
Date:         19 Dec 95 02:03:09 
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>I was (un)lucky enough to be on board a Virgin 747-200 that lost an engine
>due to a bird strike a while ago (August 2). About a minute after takeoff,
>in the clouds above SFO, there was a big bump followed shortly by fuel
>venting from what I assume to be a jettison port at the end of the wing.

Fascinating -- I watched your flight dumping fuel from my office!  At
the time, I just noticed an aircraft flying south along the coast (not
a normal pattern) with what appeared to be unusually heavy contrails,
especially for such a low altitude.  I didn't know what had actually
happened until several days later when another reader of this group
mentioned having seen the aircraft at United's maintenance base later
on, and we managed to piece together the story.

>People further forward than me reported seeing a jet of flame being
>produced by engine #1 (starboard side inner, I think...).

#1 would be the outer port (left) engine; starboard inner would be #3.
In any case, I'm not sure the flames would necessarily indicate that
the engine had completely bought the farm.  The bird ingestion most
likely would have reduced the airflow, which could result in a large
amount of unburned fuel going out the back and finally finding enough
air with which to finish burning.

>1. I thought engines were supposed to survive bird strikes? I read here
>about the GE90 failing its strike test because it vibrated too much
>afterwards or something. Presumably RB-211s aren't just allowed to
>explode....?

Engines have to survive bird strikes to a point.  My recollection of
the exact numbers is imprecise, but they must be able to ingest a
chicken (10 pounds?) and be able to continue running for 60 (90?)
minutes with no more than 10% (?) reduction in thrust.  That still
means that a large goose could destroy an engine that met all the
certification standards.

Those weren't RB.211s, BTW -- Virgin's 747-200Bs and their 747-100
all have Pratt and Whitney JT9D engines, while their 747-400s have
GE CF6-80C2 engines.

>2. Will there be an investigation into the incident and the results made
>public? Talking with other passengers it was clear that several disputed
>the bird strike story.

An in-flight engine shutdown always triggers an investigation to a
degree, especially for an engine type that's used for ETOPS even if
the engine involved in the failure was not being used in an ETOPS
application.  (The JT9D and CF6-80C2 are both used in ETOPS on the
767, A300, and A310.)

On the other hand, I'm not sure there'd be that big a deal made in
the case of a bird strike, since they're not uncommon, and assuming
it was in fact a bird strike as evidenced by bird remains in the
engine.

>3. Further to the discussion on 747s flying on 3 engines, I can report that
>despite losing one at what I assume to be a fairly critical time, and being
>fully loaded, ours did just fine. In fact until I saw the fuel venting I
>thought the bump was just one of those bangs and scrapes that happen
>naturally during takeoff....

My one experience with an in-flight engine failure was also on a 747
out of SFO, in my case a United 747-422 on a short trip to Chicago.
The #2 engine began overheating early in the takeoff roll.  We were
using runway 1R, which isn't all that long and ends up in the bay,
so the pilots elected to takeoff and return rather than reject the
takeoff, which is never a pleasant maneuver.  We suffered a series
of compressor stalls immediately after takeoff, which sounded and
felt very much like the thump of the landing gear retracting, except
*many* times louder, and repeating over about ten seconds.  Clearly
not a normal takeoff noise, yet otherwise the flight felt perfectly
normal until our usual turn to the right continued beyond the usual
90ish degrees, taking us onto a course down the bay.

--
Karl Swartz	|Home	kls@chicago.com
		|Work	kls@slac.stanford.edu
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Moderator of sci.aeronautics.airliners -- Unix/network work pays the bills