Posted on 11/12/2001 10:05:23 AM PST by Fixit
Warning Light: Airline Regulators Fret Over Several Breakups Of GE Jet
Engines ---
Company Is Racing to Avert Any More Disintegrations With Parts
Flying About ---
A Tense Incident at Newark
Wall Street Journal (Front page, Jan 2, 2001)
Authors: By William M. Carley and Scott McCartney
Abstract:
Despite the close calls, CF-6 engine failures are still rare. By one
measure -- rate of in-flight engine shutdowns -- the average CF-6 will
fly 30 years before suffering a shutdown, says GE spokesman Rick Kennedy.
But while all kinds of jet engines are subject to occasional failure, most
failures are contained within the engine casing. What is troubling about
the CF-6 failures is that they have been uncontained, with pieces flying
out to pose a risk to passengers, to other engines and to aircraft
structures
critical to flight.
GE is taking the matter seriously. It has developed better inspections
of engines to catch faults. It is redesigning certain parts to eliminate
the faults and, in the meantime, making devices to insert into engines
to prevent faults from leading to disintegration. "I can't afford another
engine failure," says Roger Seager, CF-6 project manager at GE's sprawling
jet-engine plant near Cincinnati. The company's huge aircraft-engine
division
contributes more than $10 billion of annual revenue, which is more than
9% of GE's total. The CF-6, one of three engines GE makes for big airliners,
has a nearly 60% share of the widebody-jet market.
To address this, GE has developed metal pins that will temporarily serve
as extra locks on the ring of engine nozzles. That way, even if the main
lock fails, others will keep the nozzles in place and prevent them from
rotating and shooting out of the engine. GE also is designing a new nozzle
lock that won't be subject to cracking. Mr. [Jay Pardee] says the FAA will
soon require the temporary pins and eventually order installation of the
new lock, to prevent another near-disaster like the one at Newark on April
25.
Copyright Dow Jones & Company Inc Jan 2, 2001
Full Text:
NEWARK, N.J. -- Seconds before a Continental Airlines DC-10 lifted off
at Newark International Airport last April, pilots heard a "boom" as their
left engine partly disintegrated. Like shrapnel from an artillery shell,
shards of metal bounced off the runway and smashed into the right engine,
damaging it, too. Only the tail engine was functioning normally as the
big jet thundered into the sky.
What followed was a chilling 34-minute flight as the pilots circled
over New Jersey, dumping tons of fuel to get the crippled plane down to
landing weight. In the cabin, flight attendants had the 220 passengers
chanting "bend over, heads down; bend over, heads down," in preparation
for the emergency landing. As the jet came in -- smoothly and safely --
Newark's tower controller radioed to the pilots: "Continental . . . ,
beautiful
job."
The engine that came apart was a General Electric Co. CF-6. Continental's
close call, it turned out, was only one of the more-dramatic episodes
resulting
from recent problems with GE's CF-6 engines.
In June, a CF-6 partly disintegrated on a Varig Airlines Boeing 767
in Sao Paulo, Brazil, forcing the pilot to abort his takeoff. And in
September,
two more GE engines on Continental DC-10s partly disintegrated, again
forcing
aborted takeoffs. In a third case that month, one blew apart on a taxiway
during maintenance.
The incidents have alarmed safety officials. GE's CF-6 is one of the
most widely used engines in the world. Nearly 5,000 of them power a broad
range of Boeing Co. and Airbus Industrie planes. The fear is that a CF-6
on another plane will disintegrate at the critical moment of takeoff and
cause a crash.
The Federal Aviation Administration, the National Transportation Safety
Board and GE have all launched investigations. The engine faults, the NTSB
has said, could result in a "catastrophic accident." The FAA has issued
emergency airworthiness directives intensifying engine inspections, and
says several more directives are to come.
Despite the close calls, CF-6 engine failures are still rare. By one
measure -- rate of in-flight engine shutdowns -- the average CF-6 will
fly 30 years before suffering a shutdown, says GE spokesman Rick Kennedy.
But while all kinds of jet engines are subject to occasional failure, most
failures are contained within the engine casing. What is troubling about
the CF-6 failures is that they have been uncontained, with pieces flying
out to pose a risk to passengers, to other engines and to aircraft
structures
critical to flight.
"These incidents, particularly Continental's flight at Newark, are ones
we don't want to see repeated, and we're going to make sure they're not,"
says Jay Pardee, chief of the FAA's engine directorate in Burlington, Mass.
GE is taking the matter seriously. It has developed better inspections
of engines to catch faults. It is redesigning certain parts to eliminate
the faults and, in the meantime, making devices to insert into engines
to prevent faults from leading to disintegration. "I can't afford another
engine failure," says Roger Seager, CF-6 project manager at GE's sprawling
jet-engine plant near Cincinnati. The company's huge aircraft-engine
division
contributes more than $10 billion of annual revenue, which is more than
9% of GE's total. The CF-6, one of three engines GE makes for big airliners,
has a nearly 60% share of the widebody-jet market.
Inspections mandated by the FAA have become so time-consuming that they
threaten to force planes out of regular service, disrupting airline
schedules.
To prevent this, GE is setting up special "engine hospitals" around the
world to inspect and doctor ailing engines quickly. A few of them serve
particular customers, such as one at New York's Kennedy airport for American
Airlines, a big user of the GE engines.
Two problems have been plaguing the CF-6 engine, one identified a decade
ago and one just this year. GE has developed fixes for both of them.
However,
GE says engineers so far can't figure out what went wrong in an incident
on Sept. 22, when an engine on a US Airways jet blew apart on a taxiway
at Philadelphia International during maintenance, throwing parts into the
nearby Delaware River. That case prompted the NTSB on Dec. 12 to call for
a review of part of the engine's design, racheting up the pressure on the
company.
The first of the two known CF-6 faults surfaced in 1991. Inspectors
of a Korean Air A300 were astonished to find a crack caused by a new kind
of metal fatigue. Called "dwell-time fatigue," it can arise when crystals
that form within metal during forging are aligned, permitting cracks along
the alignment.
The cracks were in engines' titanium spools. These big parts -- 3 1/2
feet long and looking a little like a beer keg -- hold the spinning blades
that compress incoming air. A cracking spool will release blades that then
shoot through the engine casing, possibly damaging the aircraft enough
to cause a crash.
This type of metal fatigue was causing cracks "much faster than we had
ever seen before," says Mr. Pardee of the FAA, which ordered frequent
inspections
to find any bad part before it could fail. Safety authorities considered
the problem solved.
But in 1993, the GE engine on an American Airlines Boeing 767 taking
off from Los Angeles partly disintegrated, spewing parts into the Pacific.
After the plane limped safely back to the airport, inspectors found that
the new type of cracking was again at fault.
The FAA ordered that inspections be still more frequent.
Then in June of this year a spool fractured again, on the Varig 767
taking off from Sao Paulo. Although rolling at 100 knots, the captain was
able to slam on the brakes and bring the jet to a stop. "I thought we had
this problem under control, and then we had Varig," says GE's Mr. Seager.
Spool inspections, it turned out, were inadequate. Cracks were developing
in new places, even faster than expected, and the configuration of the
spool made it hard to detect every crack. In September, the FAA took
Draconian
steps. It sharply increased the frequency of inspections, required an
ultrasonic
test to probe for cracks more thoroughly, and cut spools' service life
to 12,500 takeoffs from 15,000.
Because spool inspections have required taking apart and reassembling
the whole engine, a 60-day process, carriers faced having fleets of planes
without engines. GE has scrambled to develop a special computerized tool
permitting a one-week inspection, and the company is now distributing it
to carriers and to its "engine hospitals" to keep the jets flying.
GE's long-term solution to the spool cracking is a brand-new part. It
has changed forging techniques and the titanium alloy and is seeking to
have airlines insert new spools in engines now powering jets. That will
take years, but eventually, says GE's Mr. Seager, the new spools should
eliminate the troublesome cracking altogether. In the interim, better
inspections
are aimed at catching any cracks.
The CF-6's second fault came to light in April with Continental's
crippled
flight over New Jersey. The same problem arose twice more in September,
when Continental jets taking off from Newark and Amsterdam suffered engine
failures and had to abort.
What happened, engineers determined, was that locks had cracked on
nozzles
or vanes guiding air through the engines. This allowed the normally
stationary
ring of nozzles to rotate around the engine, eventually grinding through
the outer casing and then blasting metal parts in all directions.
To address this, GE has developed metal pins that will temporarily serve
as extra locks on the ring of engine nozzles. That way, even if the main
lock fails, others will keep the nozzles in place and prevent them from
rotating and shooting out of the engine. GE also is designing a new nozzle
lock that won't be subject to cracking. Mr. Pardee says the FAA will soon
require the temporary pins and eventually order installation of the new
lock, to prevent another near-disaster like the one at Newark on April
25.
That evening, as Capt. Doug Schull gunned the DC-10 down the runway
at nearly 160 knots, beginning Flight 60 to Brussels, all seemed normal
until the "boom" suddenly sounded. A white light flashed on the instrument
panel. "Power failure!" yelled co-pilot Bill Duus and engineer Bob Mazur.
The jet was at the most critical moment of takeoff, "V1 speed," below
which the pilot still has enough runway to abort but above which he must
take off.
"The airplane wanted to fly," Capt. Schull recalls in an interview.
And co-pilot Duus, a former Air Force fighter pilot, yelled "Go, go, go!"
Knowing he had lost some power in at least one engine, the captain pushed
all the throttles forward to maximum thrust. Fully loaded with passengers,
baggage and 80 tons of fuel, the jet labored into the sky. The decision
to fly was right; with thrust reversers on two of the three engines damaged
and inoperative, aborting would have meant running off the end of the
runway.
Once in the air, the DC-10 began shaking violently. Capt. Schull reduced
power on the left engine, where instruments indicated trouble. But shaking
continued. The pilots were unaware metal fragments from the partly
disintegrated
left engine had bounced off the runway and damaged the right engine.
Instinctively,
Capt. Schull reduced power on the right engine. The shaking stopped,
surprising
the crew, who now realized they had two bad engines out of three.
And there were other problems. Engine fragments had blasted 27 holes,
some as big as basketballs, in the fuselage and wing and had damaged several
tires and the landing gear.
Meanwhile, because it was lower than its normal flight path, the jet
had to dodge other planes. "We need you to turn right immediately to avoid"
a Beechcraft landing at Teterboro airport, farther north in New Jersey,
a controller radioed. "We're going to try to climb to 2,500" feet to avoid
it, co-pilot Duus replied.
The DC-10 did make 2,500 feet, then 3,000. The copilot took the controls
so Capt. Schull could oversee emergency checklists. Continental's "engine
failure/fire" checklist calls for shutting down the suspect engine. But
as Mr. Duus put his hand on the left-engine shutdown lever, he said, "We
don't really want to do this." Once shut down, the damaged engine might
not restart. "You're right," the captain said. They kept it going.
As the jet flew over Teterboro, the blast from the left engine continued
taking its toll. Parts of the plane began falling off, including a
three-foot
engine cowling that dropped onto the roof of a medical laboratory near
that airport.
A controller asked the pilots to climb to 5,000 feet and fly west over
Pennsylvania to dump fuel in a remote area. The altitude would help ensure
that the fuel evaporated before reaching the ground. But climbing also
would mean trying to increase power in the ailing engines, and moving far
from the airport could spell disaster if they lost power. Co-pilot Duus,
declining the controller's request, radioed: "We've got a real possibility
of losing a second engine here," leaving just one, "so we need to get back
into Newark as soon as possible."
They flew a tight ring around Newark, leaving just enough time to dump
fuel. As they returned to the airport, passengers were calm. "I told them
we had a problem, and we weren't sure what it was," the captain recalls.
"I told them to listen to the flight attendants, prepare for the worst,
but we'd get them all home."
As the jet made its final approach, the captain took the controls again,
gingerly adjusting only the tail-engine throttle to attain landing speed.
Because of some blown tires, spotted by another pilot, landing would be
dicey. As the jet approached the runway, the 220 passengers began their
"bend over, heads down" chant, startling the pilots -- who at first thought
a group of Hare Krishnas was on board.
The touchdown was smooth, the remaining tires holding up. Then, with
the big jet careening down the runway with only one of three thrust
reversers
operative, the pilot had to hit the brakes extra hard -- so hard they
generated
blazing heat and finally locked the wheels. But the plane rolled to a safe
stop. "By God," Capt. Schull said softly, "we did it!"
(See related letter: "Letters to the Editor: Frightful Stories" -- WSJ
Jan. 12, 2001)
Credit: Staff Reporters of The Wall Street Journal
Thanks to s2baccha for giving the link to this article on another thread.
GE's going to be (and ought to be) in very deep trouble.
Nothing's infallible, but do Rolls-Royce engines break apart from stress?
A few of them serve particular customers,
such as one at New York's Kennedy airport
for American Airlines, a big user of the GE engines.
"This incident raises serious safety concerns because, if it had occurred during flight rather than on the ground during maintenance, the airplane might not have been able to maintain safe flight. Examination of the airplane revealed that a portion of the HPT stage 1 disk penetrated the left wing just inboard of the No. 1 engine pylon. Investigators determined that this portion of the disk, which is approximately 140 square inches and 45 pounds, penetrated a dry bay, made a 1-inch-wide vertical cut through the lower half of the forward wing spar, and penetrated a fuel tank before exiting through the top of the wing and passing over the fuselage. Examination of the engine revealed that the disk rupture split the engine in half, leaving the rear of the engine joined to the front only by the fan midshaft. The disk had separated from the shaft and was completely missing from the engine. Two pieces of the disk, which amounted to about two-thirds of it, and three blade slot posts were recovered. Although an extensive search was conducted, the remaining one-third of the ruptured disk (the piece that passed through the wing) was not recovered. Trajectory analysis performed by the Safety Board indicates that it may have landed in the Delaware River, which is adjacent to the airport."
The problem is that the wreakage fell into 4 areas -- the wing pieces in the Bay, the gas station, the main wreakage, and additional unspecified wreakage several blocks away. It seems very improbable that an "unconstrained engine failure" would cause the breakage of the airplane into those separate parts. However, if the rear part of the spool disintegrated, it may be possible to break the wing spar causing the wing to break, and this might strike the tail surfaces.
It is unclear from ongoing TV reports whether the debris in Jamaica bay is wing or tail. An early report said that the divers in the Bay were searching for the flight recorders, which would indicate that it is the tail section. The recorders have been reported as found, but I haven't heard where they were found.
That article you found might merit posting on its own thread.
HA! Good one.
I'd like to bump this article, because it has some very important information that doesn't seem to be getting coverage elsewhere.
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