I remember this report ealier this year :
AIR safety experts have ordered urgent inspections of hundreds of jet engines because it is feared they could
disintegrate, blasting shards of metal into passenger cabins.
The alert follows three failures in the CF6 engine made by the American company General Electric (GE). The most commonly used engine in wide-bodied passenger jets, it has been in production for 25 years. More than 5,000 have been made, each costing up to £6m.
The Civil Aviation Authority (CAA) has carried out a risk assessment and identified 42 British planes with the engines. It is liaising with American authorities to ensure that they are inspected and overhauled.
No aircraft have been grounded, although the National Transportation Safety Board in America has given a warning that the faults
could cause a "catastrophic accident".
Aircraft engines are supposed to contain any problems; if there is internal damage, failed parts are designed to eject safely out of the rear.
If broken components shoot through the engine's casing in an "uncontained failure", this
could cause a plane to crash. If a hole is made in a plane's cabin, passengers could be sucked out by the low air pressure at high altitudes.
More than 5,000 General Electric CF6 engines have been manufactured. It is fitted to airliners such as the Boeing 767 (above), the DC-10 and the
Airbus.
The Federal Aviation Administration (FAA) has issued a stream of airworthiness directives requiring immediate scrutiny of the oldest engines.
This follows incidents which have rocked faith in the engine after 200m hours of almost trouble-free flight. They include:
Partial disintegration of the left CF6 engine on a Brussels-bound Continental Airlines McDonnell Douglas DC-10 on takeoff at Newark near New York last April. Fragments of metal ricocheted off the runway and disabled the right engine. The pilot circled for 30 minutes dumping fuel in preparation for an emergency landing. The plane landed safely using its tail engine.
In two other incidents last year Continental had to abort takeoffs at Newark and Amsterdam after engine failures. The problem was blamed on failure of a lock which caused normally stationary nozzles to rotate and cause damage. GE has introduced a metal plug to hold the nozzles in place until a new nozzle lock can be fitted.
The captain of a Varig Airlines Boeing 767 was able to brake and abort a takeoff in Sao Paulo, Brazil, in June after a CF6 engine partly disintegrated. The failure was blamed on metal fatigue inside the compressor.
This caused cracks in the titanium spools, a series of discs which hold the spinning blades that compress incoming air. If the blades come lose they can shoot through the engine casing.
GE has been ordered to increase inspections of the spools and is offering airlines large discounts to replace them with new ones.
A CF6 engine on a US Airways jet undergoing maintenance checks blew apart on a taxiway at Philadelphia in September when a disc failed in the high pressure turbine, showering parts into a nearby river.
GE admits that the cause of this latest incident is still a mystery and experts have called for a review of the design of that part of the engine. Measures to rectify the other two problems will cost the company up to £20m.
Rick Kennedy, spokesman for GE Aircraft Engines, said there was a "real sense of urgency" at the company. It had undertaken an exercise to inspect 300 engines 12 months earlier than had been planned.
He added: "There are 4,000 aircraft takeoffs each day using CF6 engines. Without minimising the seriousness of these failures, the sheer statistics are such that it is pretty rare."
A CAA spokesman said: "We are aware of the problems that have occurred. We are working closely with the FAA and liaising with British airlines to make sure they comply with the airworthiness directives that have been issued. We have not had to ground any planes."
British airlines said that where necessary they were complying with the directives. British Airways, which usually buys Rolls-Royce engines, said it had only one plane, a DC-10, with CF6 engines but it was up for sale and had not flown for several years.
Virgin Atlantic's planes have GE engines built after 1995, which have not suffered any of the problems. The charter airlines Monarch, Britannia and Air 2000 said their CF6 engines had undergone the necessary tests.
Bill Gunston, editor of Jane's Aero-Engines, said the CF6 was an engine designed 30 years ago that had experienced few problems until now. "There are captains of big jets who were not born when it was first undergoing tests, so it shouldn't be doing this sort of thing now," he said.
http://av-info.faa.gov/ad/NPRM/2000ne30.htm