My God, they're really desperate nowThe high pressure (HP) fuel pumps from both engines have unusual and fresh cavitation damage to the outlet ports consistent with operation at low inlet pressure. The evidence to date indicates that both engines had low fuel pressure at the inlet to the HP pump. Restrictions in the fuel system between the aircraft fuel tanks and each of the engine HP pumps, resulting in reduced fuel flows, is suspected.
AAIB said:....The primary challenge at Boeing is to create
the environmental conditions experienced on the flight
over Siberia, at altitudes up to 40,000 ft, in which to test
a representation of the aircraft fuel system. These tests
are collectively aimed at understanding and, if possible,
replicating the fuel system performance experienced on
the day and the potential for formation of restrictions...
I was interested in this accident from the outset when, within 24 hours, it became clear that they did not suspect any serious design problem with the plane because they did not take the usual precaution of grounding the fleet.
...Some would be surprised that the FAA should allow an ETOPS aircraft with a defect that reduces engine power by up to 77 percent on takeoff to be considered serviceable. In theory, an engine with FADEC version A.0.4.5 installed has a defect that can't be cleared and is therefore unserviceable. Others might wonder how such safety critical software can make it through the validation and verification regime into world-wide fleet service. Overall, it's shades of the previous GE90 "rollback" and IFSDs (inflight shutdowns) from earlier days. The only difference was in those cases, it was in cruise and was caused by moisture freezing in the P3B and PS3 lines to the FADEC, and it was resolved by increasing the tubing diameters. Perhaps the software now needs uppercase zeroes and ones in its coding -- or a larger pitch font...
[url=http://edition.cnn.com/2008/TRAVEL/04/16/air.accidents.ap/index.html]During 04/08 CNN[/url] said:...As hundreds of thousands of air travelers learned last week, the number of fatal accidents is not the only measure of air safety. Last week, American Airlines alone canceled nearly 3,100 flights affecting 250,000 passengers as the Federal Aviation Administration forced it to inspect wiring in its Boeing MD-80 jets. Alaska Airlines, Midwest Airlines and Delta also canceled flights for similar inspections.
The FAA was finally insisting on compliance with a September 5, 2006, order that it had given airlines 18 months to obey. The tougher FAA stance followed the revelation last month that the agency's lax enforcement of its own safety rules had allowed Southwest Airlines to fly dozens of its Boeing 737s without inspecting them as required for cracks in the fuselage.
The FAA fined Southwest a record $10.2 million and ordered an audit of maintenance records at all domestic carriers to see whether its rules had been obeyed. United had to pull some of its Boeing 777s from service to test their cargo-fire suppression systems.
No one knew whether the audit might turn up other planes that would have to be pulled from service.
"The U.S. aviation industry has produced an admirable safety record in recent years," NTSB Chairman Mark Rosenker said. "However, we must not become complacent. We must continue to take the lessons learned from our investigations and use them to create even safer skies for all aircraft operators and their passengers."
The government figures showed that scheduled U.S. airlines flew 18.7 million hours in 2007 with 24 accidents but no deaths. There was one fatality among nonscheduled U.S. carriers: A mechanic was fatally injured while working on a Sky King Inc. Boeing 737 in Tunica, Mississippi, on July 10.
Commuter airlines had 3 accidents in 302,000 hours of flight but no fatalities.
On-demand carriers had 43 deaths in 62 accidents over 3.7 million flight hours.
General aviation saw its accident fatalities plummet from 703 in 2006 to 491 in 2007. But during 23.8 million hours of private flights in 2007, the number of accidents rose to 1,631 from 1,518 in 2006.
Foreign registered aircraft accounted for 11 accidents in the U.S. in 2007, with three deaths in a single accident. Unregistered aircraft had 14 accidents, which claimed 7 lives...
This action is far from usual Tony and is only taken when there is significant indication it could affect other similar aircraft ... Too many £'s involvedI was interested in this accident from the outset when, within 24 hours, it became clear that they did not suspect any serious design problem with the plane because they did not take the usual precaution of grounding the fleet.
Extremely unlikely, modern jets do not follow a glide approach like light aircraft they approach under power to prevent spooling delays ... Besides, most turbofans nowadays aren't that unresponsive even from flight idle.My intitial thought was that it may well have been a crew operational error and I wondered if they had allowed the engines speed to reduce to far to enable them to spool up fast enough when power was required to maintain the glide path.
Again, not very likely ... Pilots may doze off across the Atlantic but the two phases of flight where they are always on the ball is Takeoff and Landing ... Takeoff in particular as it's by far the most dangerous phase of any flight.It seems to imply that the plane was in full ILS mode and the crew were leaving the systems to themselves perhaps without watching the performance as closely as I would have expected them to.
You presume correctly in all aircraft I've ever come across though I've no specific knowledge about the 777. Cavitation usually damages either the pump inlet guide vanes, its impellor, the outlet guide vanes or any combination of the three.I presume the HP pumps are fed by LP pumps although no mention was made of them in that report. What evidence does cavitation leave in the outlet ports?