Friday, March 13, 2009

N.T.S.B. Worried About Possible Engine Design Fault in Boeing 777s

I'm a little fussy, as many of you know, about aviation safety issues. So take this for what you think it might be worth:

The National Transportation Safety Board issued an "urgent safety recommendation" calling for the redesign of a Rolls-Royce engine part on Boeing 777 aircraft that use Rolls engine.

Two incidents from last year events precipitated the NTSB investigation that led to the warning. One involved a British Airways flight from Beijing that crashed short of a runway at Heathrow Airport in London on Jan. 17, 2008. Thirteen on board were injured, and the plane was badly damaged. It was later determined that one engine had lost power below the necessary thrust level.

The second incident involved a Delta Air Lines 777 that experienced a single "engine rollback" in cruise flight over Montana en route from Shanghai to Atlanta last Nov. 26. The crew recovered engine performance using Boeing procedures, and the flight landed safely in Atlanta.

Boeing then modified the procedures, based on what it learned from the Delta rolback, and that became the basis of an FAA airworthiness directive.

The basic problem, the NTSB said, is a fault in the engines' fuel/oil heat exchanger system that can allow ice build-up from water present in all jet fuel, restricting fuel flow into the engine and causing a rollback in power.

The NTSB said this week that the procedure developed by Boeing for crew to handle this rare occurrence might reduce the potential rollback risk, but "they add complexity to flight-crew operations." The procedural fix requires a descent in altitude, with possible hazards then from terrain or weather. During critical phases of flight, such as a missed landing approach, the inability to maintain necessary thrust in an engine is potentially hazardous, the NTSB said.

"The only acceptable solution," the NTSB said, is for a re-design of the engine part to eliminate any potential for ice-buildup. Rolls-Royce began working on that re-design last month and expects the fix to be ready within a year.

"With two of these rollback events occurring within a year, we believe that there is a high probability of something similar happening again," the NTSB acting chairman, Mark V. Rosenker, said.

Aviation authorities in both the U.S. and Europe and overseeing the engone design at Rolls, which affect 777-200 aircraft powered by Rolls-Royce RB211 Trent 800 series engines.

Until the fixes are in place, flight crews at least have some warning and some procedural guidance on how to handle one of these unexpected rollbacks, thanks to Boeing's guidance.

Meanwhile, the European air-safety agency said today that the 777s were safe to fly. "You can fly it safely, and it is being flown safely, if you undertake the operational procedures that we have mandated," Daniel Holtgen, a spokesman for the European Aviation Safety Agency, told Reuters.

The take-away: Engine design problem potential hazard on 777-200s. Till engine design problem is fixed, it's up to the pilots to maneuver their way out of trouble, using procedures that have been carefully drafted to address the problem.

Oh hell, don't worry. Go back to yesterday's post with the video of the dancing parrot that loves Ray Charles, what I say.


1 comment:

Juanpilot said...

Hi Joe,
I'm a B777 Captain and I'm a little concerened about this as well. I'm lucky we have GE engines in my fleet so I have never exprienced a roll back. I have as flown the B757 and the RR engines on that had rollback issues as well although for a different reason. Perhaps they should change the R in RR to rolback which now seems like a Brit euphemism for engine failure. BTW these failure are still very infrequent and thats why there has not been more aggressive action taken by the Air Agencies involved.