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NTSB PRESS RELEASE
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National Transportation Safety Board
Washington, DC 20594
FOR IMMEDIATE RELEASE: March 11, 2009
SB-09-11
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NTSB ISSUES URGENT SAFETY RECOMMENDATION TO ADDRESS ENGINE
THRUST ROLLBACK EVENTS ON B-777 AIRCRAFT
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Washington, DC - Following two engine thrust rollback events
on Boeing 777 aircraft powered by Rolls-Royce engines, the
National Transportation Safety Board issued an urgent safety
recommendation today calling for the redesign of a Rolls-
Royce engine component. The Safety Board also recommended
that, after the redesign is completed, the new system be
installed on all affected B-777 airplanes at the next
maintenance check or within six months.
These recommendations are being issued in response to the
findings in two investigations - an accident and an incident
- involving engine thrust rollbacks on Boeing 777-200ER
airplanes powered by Rolls-Royce RB211 Trent 800 Series
engines. In both cases a build-up of ice (from water
normally present in all jet fuel) on the fuel/oil heat
exchanger (FOHE) restricted the flow of fuel to the engine,
resulting in an uncommanded engine rollback.
The first event, which is still being investigated by the
UK's Air Accidents Investigation Branch (AAIB), occurred on
January 17, 2008, when a Boeing 777 experienced a dual
engine rollback on final approach and crashed short of the
runway at London's Heathrow International Airport. One
passenger was seriously injured, eight passengers and four
of the flight crew sustained minor injuries; the airplane
was substantially damaged.

The second event occurred on November 26, 2008, when a Delta
Air Lines Boeing 777 experienced a single engine rollback
during cruise flight over Montana while en route from
Shanghai to Atlanta. Normal operations resumed after the
flight crew followed Boeing's published procedure to recover
engine performance; the airplane landed safely in Atlanta.
Testing in support of the UK accident investigation led
Boeing to develop procedures to help prevent ice
accumulation, and to recover thrust in cases of ice
blockage. As more information from the Delta rollback event
was developed, Boeing modified the procedures, which became
the basis of an airworthiness directive issued by the
Federal Aviation Administration.
While the procedures may reduce the risk of a rollback in
one or both engines due to FOHE ice blockage, they add
complexity to flight crew operations, and the level of risk
reduction is not well established. And because the recovery
procedure requires a descent, the aircraft may be exposed to
other risks such as rising terrain or hazardous weather, or
the inability to achieve maximum thrust during a critical
phase of flight, such as during a missed approach.
Because of these hazards, the Safety Board has determined
that the only acceptable solution to this safety
vulnerability is a redesigned FOHE that would eliminate the
potential of ice build-up. On February 23, 2009, Rolls-Royce
indicated that a redesign of the FOHE was underway, and that
they anticipated the redesign to be tested, certified and
ready for installation within 12 months.
"With two of these rollback events occurring within a year,
we believe that there is a high probability of something
similar happening again," said NTSB Acting Chairman Mark V.
Rosenker. "We are encouraged to see that Rolls-Royce is
already working on a redesign, and we are confident that
with the FAA and EASA (European Aviation Safety Agency)
overseeing the process, this flight safety issue - even one
as complex as this - will be successfully and expeditiously
resolved."
The NTSB has made the following two recommendations to both
the Federal Aviation Administration and the European
Aviation Safety Agency:
Require that Rolls-Royce redesign the RB211 Trent 800 series
engine fuel/oil heat exchanger (FOHE) such that ice
accumulation on the face of the FOHE will not restrict fuel
flow to the extent that the ability to achieve commanded
thrust is reduced.
Once the fuel/oil heat exchanger (FOHE) is redesigned and
approved by certification authorities, require that operators
of Boeing 777-200 airplanes powered by Rolls Royce RB211 Trent
800 series engines install the redesigned FOHE at the next
scheduled maintenance opportunity or within 6 months after the
revised FOHE design has been certificated, whichever comes
first.
The NTSB and AAIB will continue to work together closely on
both of the rollback events as each of the investigations
move forward.
Safety recommendation letter to the Federal Aviation
Administration:
http://ntsb.gov/Recs/letters/2009/A09_17_18.pdf
Safety recommendation letter to the European Aviation Safety
Agency: http://ntsb.gov/Recs/letters/2009/A09_19_20.pdf
Image: Ice accumulation on the inlet face of a Rolls-Royce
RB211 Trent 800 Series Fuel/Oil Heat Exchanger during
testing >>> http://www.ntsb.gov/Pressrel/2009/FOHEface.jpg

NTSB: Some Boeing 777s at risk for power loss because of engine flaw.
News Inferno

U.S. transportation regulators are questioning the safety of some Boeing 777s built with Rolls-Royce engines. Apparently, the National Transportation Safety Board (NTSB) is not convinced that procedures recently adopted by airlines flying Boeing 777s will prevent a potentially catastrophic power loss related to a defect in the Rolls-Royce engine.

According to a report posted on Reuters.com, Boeing 777s with Rolls-Royce engines could lose power in freezing weather due to accumulation of ice in the fuel supply. The Boeing 777 engine defect has already been implicated in two accidents.

According to a report posted on TimesOnline, one occurred last January when a British Airways flight lost power in both engines during final approach and crashed at London’s Heathrow Airport. The aircraft’s landing gear was ripped off, but only one passenger out of the 152 on board was seriously hurt.

According to Reuters, a Delta Air Lines Boeing 777 suffered a similar loss of engine power while flying between Shanghai and Atlanta in November. The pilot followed a standard procedure to recover engine power and landed the jet safely at its planned destination.

Following the two incidents, Boeing issued new procedures to help prevent ice accumulation, and to recover thrust in cases of ice blockage. The NTSB said that while the mandatory procedures did reduce the risk of ice blocking the fuel supply, the added burden placed on pilots who have to implement them might cause other hazards.

According to the Atlanta Business Journal, the NTSB is recommending that the Federal Aviation Administration require Rolls-Royce to redesign the engine’s heat exchanger to prevent ice from restricting fuel flow. It is also recommending the redesigned part be installed within six months of its certification to fly or during an aircraft’s next scheduled maintenance.

Yet despite the urgent nature of its recommendation, the NTSB has not called for the grounding of Boeing 777s with Rolls-Royce engines That means that around 220 Boeing 777s with the potentially deadly engine flaw will stay in the air.

According to Reuters, the NTSB said that Rolls-Royce is working on the component change but it may not be ready for installation for another 12 months.