NTSB -- FOUR RECENT UNCONTAINED ENGINE FAILURE EVENTS PROMPT NTSB TO ISSUE URGENT SAFETY RECOMMENDATIONS TO FAA

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NTSB PRESS RELEASE

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National Transportation Safety Board

Washington, DC 20594

FOR IMMEDIATE RELEASE: May 27, 2010

SB-10-20

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FOUR RECENT UNCONTAINED ENGINE FAILURE EVENTS PROMPT NTSB TO

ISSUE URGENT SAFETY RECOMMENDATIONS TO FAA

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The National Transportation Safety Board today issued two

urgent safety recommendations to the Federal Aviation

Administration (FAA). The first recommendation asks that the

FAA require operators of aircraft equipped with a particular

model engine to immediately perform blade borescope

inspections (BSI) of the high pressure turbine rotor at

specific intervals until the current turbine disk can be

redesigned and replaced with one that can withstand the

unbalance vibration forces from the high pressure rotor. The

second recommendation asks the FAA to require the engine

manufacturer to immediately redesign the disk. The NTSB

issued an additional recommendation for a requirement that

operators perform a second type of inspection and another

recommendation related to the engine manufacturer regarding

the installation of the replacement disk.

All four recommendations apply to the low pressure turbine

(LPT) stage 3 (S3) rotor disk in the General Electric (GE)

CF6-45/50 series turbofan engines that can fail unexpectedly

when excited by high-pressure (HP) rotor unbalance.

An uncontained engine event occurs when an engine failure

results in fragments of rotating engine parts penetrating

and exiting through the engine case. Uncontained turbine

engine disk failures within an aircraft engine present a

direct hazard to an airplane and its passengers because

high-energy disk fragments can penetrate the cabin or fuel

tanks, damage flight control surfaces, or sever flammable

fluid or hydraulic lines. Engine cases are not designed to

contain failed turbine disks. Instead, the risk of

uncontained disk failure is mitigated by designating disks

as safety-critical parts, defined as the parts of an engine

whose failure is likely to present a direct hazard to the

aircraft.

In its safety recommendations to the FAA, the NTSB cited

four foreign accidents, which the NTSB is either

investigating or participating in an investigation led by

another nation, in which the aircraft experienced an

uncontained engine failure of its GE CF6-45/50 series

engine.

The date, location, and circumstances of these four events

(none had injuries or fatalities) are as follows:

On July 4, 2008, a Saudi Arabian Airlines (Saudia) Boeing

747-300 experienced an engine failure during initial climb

after takeoff from Jeddah, Kingdom of Saudi Arabia. This

investigation has been delegated to the NTSB.

On March 26, 2009, an Arrow Cargo McDonnell Douglas DC-10F,

about 30 minutes after takeoff from Manaus, Brazil,

experienced loss of oil pressure in one engine. The pilots

shut down the engine and diverted to Medellin, Columbia.

This investigation has been delegated to the NTSB.

On December 17, 2009, a Jett8 Cargo Boeing 747-200F airplane

was passing through 7,000 feet above ground level (agl) when

the flight crewmembers heard a muffled explosion and

immediately applied left rudder. With one engine losing oil

pressure, the airplane returned to land at Changi,

Singapore. The NTSB is participating in the investigation

that is being led by the Air Accident Investigation Bureau

of Singapore.

On April 10, 2010, an ACT Cargo Airbus A300B4 experienced an

engine failure while accelerating for takeoff at Manama,

Bahrain. The crew declared an emergency, rejected the

takeoff, activated the fire suppression system, and

evacuated the airplane. The NTSB is participating in the

investigation that is being led by the Bahrain Ministry of

Transportation - Civil Aviation.

The four recommendations to the FAA are as follows:

1. Immediately require operators of CF6-45/50-powered

airplanes to perform high pressure turbine rotor blade

borescope inspections every 15 flight cycles until the

low pressure turbine stage 3 disk is replaced with a

redesigned disk that can withstand the unbalance

vibration forces from the high pressure rotor.

(Urgent)

2. Require operators of CF6-45/50-powered airplanes to

perform fluorescent penetrant inspections of CF6-45-

50- low pressure turbine stage 3 disks at every engine

shop visit until the low pressure turbine stage 3 disk

is replaced with a redesigned disk that can withstand

the unbalance vibration forces from the high pressure

rotor.

3. Immediately require General Electric Company to

redesign the CF6-45/50 low pressure turbine stage 3

disk so that it will not fail when exposed to high

pressure rotor unbalance forces. (Urgent)

4. Once General Electric Company has redesigned the CF6-

45/50 low pressure turbine (LPT) stage 3 disk in

accordance with Safety Recommendation [3], require all

operators of CF6-45/50-powered airplanes to install

the newly designed LPT S3 at the next maintenance

opportunity.

The safety recommendation letter to the Federal Aviation

Administration with all four safety recommendations may be

found here: http://www.ntsb.gov/recs/letters/2010/A-10-098-

101.pdf

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NTSB Media Contact: Bridget Serchak

202-314-6100

Bridget.serchak@xxxxxxxx

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