Posts Tagged ‘Boeing 747-8’

FAA requires GE software fault on Boeing 747-8 aircraft to be urgently fixed

March 26, 2014

In the wake of the MH370 disappearance where an aircraft fault – even if considered unlikely – cannot be ruled out, any safety issue on Boeing aircraft takes on a higher profile. Glitches with the Dreamliner contribute to the a slightly more nervous environment than usual. A software fault with some GE engines which could cause Boeing’s 747-8 aircraft to lose thrust while landing and crash into the ground has to be urgently fixed according to an instruction from the FAA. The new directive reads

[Federal Register Volume 79, Number 57 (Tuesday, March 25, 2014)] [Rules and Regulations] [Pages 16173-16175] From the Federal Register Online via the Government Printing Office [www.gpo.gov] [FR Doc No: 2014-06476]

SUMMARY:

We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model  747-8 and 747-8F series airplanes powered by certain General Electric (GE) engines. This AD requires removing certain defective software and installing new, improved software. This AD was prompted by a determination that the existing electronic engine control (EEC) software logic can prevent  stowage of the thrust reversers (TRs) during certain circumstances, which could cause the TRs to move back to the deployed position. We are issuing this AD to prevent in-flight deployment of one or more TRs due to loss of the TR auto restow function, which could result in inadequate climb performance at an altitude insufficient for recovery, and consequent uncontrolled flight into terrain. 

This AD is effective April 9, 2014.

Reuters Wed Mar 26, 2014 

The U.S. Federal Aviation Administration on Tuesday ordered an immediate fix to the latest version of Boeing Co’s 747-8 plane, saying a software glitch could cause it to lose thrust when close to landing and fly into the ground. The FAA’s so-called airworthiness directive covers Boeing’s 747-8 and 747-8F planes with certain General Electric Co engines. It calls for replacing defective software with a new improved version. The rule, the fourth such directive involving the 747-8, directly affects seven airplanes in the United States, the FAA said. If adopted internationally, the rule would cover a larger number. Boeing’s website said it had delivered 66 of the four-engine jets, the company’s largest, to customers worldwide since the model was introduced in October 2011. …. …. GE said it owned the software and jointly analyzed it with Boeing, but plane maker decided to recommend the software change to customers. According to the FAA, the risk arises when a plane is changing back into “air mode” while performing a “rejected or bounced landing.” That change halts hydraulic pressure used to stow the engine thrust reversers, which slow the plane on landing, the agency said. Without hydraulic pressure, the reversers may not stow fully and might redeploy, which “could result in inadequate climb performance at an altitude insufficient for recovery, and consequent uncontrolled flight into terrain,” the FAA said. Unidentified business jet/VIP customers own the eight passenger models of the aircraft in the United States, according to Boeing’s website. Air cargo company Atlas Air is the largest U.S. commercial owner of the jet, with a fleet of eight 747-8F freighters. Among passenger carriers, Lufthansa is the largest operator, with 11. It said its planes were unaffected by the directive. “GE has confirmed that all our engines already have the software update that is required by the FAA,” a spokesman said on Wednesday. China’s Cathay Pacific has 13 freighters and Cargolux, based in Luxembourg, has nine. Korean Airlines Co, Nippon Cargo Airlines Co Ltd and Volga-Dnepr UK Ltd also own 787-8F freighters, according to Boeing’s website.

In November 2013 another long running software fault on GE engines for Boeing 787’s and 747’s which caused engine flameout in icy conditions seemed to be finally fixed.

FlightGlobal: 10th Nov. 2011 Reports of eight in-flight and four on-ground unintended shutdowns of General Electric CF6-80C2B wide-body turbofan engines have prompted the US Federal Aviation Administration (FAA) to mandate a change out of the engine’s electronic control unit (ECU). A proposed airworthiness directive, to be published on 14 November, will affect 697 CF6 engines flying on US-registered widebody aircraft. The directive supersedes a 2007 AD requiring a software upgrade (8.2.Q1) on the same ECU to increase the engine’s margin to flameout after several incidents where engines had flamed out due to exposure to ice crystals and ice shedding into the engine. With the new software in place, problems continued. FAA said it received two reports of “ice crystal condition flameouts”, which prompted GE to develop another software upgrade (8.2.R) for the ECU. The new software included “improved inclement weather capability, and enhanced fuel metering valve fault handling logic to reduce the risk of [in-flight shut down] caused by intermittent fuel metering valve feedback signals”, said the FAA. Since that time however, there have been 12 additional engine shutdowns, eight in flight and four on the ground, with engines using upgraded ECU software and other upgrades. The problem was found to be caused by ignition system induced noise that created dual-channel faults in the ECU computer.

Boeing issues warning: Further icing problems with GE GenX engines on Boeing aircraft

November 23, 2013
GenX 2B GE

GenX 2B GE

UPDATE:

Reuters: Boeing advised airlines on Friday about a risk of engine icing problems on its new 747-8 and 787 Dreamliner planes with engines made by General Electric, urging 15 carriers to avoid flying them near high-level thunderstorms. 

The move followed six incidents from April to November involving five 747-8s and one 787 when aircraft powered by GE’s GEnx engines suffered temporary loss of thrust while flying at high altitude. The problem was caused by a build-up of ice crystals, initially just behind the front fan, which ran through the engine, said a GE spokesman, adding that all of the aircraft landed at their planned destinations safely.

Boeing on Friday issued a notice prohibiting the affected aircraft from flying at high attitude within 50 nautical miles of thunderstorms that may contain ice crystals.

Icing problems with GE engines on Boeing’s Dreamliner has led to Japan Airlines pulling the Dreamliner from two international routes.

This comes on top of the icing problems noticed recently on the latest 747 cargo aircraft. A few weeks ago it was reported that a number of the latest long-haul Boeing 747 cargo aircraft fitted with the new GenX series of GE engines experienced engine icing problems when flying in particular cloud conditions at 41,000 feet:

Wall Street JournalIcing Hazards Surface on Boeing’s Newest 747 Jet

Years after aviation-safety experts thought they had eliminated the danger of airliner engines abruptly shutting down from internal ice accumulation, the same airborne hazard is showing up on a new generation of Boeing Co. jumbo jets.

The Chicago plane maker and General Electric Co., whose engines are installed on the biggest and newest Boeing 747 model, are now working together on fixes to prevent ice buildup that can prompt the giant airliner’s engines to temporarily malfunction or even stop working while cruising roughly 7 miles, or 41,000 feet, above the earth.

A GE spokesman said there are proposed software changes—which still need to be tested and then approved by the Federal Aviation Administration—designed to detect the presence of ice crystals in the atmosphere and eject the tiny particles before they form a coating deep inside engines that can melt or break into chunks.

… challenges with the GEnx-2B engines on extra-long 747 aircraft—known as 747-8s—highlight complex and nagging icing hazards that once again are forcing industry leaders and an international research team to scramble for answers. Before the partial government shutdown, according to industry officials, the FAA was moving toward mandating modifications to the 747-8’s computerized engine controls and making plans to warn pilots about susceptibility to internal engine icing while flying over storm-prone regions at roughly 40,000 feet.

Previously, experts believed such icing occurred primarily below 25,000 feet. ….

These cases of icing are different to those normally encountered and which are relatively well understood.

Aviation Week: 

….. The AirBridge Cargo event is the latest in a growing number of engine-icing incidents, which have triggered recent changes in international certification requirements. Unlike traditional engine icing, in which supercooled liquid droplets freeze on impact with exposed outer parts of the engine as the aircraft flies through clouds, engine core ice accretion involves a complex process where ice particles stick to a warm metal surface. These act as a heat sink until the metal surface temperature drops below freezing, thereby forming a location for ice and water (mixed-phase) accretion. The accumulated ice can either block flow into the core or shed into the downstream compressor stages and combustor, causing a surge, roll-back or other malfunction.

Until relatively recently, it was assumed that ice particles would bounce off structures and pass harmlessly through bypass ducts, or melt inside the engine. Now, there is evidence of an environment where a certain combination of water, ice and airflow is susceptible to accreting ice. Like many of the other known core icing events, the ABC 747-8F incident occurred near convective clouds. When incidents were first reported, investigators initially assumed supercooled liquid water, hail or rain were responsible because they had been lifted to high altitudes by updrafts. Yet most events have been recorded above 22,000 ft., which is considered the upper limit for clouds containing supercooled liquid water. ……

To find out exactly what is happening inside the convective systems that most frequently cause core icing, particularly in mid-latitude and tropical regions, an international team plans to conduct the High Ice Water Content (HIWC) test campaign in Darwin, Australia. The team includes NASA, FAA, Environment Canada, Transport Canada, Airbus, Boeing, the U.S. National Center for Atmospheric Research and the Australian Bureau of Meteorology. Also joining the effort will be the European Union’s High Altitude Ice Crystals (HAIC) project, which will be contributing a specially configured Falcon 20 research aircraft. ……

But now Boeing has warned all its clients who use aircraft with GE’s GenX engines not to fly them near certain kinds of storm clouds. And Japan Airlines whose Boeing 787 Dreamliners are powered by GenX engines has pulled the aircraft from two of its international routes:

Reuters: Japan Airlines (JAL)  said on Saturday it will pull Boeing 787 Dreamliners from two international routes after the U.S. aircraft maker notified it of icing problems in engines produced by General Electric .

Japanese carrier said Boeing notified airlines not to fly aircraft with GE’s GEnx Series engines near storm clouds following a recent incident in which a 747 aircraft experienced a loss of thrust after flying through anvil cloud.

As a result, JAL will replace Dreamliners on its Tokyo-Delhi and Tokyo-Singapore flights with other types of aircraft while also dropping a plan to use 787s for its Tokyo-Sydney route from December.

JAL will continue to fly 787s for other international and domestic routes, which are unlikely to be affected by cumulonimbus cloud for the time being.


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