787 Problèmes électriques

In lieu of the requirements of 14 CFR 25.1353(c)(1) through (c)(4), the
following special conditions apply. Lithium ion batteries on the Boeing
Model 787-8 airplane must be designed and installed as follows:

(1) Safe cell temperatures and pressures must be maintained during any
foreseeable charging or discharging condition and during any failure of
the charging or battery monitoring system not shown to be extremely
remote. The lithium ion battery installation must preclude explosion in
the event of those failures.

(2) Design of the lithium ion batteries must preclude the occurrence of
self-sustaining, uncontrolled increases in temperature or pressure.

(3) No explosive or toxic gases emitted by any lithium ion battery in
normal operation, or as the result of any failure of the battery
charging system, monitoring system, or battery installation not shown to
be extremely remote, may accumulate in hazardous quantities within the
airplane.

(4) Installations of lithium ion batteries must meet the requirements of 14 CFR 25.863(a) through (d).

(5) No corrosive fluids or gases that may escape from any lithium ion
battery may damage surrounding structure or any adjacent systems,
equipment, or electrical wiring of the airplane in such a way as to
cause a major or more severe failure condition, in accordance with 14
CFR 25.1309(b) and applicable regulatory guidance.

(6) Each lithium ion battery installation must have provisions to
prevent any hazardous effect on structure or essential systems caused by
the maximum amount of heat the battery can generate during a short
circuit of the battery or of its individual cells.

(7) Lithium ion battery installations must have a system to control the
charging rate of the battery automatically, so as to prevent battery
overheating or overcharging, and,

(i) A battery temperature sensing and over-temperature warning system
with a means for automatically disconnecting the battery from its
charging source in the event of an over-temperature condition, or,

(ii) A battery failure sensing and warning system with a means for
automatically disconnecting the battery from its charging source in the
event of battery failure.

( Any lithium ion battery installation whose function is required for
safe operation of the airplane must incorporate a monitoring and
warning feature that will provide an indication to the appropriate
flight crewmembers whenever the state-of-charge of the batteries has
fallen below levels considered acceptable for dispatch of the airplane.

(9) The Instructions for Continued Airworthiness required by 14 CFR
25.1529 must contain maintenance requirements for measurements of
battery capacity at appropriate intervals to ensure that batteries whose
function is required for safe operation of the airplane will perform
their intended function as long as the battery is installed in the
airplane. The Instructions for Continued Airworthiness must also contain
procedures for the maintenance of lithium ion batteries in spares
storage to prevent the replacement of batteries whose function is
required for safe operation of the airplane with batteries that have
experienced degraded charge retention ability or other damage due to
prolonged storage at a low state of charge.

High-energy batteries


The Dreamliner — whose electrical systems generate 1.45 megawatts of
electricity, enough to power 600 homes and four times as much as a
larger 777 jet — carries two large lithium-ion batteries, located in
forward and rear electronics bays.


The battery in the rear bay that caught fire is about one and a half times the size of a car battery.


It's used to start the auxiliary power unit (APU), a small turbine
engine in the tail that is used to provide electrical power while the
plane is on the ground, or as a backup power source during an in-flight
emergency.


According to NTSB preliminary findings, airplane maintenance and
cleaning personnel were on the airplane with the APU in operation when
they observed smoke in the cabin.


Emergency personnel who responded "detected a fire in the electronics
and equipment bay near the APU battery box," the NTSB stated. "The fire
was extinguished about 40 minutes after arrival of the first rescue and
fire personnel."


"One firefighter received minor injuries," the NTSB said.


Aviation analyst Scott Hamilton of Leeham.net
said he expects the Federal Aviation Administration (FAA) to soon issue
an airworthiness directive mandating some precautionary actions.


"I'd be surprised if the FAA doesn't quickly come out with an
inspection order," Hamilton said. "Airlines are going to be doing this
anyway."


Monday's fire at Logan follows an in-flight fire during a 2010
Dreamliner test flight, and the four more recent incidents involving
faulty electrical panels while the jet was in service.


Sinnett said the first of the electrical-panel problems occurred last
summer. He didn't name the airline, but back then only All Nippon
Airways and Japan Airlines were flying the Dreamliner. The incident
wasn't made public at the time.


He said the issue occurred again in December on a United flight that
had to be diverted to New Orleans; a few days later on a Qatar delivery
flight from Everett to Doha; and then again on a second United jet.


United in late December reported "sporadic issues with our 787 generators and power distribution panels."


Sinnett said all four incidents were traced to faulty circuit boards from a single manufacturing batch.


The person with knowledge of the problems said the flawed circuit
boards are manufactured in Mexico for United Technologies, which
supplies the power distribution panels to Boeing.


However, the person said the only impact of the arcing in the circuit
boards was to cut off some of the plane's power supply from a
generator, but not enough to present any safety issue. None of the
planes involved was ever in danger, the person said.


Sinnett said Boeing is still working to fix that problem.


Despite those in-flight incidents, he said, the 787 is "running at a
high dispatch reliability, on a par with where we were on the 777 at
this point."

The Logan fire incident is much more serious, however.


In 2007, the FAA noted that the large, high-capacity, rechargeable
lithium-ion batteries Boeing is using on the Dreamliner differ
significantly from the nickel-cadmium or lead acid batteries used on
other jets.


Commercial aviation has "limited experience" with such batteries, the
agency said, noting that in other applications "lithium ion batteries
are significantly more susceptible to internal failures that can result
in self-sustaining increases in temperature."


Also, overcharging of lithium-ion batteries can generate high
temperatures so that "the metallic lithium can ignite, resulting in a
self-sustaining fire or explosion," the FAA said.


Because of those concerns, the agency attached special safety
conditions governing the design and maintenance of the 787 batteries.


It said the jet's batteries must specifically preclude any heat
buildup and include monitoring and warning systems in case of any
failures.


Sinnett said Boeing has met those design requirements.


He said there are four levels of protection to prevent the most dangerous scenario, that the battery overcharges.


Addressing an online report by The Wall Street Journal Tuesday that
when United inspected its Dreamliner batteries after the Logan fire, it
found some faulty wiring installed, Sinnett insisted the battery system
is designed so that problems with the wiring cannot cause a fire.


He said that although the 787 uses more electric power, it uses correspondingly less hydraulics and less pneumatics.


That means less high-pressure fluid and less hot, high-pressure air moving around the aircraft in titanium ducts.


The total horsepower generated by the 787's engines in cruise flight
is actually less than on a conventionally powered aircraft, Sinnett
said, and as a result there's "less potential for something bad to
happen."

Admin a écrit:Comme tu dis
Le ramp up de la prod à l'air de se passer pile poil comme il faut

Just to orient people who are seeing the 787's aft equipment bay for the first time...

The photo is taken from the RH side of the EE bay, looking left. Right in the photo is forward in the airplane and left is aft. Mr Bauer's left hand is resting on an opening which extends to a hatch which goes down through the WTB fairing and exits the airplane. When cargo is loaded in the aft pit, this is the only way into the aft equipment bay.

Adjacent Mr Bauer's right hand is the control unit for the electric wing ice protection system. Each slot in the box represents the electric control function for a symmetrical pair of ice protection zones on each wing.

Above the APU battery slot, where Mr Baur is inspecting, is the APU power panel. This manages all power from the APU.

Directly behind Mr Bauer is the oft-discussed P100 power panel. The P200 panel is directly behind the photographer.

By Mr Bauer's left shoulder is a liquid cooled equipment rack (often referred to as an "HVDC" (high-voltage direct current) rack). This rack contains the ATRUs (auto transformer/rectifier units) and large electric motor controllers, which are the heart of the 787's more-electric system's architecture. There is an identical rack at the right shoulder of the photographer.

People
familiar with the investigation, however, said high-level Federal
Aviation Administration officials are increasingly concerned about the
spate of electrical problems, highlighted by the smoldering battery
aboard the JAL jet, that have dogged the aircraft since its
introduction.

No additional mandatory safety fixes or
government-ordered inspections of Dreamliners are expected for at least
the next day or two, partly because FAA and NTSB experts still are
trying to determine the specific cause of the battery fire. But perhaps
as soon as early next week, according to one person familiar with the
matter, regulators may call for some type of review or reassessment of
design and manufacturing issues related to the Dreamliner's electrical
systems.