FAA Grounds 787s

[RR_NDB]

New design. Big changes. New issues.

Hi,

Walnut:

Boeing decided electric cables were lighter? & simpler to transfer high load items. However unlike hydraulics which tend to leak in failure mode, electric cables if overloaded tend to catch fire.

One of the most studied, discussed, quantified, checked is the Design Philosophy and the concepts adopted. Boeing decision for the change to this innovative design involved even the engines (bleed issue) and the mentioned 1.45 MW shows the "magnitude of the electrification".

Would be fascinating to discuss in a Thread the comparison of hydraulics/pneumatic vs electric. I´m mulling the idea. After the crisis recedes.

[Rory166]

poll

I took the poll but got no results. Is that because I was not logged in? Can you copy the results here.

[sb_sfo]

Poll results

Results:
Bad luck <5%
Poor FAA/regulatory oversight <5%
Poor QC 6%
Substandard materials 6%
Poor design 6%
Too many innovations at one time 15%
Outsourced design and manufacture 24%
Insufficeint testing for worst-case scenarios 35%

For what its worth...

[syseng68k]

RR_NDB

Would be fascinating to discuss in a Thread the comparison of
hydraulics/pneumatic vs electric

Let's get started: Electrics, hydraulics or pneumatics, are
all means to transfer energy from one place to another. Electrics
are far more efficient and have less weight than either of the other
two. Hydraulics need heavy pumps, valves and lines to withstand the
high pressure and conversion efficiences are low.. Compressed
air needs a lot of ducting to get it to the right place. Wire does it
at a fraction of the cost and weight.

Moderen a/c need loads of electrical power and have large generating
systems anyway, so why not make as much of the system as possible
electrically powered to maximise efficiency ?. Sounds like a very
smart idea to me...

[RR_NDB]

787 innovated applying new concepts

syseng68k:

Let's get started: Electrics, hydraulics or pneumatics, are
all means to transfer energy from one place to another. Electrics
are far more efficient and have less weight than either of the other
two.

Let´s look to an example:

Taxiing using electric motors instead of noisy turbines.



Will need to go to a subroutine in next days in order to think about this comparison: Electrics, hydraulics or pneumatics.

But it seems electric "will be the future". (some exceptions, obviously)

And after this and painful teething of 787 i FIRED a big Li Ion pack (18650) in my electric bike and yet installed a micro APU

My only problem is: 787 battery issue ended my love with this wonderful battery. She created a trauma for me. Now i am reviewing to the least possible use of batteries in my projects. Maximum cell size? 18650. thermal runaway? Make it impossible: SEPARATED cells. Worst case scenario? (a virtually impossible one): Inerting gas and a manifold to exterior from each cell. Charger? PARALLEL!!! etc. etc. etc.

[Ex Cargo Clown]

"Inerting gas and a manifold to exterior from each cell. " Inert with what exactly? on an ETOPS flight it will just reignite. If you keep on flooding it with halon, then you'd kill everyone onboard.

Going to have a pop at Li-Mn batteries tomorrow in the lab, far better conditions than a pumpkin lol

[RR_NDB]

Ni Cads became wonderful batteries

Ex Cargo Clown:

Inert with what exactly?

To be studied. If not existent the manifold will be more elaborated.

on an ETOPS flight it will just reignite.

Each cell could die (smaller ones and with any behavior) and the remaining cells does the task (An stack is voltage redundant. Remember the parallel charger.)

If you keep on flooding it with halon, then you'd kill everyone onboard.

Fire will not be allowed to happen. Will be forced out. Like an afterburner. Batteries will not be near electronics. May be the cells distributed.

Ok, let´s go back to the proven Ni Cd´s. LOL I concede. Big problem!

Teething or GROSS ERROR?

[westerndh]

Elon Musk has offered help

Tesla / SpaceX CEO Elon Musk tweeted a few days ago he's approached 787 Chief Engineer to offer help, just saw this article:

Elon Musk: Boeing 787 battery fundamentally unsafe

[vaschandi]

Boeing gets help

...may be there is no other choice...


Now Elon Musk Is Helping Boeing Save The 787 Dreamliner - Business Insider

[TURIN]

1.45 MW is the TOTAL generating capacity of the engines & APU. It is not what the a/c needs. EG. Dispatch with one VFSG inoperable is allowed under MEL. Limit is 180 mins ETOPS.

The 787 still has lots of hydraulics by the way. Electrical actuators have replaced the brakes, 4 spoilers and (I think) stab trim. The rest is still hydraulic.
It is pneumatics that are the big change. No ATA CH 36 in the AMM on this beast.


Posted from Pprune.org App for Android

[Chuck Noris]

Lithium Battery

Since the grounding of the 787 and many other incident (DXB UPS) involving lithium battery. I would like to know if your airline have banned those on a passenger flight? Should they?

[hetfield]

Let's get started: Electrics, hydraulics or pneumatics, are
all means to transfer energy from one place to another. Electrics
are far more efficient and have less weight than either of the other
two. Hydraulics need heavy pumps, valves and lines to withstand the
high pressure and conversion efficiences are low.. Compressed
air needs a lot of ducting to get it to the right place. Wire does it
at a fraction of the cost and weight.

I fully agree.

The two batteries of the 787 have NOTHING to do with that, they are common for all airliners.

- APU start
- Elec Essential backup

[plasticmerc]

Inerting the battery could be done much like the inerting of the center fuel tanks!
Nitrogen generation system seal the battery bay/ isolate the battery and plumb in a feeder line to it with a nitrogen system.
But having read previous posts I don't think that would be very successful as when the battery goes off with a bang it produces Oxygen. Would the nitrogen rich area be enough to dilute the O2 content???

This is an interesting situation many airlines world wide have pinned their hopes and dreams on the 787, new routes, fuel saving replacements.
Just goes to show as the world gets more densely populated and a/c get bigger we realize how much we need a particular aircraft.
Turbo props have grown from the original 19-30- 50 now 70 seaters. now we see 90 seaters on the horizon, unfortunately regional airports and towns/cities can't fill the increase and then you end up having no regional services to such places.
Boeing have tried to do a shorter range 787 but that has been a flop, many airlines rely on 767 a/c not too big not to small good range good operating conditions. but it is old and there is nothing that would have replaced it until now.
I understand I have drifted off topic a bit but in my opinion it is all relevant.
This battery/ electrical defect will have huge ramifications to the whole aviation environment.

[The Dominican]

Latest report from the NTSB (came out on CNN) is that they couldn't find any problems with the battery maker nor its method of construction, the investigation is now focused on the charger.
Aviation authorities find no big problems at Dreamliner's battery maker - CNN.com

[Arjaysee]

Hi Dominican. Looks like the focus is on the monitoring systems now rather than the chargers. The most recent NTSB release I saw indicated that the chargers passed all tests and "no significant anomalies were found".

[deptrai]

[snip...thread merge took this post out of context]

[robdean]

Just because the battery and charger 'check out ok' in investigative tests is no guarantee that redesign will not be mandatory.
Irrespective of the initial cause of malfunction (which may be upstream of the battery/charger or may be due to some overlooked variable) the outcome was a non-extinguishable burning battery. Which implies at least that this system is significantly intolerant to external contingencies.
A corollary is hydrogen in airships: it is lighter and cheaper than helium, but has distinct chemical properties which can on occasion prove disadvantageous...

[fdr]

If Boeing switch to Li-Mn batteries will they have to recertify the A/C?

ECC

25.1351
25.1353
25.1355
25.1362
25.1363

§ 25.1351 General.
(a) Electrical system capacity. The required generating capacity, and number and kinds of power sources must—

(1) Be determined by an electrical load analysis; and

(2) Meet the requirements of § 25.1309.

(b) Generating system. The generating system includes electrical power sources, main power busses, transmission cables, and associated control, regulation, and protective devices. It must be designed so that—

(1) Power sources function properly when independent and when connected in combination;

(2) No failure or malfunction of any power source can create a hazard or impair the ability of remaining sources to supply essential loads;

(3) The system voltage and frequency (as applicable) at the terminals of all essential load equipment can be maintained within the limits for which the equipment is designed, during any probable operating condition; and

(4) System transients due to switching, fault clearing, or other causes do not make essential loads inoperative, and do not cause a smoke or fire hazard.

(5) There are means accessible, in flight, to appropriate crewmembers for the individual and collective disconnection of the electrical power sources from the system.

(6) There are means to indicate to appropriate crewmembers the generating system quantities essential for the safe operation of the system, such as the voltage and current supplied by each generator.

(c) External power. If provisions are made for connecting external power to the airplane, and that external power can be electrically connected to equipment other than that used for engine starting, means must be provided to ensure that no external power supply having a reverse polarity, or a reverse phase sequence, can supply power to the airplane's electrical system.

(d) Operation without normal electrical power. It must be shown by analysis, tests, or both, that the airplane can be operated safely in VFR conditions, for a period of not less than five minutes, with the normal electrical power (electrical power sources excluding the battery) inoperative, with critical type fuel (from the standpoint of flameout and restart capability), and with the airplane initially at the maximum certificated altitude. Parts of the electrical system may remain on if—

(1) A single malfunction, including a wire bundle or junction box fire, cannot result in loss of both the part turned off and the part turned on; and

(2) The parts turned on are electrically and mechanically isolated from the parts turned off.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-41, 42 FR 36970, July 18, 1977; Amdt. 25-72, 55 FR 29785, July 20, 1990]

§ 25.1353 Electrical equipment and installations.
(a) Electrical equipment and controls must be installed so that operation of any one unit or system of units will not adversely affect the simultaneous operation of any other electrical unit or system essential to safe operation. Any electrical interference likely to be present in the airplane must not result in hazardous effects on the airplane or its systems.

(b) Storage batteries must be designed and installed as follows:

(1) Safe cell temperatures and pressures must be maintained during any probable charging or discharging condition. No uncontrolled increase in cell temperature may result when the battery is recharged (after previous complete discharge)—

(i) At maximum regulated voltage or power;

(ii) During a flight of maximum duration; and

(iii) Under the most adverse cooling condition likely to occur in service.

(2) Compliance with paragraph (b)(1) of this section must be shown by test unless experience with similar batteries and installations has shown that maintaining safe cell temperatures and pressures presents no problem.

(3) No explosive or toxic gases emitted by any battery in normal operation, or as the result of any probable malfunction in the charging system or battery installation, may accumulate in hazardous quantities within the airplane.

(4) No corrosive fluids or gases that may escape from the battery may damage surrounding airplane structures or adjacent essential equipment.

(5) Each nickel cadmium battery installation must have provisions to prevent any hazardous effect on structure or essential systems that may be caused by the maximum amount of heat the battery can generate during a short circuit of the battery or of individual cells.

(6) Nickel cadmium battery installations must have—

(i) A system to control the charging rate of the battery automatically so as to prevent battery overheating;

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

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

(c) Electrical bonding must provide an adequate electrical return path under both normal and fault conditions, on airplanes having grounded electrical systems.

[Amdt. 25-123, 72 FR 63405, Nov. 8, 2007]

§ 25.1355 Distribution system.
(a) The distribution system includes the distribution busses, their associated feeders, and each control and protective device.

(b) [Reserved]

(c) If two independent sources of electrical power for particular equipment or systems are required by this chapter, in the event of the failure of one power source for such equipment or system, another power source (including its separate feeder) must be automatically provided or be manually selectable to maintain equipment or system operation.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-23, 35 FR 5679, Apr. 8, 1970; Amdt. 25-38, 41 FR 55468, Dec. 20, 1976]


§ 25.1362 Electrical supplies for emergency conditions.
A suitable electrical supply must be provided to those services required for emergency procedures after an emergency landing or ditching. The circuits for these services must be designed, protected, and installed so that the risk of the services being rendered ineffective under these emergency conditions is minimized.

[Amdt. 25-123, 72 FR 63406, Nov. 8, 2007]

§ 25.1363 Electrical system tests.
(a) When laboratory tests of the electrical system are conducted—

(1) The tests must be performed on a mock-up using the same generating equipment used in the airplane;

(2) The equipment must simulate the electrical characteristics of the distribution wiring and connected loads to the extent necessary for valid test results; and

(3) Laboratory generator drives must simulate the actual prime movers on the airplane with respect to their reaction to generator loading, including loading due to faults.

(b) For each flight condition that cannot be simulated adequately in the laboratory or by ground tests on the airplane, flight tests must be made.


How big a deal? Probably not too bad, it is a package but then there is a few DER's there in Boeing looking at improving their resume a bit, a fair incentive to keep it going. Pretty sure that the FAA ACO will put all the rest of us doing certification programs on the back burner, I for one won't object to that, the B787 program is a key program.

[Chuck Noris]

I fully understand that it is impossible to totally band them, but since I personally witness my own laptop auto combustion and that it is almost impossible to extinguish. I think that tolerating those should be enough. We don't need to have more on the NOTOC of a passenger flight.

If the legislation approved it doesn't make it safe.

This extract is taken from IATA website regarding some change in the regulation.

(The ICAO DGP does not consider however that these changes will necessarily reduce incidents involving lithium batteries. To significantly improve safety, IATA advocates for enhanced outreach of regulations applicable to the transport and testing of lithium batteries by manufacturers as well as shippers.)

[deptrai]

"ANA said it replaced 10 of the batteries in the months before [the recent incidents].

In five of the 10 replacements the main battery had showed an unexpectedly low charge. An unexpected drop in a 787’s main battery also occurred on the flight that had to make an emergency landing in Japan on Jan. 16.

In three instances, the main battery failed to operate normally and had to be replaced along with the charger. In other cases, one battery showed an error reading and another, used to start the auxiliary power unit, failed. All the events occurred from May to December of last year.

According to investigators in Japan, the battery on the jet that made the emergency landing showed a stable reading of 31 volts, near its full charge capacity, until 15 minutes into the flight when pilots detected a strange smell. About that time, sensors detected a sudden unstable discharge of the battery to near zero for reasons that Japanese investigators still cannot explain."

http://www.nytimes.com/2013/01/30/bu...pagewanted=all