Hi, to make (or repair) any carbon fibre component, am I correct in saying that you need a Big Oven, to cure the material. Where are they going to find an Oven that is 787 size?

So it looks as if carbon composites will not be used for the repair.

Big oven
 

The industry has gone away from autoclaved composites for the very reason that they need a big oven to cure, the trend is now for resins that cure at room temp and get their strength from a post cure cycle IRO 80C.

The suggestion that this will be a non composite repair is unlikely, but as I said above I suspect that it will be a metalcentric repair that fails to take advantage of the bentfits that composite construction offers.

I don't think this will be covered by the tech log. Even a really big heater blanket just won't do. Heaven forbid trying to get a vacuum bag to seal!

I am aware that the FAA and EASA are struggling to establish size limits for composite repairs, but I suggest that by the above description, this damage would exceed even their wildest ideas.

Not quite true, but the material type may be of less concern than the manner of joining the repair to the structure. Fasteners in composites in areas where they were not designed into the structure can be quite tricky because of the low bearing strength of composites in the structure. Adhesive bonding is far more efficient but the size of the bond may be prohibitive to achieve. I am sure there are a number of customers who are watching eagerly to see how/if Boeing undertake a repair of this size in composite structure.

I am also concerned about any evidence of release of carbon fibres due to combustion. Hopefully only resin was consumed and no fibres were released. If not, then the smallest particles of carbon will cause havoc with not only the aircraft electronics but those of any surrounding electrical or electronic equipment in adjacent aircraft or GSE. This would be an ideal time to determine just what the risk of fire in a composite aircraft really is.

Battery life for towing
 

For those who are interested the batteries are suppose to last for about 30 min for towing- maybe more depending if the main battery switch is set to on or not - on ovhd panel there is a batt test switch besides main batt switch - high/med/low . If high then about 15 min with main batt switch to on- if medium or low its mot recommended to tow without apu on.

Power distribution panels
 

There are 17 Remote power dist panels all over the aircraft. One is located exactly in the fire damaged area. But if you are saying the aircraft had no GPU and APU was also not running, then there is no power at these panels. The panels have 115V AC and 28V DC power supply.
This info about APU/GPU may not be correct. Some one mentioned the aircraft was getting ready for a tow to Departure area from remote parking. In which case the aircraft will be powered, most probably from the APU.

No smoke detection or fire alarm?
 

Is there no fire alarm system on these aircraft when they are left empty?

Blakmax
 

A bonded repair is the only way to go ! I agree about the heat blankets but we have a solution to address this problem but to talk about it hear would compromise my company's competitive position.

Any use of metal fasteners in this repair would be giving into the metal bashers who don't understand composites.

A&C metal bahers
 

If this was a conventional a/c it wouldn't have melted saying that feel very sorry for boeing ( am ex BAC BAe )

Ground power connected
 

According to the Boeing documents, the ground power receptacles are below the 1L door. The ground service locations can be found on the Boeing web site http://www.boeing.com/assets/pdf/com...ps/787sec5.pdf This is used by airport designers for setting out the service points on the apron. The distributed design on the 787 electrical system can also be found on-line. A photo on BBC news clearly shows that both sides are physically connected. http://news.bbcimg.co.uk/media/image...0_68706149.jpg
The access panels can be seen to be open on both sides, with the ground power cables hanging down. This would seem to be a fixed installation. behind the nose gear appears to be a cart, with an articulated cable system. The ground power converters appear to be at the base of the apron flood light masts. These would be fixed regulated solid state systems converting from 415V 50Hz to 110V 400Hz. Clearly from the photos, it is not possible to see if they are energized. There does not appear to be a tow tug or tow bar in the photo, so either they got out sharpish, or discussion about towing is not relevant.

The ground power requirement is rated at a nominal 90kVA at 110V 400Hz. Each connection can provide up to 1100 Ampere. For a typical turn around, both sockets at the nose will be connected. On a stand, they would normally be used until the APU is started. If there are any activities on the aircraft, such as cleaning or maintenance on board, it is likely that cabin lighting would be on as a minimum.

I think the concern for the industry and passengers would be if it is normal and acceptable for an overheating water heater / failing cabin air fan / discarded cigarette / overheating phone on charge / overloaded panel board to burn through the skin so quickly. Hopefully there will be a recording of voltage and electrical load conditions leading up to and during the event for analysis. This may show an event which can be used to time stamp the time of the failure. Clearly there will be no black box (FDR) recording, without the engines running, however the power system has limited data logging. One of the concerns of the NTSB in the previous battery investigation, was a lack of confidence in recorded voltage values.

I cannot claim expertise on aircraft structural repairs, although I do recall a very interesting documentary on National Geographic that had a film crew following the replacement of the rear pressure bulkhead in a 767. To summarise, everything behind the bulkhead was lifted off by crane. I presume that the photo previously posted was of the rear fuselage section on a transport jig. Aircraft sections are routinely shipped for bringing together at final assembly. If the rear pressure bulkhead is compromised, what is the chance that one of these is already being prepared for shipping to Heathrow?

To the composites experts reading this thread could I ask the following:

Is it possible to determine if the strength of a composite structure has been affected by heat or not?

This is an easy assessment if the fire has burnt a hole which has to be repaired but how far away from the hole do you have to extend the repair before you know you are back into good structure.

Repair?
 

Why are we discussing batteries? They are not involved here. This aircraft has serious fire damage. Those who have done repair of these modern composites know very well, the bonded repair etc hold good for only minor gouges or dents etc. This aircraft will require a complete re-paneling for about 10 to 12 feet of a very highly stressed portion of the fuselage. One picture clearly shows the frames and stringers exposed. Checking for heat damage to surrounding area alone will take weeks. Then these panels that have 3 dimensional shaping and of varying thickness have to be made. Stringers and frames are also of specially formed and shaped. it is not like the older aircraft where one can use raw stock to make splice repairs.
Again we have seen only one picture of the external damage. Inside will be in shambles with wiring, tubing etc burned. Galley and seats charred. Lucky the whole aircraft did not go up - thanks to the efficient response of fire dept.
Boeing will do anything to prevent a hull loss. Aircraft will have to be on a jig and leveled for repair. Ethiopian can forget about this aircraft for 5-6 months - if Boeing is doing the job. They will be better off looking for a lease to fill the gap.

On shudders to think of the internal fire/heat/smoke damage from this incident. If it had been in flight then the a/c would have depressurised for sure. I recall the NTSB lead spokesman (Deborah ??) saying a battery should never ever catch fire, so what do we have here.? Something probably much worse. This fire was extinguished by an expert fire team with all the equipment, something certainly not available for an a/c in flight.

The assumption that this was a failure of a water heater trip switch again brings into light the question of quality management/control. In the (unrelated) battery farrago there was much speculation about the quality of the parts. It would appear that a circuit breaker may have been to blame here, not necessarily performing as advertised. Sure, it may just have been one of those duff, Friday afternoon parts but Boeing can ill-afford to have such events right now.

If I was one of those Boeing Board members who are probably sat around the conference table this weekend, I know what I would be concentrating on.

Reuters: via Tawitter

Ethiopian says to continue to fly 787 fleet, LHR incident "not related to flight safety"

They must know 99.999% certain the cause.....
 

They must know 99.999% certain the cause.....presumably they are waiting to be able to answer whether type and which variants need checks/mods/grounding

IF there isn't a crew rest area above the rear galley area on ET 787s, what do they use the space for ?

Does anyone know how (and where) the structural loads from the fin are transferred to the hull structure ?

I take the PR statement to mean that it was a problem caused by the fact that there was no one around, and had it happened in flight, it could have been dealt with quickly and efficiently before it got to that stage.

If the rumours about a substantial portion of the Thomson electrical system going AWOL in flight have any truth, I guess they would be looking again at which sub-contractor is liable for the electrical design.

For all those worrying about the duration of the repair, one can imagine that the Ethiopian frame could be easily repaired before the potential second grounding is lifted. If I was in the UK CAA, I would have had a sleepless night.

What would stop an oven overheating and catching light to surrounding trim if it were left on? I am guessing an oven element left on for a full crew rest period could catch before a cb popped, especially if in-flight has been left in said oven too.

Bit of a silly idea leaving power attached if that's whats happened, my undstanding was that most stands used by the internationals at lhr have integrated power at the ramp. Rather than a gpu.

I have a feeling this is systems unrelated. I'm also guessing Boeing are relieved this happened on a Friday as if it had been a weekday, there wouldn't have been the time to do a full investigation prior to press releases we can expect late tomorrow or early Monday prior to the markets re-opening.

I don't think the the hull 'ignites' at 540F! I am not a composites person but I think the 540F number has more to do with the degradation of the material on exposure to high temperatures and there are, indeed, specifications for how hot things can be if they are in contact with the 787 composite. This material (or to be more accurate the resin within it) can self ignite given enough heat input but it takes a lot - around 31KW/sq metre with surface temps >500C or lower heat inputs if a flame is already present. See: http://www.fire.tc.faa.gov/pdf/07-57.pdf for the FAA report on 787 composite flam tests.

BBC News web site

Ethiopian Airlines took delivery of four Dreamliners in 2012.
The company said its plane had been parked at Heathrow for eight hours before smoke was spotted.
"We have not grounded any of our aircraft," the carrier said in a statement.
"The incident at Heathrow happened while the plane was on the ground... and was not related to flight safety."

Fit sprinklers.

Well, they would say that, wouldn't they?

Carefully-worded PR statement.

External power provided by the jetway is AC not DC. Most modern jets have a service mode on the external electrical control panel for when the aircraft is left unattended, this is so cleaners have lights etc. Yes some galley items are on the service bus on the plane I fly such as water line heaters and coffee pots.

Ref to MilktrayUK and the Boeing Doc, I find it strange that Boeing place the GP receptacle on the LH side, mostly they are found RH or centre and as the vehicle plan shows a GPU on the RH side, there must be extra long cables.
Perhaps Hi_Tech could qualify whether similar to other Boeings the GP can be on a service mode to allow cargo door/loading and limited galley power for start up of coolers and of course to get the kettle (rapid boiler) on for the Capt. tea.
I found it distressing to watch on tv, a 'Fireman' climb a ladder at the aft cargo door, mostly unsupported and attempt to unlock, by over-reaching, the door; this raises the question in my mind as to their knowledge of modern airliners if power was not on-line. Also not good was to see so many Firemen standing around with what appears very little direction when the airport could have been made operational earlier by their return to standby.

From Boeing's website

Why unusual to put GP on LHS? GP often comes from the jetway after all.

I have edited my earlier post, with a photo. You are correct that on narrow bodied aircraft, this connector would be on the LH. For wide bodied aircraft, one connector cannot supply enough power for the full electrical loads. Calculating the length of cables and power losses for each aircraft model using the stand would be part of the stand design process for a fixed installation!

I should add that the system includes a feedback mechanism controlled by the aircraft, so the supply is de-energised if the load is dropped by he aircraft electrical system. The common on-line reference sites do not describe systems for fixed installations, or list relevant photos. System descriptions can be found on supplier websites.

For starting the 787 engines with the APU unserviceable, a third GPU is recommended. This connection is located behind the wing, serving the aft electrical bay, where the main generator feeds connect into the power system. Most likely a diesel power cart would be used in that scenario, but I do wonder about the operational procedures needed with ground staff working behind running power plants and main gear.:hmm:

Parts and the quality of will IMHO be the answer here.
It really will be as simple as that.

But not compulsory. It's all covered here: AERO - Preparing Ramp Operations for the 787-8

Ethiopian Airlines "statement" and more: Ethopian Airlines Releases Statement On Smoldering Dreamliner; UTX Climate System Implicated In Fire | Zero Hedge

Eclectic, thanks for posting a worthless link to a shameless urban rumour/scandalmongering site that adds precisely nothing to the debate, rather sets it back.

Fail.

Sorry this is off topic, I just wish people with no knowledge would keep their fingers off the keyboard.


How wrong can you be NAROBS. As someone who maintained a large building in London I can tell you how fire cover works.
Buildings are graded by the fire services, in my case the building was called a section 20. This required high temperature detectors in non-operational areas and a 24 hour cover by my staff. If a temperature alarm went off it had to be investigated and the fire services called if a fire was found.

This arrangement led to an embarrassing episode. One night in the early hours an alarm went off, two staff went to investigate. One was a rugby player the other one could handle himself. When they opened the door to the room with the alarm, they were jumped on and a fight took place. The end result was Building Maintenance 1 – 0 Met Police. The police had been given a heater to keep themselves warm, yes they had it under a temperature detector. The police were using the higher floors of the building a watch tower.


Personally I think the airport authorities acted correctly in closing the airport. If most units had been called out to two suspect fires, they had no option but to stop all aircraft movements.

787 issues
 

what ever the fault turns out to be, you can imagine the PR staff at Boeing is working overtime. But realistically mr joe public will forget about this with one click of the mouse and on to the next news headline. The NTSB might be a different story........

Damage Limitation
 

Rather than talk about what has happened let me predict Boeings next move.

They will pressure their own engineers to apply a temporary fix to what is possibly a write off.

They will then fly it unpressurised somewhere very quiet and re build it in a secure hangar using all resources regardless of cost.

The FAA will not ground it again and the spin machine will distract us with more PR while engineering goes round the world applying yet another fix to customer aircraft.

All will be well until the next fire happens.

No different to a current ASU start protocol. They dont work behind any running plant.


If connection is on LHS (as in this case) then the connection (pneumo or elec) is made, chocks (Nose and LHS) remain in.
Ground crew withdraw
No2 engine (i.e. RHS) is started,
Crew move back in to remove connections and chocks
Aircraft pushed back
Other engine(s) started by cross-bleed (or using elec from the No2 generators in this case).

The crew aren't working behind any running plant but on the opposite side of the aircraft body.

BBC reporting:

BBC News - Batteries 'not linked' to 787 fire

In fairness, most of the MSM reporting I have seen has been pretty good - its tended to be 'Too early to tell, batteries have been a problem in the past - but we don't know its the case here'

AAIB press release

http://www.aaib.gov.uk/cms_resources...%20Release.pdf

Please be gentle with me; I only flew professionally for the best part of half a century. I admit to being a reasonable pilot and operator but I never really did understand advanced "wiggly amps" (despite flying the Short Belfast for 6 years).

Now, I think I have got my head around the fact that the 787 has (had) a great deal of trouble with lithium batteries. (During my career I had a ni-cad battery blow up one night over Northern Kenya which then involved us in an emergency descent).

So, after a very expensive grounding, the 787 has been cleared to fly again (because they have now encased the suspect batteries inside an indestructable titanium box).

Have they actually solved the problem?

Now we have an incident that managed to close Heathrow for a couple of hours because all the fire engines were required to attend a fire on board a 787 which was being prepared for towing to the gate to go flying.

We are expected by some to celebrate the fact that the batteries had nothing to do with the fire in the galley that burnt a hole or two through the roof and some are indeed celebrating this as a source of vindication.

Could someone just explain to me, in very simple terms, how it is that one of the girls forgets to switch off one of the hot cups and eight hours later, when the aircraft is powered up to be towed to the gate, the amazingly modern electrical system in the 787 allows the aircraft to become a potential write off (melt down even) to say nothing of the expense of closing Heathrow for an hour or two.

It seems to me (as a stupid pilot) that such a complex aircraft should be able to survive the possibility of a hot cup left on or even a handbag left in one of the ovens by one of the girls. Just how far have we come?

Perhaps someone could make a fortune by selling the designers of the 787 electrical system a supply of RCCBs and some 13 amp fuses.

Perhaps the whole aeroplane is too clever for its own good.

I certainly will not get in one for a very long time.