VIRGIN A340 fire incident
 

13 FEB 2009 AAIU finds electric wiring problems in A340 fire incident investigation

Related links » Airbus A340 safety profile
» Accident description


Irish air accident investigators released a preliminary report regarding an incident involving a Virgin Atlantic Airbus A340 en route from Heathrow to Chicago in January 2009.
A small fire broke out in the bottom of the waste bin storage compartment of the bar unit in the First Class area. The fire was located in a hole in the floor of the compartment. The crew noted that a damaged electric cable loom appeared to emanate from this hole. Arcing was observed in the hole. Crew members used fire extinguishers but they could not put the blaze out. An emergency landing was carried out at Shannon.
The Investigation found that the cable loom in the bottom of the waste bin compartment had been completely severed and bore strong evidence of burning/arcing. The loom in question consists of ten wires in a protective sheath, six wires carrying 28 V DC and the other four carrying 115 V AC. This wiring provided power and dimming circuits for “mood” lighting which is recessed into the bar unit counter-top. Initial indication was that the lower edge of the metal waste bin made contact with the wiring loom. Information from drawings provided by the Operator indicated that two runners should be installed in the bottom of the compartment to keep the bin above the wiring loom, thereby avoiding contact. Furthermore, a protective metal cover should be installed over the loom in the bottom of the compartment. No evidence of the presence of the loom cover or rails was found. Initial inspection indicated the possibility that they were never fitted.
A fleet inspection of the Operator’s A340-300 and A340-600 (which have a similar bar unit fitted but a different part number) aircraft found that a number of these aircraft also had problems relating to missing covers, rail screws and cable routing in this area. Damage to the loom was found on one other aircraft.

Kapton is still being used in all Airbus aircraft with the exception of the A380. Boeing models built prior to the mid/early 1990's also used Kapton. Later builds and the 777 and 787 do not use Kapton insulated wiring.

Kapton/Polyimide
 

As I'm fast suffering from 'wheneye' - it seems that the lessons of the 80's seem to have been forgotten, or is it more 'familiarity breeds contempt'?

The party line was always that Kapton is/was OK as long as it was installed correctly, kept clean and dry and not jumped on! Should you forget any of that and go for too tight bend radii or wiggly looming, throw in a splash of hydraulic oil and a touch of chafe - it was :mad: lethal!

IIRC there used to be a couple of videos that graphically demonstrated 'arc tracking', one for aircrew that was somewhat less dramatic than the groundcrew one, it might be time to resurrect them!

Aircraft Wiring
 

Following incidents such as SR111, how can this possibly happen...

Quoted from a report on Flightglobal.com
Initial inspection of Virgin Atlantic's long-haul Airbus fleet, after a fire emergency on an A340-300, has found a number of aircraft missing wiring-protection components in the area of their on-board bar units.
The 11-year old A340 involved had been en route from London Heathrow to Chicago O'Hare last month when it diverted to Shannon with a small fire and electrical arcing in the waste-bin storage compartment in the first-class bar area.
Ireland's Air Accident Investigation Unit discovered that a 10-wire cable loom for the bar's "mood lighting" had been completely severed, with evidence of contact from the bar's metal waste-bin.
Two runners are supposed to keep the bin away from the wiring loom, which is also meant to be protected by a metal cover. Neither of the components was found by investigators.
"Initial inspection indicated the possibility that they were never fitted," says the AAIU, which points out that the bar unit is a specific modification to the Virgin long-haul fleet.
Inspection of the carrier's other A340-300s and -600s found that another aircraft had damaged to the wiring loom, and that "a number" of the jets also had problems relating to missing covers, runner screws and cable routing in the bar area.

Unquote.

NEVER FITTED!

So it appears in this case anyway, Kapton was not the issue.
Lead dress and routing support were.