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JAL Boeing 787 -8 JA835J DCS_0606 (1)

JAL Boeing 787 -8 JA835J DCS_0606 (1)

This one sat for a bit before gathering itself up and leaving. A pretty airplane and untroubled by the engineering management problems that have grounded all 737-8 MAXes.

787s had a LiPo battery problem, including a fire, on the ground, but the FAA and Boeing grounded the fleet, promptly, and sorted it out. Changes included:

1) A more fireproof steel box around the battery;
2) completely sealing the battery off from the inside of the plane;
3) restricted airflow from outside to starve any fire of oxygen;
4) reducing charging rate and end-point to reduce stress on the cells,
5) redesign of the battery to remove/mitigate thermal runaway in one cell cascading to the rest;
and. most important,
6) getting the battery manufacturer (Yusa), and Boeing's own power, structure and safety engineers all reading the same pages. A number of people had "thought" they had countermeasures in place to prevent battery fires. mitigate them if they started, etc. But there was room for improvement.

A more "holistic" approach, getting all the requirements in front of all the players and evaluating a larger set of possible failures, "looking for trouble", all under the laser focused gaze of upper management, customer engineers and regulators, got the job done, right, the second time. "Never wanting to have that happen again" can be strong medicine. A Yusa employee's comment that the 787's battery installation is now the most studied in history, may or may not be true, but it certainly wasn't the case originally.

An unexpected bonus from this work was discovery that the 787 cockpit voice recordings contained more ambient noise and less aircrew speaking than it should. That problem was fixed too.

Remarkably, but mentioned more in sorrow than in anger, there was a subsequent fire, in a 787, also on the ground. It was parked, unattended, and the LiPo battery was in the (a?) Emergency Locator Transmitter. This is a radio beacon that is activated by a crash and transmits automatically, to assist finding a crash. Poor design but bad manufacturing, created an opportunity, the short circuit in the cabling ignited the battery and the smoky, slow-burning fire, eventually involved heat-damaged resin from the crown of the composite fuselage. It took fire-fighters over 20 minutes to identify where combustion was taking place, and both Halon and water mist were used to extinguish the fire and cool the remains. Thermal imaging helped locate the multiple hot-spots.

Had the ELT been mounted "old school", in the vertical fin or unpressurized tail-cone, like a Flight Data Recorder or Cockpit Voice Recorder, it would have been easier to spot the fire and put it out. This may reflect un-desired experience in searching for recorders (and wrecks) highlighted the danger of a recorder or transmitter in an extremity that might be destroyed or lost a considerable distance from the site of the crash, I have seen suggestions to put recorders nearer the center of mass. The reader is invited to write their own sermon considering whether to mandate data recorder and emergency transmitter vaults made from billet titanium and lined with space shuttle re-entry tile insulation. Vault location would be mandated inside or behind the main wing box / fuel tank, or in the crown of the fuselage above the trailing edge of the wing root...

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Photo taken on 23 March 2019 (© wbaiv / Flickr)

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