The plane continued its nine-hour flight but when the aircraft landed in Chennai, maintenance technicians discovered an unusual level of damage: more than 40 holes in the fuselage from the lightning strike.
The major danger from a strike is that if it were to penetrate the wing skin it could ignite the fuel vapor inside the wing, which acts as a fuel tank. When the 787 was designed as a carbon composite airframe, the FAA added a special condition requiring various design details to avoid such an explosion.
In addition to the copper foil that dissipates the energy, metal fasteners on the wing are sealed so that there is no direct metal channel all the way through from the outside to the inside of the wing skin.
That said, later the FAA also loosened a more stringent requirement established after the explosion of TWA 800 to prevent a fuel tank explosion. Bahrami, then head of the FAA's Seattle office, led that rule change. He argued that manufacturers had found it impractical to comply.
DeFazio's letter notes that the FAA just last month asked Boeing to perform a "risk assessment of the fuel tank explosion risk from lightning related ignition sources" on the 787 and "to determine if any corrective actions to reduce the risk of a fuel tank explosion should be required."
However, it laments that this action is so late.
And DeFazio adds that "Boeing reportedly produced approximately 40 airplanes prior to the FAA's approval of the design change." He says this "suggests either willful neglect of the Federal aviation regulatory structure or an oversight system in need of desperate repair."
His letter asks what the safety regulator is doing "ensure that manufacturers do not have an incentive to attempt end-runs around FAA technical specialists by going to senior FAA management."
(c)2019 The Seattle Times
Visit The Seattle Times at www.seattletimes.com
Distributed by Tribune Content Agency, LLC.