The Danger Of Lightning, Weak Electrical Bonding

The crash of a Bellview Airlines B737 in Nigeria last week may have resulted from a lightning strike, although the investigation into probable cause is just getting started. This is the sort of thing that can happen if an airplane's electrical bonding has lost its integrity and the airplane flies through a severe thunderstorm. The bonding protects the electrical system and delicate electronics against the severe jolt of a lightning strike.

Bonding strips ensure that each metal component is connected to other metal components so that the Faraday Cage protection is complete and that between the entrance and exit points all the current from the lightning will flow through the aircraft's outer skin only. Despite good bonding, some antennas often will still be affected and some systems can be knocked off line. In addition, scorch marks and/or pinholes will be evident at the entrance and exit points of the lightning strike. If bonding is not good, the lightning's current can route haphazardly through systems and wreak havoc inside delicate black box avionics. These are the hazards of Third World maintenance; the accident aircraft had its last heavy maintenance in Morocco.

It would appear that the pilot may have lost his flight instruments and/or cockpit lighting, and then inevitably lost communications and control, tearing the wings off.