Damages from Lightning Strikes
 

Damages from Lightning Strikes

Was advised of a Metroliner of Brindabella Airlines - Canberra Oz- which suffered a Lightning Strike.

Close inspection revealed the effects of electrical arcing on an engine's bearings so it is likely that the strike was through a propeller.

Damage seems unusual considering the extent of bonding required in aircraft designs.

Most lightning strikes tend to burn a hole in an aircraft's skin but often there is some obscure internal damage.

Must be a few interesting stories out there.

whats radar for
 

it still amazes me other than a lightning strike say on take off and landing how is it with all the weather radar and raim that you fly boys still fly through cells with massive amounts of static. do you like the light show,because we greasers hate the inspections,last ls insp 30 burnt rivets,one t/r cowl trashed and multiple repeat inspections

Most lightning strikes occur when the plane is near the freezing level, which means on climbout or descent, where there are fewer options for avoidance.

My flight instructor, who flew transports in WWII and the Berlin Airlift, said they used to fly toward the lightning at night, because that was between the clouds...

GB

lightning strike damage
 

some years ago flying a similar type to the metroliner, descending into a major European airport whose controllers were well known for advising aircraft if they were flying towards an area of "radar intense returns" we suffered 2 lightning strikes inside 1 minute. Nothing at all showing on our or their radar, no turbulence ,very little precipitation and the cloud through which we were descending was a stratus type . Damage was a small hole in the starboard aileron (entry point) and the complete wingtip disappeared (exit point), lots of wires hanging down etc. Second strike blew the autopilot, most of the radios and the radar. Landed ok but just shows doesn't always happen when you expect it. Concentrates the mind a bit though!

Alli....the saying "bolt out of the blue" comes from lx strikes where there was no Cb anywhere near the ground impact point.

This is described in the sticky as a must see url...http://www.crh.noaa.gov/pub/ltg/plane_japan.php

electrical damage to bearings
 

I read somewhere that there are frequent cases of minor lightning strikes to turbo-prop aircraft which result in current flow through the main reduction gearbox (presumably as the prop blades are exposed pointy thingys that attract strikes?) Because the contact face of a ball or roller bearing is so miniscule, the resulting current densities are very high & cause micro-pitting to the bearing faces. This pitting leads to premature failure of the bearing, many hours after the strike that caused it. I assume it cannot be directly detected, without dismantling & inspecting every bearing - clearly impractical.
I guess pure turbines do not attract strikes through their bearings as the engine is fully contained in the pod?
The same thing can occur with large electric motors running with variable speed drives - stray circulating currents of low magnitude find their way through the bearings and cause premature failure.