747 Engine Inlet Sparks — Tech Ops Forum

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747 Engine Inlet Sparks

dl757md From United States of America, joined May 2004, 1555 posts, RR: 18
Posted (2 years 4 months 3 weeks 3 days 13 hours ago) and read 1993 times:

Regarding the following picture

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Photo © Thomas Merkl

I work around engines all the time at night and I'm quite familiar with the phenomenon of static electricity discharging from the fan blades which is more common in the winter due to the lower relative humidity. This picture is the first one I've seen on Anet of the phenomenon (I'm sure there are others) and it struck me as unusual because when I've seen static discharge it's not usually localized at the blade tips as on engines 1,2 and 4 on this Qantas bird. It's usually more dispersed across the disc.
It's possible it could be the tips rubbing the abradable shroud but then why only from the 5 o'clock to 7 o'clock positions? Why is it not doing it on nbr 2 engine? Anyone care to float a theory?

DL757Md

757 Most beautiful airliner in the sky!

4 replies: All unread, jump to last

futureualpilot From United States of America, joined May 2000, 2561 posts, RR: 8
Reply 1, posted (2 years 4 months 3 weeks 3 days 13 hours ago) and read 1984 times:

Given the angle at which it appears the sun is illuminating the rest of the airplane I'm thinking its just the way the sunlight is hitting the fan, not actual discharges of electricity.

Life is better when you surf.

dl757md From United States of America, joined May 2004, 1555 posts, RR: 18
Reply 2, posted (2 years 4 months 3 weeks 3 days 13 hours ago) and read 1978 times:

That would explain why number three has no "sparks" being that it's in the shadow of the fuselage. Thanks!

757 Most beautiful airliner in the sky!

EMBQA From United States of America, joined Oct 2003, 9286 posts, RR: 13
Reply 3, posted (2 years 4 months 3 weeks 3 days 10 hours ago) and read 1901 times:

The snow causes it ..............

"It's not the size of the dog in the fight, but the size of the fight in the dog"

boeingfixer From Canada, joined Jul 2005, 490 posts, RR: 0
Reply 4, posted (2 years 4 months 3 weeks 3 days 8 hours ago) and read 1841 times:

Quoting EMBQA (Reply 3):
The snow causes it ..............

Not in this case. Everything in shadow is dark indicating that this is just reflected sunlight.

Although snow can cause static electricity discharges on fans it is not as drastic as one would think. During daylight this phenomenon is all but unnoticeable.

Cheers,

John

Cheers, John YYC