Thank you for taking the time to report the following comment to the administrator of this site.
Please complete this short form and click the submit button to process your report.
By: Mike Hughes (Guest IP 195.66.233.192) on 19-01-2008
I've noticed that the 777 is particularly bad for this fan-sync (or lack of) induced vibration, which I guess is down to the enormous fan size on the 777.
Having flown on lots of different 777s, and usually sat in roughly the same area of the aircraft, I found that Pratt engined 777s (e.g. UA) are the worst for this resonant vibration caused by the fans being out of sync, whilst Rolls engined aircraft (NZ, SQ, BA) hardly seem to suffer it at all.
I guess that quads such as the 747 don't show this as much because there's more "randomness" across 4 engines, giving a cancellation effect.
Flying the Plane 
Harmonic Resonance - lack of fan sync
By: Mike Hughes (Guest) on 19-01-2008