Scaredflyer21 From United States of America, joined Oct 2000, 355 posts, RR: 0 Posted (7 years 9 months 1 week 4 days 8 hours ago) and read 2108 times:
I have noticed on my recent flights that as soon as the engines are started there seems to be a ding in the cabin. Is this simply the system being switched over from aux. power (I would guess this), or is it a confirmation to the flight attendants from the flight deck?
JetSetter001 From Germany, joined Oct 2006, 31 posts, RR: 0
Reply 2, posted (7 years 9 months 1 week 4 days 7 hours ago) and read 1988 times:
I would rather guess that it is sme sort if signal as the power supply changes from apu to engine power. Normally the "ding" is to hear after a short flicker of the lights (very short "loss" of power) which is due to the engines now being responsible for the oboard power.
Amazonphil From United States of America, joined Oct 2003, 561 posts, RR: 1
Reply 4, posted (7 years 9 months 1 week 3 days 22 hours ago) and read 1710 times:
As stated above, this is the switch from APU power through the transfer bus to engine generator power. Some a/c make a "ding or dong" and lights momentary flicker while other a/c just have the lights flicker for a sec.