Beechbarron From United States of America, joined May 2000, 134 posts, RR: 0 Posted (11 years 9 months 2 weeks 2 days 13 hours ago) and read 2418 times:
The other day spotting at Hartsfield I noticed something I haven't before. I was watching a Delta 727-200 start his roll from a close vantage point and noticed that he spooled up all 3 engines at different times. He throttled up #1 and released the brakes, started rolling and throttled up #2. A few yards later, I heard #3 come up to take-off power as well. Why is this? I thought that all engines were spooled at the same time, with the instruments being closely monitored for takeoff EPR and stabilization. Is this a JT8D thing, or do all pilots do it with all types of engines?
JETPILOT From United States of America, joined May 1999, 3128 posts, RR: 37 Reply 1, posted (11 years 9 months 2 weeks 2 days 9 hours ago) and read 2268 times:
All the engines are spooled up simultaneously. But in 2 different stages.
When the pilot pushes up the throttles he stops at 1.4 EPR for about 4 seconds to do a 1.4 EPR check making sure the interstage bleed valves have closed.
He then advances the power and hands off the throttles to the non-flying pilot who makes the final TO power setting.
CP744 From Canada, joined Jul 2000, 200 posts, RR: 0 Reply 2, posted (11 years 9 months 2 weeks 1 day 15 hours ago) and read 2221 times:
Jetpilot: Is there any other reason for spooling up the engines in two stages? I'm wondering if this is a manufactures request... requirement....airline policy... or what? The reason I ask is every airline I remember does spool up in two stages... with the exception of one airline. Now maybe I just noticed this one airline for some reason... but I did note that the 8-10 T.O.'s I've watched by........well OK......KAL, spooled to whatever the takeoff EPR was, right away. Just curious....
Beechbarron From United States of America, joined May 2000, 134 posts, RR: 0 Reply 3, posted (11 years 9 months 2 weeks 1 day 13 hours ago) and read 2200 times:
Thanks Jetpilot. The way you described the spool up and EPR settings is the way I always thought it was, (and the way my ears always heard it) until that day. I don't know what he was doing, but the engines were definately spooled at different intervals. Granted, he was using Hartsfield's longest runway at 11,800 ft, so maybe he was just doing something different for the fun of it, or the other couple of engines just took much much longer to spool than the first. Any ideas???
EWR757 From United States of America, joined Apr 2000, 360 posts, RR: 9 Reply 4, posted (11 years 9 months 1 week 3 days 19 hours ago) and read 2144 times:
If the engines are not trimmed right, they may spool unevenly. Normal procedure is to stand the throttle up a bit for initoial spool then advance for T/O.
Also, when I flew the 727, under high crosswind conditions we would spoll 1,3 gain speed to get some ram air down the s duct then bring up 2. # 2 had a habit of compressor stalling some times under these high x wind conditions.
Beechbarron From United States of America, joined May 2000, 134 posts, RR: 0 Reply 6, posted (11 years 9 months 1 week 3 days 5 hours ago) and read 2117 times:
Thanks, EWR757. Now that I think back, it was a windy day.
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