Hush-kit From Germany, joined Sep 2000, 124 posts, RR: 0 Posted (11 years 3 months 6 days 18 hours ago) and read 1355 times:
question 2 all trans-atlantic pilots:
on my last trip from cdg to jfk (DL, 763) I am sure
the main gear went down and after a while
(maybe 2 or 3 minutes) it was rejected
while enroute over canada, about 1, maybe 1 1/4
hour before touchdown at jfk ! Is that common ???
(Never experienced it on all my transatlantic flights)
What could be the reason ???
AND GUYS: It was the gear what went down, no flaps or anything else,
it was that typical gear down noise!!!
Any ideas why that happened are welcome.
CU here
Hush-Kit
NormalSpeed From , joined Dec 1969, posts, RR: Reply 1, posted (11 years 3 months 6 days 15 hours ago) and read 1241 times:
Are you absolutely sure it was the gear? I mean, sometimes those sounds can be decieving. A gear extension at enroute speeds would probably cause a lot of damage to the landing gear itself, if not rip it off completely.
FDXmech From United States of America, joined Mar 2000, 3251 posts, RR: 38 Reply 2, posted (11 years 3 months 6 days 15 hours ago) and read 1213 times:
What do you mean the gear went down and was rejected?
FDXmech From United States of America, joined Mar 2000, 3251 posts, RR: 38 Reply 3, posted (11 years 3 months 6 days 14 hours ago) and read 1195 times:
I guess you meant the gear was retracted after a couple of minutes.
One plausible scenario is perhaps he got a faulty gear indication. With the gear up and locked, there should be no lights on.
If he had a gear door unlock indication, or an unsafe gear indication (red light) or even an EICAS fault message, he probably cycled the gear in accordance with his checklist to check/clear the fault.
I'm sure before the gear was extended and retracted the aircraft was slowed to the safe gear extension speed.
Jetpilot500 From United States of America, joined Nov 2000, 78 posts, RR: 0 Reply 4, posted (11 years 3 months 6 days 14 hours ago) and read 1178 times:
Even if they did slow down, most airplanes have a maximum altitude where they could cycle the landing gear, usually 20,000' or so. I'm not sure what the limitation is for, maybe structural integrity of the airframe while it is pressurized?
Jetpilot500 From United States of America, joined Nov 2000, 78 posts, RR: 0 Reply 5, posted (11 years 3 months 6 days 14 hours ago) and read 1166 times:
Sounds a little fishy to me, I really doubt the landing gear was cycled.
EssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2 Reply 6, posted (11 years 3 months 6 days 12 hours ago) and read 1151 times:
Who knows what he heard, but-
Even if gear extension speeds are exceeded, there is no way dynamic loading would be sufficient to "rip the gear off"...
The loads imposed on a typical landing are far greater than the dynamic loads from a 300 kias airstream. The limit is there due to avoid the aerodynamic disruption created by the gear at higher than limited speeds, which can lead to control issues.
Many a/c have, as part of their CDL, reduced speed limits if some of the fairings on the gear are removed due to the fact that these FAirings could flutter or be damaged at higher airspeeds-but the gear isn't going to be ripped off (come on!)
FDXmech From United States of America, joined Mar 2000, 3251 posts, RR: 38 Reply 7, posted (11 years 3 months 6 days 10 hours ago) and read 1109 times:
Hush-kit From Germany, joined Sep 2000, 124 posts, RR: 0 Reply 8, posted (11 years 3 months 5 days 20 hours ago) and read 1033 times:
Hi FDXmech,
You wrote: "A gear extension at enroute speeds would probably cause a lot of damage to the landing gear itself, if not rip it off completely."
Remember mid-summer 00, when a German 310 (Hapag
LLoyd) opert'd with extracted gear the entire route from a Greek island ( bound for HAJ ), and finaly
made an emergency touch down in Vienna, cause they were running out of fuel ???, see the pic:
In my case, I guess they had a false alert on I-don't-
know-what-it-was, and there were no further incidents
while we proceeded to jfk.
As I said... Never experienced anything like that...
BR Chris
FredT From United Kingdom, joined Feb 2002, 2184 posts, RR: 26 Reply 9, posted (11 years 3 months 5 days 18 hours ago) and read 1022 times:
While the gear probably could take it (although I for one wouldn't try it - who knows what the aerodynamical forces might do to a hydraulic line at M.85) it is likely that gear doors etc wouldn't. Note that for many aircraft, there's a lower speed limit for operating the gear than for having it extended. Part of the reason is that when the gear is fully extended the gear doors will be flush again.
Cheers,
Fred
I thought I was doing good trying to avoid those airport hotels... and look at me now.
FDXmech From United States of America, joined Mar 2000, 3251 posts, RR: 38 Reply 10, posted (11 years 3 months 5 days 18 hours ago) and read 1016 times:
Hello Chris
I didn't post the "damage at enroute speed" thread.
I wrote the possible scenario of a gear "up and locked" indication problem directly below it, and some gear placard speeds below that.
Also, I checked the MD10 redtabs and it confirmed that cycling the gear (within the IAS/M envelope [no altitude restriction) is standard procedure for gear unsafe light with gear handle up.
727pfe From , joined Dec 1969, posts, RR: Reply 11, posted (11 years 3 months 4 days 11 hours ago) and read 916 times:
One possible explanation maybe that the gear is sometimes used as a drag device. Since on most aircraft, the gear can be lowered at a higher airspeed than the flaps, gear is sometimes used. On the aircraft I flew in the past, it was a common procedure when you had to get down fast, but did not want to get a large speed increase. Then when you got to the desired altitude/airspeed, you raised the gear and or lowered the flaps.
EssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2 Reply 12, posted (11 years 3 months 4 days 3 hours ago) and read 877 times:
It would be a poor design indeed, if the hydraulic lines weren't an issue at a max gear extension speed of say 250 kias, but were in danger of failing due to aerodynamic loads at max limit of, say, 320 kias.
That's only 128 % of the normal, operational limit...
I said fairings, as not all a/c have gear doors...
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