hush-kit
Posts: 107
Joined: Thu Sep 07, 2000 4:43 pm

2 All Pilots: Gear Down Enroute

Wed Feb 20, 2002 8:56 pm

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
 
Guest

RE: 2 All Pilots: Gear Down Enroute

Wed Feb 20, 2002 11:45 pm

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
Posts: 3219
Joined: Sun Mar 19, 2000 9:48 pm

RE: 2 All Pilots: Gear Down Enroute

Thu Feb 21, 2002 12:06 am

What do you mean the gear went down and was rejected?

You're only as good as your last departure.
 
FDXmech
Posts: 3219
Joined: Sun Mar 19, 2000 9:48 pm

RE: 2 All Pilots: Gear Down Enroute

Thu Feb 21, 2002 12:31 am

I guess you meant the gear was retracted after a couple of minutes.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.
You're only as good as your last departure.
 
Jetpilot500
Posts: 78
Joined: Wed Nov 29, 2000 1:54 am

RE: 2 All Pilots: Gear Down Enroute

Thu Feb 21, 2002 12:58 am

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
Posts: 78
Joined: Wed Nov 29, 2000 1:54 am

RE: 2 All Pilots: Gear Down Enroute

Thu Feb 21, 2002 12:59 am

Sounds a little fishy to me, I really doubt the landing gear was cycled.
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: 2 All Pilots: Gear Down Enroute

Thu Feb 21, 2002 2:21 am

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
Posts: 3219
Joined: Sun Mar 19, 2000 9:48 pm

RE: 2 All Pilots: Gear Down Enroute

Thu Feb 21, 2002 4:55 am

Can't find my old 767 manuals but,

757 gear extend placard speed.....270K - .82M
757 gear extended "......."...........320K - .82M

DC10/MD10 gear limit speeds
Extend 260 KIAS/.70M
Down..300 KIAS/.70M
Ret.....230 KIAS/.70M

777 gear retract & extend placard speeds
270K/.82M

It would appear from these numbers that the Douglas is more sensitive to altitude when cycling the gear than Boeing.
You're only as good as your last departure.
 
hush-kit
Posts: 107
Joined: Thu Sep 07, 2000 4:43 pm

2: FDXmech

Thu Feb 21, 2002 6:37 pm

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:
Click for large version
Click here for full size photo!

Photo © Marcus Weigand


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
Posts: 2166
Joined: Thu Feb 07, 2002 9:51 pm

RE: 2 All Pilots: Gear Down Enroute

Thu Feb 21, 2002 8:17 pm

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
Posts: 3219
Joined: Sun Mar 19, 2000 9:48 pm

Hush-kit

Thu Feb 21, 2002 8:29 pm

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.

You're only as good as your last departure.
 
Guest

RE: 2 All Pilots: Gear Down Enroute

Sat Feb 23, 2002 3:22 am

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
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: 2 All Pilots: Gear Down Enroute

Sat Feb 23, 2002 11:32 am

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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