Boeing Landing Gear Lever: UP & OFF

[TheCosmicFrog]

Hi there,

A question regarding the "Landing Gear" lever on Boeing aircraft.

What is the difference between the "UP" and "OFF" positions?

As well as this, do you not have to pass the lever through the "OFF" position to get to the "UP" position? Why can you not just move the lever from "DOWN" to "OFF" upon reaching positive climb?

Thanks for any insight offered!

[billyt]

If you did then nothing would happen. The gear would stay down. You need to select them up to get them up. Selecting them to off isolates the hydraulics from the gear selection system.

The B777 does not have the "OFF" position.

[BigJoeRice]

"What is the difference between the "UP" and "OFF" positions?"

Up - the gear is hydraulically powered up
Off - as 'Billyt" says; the gear is held up by the mechanical uplocks because the gear hydraulics are shut off. In the event of turbulence the gear handle is selected back to UP to provide hydraulic up pressure to reduce structural loads on the mechanical uplocks.

[Mark1234]

The general principle (not aircraft specific, I'm sure there are exceptions) is that with the gear selector up or down, the gear hydraulics are pressurised in the appropriate direction, and move the gear appropriately.

Once it is up, and the (generally mechanical) uplocks are engaged, you go to off, which relieves the pressure in the gear hydraulics. Passing through off makes sense as you need to reverse the direction of actuation.

As billyt points out, if you simply selected off after leaving the ground, the gear would go nowhere - it's off, not 'up and off'.

[billyt]

"In the event of turbulence the gear handle is selected back to UP to provide hydraulic up pressure to reduce structural loads on the mechanical uplocks."

Never heard of selecting "UP" in turbulence. It's new one on me.

[Capt Chambo]

In the event of turbulence the gear handle is selected back to UP to provide hydraulic up pressure to reduce structural loads on the mechanical uplocks.

Never heard of this before:ooh:

[SMOC]

Plus it was during turbulence on a departure one day that while the PM was moving the handle from UP to OFF that we got a bump and slipped back towards DOWN we heard the rumble of the doors opening again.

I wouldn't go anywhere near the gear handle during turbulence.

On the 777 with the landing gear retracted and all doors closed, the landing gear hydraulic system is automatically depressurized.

[spannersatKL]

Same on the A330/340........speed dependant.......another job taken off the poor pilot! :ok:

[Henry VIII]

Let's say an update toward the current modern technology !
The Boeing 75/76 ldg gear lever (http://www.airliners.net/photo/LAN-Airlines/Boeing-767-383-ER/1337193/L/&width=1024&height=780&sok=keyword_%28%27+%22767%22_+%22cockpit%22%27_IN_BOOLEAN_MO DE%29%29_&sort=_order_by_photo_id_DESC_&photo_nr=6&prev_id=1343777&next_id=1208312)looks like old fashion car (http://www.worldofstock.com/closeups/TRC4293.php) :}

[yrvld]

"In the event of turbulence the gear handle is selected back to UP to provide hydraulic up pressure to reduce structural loads on the mechanical uplocks."

This has to be a new one. I wonder if you do that at FL 390 at .79 in a 737 NG. Or any other Boeing for that matter. And when the turbulence stops you put it back to OFF ? :ok:

[BigJoeRice]

I say, steady on chaps............

All I can say is that I seem to recall this procedure back in the early 70's as a flying spanner on 747 Classics - or perhaps DC8's. I thought it was a safety precaution related to the weight of the bogie gear, so perhaps N/A on 737's and such like.

And yes, part of the "uplock check" when you went from UP to OFF was to ensure that none of the gear door lights (front or back) came on indicating something amiss; if so the handle went back to UP and stayed up.

And yes it went back to OFF when out of the turbulence.

And yes a lot of Ruddles County has gone under the bridge since then, so I'm always ready to stand corrected if I'm remembering it wrong.

[Intruder]

Not a procedure in the 747 Classic -- must have been some other airplane! ;)

[BigJoeRice]

Thanks for the feedback Intruder.

Next I'll be forgetting my........er.........my........er..........................

[yrvld]

All I can say is that I seem to recall this procedure back in the early 70's as a flying spanner on 747 Classics - or perhaps DC8's. I thought it was a safety precaution related to the weight of the bogie gear, so perhaps N/A on 737's and such like.

Might have been something back in the day... Not on the 747 classic though and certainly not on the more recent Boeing models.
DC 8 no clue, but you might be right.

[RWEDAREYET]

Can't say for the 747, but I remember on the 727, the gear went up and then off after clean and climbing to check the uplocks. I do remember putting the gear back to up when at high speed the gear doors would rumble. I flew the 8 also, but I can't remember an off position with the gear handle. I think that was a Boeing thing. Mind you, it's been a long time for both aircraft, so I could be wrong.

[mutley320]

737- 500, in cruise over bay of biscay, noticed RED gear light for nose wheel. No sounds or other indications.I dont recall there was an actual checklist for this, but anyway, i selected the lever to up position and the light went out, i left it there for a while and then very gingerly selected the off position.It worked. Obviously wrote it up and they found a microswitch out of kilter.
Dont want a big discussion about VLE's and such like but it was my solution on the day.

[CV880]

DC8 normally flew with the gear lever in the UP position but after retraction it was selected to UPLATCH CHECK to isolate the hydraulics to ensure everything was mechanically locked up, then returned to UP for the rest of the flight (until DOWN was required).
DC10, as far as I can remember, only had UP and DOWN positions and also flew in UP all the time with hyd pressure ON as there was no system for isolating hydraulic pressure.

[TheCosmicFrog]

Thanks guys!

[Manual Braking]

Probably due to inadvertant lowering of the gear, there is a memo that has just come out from our company on how to 'hold' the landing gear lever when positioning it from UP to OFF (including a do and don't illustration!!).

Memo on how to wipe our a:mad::mad:e next week no doubt.

MB

[BOAC]

Memo on how to wipe our ahttp://static.pprune.org/images/smilies/censored.gifhttp://static.pprune.org/images/smilies/censored.gife next week no doubt - well, MB, I needed to be told! Many moons ago I was P2 on a 737 which had a worn 'GEAR OFF' detent, and in moving to 'OFF' I slipped the lever about 1mm past the position and VOILA - big rushy noise and much embarrassment, plus whack around ears from the boss. Since our SOP was to do this before we went transonic, no damage done other than to ego, so it IS good advice, just for that day when the ship is not rigged right. That particular a/c was snagged and fixed, incidentally.

[Jumbo Driver]

As I'm sure BigJoeRice will also recall, there was an additional WING GEAR position on the early Classics - between OFF and DOWN and much closer to OFF - for use as an airbrake, I seem to remember ...


JD
:)

[411A]

Quote:
In the event of turbulence the gear handle is selected back to UP to provide hydraulic up pressure to reduce structural loads on the mechanical uplocks.

Never heard of this before:ooh:

Quite likely because you are not old enough.

A common procedure on the B707, if needed.

[Mshamba]

Plus it was during turbulence on a departure one day that while the PM was moving the handle from UP to OFF that we got a bump and slipped back towards DOWN we heard the rumble of the doors opening again.

happened to me the other day, should have red your post before ;)

[Nightfire]

Plus it was during turbulence on a departure one day that while the PM was moving the handle from UP to OFF that we got a bump and slipped back towards DOWN we heard the rumble of the doors opening again.

This hasn't happened to me before, but I recall that, on the 737, the speed limit for retracting the gear is 270kts. I haven't flown that plane for a few years now, and don't remember the exact limitations for the gear extention, but it was higher (was it 320kts?).
Just out of interest: Therefore, if you extended the gear during cruise (even though just slightly), it'd be one thing. But you would then have to slow down to 270 knots before placing the lever back to the UP position, otherwise you would, strictly speaking, exceed the limitation.
But it has been a while, perhaps I'm thinking wrong here.

[stilton]

We operate two versions of the 767, the -200 with the dn/off/up gear lever and the -400 with the 777 type up or down lever.

After take off checklist on the -200 calls for gear 'off' more than once, on the -400 people have inadvertently placed the gear down looking for a 'nonexistent' off position !

Fortunately the sequence logic allows you to immediately raise the handle, you do not have to wait for the gear to extend completely before 'reretracting'

[BOAC]

the speed limit for retracting the gear is 270kts. - it is 235kts, hence the need for 'care'.

[HAWK21M]

UP:- Hydraulic pressure to retract the gear.
Down:- Hydraulic pressure to entend gear.
Off:- No pressure,held by Bungee springs mechanically,normally used in flight after gear retraction.
regds
MEL