B737 classic DOWN 3 GREENS

[LEM]

You are on final, select gear down, and get two green lights only.

No red lights.

Do you accept it for a valid down and locked indication?


I've kept various manuals from old companies, and noticed, for example, on page 14.10.1, December 1, 2000:

Red light:
Extinguished - landing gear is up and locked with landing gear lever up or off.


while in a newer manual, same page, December 5, 2003, a new line is added:

Extinguished
....
- landing gear is down and locked with landing gear lever DN.


In fact, it would be possible to design a landing gear indicating system with red lights only.
No green lights.
Red lights extinguished would always mean no disagreement.

It seems the new line they've added means just that.

So what do you do? go around and go to the back to check in the middle of passengers?

Or do a light test and accept the red light extinguished as a down and locked indication, as the manual states?

[Willit Run]

Pull one thrust lever to idle, if you don't get a landing horn, with landing flaps selected, you can land!

[LEM]

Hi Willit Run, on the 737 you don't need to pull one thrust lever to get the horn with landing flaps selected, if one leg is not down and locked.

Hi ASFKAP, it doesn't matter which green light...
Let's say the right main gear.

Another question, as raised by Willit Run:
if the horn and the GPWS also at 500ft remain silent, the gear is probably down and locked.

Do these two additional systems receive their inputs from the same proximity switch of the green/red lights?

How many proxy switches are installed on each leg?

Some airplanes, and all cargo airplanes, have a double set of green lights.
I've heard this secondary indicating system is connected to the Horn/GPWS system, so to the same proxys.
Is it true?

[junior_man]

737 has viewing windows so you can look through there and see if the stripes line up indicating that the gear is locked down.
Nose gear viewer is in the cockpit floor right at the cockpit door. Main gear viewer is under an aisle seat and has a place to peel the carpet back (if the interior is put in correctly). Good that you checked that the viewing windows and stripe were clean on your preflight.

No green light step one is press to check if the bulbs are good. If bad install new bulbs or swap with another light cap. If not get out the non normal and follow the procedure.

Did see a guy retract the gear once and one of the green light caps popped out and disappeared. Was missing for a while but it was found in his coffee a little while later.

[LEM]

Hi junior_man,
I would suggest a light test to check if the bulbs are good, instead of pressing the light cap.

It has happened the light cap got stuck depressed in, so you get the impression that by depressing it you solved the problem, while actually it just stays depressed!
Be careful!

Btw, you haven't answered my question: is the absence of the red light (after you make sure the bulbs are working with a light test) equivalent to you to a green light?

Volume 2 states so.

:hmm:

[junior_man]

I would not land just because no red light either unless the non normal advised to. Little hard to justify that you didn't bother to look in the gear viewers to see if it was down and locked. No rush here.

[I-2021]

I would say (and I would do without overhead landing gear lights)

step 1) recycle the landing gear. You will find yourself with Flaps 15 and the gear up for a few seconds, so you can make sure that the landing gear horn works properly. Anyway the horn sounds if one gear is not down and locked.
2) If the green light is still out, light test, as you said. If the bulb has burned, You have the solution.
3) Go around, change the bulb, and land with 3 green lights ;) That will make your insurance happy.

I think it is always better to burn 700 kg extra fuel for a go around than having to deal with a gear collapse pax evacuation:ugh:

[LEM]

Ciao I-2021, as I thought the Red Light
Extinguished
....
- landing gear is down and locked with landing gear lever DN.

is not very popular.

But it is an official information, why not take advantage of it if short of fuel or any other stressful situation...


Btw, recicling the gear is NOT recommended by the Training Manual, and you lower the gear at latest with Flaps 5, not 15.
In your scenario, you already have Flaps 15, so no need to raise the gear to make sure the horn is working.
You will already get the warning horn with F15 if one leg is not extended.

[I-2021]

Hi LEM,

In step number one I said that anyway the horn will sound if one leg is not down and locked. Recycling the gear is not recommended, I agree, but in any case if you have to perform the go around you will find yourself with Flaps 15 and gear up. Off course You lower the gear with Flaps 5... that's not the point. If you do not wait 3 greens before taking Flaps to 15 You will end up in this situation.
The FCTM states : "Land on all available gear. Recycling the landing gear in an attempt to extend the remaining gear is not recommended. A gear up or partial gear landing is preferable to running out of fuel while attempting to solve a gear problem [...]"
I think we all agree here... but I hope I took enough fuel to perform a go around and make an extra approach with all the things fixed up before landing or starting to burn the MDF. If not, well no need to argue... Vol 2 states

:Extinguished
....
- landing gear is down and locked with landing gear lever DN.

And I agree with you 100%, you can land.

[junior_man]

Easy answer, use the non normal checklist. Do what it tells you to do.
Your own procedure doesn't sound too good at the hearing if something went wrong and you left something out.

[Escape_Slide]

If you have any gear indication problems, you should immediately exit from the landing phase, execute a go-around, advise ATC, with permissions climb to a safe altitude above MSA away from the airport, turn on your landing lights, put the aircraft into a hold or fly a triangle on heading and time. Watch your fuel. One pilot to do the visual inspection via the viewers, the other must fly the airplane. If it is not possible to view the downlock indicator, you must arrange a flyover inspection at nearest suitable airport. If the gear is not down, follow handbook procedures for gear up landing. You must not retract the gear for a second try, unless your procedures say otherwise, as the outcome is unpredictable. A broken walking beam on a 737 could, for instance, snag the roll-spoiler cables. You don't want to be in a situation where no one is flying the aircraft or adding extra complications because you decided to experiment. If you can fly the airplane leave experimenting off the agenda. Always carry enough fuel for such an event (normal trip plan).