View Full Version : 777 landing gear

13th Mar 2008, 06:09
If the landing gear lever won't budge after t/o, does anyone know any reason to leave the gear down and land rather than accomplish the checklist, raise the gear and continue.
There is the question of gear tilt and gear doors to consider. :ugh:
I had a sim session recently that raised the question and now I am seeking some help.....

13th Mar 2008, 14:05
Obviously something is wrong with either the landing gear itself, or the raising mechanism.

Now consider this:

B777 is capable of N-1 catIIIb autoland. This means that the weather will not be a factor in your decisionmaking process, unlike other types who will have to divert in those conditions.

B777 will generally be able to land on the same runway you took off from, even if you do not jettison fuel. Only exception maybe when you took off from a heavily contaminated runway.

So, leaving the gear down will be the safest option. If you have enough fuel to reach destination, you might consider to go for it. But as it is normally long haul, your best bet is to go back to your departure field.

In any case you will have plenty of time to confer this with your crew and company.

Spooky 2
13th Mar 2008, 14:10
Unlikely that you would proceed to your destination gear down but if for some reason your T.O. CLB performance counted on a gear up configuration, then retarcting the gear using the alternate method might be the only choice one would have.

Check Airman
13th Mar 2008, 14:13
B777 is capable of N-1 catIIIb autoland.

What does N-1 mean?

13th Mar 2008, 14:29
And you call yourself "check airman" (:

N-1 means single engine on a two engine aircraft. N being the total amount of engines available. In other words, you have an engine failure.

13th Mar 2008, 14:42
I've been a commercial airline pilot since 1988 and that is the first time I have seen N1 as a reference for single engine. N1 typically refers to the fan section of a turbofan engine. To use it in the manner you did, without an explanantion is confusing at best.

Nowhere in the B777 FCOM or FCTM does it say "B777 is capable of N1 - CatIIIb autoland" However there are many reference to it in regards to the engine N1.

To attack someone for questioning the use of N1 in this manner is a no-no :=


square leg
13th Mar 2008, 17:30
TP, it's not N1, but "N minus 1" (N-1). Typically pilots of 2 and 4 engine aircraft use the term "N-1" or better still "OEI" (one-engine-out), which I think is better to use than "N-1" or "single-engine ops", especially if rated on 2 and 4 engine aircraft as this evidently causes confusion. But I know you knew this!

13th Mar 2008, 18:07
yep, started out on 747's in 1988. Called it N-1 ( N minus 1 ) then and still do. In fact you got slapped on the wrist if you said "single engine". Could be a european thing too.

ps, didn't you see the smiley (: , it was no attack on anybody.

Pool Boy
14th Mar 2008, 01:51
wow, you learn something new every day. currently operating the 777 using boeing sops and never heard or seen the phrase N1 in that context!

Flight Detent
14th Mar 2008, 03:17
Me too....!

Been flying multi-engined airplanes since '77, and I also will join the band of guys never having heard this reference to operations with one engine inoperative!

I'll be sticking with the "One engine out" or similar reference, it's plain language and non-confusing!

Cheers...FD :)

14th Mar 2008, 10:23
Yep, N-1 is new to me. Must be a European thing indeed! :ugh:

Dream Land
14th Mar 2008, 11:10
I've been a commercial airline pilot since 1988 and that is the first time I have seen N1 as a reference for single engine. N1 typically refers to the fan section of a turbofan engine. To use it in the manner you did, without an explanantion is confusing at bestMe too. :(

Terry McCassey
14th Mar 2008, 11:18
My 36 years in aviation taught me N1 is fan rotor speed, - over and out !

14th Mar 2008, 11:42
The fault lies with the MLG safety sensors. They control a lot of things, which include but not limited to: ground/flight spoilers, pressurization control. If the sensors are failed in the ground mode, which would be the case for not being able to raise the gear lever, the pressurization is failed to the ground mode, hence, passing 10,000 feet...down come the O2 masks. If the speedbrakes were extended, you would then get the ground spoilers. There are other goodies that can come up to get you as well. So, best idea is to return to departure airport. The idea of continuing on to destination is fraught with problems.
The situation is easily demonstrated in the simulator and is always a fun one when a student is faced with the situation: Gear lever locked down and ATC requests an expedited climb to 14,000 feet. Its interesting to watch from the instructors' console.

14th Mar 2008, 11:59
Ok everybody, although I am used to the term N-1 (note the dash) it isn't in the boeing books and obviously not used by other countries and operators. Mea culpa.

30th Mar 2008, 08:32
Many thanks for that input..we did get sidetracked for a while so good to get your valuable input.:D

low n' slow
30th Mar 2008, 09:07
Forgive me for asking a couple of stupid questions but:
If the gear isn't coming up, will there be any problems for it to come down? Is that possibly a reason for returning?
And also, I don't know what your operations look like, but do you typically have maintenance available on the outstations that you fly to and from?
In my line of work, we usually do not and that is a big factor in the return or continue decision. That is, will you be grounding the plane in a place where it can't be mended?

Regards/ LnS

Swedish Steve
30th Mar 2008, 10:21
There are two reasons that the Selector lever is baulked.
1. the Air sense is still in ground mode. You can override this to get the gear up, but will then gets loads of new problems so a return is your best option.
2. The gear tilt actuator has not put the gear into the retract position. If you retract the gear like this it will miss the wheel well with expensive graunching noises!.
So if performance does not require it, using the override lever on the gear selector is to be treated with caution, and thought. Don't do it instinctively.

30th Mar 2008, 11:14
might be worth looking deeper into the documents, you will find that OPSPECS (FAA) will normally preclude CAT IIIb OEI, but CAT IIIa is allowed. TBC's AFM is fairly vague on the issue, but the manufacturers POM wasn't back in '00. FWIW, the simulator does a nice OEI operation well within the required tolerances for low minima approaches, but I analysed data of one OEI approach of a -300 which didn't get close to an acceptable autocoupled approach in very stable environmental conditions, yet had worked immediately before very well on 2 engines...

Terry McCassey
30th Mar 2008, 11:37
Swedish Steve - unless it has changed, the gear will retract with the gear in the non tilted position. After lift off, the gear uses centre system to point the truck 19 nose up. When the retract lever is moved up, the gear will start to retract and the truck will reposition to 3 nose down. UAL had an airplane destroy a main gear door early in the programme due I believe, to leakage across the hydraulic swivel couplings on the drag strut. This would certainly have made the graunching noises you mention, and some !