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Topic: Landing Gear Placard Limit
Username: smartt1982
Posted 2012-10-09 13:22:02 and read 5919 times.

On the landing Gear limit speed placard on our aircraft it says 270 -.82M. Would I need to be at a speed below both of these or just one. Thinking of a case if I was 285 knots indicated but only .69M etc.

Would I just whatever one I was using as a reference at that time?

Topic: RE: Landing Gear Placard Limit
Username: Fabo
Posted 2012-10-09 13:53:38 and read 5904 times.

under both.

filler filler

Topic: RE: Landing Gear Placard Limit
Username: HAWK21M
Posted 2012-10-17 00:32:40 and read 5465 times.

That is the range.........Not to exceed BOTH.

Topic: RE: Landing Gear Placard Limit
Username: bueb0g
Posted 2012-10-17 01:43:11 and read 5450 times.

Quoting HAWK21M (Reply 2):
That is the range.........Not to exceed BOTH.

You mean not to exceed either?

Topic: RE: Landing Gear Placard Limit
Username: barney captain
Posted 2012-10-17 02:16:23 and read 5434 times.

So - you FLY the aircraft, yet don't understand the placard speed - is that correct?

Topic: RE: Landing Gear Placard Limit
Username: tb727
Posted 2012-10-17 09:10:15 and read 5356 times.

Well there is one thing you can count on, it's gonna be loud at high speed.

Topic: RE: Landing Gear Placard Limit
Username: Roseflyer
Posted 2012-10-17 09:23:54 and read 5350 times.

Usually you have 4 speeds for landing gear. A maximum speed for extension in Mach. A maximum speed for extension in Knots. A maximum gear extended speed in Mach. A maximum gear extended speed in Knots. Exceeding any limit requires a landing gear inspection.

I have been on an airplane exceeding the gear extended speed and the buffet is extreme. It is loud and the airplane is shaking violently (in buffet rather than turbulence).

Topic: RE: Landing Gear Placard Limit
Username: PGNCS
Posted 2012-10-17 10:00:11 and read 5336 times.

Quoting barney captain (Reply 4):
So - you FLY the aircraft, yet don't understand the placard speed - is that correct?

I frankly find this beyond belief too.

Topic: RE: Landing Gear Placard Limit
Username: horstroad
Posted 2012-10-17 10:00:49 and read 5336 times.

Quoting barney captain (Reply 4):
So - you FLY the aircraft

did he say that? maybe he is a mechanic, FA, ramp agent or whatever

Topic: RE: Landing Gear Placard Limit
Username: PGNCS
Posted 2012-10-17 10:05:43 and read 5332 times.

Quoting horstroad (Reply 8):
Quoting barney captain (Reply 4):
So - you FLY the aircraft

did he say that? maybe he is a mechanic, FA, ramp agent or whatever

Not here but elsewhere, plus it's in his profile.

Barney captain has good reason to ask this question as this is an EXTREMELY basic piece of information for a pilot of any sort to know.

Topic: RE: Landing Gear Placard Limit
Username: CosmicCruiser
Posted 2012-10-17 16:00:59 and read 5264 times.

Quoting Roseflyer (Reply 6):
Usually you have 4 speeds for landing gear.

And a max retraction speed.

Topic: RE: Landing Gear Placard Limit
Username: tb727
Posted 2012-10-17 18:14:02 and read 5217 times.

Quoting CosmicCruiser (Reply 10):
And a max retraction speed.

Which is the tricky one. It's significantly lower in the plane I fly, if you throw the gear for an emergency descent, you have to remember you are gonna have to slow it back up to put it up again if you so choose. Not a big deal really, just another step.

Topic: RE: Landing Gear Placard Limit
Username: 9VSIO
Posted 2012-10-17 19:06:33 and read 5191 times.

Quoting horstroad (Reply 8):
did he say that? maybe he is a mechanic, FA, ramp agent or whatever

Well, he's been asking quite a lot of pilot related questions, and said in one of the other threads that he also instructs in the 737 sim for the type rating. His profile has already been mentioned on here. His questions are normally interesting though  

Topic: RE: Landing Gear Placard Limit
Username: Max Q
Posted 2012-10-17 21:37:44 and read 5133 times.

It's not really an issue, at low altitude, below say 27000 feet your Mach No is going to be so much lower than the KIAS limit for gear extension it's not a factor, and at high altitude your KIAS will be so much lower than the mach limit it's not a factor.


Most, if not all modern Boeings use just one Mach / Speed limit for extension/ extended these days keeping it simple.


270 / .82 Is the limit on the 757 / 767 and I suspect it's pretty close to that on all subsequent Boeing models.

Topic: RE: Landing Gear Placard Limit
Username: tb727
Posted 2012-10-18 10:07:15 and read 5010 times.

Quoting Max Q (Reply 13):
270 / .82 Is the limit on the 757 / 767 and I suspect it's pretty close to that on all subsequent Boeing models.

Seems to be!

727 is 270/.83 to extend
200 to retract
VLE/MLE is 320/.83 and I am pretty sure you are gonna go deaf and/or chug through some fuel if you do that.

747 Classic
VLE/MLE 320/.82
VLO 270/.82
Gear retract can be 270/.82 or 250/.82 depending on plane.

Topic: RE: Landing Gear Placard Limit
Username: CitationJet
Posted 2012-10-18 14:04:24 and read 4944 times.

Cessna actually specifies six landing gear design speeds for some Citations. However many of the speeds are the same for a given aircraft.
Vlo (extending) - Mach
Vlo (extending) - knots
Vlo (retracting) - Mach
Vlo (retracting) - knots
Vle (extended) - Mach
Vle (extended) - knots

Ref: FAA TCDS A1WI, for model Citation 525B, page 15.

Topic: RE: Landing Gear Placard Limit
Username: Max Q
Posted 2012-10-18 21:16:17 and read 4892 times.

Quoting tb727 (Reply 14):

VLE/MLE is 320/.83 and I am pretty sure you are gonna go deaf and/or chug through some fuel if you do that

Boy you have that right..

Topic: RE: Landing Gear Placard Limit
Username: HAWK21M
Posted 2012-10-19 00:42:18 and read 4864 times.

Quoting bueb0g (Reply 3):
Quoting HAWK21M (Reply 2):
That is the range.........Not to exceed BOTH.

You mean not to exceed either?

Thats correct.

Topic: RE: Landing Gear Placard Limit
Username: zbbylw
Posted 2012-10-24 07:39:32 and read 4443 times.

Quoting barney captain (Reply 4):

So - you FLY the aircraft, yet don't understand the placard speed - is that correct?

  

Remember that during your ground school, the instructor is there for you. The airline or in the case of the UK sometimes, you are paying for that guy to teach you. I don't know what airplane you're on but it may be your first jet and some of the high speed/high altitude aerodynamics may be new. Make sure you get the airlines money out of your instructor!

Topic: RE: Landing Gear Placard Limit
Username: smartt1982
Posted 2012-11-04 02:18:30 and read 3789 times.

Quoting zbbylw (Reply 18):
Quoting PGNCS (Reply 9):
Quoting barney captain (Reply 4):

I would just like to clarify something here if I could, this is a forum for finding out technical issues. As has been pointed earlier in this forum thread, yes I am a current 737 line pilot and a sim instructor. I have had very good experiences with the airliners forum in the past with clarifying issues in the past, up until this point!

I would like to add that I did expect that you have to obey both speed limit placards but I had heard from some students that they only had to obey one by another instructor. This puzzled me but I could not actually find in the Boeing manuals a definite AND clear answer. Too often in aviation you are told things both technical and operational and the person cannot point or refer to where this info has come from, hence the resson why I took the time to ASK the question on this forum.

Some of the replies posted here appear to be very negative and more casting an opinion on the person posng the question.

Think of me however you wish but I thought this forum was for finding out tech questions that could not be clearly answered else were

Thank you

Topic: RE: Landing Gear Placard Limit
Username: Fabo
Posted 2012-11-04 09:08:43 and read 3706 times.

I suspect there is a "whichever is lower" or similar in the AFM, but cannot confirm right now.

Topic: RE: Landing Gear Placard Limit
Username: tdscanuck
Posted 2012-11-04 09:28:48 and read 3695 times.

Quoting Fabo (Reply 20):
I suspect there is a "whichever is lower" or similar in the AFM, but cannot confirm right now.

Nope. The words out of the 737-800 AFM are:
"LANDING GEAR PLACARD SPEEDS - KNOTS IAS, INDICATED MACH
RETRACT V_LO(RET) = 235
EXTEND V_LO(EXT) = 270, M_LO(EXT) = 0.82

EXTENDED V_LE = 320, M_LE = 0.82"

There is no need for a "whichever is lower" because they're independent, not coupled, limits. If you're over M0.82 it doesn't matter what your IAS is, you can't extend the gear. If you're over 235 knots it doesn't matter what your Mach is, you can't extend the gear.

Because of the way the Mach and IAS lines work out, IAS is more limiting at low altitude and Mach is more limiting at high altitude but both limits are in force all the time.

Tom.

Topic: RE: Landing Gear Placard Limit
Username: Fabo
Posted 2012-11-04 09:36:10 and read 3687 times.

Quoting tdscanuck (Reply 21):
Because of the way the Mach and IAS lines work out, IAS is more limiting at low altitude and Mach is more limiting at high altitude but both limits are in force all the time.

Which is in effect the same thing. But you are the one with the AFM, not me, so there is that.

Topic: RE: Landing Gear Placard Limit
Username: SKC
Posted 2012-11-04 10:35:01 and read 3672 times.

Quoting smartt1982 (Reply 19):
I would just like to clarify something here if I could, this is a forum for finding out technical issues. As has been pointed earlier in this forum thread, yes I am a current 737 line pilot and a sim instructor. I have had very good experiences with the airliners forum in the past with clarifying issues in the past, up until this point!

So, what did the other sim instructors or your chief pilot(s) say when you asked them this question? Did they all have different answers? Has to be listed in a company manual somewhere.

While this may be a technical forum, and the given info may be correct, I'd be careful about taking perfomance data from a group of anonymous internet people. There's no background check to register here.

Topic: RE: Landing Gear Placard Limit
Username: CosmicCruiser
Posted 2012-11-04 11:31:42 and read 3655 times.

Quoting tdscanuck (Reply 21):
Because of the way the Mach and IAS lines work out, IAS is more limiting at low altitude and Mach is more limiting at high altitude but both limits are in force all the time.

You beat me to it but yeah. just think though at high alt. mach is the only concern, you may not even be able to slow to the IAS speed.

Topic: RE: Landing Gear Placard Limit
Username: smartt1982
Posted 2012-11-04 15:32:07 and read 3652 times.

Quoting SKC (Reply 23):

A very valid point indeed. Your very true in what you say and I do whenever I can speak to as many different people as possible but the great thing about the airliners forum is that there is a lot of very experienced people from all different aspects of aviation. So even though it may not be 100% official their info can help explain the reasons why something operates or works the way it does or point you in the right direction

Topic: RE: Landing Gear Placard Limit
Username: Jetlagged
Posted 2012-11-04 17:02:07 and read 3621 times.

Quoting smartt1982 (Reply 19):
I would like to add that I did expect that you have to obey both speed limit placards but I had heard from some students that they only had to obey one by another instructor.

I think it's more likely a case of the students not understanding what the other instructor has said correctly. You will either reach the 270 knot limit or the 0.82 Mach limit first. So in a sense only one limit applies, but in fact you must observe both.

If you think about it, the placard limit could only mean either

270 knots or Mach 0.82

or

270 knots and Mach 0.82

The "and" interpretation makes no sense at all in aviation terms, so "or" is the only logical interpretation.

Quoting smartt1982 (Reply 19):
Some of the replies posted here appear to be very negative and more casting an opinion on the person posng the question.

That's because there's a history of people on this forum claiming to be what they aren't. The answer to this question seems so obvious that people are bound to wonder why you asked it. You already knew the answer, but couldn't find anything to prove it in the manuals. If you'd asked that question in the first place no one would have doubted you.

Topic: RE: Landing Gear Placard Limit
Username: Mir
Posted 2012-11-05 09:54:58 and read 3566 times.

Quoting Jetlagged (Reply 26):
If you think about it, the placard limit could only mean either

270 knots or Mach 0.82

or

270 knots and Mach 0.82

The "and" interpretation makes no sense at all in aviation terms, so "or" is the only logical interpretation.

Actually, it's the other way around. You've got a VLO (in knots) and an MLO (in Mach). Both limits apply at all times. It's not one or the other.

Quoting Jetlagged (Reply 26):
That's because there's a history of people on this forum claiming to be what they aren't. The answer to this question seems so obvious that people are bound to wonder why you asked it.

And, to be perfectly honest, certain other questions that have been asked as well.

-Mir

Topic: RE: Landing Gear Placard Limit
Username: smartt1982
Posted 2012-11-05 11:50:19 and read 3563 times.

Quoting Mir (Reply 27):


Mir, are you referring to my previous questions?

[Edited 2012-11-05 12:30:08]

Topic: RE: Landing Gear Placard Limit
Username: Jetlagged
Posted 2012-11-06 04:05:47 and read 3560 times.

Quoting Mir (Reply 27):
Actually, it's the other way around. You've got a VLO (in knots) and an MLO (in Mach). Both limits apply at all times. It's not one or the other.

Logically it's still an OR (which means both limits apply, lowest one first). If it was 270 and 0.82 then you wouldn't reach the limit until both conditions were satisfied.


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