smartt1982 From United Kingdom, joined Nov 2007, 212 posts, RR: 0 Posted (8 months 1 week 5 days 13 hours ago) and read 3875 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?
Roseflyer From United States of America, joined Feb 2004, 8785 posts, RR: 52 Reply 6, posted (8 months 4 days 17 hours ago) and read 3306 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).
If you have never designed an airplane part before, let the real designers do the work!
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.
9VSIO From United Kingdom, joined Dec 2006, 645 posts, RR: 2 Reply 12, posted (8 months 4 days 7 hours ago) and read 3147 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
Me: (Lining up on final) I shall now select an aiming point. || Instructor: Well, I hope it's the runway...
Max Q From United States of America, joined May 2001, 3326 posts, RR: 19 Reply 13, posted (8 months 4 days 4 hours ago) and read 3089 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.
The best contribution to safety is a competent Pilot.
CitationJet From United States of America, joined Mar 2003, 2249 posts, RR: 3 Reply 15, posted (8 months 3 days 12 hours ago) and read 2900 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.
zbbylw From Canada, joined Nov 2006, 1927 posts, RR: 7 Reply 18, posted (7 months 3 weeks 6 days 18 hours ago) and read 2399 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!
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
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80 Reply 21, posted (7 months 2 weeks 2 days 16 hours ago) and read 1651 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.
Fabo From Slovakia, joined Aug 2005, 1111 posts, RR: 1 Reply 22, posted (7 months 2 weeks 2 days 15 hours ago) and read 1643 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.
The light at the end of tunnel turn out to be a lighted sing saying NO EXIT
SKC From United States of America, joined Oct 2012, 64 posts, RR: 0 Reply 23, posted (7 months 2 weeks 2 days 14 hours ago) and read 1628 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.
CosmicCruiser From United States of America, joined Feb 2005, 2222 posts, RR: 16 Reply 24, posted (7 months 2 weeks 2 days 14 hours ago) and read 1611 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.
25 smartt1982: 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 a
26 Jetlagged: 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 li
27 Mir: 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. And
28 smartt1982: Mir, are you referring to my previous questions?[Edited 2012-11-05 12:30:08]
29 Jetlagged: 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 con
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