Aeroflot001 From Argentina, joined Oct 2009, 384 posts, RR: 0 Posted (2 years 10 months 1 week 5 days 21 hours ago) and read 5700 times:
I kept on pushing this back and back but today I finally decided to do it. Back in February I flew MIA-DCA to see the snow right after the 2 consecutive blizzards that passed through the DC area.
I was happy to be going up to the snow and I was also happy to have a seat in F.
As much as I love flying I am still a bit nervous so as we took off it sure didn't help to have a strong crosswind together with this incredibly strange grinding noise. Fortunately I had my camera out so you can see and hear the video I took during take off rather than explaining what the sound was like. The sound starts at around 11 seconds. Thanks for your help!
yvphx From United States of America, joined Jul 2009, 227 posts, RR: 0 Reply 3, posted (2 years 10 months 1 week 5 days 20 hours ago) and read 5584 times:
I agree its the nose wheel. When I fly my little c-172 if I don't tap the breaks after liftoff I get that same sound and vibration, to a smaller extent of course.
Atlwest1 From United States of America, joined Jan 2009, 1046 posts, RR: 1 Reply 4, posted (2 years 10 months 1 week 5 days 20 hours ago) and read 5551 times:
Hey i just listened to the sound and its totally nothing to be allarmed about. It is the noise of the gears retracting specifically the forward gear. I hear it on a daily basis. Fiirst time I heard it, it was startling but its all good Just sit back relax and enjoy your flight.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co. or Airt
jpetekyxmd80 From United States of America, joined Jul 2003, 4238 posts, RR: 29 Reply 5, posted (2 years 10 months 1 week 5 days 20 hours ago) and read 5551 times:
I noticed nearly the exact same thing the first time I flew an AA 738 in F. Freaked me out a bit as well!
Aeroflot001 From Argentina, joined Oct 2009, 384 posts, RR: 0 Reply 6, posted (2 years 10 months 1 week 5 days 19 hours ago) and read 5420 times:
The reason it startled me so much though was because I had previously flown in F on the 737 with AA and never heard that noise. When the gear would go up I would just hear something like a small motor. Just a few weeks ago I flew to IAD up front and no loud vibrating noise and then on IAD-SJU no vibrating noise either. Anyways thanks for the help!
JBirdAV8r From United States of America, joined Jun 2001, 4459 posts, RR: 22 Reply 7, posted (2 years 10 months 1 week 5 days 19 hours ago) and read 5357 times:
Quoting Atlwest1 (Reply 4): Hey i just listened to the sound and its totally nothing to be allarmed about. It is the noise of the gears retracting specifically the forward gear. I hear it on a daily basis.
Specifically it sounds like the nosewheel tires slowly spinning down as the assembly no longer supports weight on rotation.
You can hear it on just about any aircraft if you're sitting in the right place.
Aeroflot001 From Argentina, joined Oct 2009, 384 posts, RR: 0 Reply 8, posted (2 years 10 months 1 week 5 days 19 hours ago) and read 5330 times:
Quoting JBirdAV8r (Reply 7): Specifically it sounds like the nosewheel tires slowly spinning down as the assembly no longer supports weight on rotation.
CO777DAL From United States of America, joined Feb 2007, 476 posts, RR: 0 Reply 9, posted (2 years 10 months 1 week 5 days 18 hours ago) and read 5228 times:
Quoting Spacepope (Reply 1): Yes the fact that it started at rotation is what made it more worrying.
Watched your video and heard the noise. Puzzling! What I find odd is that I'm in First all the time on Continental 737s and never heard that sound. CO has a ton of 737s. I also have a over a hundred videos and can't remember ever hearing it on on any of them. It was very loud in your AA video. Other have said they hear it on AA. Could CO have something the pilots do so it doesn't make that sound. I just find it odd, in my hundreds of flight with CO I have never heard what you recorded on AA.
I should've flown with someone else or gone by car cause United breaks guitars.
Aeroflot001 From Argentina, joined Oct 2009, 384 posts, RR: 0 Reply 10, posted (2 years 10 months 1 week 5 days 17 hours ago) and read 5132 times:
Quoting JBirdAV8r (Reply 7): Specifically it sounds like the nosewheel tires slowly spinning down as the assembly no longer supports weight on rotation.
But why would it make such a loud noise though?
Quoting CO777DAL (Reply 9): Watched your video and heard the noise. Puzzling! What I find odd is that I'm in First all the time on Continental 737s and never heard that sound. CO has a ton of 737s. I also have a over a hundred videos and can't remember ever hearing it on on any of them. It was very loud in your AA video. Other have said they hear it on AA. Could CO have something the pilots do so it doesn't make that sound. I just find it odd, in my hundreds of flight with CO I have never heard what you recorded on AA.
AA737-823 From United States of America, joined Mar 2000, 5338 posts, RR: 11 Reply 11, posted (2 years 10 months 1 week 5 days 16 hours ago) and read 4983 times:
I have watched your video, and know exactly what the issue is.
The issue is an out-of balance nosewheel. This is most commonly caused by uneven wear on the tires, which have the added strain of steering the aircraft (compared to the mains, I mean) and so often wear in strange patterns.
For this problem, the only remedy is a dual nosewheel replacement. That's cost ineffective, so most carriers will let it go until the tires actually need to be replaced. It doesn't hurt anything, it just makes the airplane sound cheap!
The balance weights sometimes fall off of the wheels. They shouldn't, but I've seen it happen.
Quoting JBirdAV8r (Reply 7): Specifically it sounds like the nosewheel tires slowly spinning down as the assembly no longer supports weight on rotation.
Yup- hence the frequency of the vibes diminishes... I think you're exactly right.
Quoting Aeroflot001 (Reply 8): But why would it make such a loud noise though?
Because they're relatively heavy, and turning at a very high rate, and have nowhere to transmit their vibrational loads to but INTO THE AIRFRAME.
Quoting CO777DAL (Reply 9): Could CO have something the pilots do so it doesn't make that sound. I just find it odd, in my hundreds of flight with CO I have never heard what you recorded on AA.
Nope. In fact, CO's 737-9ER aircraft ALL seem to make an odd nose wheel noise, from about 30 mph on to gear up. At least, all the ones I've ever flown on have. Which is odd to me, because their -900's don't make that noise.
Anyhow, all this is the opinion of a 737NG mechanic (although not for CO, nor-as my username would imply- for AA).
Aeroflot001 From Argentina, joined Oct 2009, 384 posts, RR: 0 Reply 13, posted (2 years 10 months 1 week 5 days 14 hours ago) and read 4856 times:
Quoting AA737-823 (Reply 11): I have watched your video, and know exactly what the issue is.
The issue is an out-of balance nosewheel. This is most commonly caused by uneven wear on the tires, which have the added strain of steering the aircraft (compared to the mains, I mean) and so often wear in strange patterns.
For this problem, the only remedy is a dual nosewheel replacement. That's cost ineffective, so most carriers will let it go until the tires actually need to be replaced. It doesn't hurt anything, it just makes the airplane sound cheap!
The balance weights sometimes fall off of the wheels. They shouldn't, but I've seen it happen.
Phenomenal response now I really understand what was going on.
Spacepope From Vatican City, joined Dec 1999, 2736 posts, RR: 1 Reply 14, posted (2 years 10 months 1 week 5 days 10 hours ago) and read 4587 times:
Quoting AA737-823 (Reply 11): I have watched your video, and know exactly what the issue is.
The issue is an out-of balance nosewheel. This is most commonly caused by uneven wear on the tires, which have the added strain of steering the aircraft (compared to the mains, I mean) and so often wear in strange patterns.
Yay, I guessed right!
Had this happen with one of the maingear tires on the LH 744 I flew last fall. Those things shake pretty bad since they are so large. Concerned a lot of passengers. Luckily it stopped quickly when the retraction sequence started.
MadDogJT8D From United States of America, joined Oct 2009, 350 posts, RR: 1 Reply 16, posted (2 years 10 months 1 week 5 days 9 hours ago) and read 4511 times:
I've felt vibrations in the forward cabin of the 767 right after rotation as well until the gear has been retracted. The first time, I wondered what it was, but after a few flights I got used to it. Nothing to be alarmed about - airframes are designed to handle certain amounts of vibration.
Chase From United States of America, joined Nov 2005, 1054 posts, RR: 0 Reply 17, posted (2 years 10 months 1 week 5 days 9 hours ago) and read 4434 times:
Not to be a jerk, but why were you taking video at liftoff, when electronic devices are not allowed to be used?
AA737-823 From United States of America, joined Mar 2000, 5338 posts, RR: 11 Reply 18, posted (2 years 10 months 1 week 5 days 7 hours ago) and read 4291 times:
Quoting Spacepope (Reply 14): Had this happen with one of the maingear tires on the LH 744 I flew last fall. Those things shake pretty bad since they are so large. Concerned a lot of passengers. Luckily it stopped quickly when the retraction sequence started.
Mains will stop vibrating more quickly. When the gear handle is put into the UP position, part of the retraction sequence is a quick, short application of the brakes. This stops them from rotating, the fear being that IF a tire were to have blown, you really don't want it spinning at 150+ MPH inside the wheel well, where large sections of tread could easily start slapping out hydraulic lines and so forth.
The nosewheel doesn't have a brake on most modern air transports (nosewheel brakes were optional on certain 727 aircraft, as was Jet-Assisted-Takeoff). So, instead, there are snubbers in the ceiling of the nosewheel well, and they rub on the nose tires quite firmly, applying sufficient friction to stop the tires pretty quick. BUT anyhow, mains are stopped before they enter the well, noses after.
The nose wheel snubbers are most noticeable on 757 aircraft... the entire first class cabin shakes like crazy when I fly on those birds!
Goldenshield From United States of America, joined Jan 2001, 5427 posts, RR: 12 Reply 19, posted (2 years 10 months 1 week 5 days 7 hours ago) and read 4260 times:
Quoting AA737-823 (Reply 18): The nose wheel snubbers are most noticeable on 757 aircraft... the entire first class cabin shakes like crazy when I fly on those birds!
They would also be noticable to passengers flying in the nose of a 747.
Two all beef patties, special sauce, lettuce, cheese, pickles, onions on a sesame seed bun.
aviatorcraig From United Kingdom, joined Mar 2010, 83 posts, RR: 0 Reply 20, posted (2 years 10 months 1 week 5 days 7 hours ago) and read 4221 times:
Quoting AA737-823 (Reply 18): The nosewheel doesn't have a brake on most modern air transports (nosewheel brakes were optional on certain 727 aircraft, as was Jet-Assisted-Takeoff).
I thought all 727s had jet assisted take-off!
Some that were used for hot and high ops (e.g. Mexicana) had rocket assisted take-off as well
AA737-823 From United States of America, joined Mar 2000, 5338 posts, RR: 11 Reply 21, posted (2 years 10 months 1 week 4 days 23 hours ago) and read 3865 times:
Some that were used for hot and high ops (e.g. Mexicana) had rocket assisted take-off as well
FINE FINE FINE, get all technical on me why don't ya?!?! Come to think of it, the acronym is JATO If it's rockets (which it is), shouldn't it be RATO? Rockets are, in fact, a type of jet engine- they're not a GTE (gas turbine engine), but they do produce a jet of exhaust gases, which makes them.... a jet engine.
So... now that that's clear as mud!!!
Quoting Goldenshield (Reply 19): They would also be noticable to passengers flying in the nose of a 747.
It's noticeable to any passenger sitting in the forward cabin of any aircraft equipped with a retractable nosewheel. My point was simply that the 757 makes a particularly pronounced noise.
Daysleeper From UK - England, joined Dec 2009, 800 posts, RR: 1 Reply 22, posted (2 years 10 months 1 week 4 days 22 hours ago) and read 3792 times:
Quoting AA737-823 (Reply 21): FINE FINE FINE, get all technical on me why don't ya?!?! Come to think of it, the acronym is JATO If it's rockets (which it is), shouldn't it be RATO? Rockets are, in fact, a type of jet engine- they're not a GTE (gas turbine engine), but they do produce a jet of exhaust gases, which makes them.... a jet engine.
So... now that that's clear as mud!!!
If you have a look towards the bottom of the wiki page here http://en.wikipedia.org/wiki/JATO both JATO and RATO are used to describe what looks like the same thing... so yeah clear as mud
I never knew these were an option on the 727 though, does anyone know if any airline ever used them in service? I mean personally (and im sure im not alone on here) I would have loved to experiance a JATO take off and actually gone out of my way too, but i'd imagine it would be a little scary for the average pax.... and for a nervous flyer.....
I guess also, unless there was a way to jettison them in a safe manner then there would be no possible way to abort take off once they are lit..
JBirdAV8r From United States of America, joined Jun 2001, 4459 posts, RR: 22 Reply 23, posted (2 years 10 months 1 week 4 days 21 hours ago) and read 3688 times:
Quoting Chase (Reply 17): Not to be a jerk, but why were you taking video at liftoff, when electronic devices are not allowed to be used?
Not to be a jerk? What do you expect his response to be? What do you want it to be?
Some that were used for hot and high ops (e.g. Mexicana) had rocket assisted take-off as well
JATO is a technically correct term. And actually, JATO is by far the most commonly used description for...we'll call it takeoff assisted by alternative propulsion devices. Besides, "jet" can be defined as the "occurrence of a sudden discharge"--which fits the bill of a rocket, no?
Aeroflot001 From Argentina, joined Oct 2009, 384 posts, RR: 0 Reply 24, posted (2 years 10 months 1 week 4 days 21 hours ago) and read 3661 times:
Quoting Chase (Reply 17): Not to be a jerk, but why were you taking video at liftoff, when electronic devices are not allowed to be used?
Because American Airlines allowed a filming of a documentary on board one of its aircraft American Airlines a Week in the life during takeoff and its clearly shown.
Interesting to see that many others have experienced this, and reassuring as well
25 Goldenshield: My point was that those passengers sit right ABOVE the wheel well. For the 757, it's most likely because the mount for the nose wheel is right below
26 BY738: Shouldnt this be in the technical forum along with all the other 737 grinding noises questions?
27 aviatorcraig: On this side of the pond it is RATO Accepted usage here is Rocket Assisted Take Off for things that once lit cannot be turned off until they are done
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