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VIflyer
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Joined: Wed May 26, 1999 2:29 pm

Embraer E-jet questions.

Mon Aug 02, 2021 8:26 am

I work for a carrier that fairly recently acquired the EMB-175 and while writing on it I've noticed 2 things that over never got a answers for or multiple answers which sound plausible but can't find anything on the web to verify it.

The first is during climb and sometimes decent from around the mid teens (13,000 to round FL250 or so) there is a loud low frequency buzz that emanates from the 1R door. It stops usually around leveling off at the higher Flight levels (300 range) but picks up again during decent. It doesn't happen all the time even on the same ac on consecutive flights. It's just oddly only that door and none to the others. I've tried to localize the sound is not from the seals not the vent flap from what I can tell. Just curious if anyone knows the source of it and why it's so random?

The other question is that the 175 tend to be tail happy in even light chop and of the explanations I've got (aside from it being naturally that way) is my carrier sop is to load the forward cargo first and use the aft for any overfill hence the cg is forward enough to make it more "sensitive" with gusts. Or that there is an option for a second or different servo for the rudder that supposedly would lessen the amount of yaw and my carrier didn't opt for it. Is there even such an option? I've flown on other carriers 170,175, and 190s and haven't noticed as much tail happiness but that just could be luck of the draw so can't use that as a benchmark.

So if anyone knows any info on these (the loud 1R door and the supposed extra servo option) for the E-jet it would be appreciated.
 
slcguy
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Re: Embraer E-jet questions.

Mon Aug 02, 2021 12:02 pm

Are you a FA? As a regular passenger on E175s that normally sits in first. row one I have never heard any noise from L1 or R1 doors. If there is any noise from that door only a FA would notice since that is their work area. As for the tail wag, most wing mounted engine aircraft have some, tail mounted not so much.
 
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zeke
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Re: Embraer E-jet questions.

Mon Aug 02, 2021 12:19 pm

VIflyer wrote:
The first is during climb and sometimes decent from around the mid teens (13,000 to round FL250 or so) there is a loud low frequency buzz that emanates from the 1R door. It stops usually around leveling off at the higher Flight levels (300 range) but picks up again during decent. It doesn't happen all the time even on the same ac on consecutive flights. It's just oddly only that door and none to the others. I've tried to localize the sound is not from the seals not the vent flap from what I can tell. Just curious if anyone knows the source of it and why it's so random?


I would wager that is a small stone between the door seal and the fuselage.
 
Dalmd88
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Re: Embraer E-jet questions.

Mon Aug 02, 2021 1:37 pm

The buzz you hear is likely a seal issue. As Zeke said, possibly some debris in the door frame. The seal is good but there is something preventing it to seal at lower differential pressures. The place to look is the frame surface of the fuselage. Many aircraft have body filler in the seal area to make the surface as smooth as possible. If that is damaged it can cause the buzz.
 
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VIflyer
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Re: Embraer E-jet questions.

Mon Aug 02, 2021 2:25 pm

slcguy wrote:
Are you a FA? As a regular passenger on E175s that normally sits in first. row one I have never heard any noise from L1 or R1 doors. If there is any noise from that door only a FA would notice since that is their work area. As for the tail wag, most wing mounted engine aircraft have some, tail mounted not so much.


Yes I'm and FA and unless your right near the door you don't really hear it... When you stand in galley yeah but by the first row of seats you can't really hear it.

Dalmd88 wrote:
The buzz you hear is likely a seal issue. As Zeke said, possibly some debris in the door frame. The seal is good but there is something preventing it to seal at lower differential pressures. The place to look is the frame surface of the fuselage. Many aircraft have body filler in the seal area to make the surface as smooth as possible. If that is damaged it can cause the buzz.


I originally thought it was the seal, been doing this for over 20 years and have hear my fair share of leaky seals on various ac types (SF340, Emb-145, Crj-700, Atr that one's seals leaked like a sieve, Dash 8). But this one it doesn't seem to be localized to the seals, seems more central located. Also with my carrier the 1R door is pretty much never opened in normal situations, all catering is loaded via 2L door and obviously 1L is used for boarding. Aside for an emergency the only people that would open that door is maintenance and aside from scheduled check that's not very often, it's primarily an emergency exit door. Only thing I can come up with is if there is a rain guard above the door at certain aoa it creates a harmonic due to airflow in climb and decent? But it doesn't do it ever since flight. Plus not sure if there is a rain guard above that door, 1L/2L definitely do.
Also fyi it a nuisance than anything else, it been brought up to MX when we first got the planes and we're told that nothing was wrong with the door. But never heard why it was doing it.
 
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fr8mech
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Re: Embraer E-jet questions.

Mon Aug 02, 2021 3:13 pm

Not sure what the operating mechanism of the door look like (no experience on an EMB175), but we’ve had small leaks on our A300’s where the air is escaping through the seals in the operating mechanism.

Pressurization leaks are either real easy to find, or a bastard. Those small leaks that come and go are a pain. They are usually caused by seal that doesn’t seat correctly, either due to debris or age (seals get brittle as they age). Sometimes the seal seats, sometimes it doesn’t.
 
battlegroup62
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Re: Embraer E-jet questions.

Tue Aug 03, 2021 8:59 am

It may not be the door. Does your G1 galley have a sink, if it does dump some water in it when you hear the sound and see what happens. If it stops or changes pitch its the drain valve leaking due to lower cabin pressure. Try pulling the drain valve knob to reseat it.
As for the yaw, there is only a single rudder servo or none, but its for the autopilot. The yaw damper is separate from the autopilot.
 
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VIflyer
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Re: Embraer E-jet questions.

Tue Aug 03, 2021 11:05 pm

battlegroup62 wrote:
It may not be the door. Does your G1 galley have a sink, if it does dump some water in it when you hear the sound and see what happens. If it stops or changes pitch its the drain valve leaking due to lower cabin pressure. Try pulling the drain valve knob to reseat it.
As for the yaw, there is only a single rudder servo or none, but its for the autopilot. The yaw damper is separate from the autopilot.


We do have a sink in the forward galley, I'll try that out didn't think of that.
 
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Crosswind
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Re: Embraer E-jet questions.

Wed Aug 18, 2021 12:35 pm

VIflyer wrote:
I work for a carrier that fairly recently acquired the EMB-175 and while writing on it I've noticed 2 things that over never got a answers for or multiple answers which sound plausible but can't find anything on the web to verify it.

The first is during climb and sometimes decent from around the mid teens (13,000 to round FL250 or so) there is a loud low frequency buzz that emanates from the 1R door. It stops usually around leveling off at the higher Flight levels (300 range) but picks up again during decent. It doesn't happen all the time even on the same ac on consecutive flights. It's just oddly only that door and none to the others. I've tried to localize the sound is not from the seals not the vent flap from what I can tell. Just curious if anyone knows the source of it and why it's so random?


It’s not the door seal it’s self, it’s the external rubber weather seal over the top of the door. If it’s worn or damaged it can be a bit noisy at high speed.

Below FL100 the aircraft is usually below 250kt. Above this we accelerate to 270-300kt but then as the aircraft climbs the Indicated airspeed reduces, so it’s generally noisiest just above FL100 and the same in reverse during the descent.

The weather seal doesn’t serve any function with the pressurisation or sealing the door, except to aerodynamically cover the small gap at the top of the door frame when it is closed. It’s the grey horizontal strip across the top of the door in these photos.

Some aircraft are worse than others, it’s mainly a function of speed, so if it varies by sector I’d expect that it’s because of a different flight profile.

VIflyer wrote:
The other question is that the 175 tend to be tail happy in even light chop and of the explanations I've got (aside from it being naturally that way) is my carrier sop is to load the forward cargo first and use the aft for any overfill hence the cg is forward enough to make it more "sensitive" with gusts. Or that there is an option for a second or different servo for the rudder that supposedly would lessen the amount of yaw and my carrier didn't opt for it. Is there even such an option? I've flown on other carriers 170,175, and 190s and haven't noticed as much tail happiness but that just could be luck of the draw so can't use that as a benchmark.


My company loads aircraft with an aft C of G, it’s more fuel efficient and actually gives better take off performance. So with a full passenger load, most of the bags will be in the rear hold unless there are a lot of them.

There is an option for a second parallel rudder on the E-Jet. It’s part of the Cat 3 auto-land system, so if your aircraft are not auto-land capable then they won’t have it. The parallel rudder is only engaged at 1500ft on the approach when all the conditions for an auto land are met, and disengaged with the autopilots after touchdown or selection of a different autopilot vertical mode on a missed approach. So having or not having the parallel rudder would make no difference to how the aircraft handles turbulence inflight as it would never be active during any other phase of flight.

All aircraft tend to experience a rougher ride at the rear of the cabin, on the E-Jet it’s definitely more noticeable at the back according to the cabin crew on the 190/195 in a mixed fleet with the 170/175.

Hope that answered your questions.

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