Bio15 From Colombia, joined Mar 2001, 1089 posts, RR: 7 Posted (8 years 8 months 3 weeks 5 days 17 hours ago) and read 4692 times:
I noticed that the ERJ 145 has a sort of carcass over one of the two main tires on each assembly. Judging from the pictures, it seems to rotate over the wheel depending on whether the aircraft is airborne or not. I was thinking that it is some sort of FOD protector for the tires, is this assumption correct? If so, why does it rotate?
Troubleshooter From Germany, joined Feb 2005, 423 posts, RR: 5 Reply 1, posted (8 years 8 months 3 weeks 5 days 16 hours ago) and read 4508 times:
Just have a look here: http://www.airliners.net/discussions/tech_ops/read.main/113566/
You are talking about the auxiliary gear door. As it is fixed to the landing gear leg, it is not moving. When the aircraft is airborne, the strut extends and the relative position of the wheels to that door has changed. That´s why you think it rotates. Look at the link above. There you´ll find it.
TWAMD-80 From United States of America, joined Oct 2001, 1006 posts, RR: 4 Reply 2, posted (8 years 8 months 3 weeks 5 days 16 hours ago) and read 4498 times:
Interesting, I don't think I have seen that before. To me it looks like part of the landing gear cover. Also, the ERJ-145 series uses a trailing-link landing gear, which would help explain the change of position seen when the gear is compressed and uncompressed. When I first saw the topic of this post, I though the ERJ ran over some roadkill .
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Bio15 From Colombia, joined Mar 2001, 1089 posts, RR: 7 Reply 4, posted (8 years 8 months 3 weeks 5 days 15 hours ago) and read 4397 times:
Hi Troubleshooter, thanks for your response. Now I know this is an auxiliary gear door, not an FOD protection element as I thought . I saw your response on the other thread, it's clear how this auxiliary door goes flush with the fuselage to complete the missing area of the main gear door, which is the flat rectangular door. It's necessary to fit the part that has the curvature of the belly border.
However, I still see that the angle position of the auxiliary gear door changes when the aircraft is on the ground. Here are some pictures that illustrate this clearly:
Ground position: The upper part of the door (the small rectangular part perpendicular to the ground) is 'facing down'. In other words, the left border is not straight, but instead it is angled to the left from the vertical position.
Based on the images, I would say that the auxiliary gear door is moving together with the tires, and that it rotates forward when the strut compresses. I am just basing myself on the pictures, not playing smartass! I hope I was clear on my typing
Troubleshooter From Germany, joined Feb 2005, 423 posts, RR: 5 Reply 7, posted (8 years 8 months 3 weeks 5 days 1 hour ago) and read 4217 times:
Quoting Bio15 (Reply 4): However, I still see that the angle position of the auxiliary gear door changes when the aircraft is on the ground
none of the doors changes it´s position as both are fixed to the main landing gear leg. The main door is hinged to rotate during gear retraction.
The wheels change their relative position to the auxiliary door as a result of a different position of the main gear trailing arm due to an extended strut. The auxiliary gear door is completely fixed to the gear leg and doesn´t move with strut extension.
Bio15 From Colombia, joined Mar 2001, 1089 posts, RR: 7 Reply 8, posted (8 years 8 months 3 weeks 4 days 19 hours ago) and read 4121 times:
Quoting Troubleshooter (Reply 7): none of the doors changes it´s position as both are fixed to the main landing gear leg. The main door is hinged to rotate during gear retraction.
Hi Troubleshooter. I see that the auxiliary gear door is fixed to the lower gear leg, but not the upper, thus it may seem to rotate. The gear leg does change it's angular position when it's on the ground because it flexes to work as suspension for the aircraft, and moves along with the auxiliary gear door, that's why I say it "rotates". I elaborated a diagram to show what I am saying.
I'm feeling bad because I may sound as trying to contradict you, but it is not at all that way. I saw nearly 200 photos in the database, and they all show this behavior I put on the diagram. I'm thinking we're both probably saying the same thing, but I'm not understanding your way of putting it into words, or I've gone competely stupid & blind this time! Please excuse me in any case for being a pain in the ass.
Meister808 From United States of America, joined Jan 2000, 973 posts, RR: 1 Reply 9, posted (8 years 8 months 3 weeks 3 days 12 hours ago) and read 3977 times:
I'm with Alfredo on this one, unless, like he, I have gone completely blind and stupid. That door rotates with the rotation of the trailing-linkage suspension.
Interesting that they even put this part on, though, because it has been demonstrated on many, many airplanes(the B737 comes to mind instantly) that there really isn't a need to have a cover over this part of the gear while the airplane is in flight. It seems like Embraer is overly complicating the issue for a minimal gain.
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Troubleshooter From Germany, joined Feb 2005, 423 posts, RR: 5 Reply 10, posted (8 years 8 months 3 weeks 3 days 9 hours ago) and read 3951 times:
Quoting Bio15 (Reply 8): I see that the auxiliary gear door is fixed to the lower gear leg, but not the upper
I had a brief look at the AMM this morning. The auxiliary gear door is attached to the trailing arm axle. So it moves during strut extension with the trailing arm. I was a bit wrong on that as I was thinking it is fixed to the gear leg.
Quoting Bio15 (Reply 8): I'm feeling bad because I may sound as trying to contradict you, but it is not at all that way.
You don´t have to feel bad, because you are right. I didn´t want to attack you, so I have to apologize if you thought that.
I hope the question is answered now. Thanks for this good discussion!