"They look like oversized electrical fusesMe thinks there fuses alright, but not for the Electrical Sytem ;-)RegardsPaul Gollnick :-coolTechnical Operations/Customer Operational SupportPrecision Manuals Development Groupwww.precisionmanuals.com

Ian,From what I can see on that picture the rubber seal is not flush with the fuselage. It's rather mounted 2 inches inside of the edge? So means you still have some cavities between the wheel and the fuselage?Cheers,

"Me thinks they're fuses alright, but not for the Electrical System"Thanks, Paul.I couldn't find a picture of them in Chapter 29 (Hydraulics), but found them in 78 (Exhaust)."Volumetric hydraulic fuses in the thrust reverser (T/R) control system... close and stop hydraulic fluid flow to prevent a complete loss of system hydraulic fluid if a leak occurs"."The volumetric fuse lets approximately 175 cubic inches of fluid flow through before it closes. The fuse opens when the hydraulic presssure on the two sides of the fuse are approximately the same".How odd it is that the shape is the same as an electrical fuse... I can't wait to see the hydraulic equivalent of a resistor :-)Cheers.Ian.

I was hoping you wouldn't notice that, Mats :-lol

:-lolSorry Ian! Must be that nosy engineer in me... ;-)Cheers,

It has been sometime since I was involved with the testing of the 737-200's, but as I recall, at that time the seals were inflateable. When the gear was retracted the seal inflated to form a tight seal with the tire. During the extension cycle it would deflate just prior to the gear extending. I don't know what system the NG's have but I would be surprised if it has changed except for maybe an up date of the seal.Tom

Tom,I know all the Southwest 200's have the same basic blade seal in the wheelwell as the NG types. The seals do not deflate or inflate.Regards,Chris

paNMAN"Also factor in, is the oleo going to have the EXACT same extension everytime the wheel is retracted, to add a mechanism that ensures that this is the case is going to add to weight and complexity of the landing gear."The oleo will have the same exact extension everytime. Gravity and the fact that the strut is filled with 1000 to 5000 psi of nitrogen depending on the weight of the aircraft at the time of servicing the nitrogen. This will drive the oleo to full extension everytime."What happens if for some reason the tyre where to explode, this would mean it would damage the part of the airframe that it was in contact with: 170 psi is a lot of force to contend with."The gear system has what is called a frangible fitting. Here is what it does.-a section of tread partially seperates from a main landing gear tire-the landing gear starts to retract-the gear retract brake has a fault and does not stop the wheel before it moves into the wheel well-the section of tread removes the lever from one or both frangible fittings-the frangible fitting opens-up pressure is removed from the main landing gear actuator-the main landing gear that has the damageed tire stops retraction and moves towards the extended position.-the fuse in the up pressure line closes, which stops the loss of fluid from the hydraulic system.So the blown tire will never make it all the way into the wheel well preventing a lot of damage. Of couse the crew will then have to deal with the gear unsafe light they will get now!!!Hope this helpsChris