DocLightning wrote:During a long taxi, frequent use of the brakes can cause them to get a little on the warm side. Not so warm that they are a danger if a takeoff needs to be aborted, but warm enough that you wouldn't want to pull them into the gear bay without cooling them off first. So they just let them dangle for a few minutes, they cool down, and then they retract.
Also, depending on how short the turn was, they can also be hot from landing.
zeke wrote:A brake inop.
Normally after liftoff when gear up is selected up brakes are applied to stop the main wheels from rotating. The rotating wheel assemblies are like gyros, if the gear is retracted with them rotating it causes torque and vibration tp be ransmitted to the Airframe.
Leaving them down for 2 minutes allows the wheels with the inop brakes to run down to reduce the toque and vibration when retracted. If there was an engine failure they would retract the gear regardless.
To understand this more look at the spinning bicycles wheel torque on the internet, bound to be some videos.
Curiously, I was struck by the time of 2 minutes, which is the same time in the C-5 when the retract brake system was inoperative. Funny, that.
Military Aircraft Every type from fighters to helicopters from air forces around the globe
Classic Airliners Props and jets from the good old days
Flight Decks Views from inside the cockpit
Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior
Cargo Aircraft Pictures of great freighter aircraft
Government Aircraft Aircraft flying government officials
Helicopters Our large helicopter section. Both military and civil versions
Blimps / Airships Everything from the Goodyear blimp to the Zeppelin
Night Photos Beautiful shots taken while the sun is below the horizon
Accidents Accident, incident and crash related photos
Air to Air Photos taken by airborne photographers of airborne aircraft
Special Paint Schemes Aircraft painted in beautiful and original liveries
Airport Overviews Airport overviews from the air or ground
Tails and Winglets Tail and Winglet closeups with beautiful airline logos