SVA and QTR A333 - Brake Fans? [Archive]

shorthauler72

30th Apr 2018, 11:57

I have a good view on planes taking off from HSSS / KRT where we are north of 40 °C now. I just for a second time saw a SVA A333 taking off and leaving their gear extended for quite some time (until they disappear out of sight). This must be to cool down the brakes. The taxiways in Khartoum require you to backtrack on the runway - possibly requiring quite some braking action while doing the 180 before take-off. But the Qatar A333 don't do that. Could it be that the QTR A333 are equipped with brake fans whilst the SVA are not?

Best,
shorthauler

Romasik

30th Apr 2018, 14:56

I have a good view on planes taking off from HSSS / KRT where we are north of 40 °C now. I just for a second time saw a SVA A333 taking off and leaving their gear extended for quite some time (until they disappear out of sight). This must be to cool down the brakes. The taxiways in Khartoum require you to backtrack on the runway - possibly requiring quite some braking action while doing the 180 before take-off. But the Qatar A333 don't do that. Could it be that the QTR A333 are equipped with brake fans whilst the SVA are not?

Best,
shorthauler
It seems QTR is equipped with brake pads and sufficient maintenance manpower. SVA is equipped with MEL and TTH (Transfer To Hold). These gear down takeoffs are because of one or two brakes deactivated (for simple brake wear reason) to stop wheels spinning before retraction.

shorthauler72

30th Apr 2018, 15:45

I hope you are not pulling my main gear ... er ... leg. Amazing - if I have ever to explain the gyroscopic effect again, I will pull out this example. Thanks for the clarification!

Romasik

30th Apr 2018, 16:11

I hope you are not pulling my main gear ... er ... leg. Amazing - if I have ever to explain the gyroscopic effect again, I will pull out this example. Thanks for the clarification!

Absolutely serious. Big widebodies main gear wheels are big gyros. In case of some brakes inop they are kept down for two minutes before retraction. Easy to forget, by the way. It’s in our blood: Positive Climb - Gear UP!)

shorthauler72

30th Apr 2018, 19:19

Similar thread:

https://www.pprune.org/questions/605643-two-questions-one-antonov-24-26-one-ilyushin-il-76-a.html

Jetjock330

1st May 2018, 14:32

If a brake is deactivated under MEL, extra fuel is carried, (little bit) and the gear is left down 2 minutes, in order to allow the wheel to spool down. Large gyroscopic forces at play when trying to move it up. In the event of an engine failure, the gear is lifted right away if need it be.

shorthauler72

1st May 2018, 19:50

So what is the penalty for operating under MEL, then? Reduced MTOW, so a rejected TO can still be performed safely?