737NG alternate flaps
 

Hi all,
I'd be interested to hear your interpretations of the NG alternate flaps duty cycle limitation.
I understand that,
a/with a loss of system B, Boeing recommends landing with flaps 15, which should take about 2 minutes.
b/the maintenance manual limits the cycle to 4 minutes (then 25 mins off) - but with no air loads.
c/Boeing also recommends that anytime the alt flaps position switch is released, a minimum of 15 seconds should pass until any further selections.

But, for the life of me, I can't fathom the table into a logical, clear limitation, if I want to use flap 30, for instance.
OK, so I stop at 15 for 5 minutes, then what, unless I go directly to 30, I need to stop for 25 minutes at some intermediate setting, I don't think so!
Thats the way it seems to read, or can be!

NB: The 15 seconds min stopped thingy is to allow the DC motor to stop spinning down following the release of the clutch when the position switch was released, allowing a less violent re-engagement of the two.

ideas!!

Cheers, FD :bored:

- well, unless it was a dire emergency, ie MUST have Flap 30 or die, why would you select more than 15 on the alternate? You would be badly placed on an engine-inop on finals or during g/a.

If you really MUST have it, to hell with the limitations!??

let's say I'm a normal jon doe average pilot,and I don't have acces or interest in any maintenance manual.How would I know of or why should I care about the 25 min off restriction? It's not in our FCOM's or QRH? Then ....
Anyway,you wouldn't use flap 30 for go-around reasons,and maybe ,due to assymetry risk also..
Badly need flap 30? well,maybe burn some more fuel,and use flap 15 or use other airport,or use flap 15 with max brake and reverse thrust...

Right! ... nothing!
AMM restrictions are related to the maintenance and the temperature on ground.
The time limits are primarily to extend livetime of parts

(Edit Typo)

See,spot on ,Ifixplanes....
This is the risk when you knew and learn too much..:D ..you'll start mixing things soon...
Brgds