View Full Version : Anti ice inop
Instant Hooligan
16th May 2010, 16:18
Can somebody please post the wording from the 777 MEL for inop anti ice valve. Closed postion. In particular the operational requirements for flight in known/forecast icing conditions or flight at night.
Many thanks
IH
Mad (Flt) Scientist
16th May 2010, 17:25
FAA MMEL Rev.#16, 2009-09-12m from TCCA website here (http://wwwapps.tc.gc.ca/Saf-Sec-Sur/2/MEL-LEM/m_e_l_s.aspx?lang=eng)
30 ICE AND RAIN PROTECTION
-11-1 Wing Anti-Ice Systems (C)
2 installed
0 required for dispatch
(M) May be inoperative provided:
a) Associated valve is locked closed,
b) Wing anti-ice control switch remains OFF, and
c) Airplane is not operated in known or forecast icing conditions.
reformatted from the somewhat tortuous MMEL format.
There's no MMEL item specifically for the valve, it's just the systems as a whole.
Instant Hooligan
16th May 2010, 19:32
Thankyou.:ok:
ballyboley
16th May 2010, 22:36
Can anyone tell me why the aircraft is no longer CAT3 if MEL dispatched with a cowl ice valve stuck OPEN i.e. anti ice stuck on?
Thanks
Bolty McBolt
17th May 2010, 01:48
My I ask which anti ice valve? Engine or wing?
Other people may have different experiences, but for mine I have never been able to get a tech crew agree to dispatch with the anti ice inop in the closed position and to be honest I have only ever offered the MEL to see the reaction. ( I have often wondered why we have the MEL available to us as I am yet to see a practical use)
The reason, weather being the fickle thing that it is, no one is willing to guarantee the weather conditions at the destination to risk dispatch into icing conditions without protection..
Just to clarify, I have no experience on the 777 , only many other Boeings and Airbii
Mad (Flt) Scientist
17th May 2010, 02:38
Can anyone tell me why the aircraft is no longer CAT3 if MEL dispatched with a cowl ice valve stuck OPEN i.e. anti ice stuck on?
Thanks
Well, the MMEL on the TCCA website doesn't even seem to recognise that as a possibility.
But if I had to guess, I might hazard that the loss of go-around thrust due to a possibly stuck-open AI valve might throw into doubt the minimum GA height data, and so scupper the CAT 3 certification. But that is, as i say, a guess.
ballyboley
17th May 2010, 11:47
Sorry, didnt RTFQ! I was referring to 737 where I had an engine cowl ice stuck open, but they downgraded us to CAT1 for some reason. I'm not sure the loss of GA thrust would be the reason as surely you would have anti-ice on during most CAT3 and therefore subsequent go around's anyway?
Mad (Flt) Scientist
17th May 2010, 16:45
Sorry, didnt RTFQ! I was referring to 737 where I had an engine cowl ice stuck open, but they downgraded us to CAT1 for some reason. I'm not sure the loss of GA thrust would be the reason as surely you would have anti-ice on during most CAT3 and therefore subsequent go around's anyway?
Well, the FAA MMEL on the TCCA website doesn't appear to have that CAT1 downgrade as a specific item (see pages 142 to 146 depending on the specific model (http://wwwapps.tc.gc.ca/saf-sec-sur/2/MEL-LEM/tcbbs/mmels/B_737.pdf)).
There are significant thrust penalties though, and a limitation on operation in icing. Therefore, I might suggest:
If you are operating a CATIII approach IN ICING, you already can't do it per the icing limitations.
If you are operating and NOT IN ICING, the thrust deficit may mean that any weight restrictions applicable to CATIII have to be recalculated.
If, as you suggest, the vast majority of CATIII is in icing anyway, the operator may have elected to impose the CATI degrade as a more conservative version of the MMEL (The MEL can always be more conservative, but never less, than the MMEL)
Instant Hooligan
17th May 2010, 17:32
Bolty,
Engine anti ice.
777 with trent would be normallly dispatched with valve locked open , with a fuel burn penalty.
de facto
18th May 2010, 02:45
quote Airplane is not operated in known or forecast icing conditions.unquote
Ballyboly,
The forecast icing condition is AS(if not more) important as operated in known icing.Therefore avoiding to arrive for a cat 3 and as you said having to go around.
It would have to be a real nice high pressure,clear skys day from my place of departure to my destination to accept inop engine anti ice.(737)
For the rest maybe one should read the definition of Icing conditions.....:eek: