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B737NG Techs: Smyd Issue  
User currently offlineCdfmxtech From United States of America, joined Jul 2000, 1341 posts, RR: 26
Posted (11 years 8 months 1 week 6 hours ago) and read 4019 times:

What does your company MEL specify No.1 Stall Warning system inoperative?

The SMYD 1 controls both Stall Warning AND Yaw Damper functions. Does it tell u tell pull any circuit breakers for the SMYD??

.

6 replies: All unread, jump to last
 
User currently offlineAvioniker From United States of America, joined Dec 2001, 1109 posts, RR: 11
Reply 1, posted (11 years 8 months 1 week 5 hours ago) and read 4003 times:

Our MMEL states:
One system may be inoperative provided:
(M)
-Associated auto slat system is placarded inoperative in accordance with MEL item 27-7 and
-Associated pitch limit indicator (PLI) is placarded inoperative in accordance with MEL item 34-34, and
-Associated maximum speed and maximum maneuvering speed indications are placarded inoperative in accordance with MEL item 34-2d, and
-Associated mach trim system is placarded inoperative in accordance with MEL item 22-6, and
If system No. 1 is inoperative, yaw damp is placarded inoperative in accordance with MEL item 22-4, and
-Normal operation of the ramaining system is verified per MPM 27-08, prior to first flight with this condition, and
-This verification and Maintenance Logbook entry signifying accomplishment are repeated prior to each departure until restoration is made, and
-An appropriate MEL placard is used.

The MEL/CDL MPM states:
Placard Associated Stall Warning Test Switch - NO.1 or NO.2 STALL WARNING SYSTEM INOP.
A. Stall Warning System No. 1 may be deactivated by opening and collaring the P18-2 Panel circuit breakers labeled; STICK SHAKER LEFT. If the captains PLI, lower amber band symbols are displaying erroneous data, open/collar P18-2 Panel circuit breakers labeled: SMYDC-1 SNSR EXC AC.

NOTE: Opening the SMYDC-1/2 SNSR EXC AC circuit breakers will deactivate: (1) the associated Auto Slat System (See MEL Item 27-7), (2) the associated PLI see MEL Item 34-34), (3) the associated upper/lower bands (see MEL Item 34-2), (4) the associated Mach Trim System (see MEL Item 22-6), and (5) in addition, if the SMYDC-1 SNSR EXC AC circuit breaker is opened, the Yaw Damper (MEL 22-4) will be activated.
Prior to each departure, verify the operative Stall Warning System is operating normally by pressing the associated Stall Warning Test Switch and checking that the appropriate stick shaker operates. With one Stall Warning System operating normally, the airplane may be dispatched.



One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
User currently offlineCdfmxtech From United States of America, joined Jul 2000, 1341 posts, RR: 26
Reply 2, posted (11 years 8 months 6 days 18 hours ago) and read 3905 times:

Did you mean Yaw Damper will be deactivated?? Because that is what I am looking for.

You wrote: if the SMYDC-1 SNSR EXC AC circuit breaker is opened, the Yaw Damper (MEL 22-4) will be activated

Whats weird is our MEL is really not clear at all regarding the relationship between the Stall Warning and Yaw Damper functions in the SMYDs. There are a couple of breakers that supply power to the SMYD. The MEL is not really clear on which breakers should be pulled, but states that some cbs may need to be pulled. Not in those words, but don't feel like typing everything it says. Just want to know if other airlines mention the possible deactivation of the Yaw Damper system if breakers are pulled. Thanx.


User currently offlineAvioniker From United States of America, joined Dec 2001, 1109 posts, RR: 11
Reply 3, posted (11 years 8 months 6 days 7 hours ago) and read 3887 times:

If you want to give me a call, send me an email at avioniker@aol.com
It gets a little complicated



One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
User currently offlineAvioniker From United States of America, joined Dec 2001, 1109 posts, RR: 11
Reply 4, posted (11 years 8 months 6 days 7 hours ago) and read 3868 times:

The very short answer is: That's correct but it isn't that big a deal...


One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
User currently offlineDc10hound From United States of America, joined Dec 2000, 463 posts, RR: 5
Reply 5, posted (11 years 8 months 5 days 22 hours ago) and read 3851 times:

Whats weird is our MEL is really not clear at all regarding the relationship between the Stall Warning and Yaw Damper functions in the SMYDs. There are a couple of breakers that supply power to the SMYD. The MEL is not really clear on which breakers should be pulled, but states that some cbs may need to be pulled. Not in those words, but don't feel like typing everything it says. Just want to know if other airlines mention the possible deactivation of the Yaw Damper system if breakers are pulled. Thanx.

In addition to the MEL, AAL uses a document called the Maintenance Procedures Manual (MPM). The MPM tells the technician what, if any procedures that are required to placard a system inoperative.

In the example above, I think Avioniker meant to write:

(5) in addition, if the SMYDC-1 SNSR EXC AC circuit breaker is opened, the Yaw Damper (MEL 22-4) will be deactivated.

Avioniker: Your profile says your location is MCI. Does this mean you are employed by AA? (The MPM procedure you posted is verbatim of what I found)





"Eagles soar. But weasels never get sucked into jet intakes.."
User currently offlineAvioniker From United States of America, joined Dec 2001, 1109 posts, RR: 11
Reply 6, posted (11 years 8 months 5 days 5 hours ago) and read 3834 times:

The Yaw Damper System is deactivated thus activating the MEL.
Every airline has to have maintenance procedures to impliment the MEL. Some have a separate book like AA but more have the procedures at the end of the MEL/CDL. Actually most of the MEL/CDL items and procedures are derived or copied directly from the Master MEL which is originally published by the manufacturer and then one airline or operator is charged with maintaining it and keeping it up to date and relevant to the numerours service bulletins and AD's that are issued against the plane. The master MEL/CDL is accessable on the internet if you know who maintains it and where to find it and have a password.
I believe Northwest has the 747 (I know they used to) but I don't know who has the 737. Someone told me it was United or Delta but I really don't have any idea. We only have 78 of the planes so it isn't us.
Without dragging the name of an airline into it I'm an Avionics and Systems Maintenance Instructor on the 37's and I used to do the 717's among other things (and whatever else the boss thinks is important this month) .
The company takes a dim view of having their name dragged into public forums. That's why I don't mention it. Don't need to GIVE them a reason to reduce the payroll now do we?



One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
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