De-Icing Question

[floatflyer99]

Wondering what your SOPs are for de-icing on the CRJ-200 where you work.

Do you leave the flaps up or do you already have them at Flaps 8 or 20 when getting de-iced.

The reason I'm asking is that the company where I work has had a lot of flap problems recently and my theory is that de-icing fluid is getting forced into the actuators when the a/c is being sprayed from behind with the flaps down.

Any comments?

Thanks.

 

[DoinTime]

Flaps in T/O setting at PCL. CRJ's have lots of flap problems year around. I don't think its related to de-iceing.

 

[SSDD]

Skywest replaced all the trouble actuators quite a while back and have had very few, if any flap twist problems since. We no longer have to visually inspect the takeoff flap position. We deice with the flaps up.

 

[SpoilerFault]

I don't think that the de-icing fluid will hurt the actuators. The actuators themselves are a mechanical ballscrew which are sealed and are pretty durable. Two other key components of the system which are exposed to the elements are the PDU (drive unit) which is in the wheel well and the BPSU(brake position and sensing unit) that is under a panel just inboard of the aileron. Both are sealed units that don't tend to fail that often. I've found that 90% of CRJ flap problems are from rigging issues. It's a very tempermental system and just as important as the acutal mechanical rigging is the "electrical rigging". The BPSU has an electrical value that that must be set to let the FECU know where the flaps are what to do next. In the process there are often overlooked steps that involve adjusting pots on the FECU itself to set certain electrical null points. It's not hard at all but some folks overlook these things and it may work but a value may be just on the fringes and cause a fault later on. Another thing just for info about indication problems with those flaps is the rigging of the flaps for proper operation by the FECU isn't related to the indication on EICAS for flap position. It is taken from a potentiometer on the inboard flaps. Sorry to write a book here but I've had to deal with flaps all the time when I worked on the CRJ.

 

[shamrock]

Flaps in T/O setting at PCL.

Ditto at ASA.

On a related note, do other 200 operators put the stab trim to up to 15 when deicing like we do at ASA? I'm reminded of that Alaska Airlines Mad Dog crash every time I do it.

 

[DoinTime]

Trim also gets set to T/O position at PCL.

 

[floatflyer99]

Thanks for the responses. It's interesting that skywest always uses flaps zero for de-icing and haven't had any recent problems. From what I can gather here, though, there's certainly a mix of procedures and results and the two may not be related at all.

Anyone else care to comment?

 

[Chest Rockwell]

"General Rules" of deicing: If the aircraft is being deiced for accumulation while the flaps were retracted, deicing with the flaps up make sense. If the aircraft is being treated for accumulation that occurred while the flaps were extended )inflight, on approach), they were likely not retracted after landing to prevent damage. If the aircraft is being treated to prevent accunulation of falling precipitation (holdover time), the aircraft should be treated with the flaps in the takeoff position.