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I have a question about the erj. I noticed that we recently were leaving Syracuse and as we were taxing, the engine began to run very high for a minute or two. Today, I asked a erj pilot about this. He said that this is what happens when you do a crossfeed start as opposed to using the apu. He said you need to use the crossfeed after deicing and not the APU.

My questions:
1. Why can't you use the APU after a deice?
2. How do you start up the first engine after deicing if you can't use APU?

Thanks

Your title is correct. It’s called a crossbleed start and not crossfeed.

The APU will ingest the fumes from the deice fluid and contaminate the cabin air.

Usually you leave the engine(s) running for deice so there’s no need to run the APU for engine start after deicing. If only one engine is running, you use the bleed air from the running engine to start the other engine(s). If there is a need to deice with the engines shutoff, then the APU left running during deice, and it is also used for engine start and the PACKs are turned off. After several minutes then packs are turned back on. Although deice crews are trained to avoid spraying the APU intake with deice fluid, sometimes if the APU ingests too much deice fluid, it flames out the APU, it shuts down and now you’re sitting on the deice pad dark and derelict. so deicing with only the APU running is not recommended.

Thanks!

The intake of the APU is a pretty bad design on the 145. It's very easy to get fluid into it since there's a big hole on the upper right side of the fuselage and as a result, deicing with it running is not advisable.

The reason that the running engine has to be run up is to get the minimum required bleed duct pressure to turn the other engine. Advance the thrust, and the high pressure bleed valve will open to increase the amount of air flow in the bleed line.

Guess they did not deice much in Brazil

COSPN wrote:

Guess they did not deice much in Brazil

The Canadian jets do it the same way.

The damage done to the APU impeller is quite impressive when hit by Deice fluid.

Little of subject, the ERJ maintenance manual also has a procedure to “jump start” one plane with another. Basically you install a clothes pin looking device into the flapper of ground bleed connection of the plane being used for air. Connect the two planes together by a bleed hose and “jump start” the other plane. Never seen it done, but interesting idea. Any other plane has tools to perform such a procedure?

A10WARTHOG wrote:

The damage done to the APU impeller is quite impressive when hit by Deice fluid.

Little of subject, the ERJ maintenance manual also has a procedure to “jump start” one plane with another. Basically you install a clothes pin looking device into the flapper of ground bleed connection of the plane being used for air. Connect the two planes together by a bleed hose and “jump start” the other plane. Never seen it done, but interesting idea. Any other plane has tools to perform such a procedure?

The C-130 can do a 'buddy' start from any large enough turbo-prop plane. Useful when the APU/GTC has gone U/S, or a starter won't work and you need 4 engines to depart.

Also, if the battery is flat and you need to get the duck out of fodge, you can pull two of them together so the crew doors line up and use the 28VCD form the winch outlet to plug into the other aircraft's DC receptacle to start the APU.

https://www.youtube.com/watch?v=RXU4fRNFS1U