Narrative:

The captain and I shot a CAT ii approach due to low ceilings and visibility. There were reports of freezing fog at the field during the time of our arrival as well. After landing; we taxied into the gate with no adverse indications. I then completed my post-flight walk around and noticed some icing on both of the engine inlets. I reported my findings to the captain soon thereafter. We discussed what to do as he searched through the 'operations guide' on his ipad. It had a note saying that this is normal while flying in icing conditions but didn't have any specific instructions or limitations on how to proceed. Due to the meteorological conditions present on our arrival and also expected on the departure; we planned to push back and taxi to the pad for deicing prior to takeoff. While pushing back; I completed a normal start on engine #1. While starting engine #2; we started feeling increasing vibrations as it spooled up. I immediately focused my attention on our vibration indicator and pointed it out to the captain that it was rising. At around 4.0; the indicator changed to amber as the vibrations got more substantial so he quickly commanded me to stop the engine start. We then ran the QRH for an engine abnormal start. We were not immediately positive what the cause of this abnormality was so we attempted a dry motor as instructed by the QRH. We experienced the same vibrations on the second start so I aborted again as advised by the captain. I then made a comment that the icing is a probable cause of this and he agreed. We contacted maintenance/operations and proceeded with a gate return to get the ice removed. Maintenance was well aware of this issue with icing in the engines so they knew to go ahead and deice our engines at the gate then run them up to make sure they were functioning properly after the ice was removed. We then boarded the plane again; pushed back; started the engines normally; and deiced the rest of the plane at the pad. The flight proceeded normally from there on out and was completed without disruption. Overall; we had no intention to depart with ice on the plane or operate in an unsafe manner. Rather; we discussed the issue at length after I discovered the ice on the engines and tried to cover all the bases as best we could before leaving the gate. In retrospect; the issue in our decision making came in the fact that we would have to run the engines to taxi out to the pad and that deicing protocol negates spraying the engines anyway. We did not know at the time that maintenance was capable of removing the ice at the gate prior to pushback or else we would have done so. We are also now aware of more lengthy recommendations regarding icing protocol found in a difference section of the operations manual for future guidance.

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Original NASA ASRS Text

Title: EMB-175 First Officer reported discontinuing an engine start during pushback because of excessive engine vibration later traced to ice in the engine.

Narrative: The Captain and I shot a CAT II approach due to low ceilings and visibility. There were reports of freezing fog at the field during the time of our arrival as well. After landing; we taxied into the gate with no adverse indications. I then completed my post-flight walk around and noticed some icing on both of the engine inlets. I reported my findings to the Captain soon thereafter. We discussed what to do as he searched through the 'Operations Guide' on his iPad. It had a note saying that this is normal while flying in icing conditions but didn't have any specific instructions or limitations on how to proceed. Due to the meteorological conditions present on our arrival and also expected on the departure; we planned to push back and taxi to the pad for deicing prior to takeoff. While pushing back; I completed a normal start on engine #1. While starting engine #2; we started feeling increasing vibrations as it spooled up. I immediately focused my attention on our vibration indicator and pointed it out to the Captain that it was rising. At around 4.0; the indicator changed to amber as the vibrations got more substantial so he quickly commanded me to stop the engine start. We then ran the QRH for an Engine Abnormal Start. We were not immediately positive what the cause of this abnormality was so we attempted a dry motor as instructed by the QRH. We experienced the same vibrations on the second start so I aborted again as advised by the Captain. I then made a comment that the icing is a probable cause of this and he agreed. We contacted maintenance/operations and proceeded with a gate return to get the ice removed. Maintenance was well aware of this issue with icing in the engines so they knew to go ahead and deice our engines at the gate then run them up to make sure they were functioning properly after the ice was removed. We then boarded the plane again; pushed back; started the engines normally; and deiced the rest of the plane at the pad. The flight proceeded normally from there on out and was completed without disruption. Overall; we had no intention to depart with ice on the plane or operate in an unsafe manner. Rather; we discussed the issue at length after I discovered the ice on the engines and tried to cover all the bases as best we could before leaving the gate. In retrospect; the issue in our decision making came in the fact that we would have to run the engines to taxi out to the pad and that deicing protocol negates spraying the engines anyway. We did not know at the time that maintenance was capable of removing the ice at the gate prior to pushback or else we would have done so. We are also now aware of more lengthy recommendations regarding icing protocol found in a difference section of the Operations Manual for future guidance.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.