Date: 201911
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: EMB ERJ 145 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Aircraft component: Hydraulic Main System
Component problem: Improperly Operated
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Human factors: Communication Breakdown
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Object
Detector: Person Flight Crew
When detected: Taxi
Result: Aircraft Aircraft Damaged; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Chart Or Publication; Procedure; Human Factors
Primary problem: Chart Or Publication

Narrative: Upon arriving into ZZZ; flight was assigned to arrive at [gate]; a tow-in gate. Upon parking the aircraft to complete the tow-in; the crew conducted the portions of the Shutdown Flow to be completed before tow-ins. At this time; disagreement arouse between Captain and First Officer over the electric hydraulic pump switch position; with First Officer wanting to turn both switches off and Captain desiring to turn off #1 and leave on #2 so as to comply with information presented in [manual]; which states pump #2 should be left on to allow for braking in event of disconnect from the tug. Captain was unable to find the information contained in the [manual] quickly; but First Officer was able to find AOM portion regarding tow-in which states both pumps are to be selected off. Crew proceeded using the #2 pump on method. When ground personnel attempted to turn aircraft to tow into [gate]; the tug became disconnected from the aircraft; resulting in damage to the tow bar and the aircraft. Crew used toe brakes to bring Aircraft X to a stop. Ground personnel retrieved new tow bar and contacted [Company] maintenance. Ground personnel asked crew to verify the proper hydraulic settings; at which point Captain repeated pre-tow in shutdown flow; except with #2 pump this time selected off. At this point; the ground crew was able to tow aircraft into [gate]. Aircraft suffered damage; the inbound flight arrived with a delay of 3 minutes; and the outbound flight required an aircraft swap and suffered further delay.On the issue of the disagreement that existed due to positions of Hydraulic Pump switches; when in doubt of procedures; flight crews should defer to the AOM/GOM on which procedures to follow. Additionally; if a conflict such as this exists between crew members; it may be helpful to follow the more conservative opinion. On the issue of the hydraulic pump selection itself; some confusing language exists in the manuals. [Manual] 19-08 states to leave #2 Hydraulic Pump on to allow use of toe brakes. AOM XXXVI-5.2.1 (Section 5 Page 3) 'PIC-Shutdown Flow' states to turn only #1 pump off; and does not state anything about #2. AOM XXXVI-5.2.2 (Section 5 Page 4) 'SIC - Shutdown Flow' states for the FO to verify both Electric pump knobs off; contradicting [Manual] 19-08 directly; and partially contradicting the previous section of the AOM. It may be beneficial to remove these contradictions from the manual. On the issue of aircraft damage during tow-in and tow-in issues in general; as it stands now; the tow-in procedure involves a flow that is; midway through; interrupted for a few minutes so as to complete the tow in procedure; with said flow not backed up by a checklist until parking and completing the shut-down check. This is somewhat of a departure from the normal philosophy regarding checklists and flows; with flows usually immediately being back up by a checklist; and with flow/checklist interruptions of significant length demanding a restart of the entire procedure. This issue manifests itself strongly with tow-in procedures; as the gate tow procedure is not something done by crews on a regular basis; so this gap in time between the beginning of the flow; the completion of the flow; and the re-affirming checklist proves to add difficulty. To alleviate this; it may be beneficial to modify the 'Gate Tow' procedure to include an actual checklist to verify items such as the engine shut down; disconnecting of steering; hydraulic pump positions; etc. that are normally part of the shutdown flow but important to safety of the tow and that are initiated at the beginning of the gate tow procedure but not backed up with a checklist until the aircraft is parked. By instituting such a 'Gate Tow' checklist; it would help to alleviate both the irregularity with which gate tows are performed and alleviate the large gap in time existing between the initiation and completion of the flow; similar in nature to the Pre Anti-Ice and Runway Change checklist.It may also be beneficial for crew members to leave their finger on the 'Steering Disconnect' trigger switch throughout the duration of the town.


Second narrative: We were taxi instruction for the tow in [gate] at ZZZ. As we pulled close to the gate for the tow in; we performed our shut down flow. As First Officer; flow requires me to turn off both hydraulic pumps off. Myself and Captain had a disagreement upon only turning off hydraulic pump one and leaving hydraulic pump two on. I reviewed the AOM and showed the Captain about turning both pumps off. Eventually we decided upon leaving hydraulic pump two on. As the tug showed up and started pulling us into the gate; the tug suddenly started to swing all the right breaking the tow bar. We didn't know what went wrong; and waited for Maintenance to show up and bought a new tow bar to complete the tow in process to the gate. Once at the gate; as per my post flight walk around I noticed the number two engine was still running. I got back to the Captain and mentioned about the number two engine still running. Although Captain had turned off both start/stop selector switch to off position; Captain then noticed the number two thrust lever was slightly above idle which had failed to shut down number two engine when the start/stop selectors were selected to off position.


Synopsis: ERJ flight crew reported that failure to correctly configure the aircraft for towing resulted in damage.